LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
* [PATCH v4 00/34] KVM: arm64: A stage 2 for the host
@ 2021-03-10 17:57 Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 01/34] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
                   ` (33 more replies)
  0 siblings, 34 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Hi all,

This is the v4 of the series previously posted here:

  https://lore.kernel.org/lkml/20210302150002.3685113-1-qperret@google.com/

This basically allows us to wrap the host with a stage 2 when running in
nVHE, hence paving the way for protecting guest memory from the host in
the future (among other use-cases). For more details about the
motivation and the design angle taken here, I would recommend to have a
look at the cover letter of v1, and/or to watch these presentations at
LPC [1] and KVM forum 2020 [2].

Changes since v3:

 - removed the PROT_NONE concept in favor of tracking page owners in
   the topmost bits of invalid mappings;

 - split up the *idmap_greedy() function in two parts, and refactored the
   reduce_range part to simplify it, and make the loop bound more obvious;

 - fixed two bugs that could lead to -ERANGE in the host memory abort
   path;

 - added the set_sctlr_el2 macro based on its el1 counterpart;

 - cosmetic changes, added comments, and small improvements all over;

 - rebased on v5.12-rc2.

Big thanks to Will for the review.

This series depends on Will's vCPU context fix ([3]) and Marc's PMU
fixes ([4]). And here's a branch with all the goodies applied:

  https://android-kvm.googlesource.com/linux qperret/host-stage2-v4

Thanks,
Quentin

[1] https://youtu.be/54q6RzS9BpQ?t=10859
[2] https://youtu.be/wY-u6n75iXc
[3] https://lore.kernel.org/kvmarm/20210226181211.14542-1-will@kernel.org/
[4] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/pmu-undef-NV

Quentin Perret (31):
  KVM: arm64: Initialize kvm_nvhe_init_params early
  KVM: arm64: Avoid free_page() in page-table allocator
  KVM: arm64: Factor memory allocation out of pgtable.c
  KVM: arm64: Introduce a BSS section for use at Hyp
  KVM: arm64: Make kvm_call_hyp() a function call at Hyp
  KVM: arm64: Allow using kvm_nvhe_sym() in hyp code
  KVM: arm64: Introduce an early Hyp page allocator
  KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp
  KVM: arm64: Introduce a Hyp buddy page allocator
  KVM: arm64: Enable access to sanitized CPU features at EL2
  KVM: arm64: Factor out vector address calculation
  arm64: asm: Provide set_sctlr_el2 macro
  KVM: arm64: Prepare the creation of s1 mappings at EL2
  KVM: arm64: Elevate hypervisor mappings creation at EL2
  KVM: arm64: Use kvm_arch for stage 2 pgtable
  KVM: arm64: Use kvm_arch in kvm_s2_mmu
  KVM: arm64: Set host stage 2 using kvm_nvhe_init_params
  KVM: arm64: Refactor kvm_arm_setup_stage2()
  KVM: arm64: Refactor __load_guest_stage2()
  KVM: arm64: Refactor __populate_fault_info()
  KVM: arm64: Make memcache anonymous in pgtable allocator
  KVM: arm64: Reserve memory for host stage 2
  KVM: arm64: Sort the hypervisor memblocks
  KVM: arm64: Always zero invalid PTEs
  KVM: arm64: Use page-table to track page ownership
  KVM: arm64: Refactor stage2_map_set_prot_attr()
  KVM: arm64: Add kvm_pgtable_stage2_find_range()
  KVM: arm64: Wrap the host with a stage 2
  KVM: arm64: Page-align the .hyp sections
  KVM: arm64: Disable PMU support in protected mode
  KVM: arm64: Protect the .hyp sections from the host

Will Deacon (3):
  arm64: lib: Annotate {clear,copy}_page() as position-independent
  KVM: arm64: Link position-independent string routines into .hyp.text
  arm64: kvm: Add standalone ticket spinlock implementation for use at
    hyp

 arch/arm64/include/asm/assembler.h            |  14 +-
 arch/arm64/include/asm/cpufeature.h           |   1 +
 arch/arm64/include/asm/hyp_image.h            |   7 +
 arch/arm64/include/asm/kvm_asm.h              |   9 +
 arch/arm64/include/asm/kvm_cpufeature.h       |  19 +
 arch/arm64/include/asm/kvm_host.h             |  19 +-
 arch/arm64/include/asm/kvm_hyp.h              |   8 +
 arch/arm64/include/asm/kvm_mmu.h              |  23 +-
 arch/arm64/include/asm/kvm_pgtable.h          | 129 ++++++-
 arch/arm64/include/asm/sections.h             |   1 +
 arch/arm64/kernel/asm-offsets.c               |   3 +
 arch/arm64/kernel/cpufeature.c                |  13 +
 arch/arm64/kernel/image-vars.h                |  30 ++
 arch/arm64/kernel/vmlinux.lds.S               |  74 ++--
 arch/arm64/kvm/arm.c                          | 199 ++++++++--
 arch/arm64/kvm/hyp/Makefile                   |   2 +-
 arch/arm64/kvm/hyp/include/hyp/switch.h       |  34 +-
 arch/arm64/kvm/hyp/include/nvhe/early_alloc.h |  14 +
 arch/arm64/kvm/hyp/include/nvhe/gfp.h         |  68 ++++
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  36 ++
 arch/arm64/kvm/hyp/include/nvhe/memory.h      |  52 +++
 arch/arm64/kvm/hyp/include/nvhe/mm.h          |  96 +++++
 arch/arm64/kvm/hyp/include/nvhe/spinlock.h    |  92 +++++
 arch/arm64/kvm/hyp/nvhe/Makefile              |   9 +-
 arch/arm64/kvm/hyp/nvhe/cache.S               |  13 +
 arch/arm64/kvm/hyp/nvhe/cpufeature.c          |   8 +
 arch/arm64/kvm/hyp/nvhe/early_alloc.c         |  54 +++
 arch/arm64/kvm/hyp/nvhe/hyp-init.S            |  42 ++-
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  69 ++++
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S             |   1 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 279 ++++++++++++++
 arch/arm64/kvm/hyp/nvhe/mm.c                  | 173 +++++++++
 arch/arm64/kvm/hyp/nvhe/page_alloc.c          | 195 ++++++++++
 arch/arm64/kvm/hyp/nvhe/psci-relay.c          |   4 +-
 arch/arm64/kvm/hyp/nvhe/setup.c               | 214 +++++++++++
 arch/arm64/kvm/hyp/nvhe/stub.c                |  22 ++
 arch/arm64/kvm/hyp/nvhe/switch.c              |  12 +-
 arch/arm64/kvm/hyp/nvhe/tlb.c                 |   4 +-
 arch/arm64/kvm/hyp/pgtable.c                  | 350 ++++++++++++++----
 arch/arm64/kvm/hyp/reserved_mem.c             | 113 ++++++
 arch/arm64/kvm/mmu.c                          | 115 +++++-
 arch/arm64/kvm/perf.c                         |   3 +-
 arch/arm64/kvm/pmu.c                          |   8 +-
 arch/arm64/kvm/reset.c                        |  42 +--
 arch/arm64/kvm/sys_regs.c                     |  21 ++
 arch/arm64/lib/clear_page.S                   |   4 +-
 arch/arm64/lib/copy_page.S                    |   4 +-
 arch/arm64/mm/init.c                          |   3 +
 48 files changed, 2471 insertions(+), 234 deletions(-)
 create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/early_alloc.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/gfp.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/memory.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mm.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/spinlock.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S
 create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/early_alloc.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/mm.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/page_alloc.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/setup.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/stub.c
 create mode 100644 arch/arm64/kvm/hyp/reserved_mem.c

-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 01/34] arm64: lib: Annotate {clear,copy}_page() as position-independent
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 02/34] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
                   ` (32 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

From: Will Deacon <will@kernel.org>

clear_page() and copy_page() are suitable for use outside of the kernel
address space, so annotate them as position-independent code.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/lib/clear_page.S | 4 ++--
 arch/arm64/lib/copy_page.S  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/lib/clear_page.S b/arch/arm64/lib/clear_page.S
index 073acbf02a7c..b84b179edba3 100644
--- a/arch/arm64/lib/clear_page.S
+++ b/arch/arm64/lib/clear_page.S
@@ -14,7 +14,7 @@
  * Parameters:
  *	x0 - dest
  */
-SYM_FUNC_START(clear_page)
+SYM_FUNC_START_PI(clear_page)
 	mrs	x1, dczid_el0
 	and	w1, w1, #0xf
 	mov	x2, #4
@@ -25,5 +25,5 @@ SYM_FUNC_START(clear_page)
 	tst	x0, #(PAGE_SIZE - 1)
 	b.ne	1b
 	ret
-SYM_FUNC_END(clear_page)
+SYM_FUNC_END_PI(clear_page)
 EXPORT_SYMBOL(clear_page)
diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index e7a793961408..29144f4cd449 100644
--- a/arch/arm64/lib/copy_page.S
+++ b/arch/arm64/lib/copy_page.S
@@ -17,7 +17,7 @@
  *	x0 - dest
  *	x1 - src
  */
-SYM_FUNC_START(copy_page)
+SYM_FUNC_START_PI(copy_page)
 alternative_if ARM64_HAS_NO_HW_PREFETCH
 	// Prefetch three cache lines ahead.
 	prfm	pldl1strm, [x1, #128]
@@ -75,5 +75,5 @@ alternative_else_nop_endif
 	stnp	x16, x17, [x0, #112 - 256]
 
 	ret
-SYM_FUNC_END(copy_page)
+SYM_FUNC_END_PI(copy_page)
 EXPORT_SYMBOL(copy_page)
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 02/34] KVM: arm64: Link position-independent string routines into .hyp.text
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 01/34] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 03/34] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
                   ` (31 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

From: Will Deacon <will@kernel.org>

Pull clear_page(), copy_page(), memcpy() and memset() into the nVHE hyp
code and ensure that we always execute the '__pi_' entry point on the
offchance that it changes in future.

[ qperret: Commit title nits and added linker script alias ]

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/hyp_image.h |  3 +++
 arch/arm64/kernel/image-vars.h     | 11 +++++++++++
 arch/arm64/kvm/hyp/nvhe/Makefile   |  4 ++++
 3 files changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
index 737ded6b6d0d..78cd77990c9c 100644
--- a/arch/arm64/include/asm/hyp_image.h
+++ b/arch/arm64/include/asm/hyp_image.h
@@ -56,6 +56,9 @@
  */
 #define KVM_NVHE_ALIAS(sym)	kvm_nvhe_sym(sym) = sym;
 
+/* Defines a linker script alias for KVM nVHE hyp symbols */
+#define KVM_NVHE_ALIAS_HYP(first, sec)	kvm_nvhe_sym(first) = kvm_nvhe_sym(sec);
+
 #endif /* LINKER_SCRIPT */
 
 #endif /* __ARM64_HYP_IMAGE_H__ */
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 5aa9ed1e9ec6..4eb7a15c8b60 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -104,6 +104,17 @@ KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
 /* PMU available static key */
 KVM_NVHE_ALIAS(kvm_arm_pmu_available);
 
+/* Position-independent library routines */
+KVM_NVHE_ALIAS_HYP(clear_page, __pi_clear_page);
+KVM_NVHE_ALIAS_HYP(copy_page, __pi_copy_page);
+KVM_NVHE_ALIAS_HYP(memcpy, __pi_memcpy);
+KVM_NVHE_ALIAS_HYP(memset, __pi_memset);
+
+#ifdef CONFIG_KASAN
+KVM_NVHE_ALIAS_HYP(__memcpy, __pi_memcpy);
+KVM_NVHE_ALIAS_HYP(__memset, __pi_memset);
+#endif
+
 #endif /* CONFIG_KVM */
 
 #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index a6707df4f6c0..bc98f8e3d1da 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -9,10 +9,14 @@ ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
 hostprogs := gen-hyprel
 HOST_EXTRACFLAGS += -I$(objtree)/include
 
+lib-objs := clear_page.o copy_page.o memcpy.o memset.o
+lib-objs := $(addprefix ../../../lib/, $(lib-objs))
+
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
 	 hyp-main.o hyp-smp.o psci-relay.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
+obj-y += $(lib-objs)
 
 ##
 ## Build rules for compiling nVHE hyp code
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 03/34] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 01/34] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 02/34] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 04/34] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
                   ` (30 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

From: Will Deacon <will@kernel.org>

We will soon need to synchronise multiple CPUs in the hyp text at EL2.
The qspinlock-based locking used by the host is overkill for this purpose
and relies on the kernel's "percpu" implementation for the MCS nodes.

Implement a simple ticket locking scheme based heavily on the code removed
by commit c11090474d70 ("arm64: locking: Replace ticket lock implementation
with qspinlock").

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/include/nvhe/spinlock.h | 92 ++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/spinlock.h

diff --git a/arch/arm64/kvm/hyp/include/nvhe/spinlock.h b/arch/arm64/kvm/hyp/include/nvhe/spinlock.h
new file mode 100644
index 000000000000..76b537f8d1c6
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/spinlock.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * A stand-alone ticket spinlock implementation for use by the non-VHE
+ * KVM hypervisor code running at EL2.
+ *
+ * Copyright (C) 2020 Google LLC
+ * Author: Will Deacon <will@kernel.org>
+ *
+ * Heavily based on the implementation removed by c11090474d70 which was:
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#ifndef __ARM64_KVM_NVHE_SPINLOCK_H__
+#define __ARM64_KVM_NVHE_SPINLOCK_H__
+
+#include <asm/alternative.h>
+#include <asm/lse.h>
+
+typedef union hyp_spinlock {
+	u32	__val;
+	struct {
+#ifdef __AARCH64EB__
+		u16 next, owner;
+#else
+		u16 owner, next;
+#endif
+	};
+} hyp_spinlock_t;
+
+#define hyp_spin_lock_init(l)						\
+do {									\
+	*(l) = (hyp_spinlock_t){ .__val = 0 };				\
+} while (0)
+
+static inline void hyp_spin_lock(hyp_spinlock_t *lock)
+{
+	u32 tmp;
+	hyp_spinlock_t lockval, newval;
+
+	asm volatile(
+	/* Atomically increment the next ticket. */
+	ARM64_LSE_ATOMIC_INSN(
+	/* LL/SC */
+"	prfm	pstl1strm, %3\n"
+"1:	ldaxr	%w0, %3\n"
+"	add	%w1, %w0, #(1 << 16)\n"
+"	stxr	%w2, %w1, %3\n"
+"	cbnz	%w2, 1b\n",
+	/* LSE atomics */
+"	mov	%w2, #(1 << 16)\n"
+"	ldadda	%w2, %w0, %3\n"
+	__nops(3))
+
+	/* Did we get the lock? */
+"	eor	%w1, %w0, %w0, ror #16\n"
+"	cbz	%w1, 3f\n"
+	/*
+	 * No: spin on the owner. Send a local event to avoid missing an
+	 * unlock before the exclusive load.
+	 */
+"	sevl\n"
+"2:	wfe\n"
+"	ldaxrh	%w2, %4\n"
+"	eor	%w1, %w2, %w0, lsr #16\n"
+"	cbnz	%w1, 2b\n"
+	/* We got the lock. Critical section starts here. */
+"3:"
+	: "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
+	: "Q" (lock->owner)
+	: "memory");
+}
+
+static inline void hyp_spin_unlock(hyp_spinlock_t *lock)
+{
+	u64 tmp;
+
+	asm volatile(
+	ARM64_LSE_ATOMIC_INSN(
+	/* LL/SC */
+	"	ldrh	%w1, %0\n"
+	"	add	%w1, %w1, #1\n"
+	"	stlrh	%w1, %0",
+	/* LSE atomics */
+	"	mov	%w1, #1\n"
+	"	staddlh	%w1, %0\n"
+	__nops(1))
+	: "=Q" (lock->owner), "=&r" (tmp)
+	:
+	: "memory");
+}
+
+#endif /* __ARM64_KVM_NVHE_SPINLOCK_H__ */
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 04/34] KVM: arm64: Initialize kvm_nvhe_init_params early
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (2 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 03/34] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 05/34] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
                   ` (29 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Move the initialization of kvm_nvhe_init_params in a dedicated function
that is run early, and only once during KVM init, rather than every time
the KVM vectors are set and reset.

This also opens the opportunity for the hypervisor to change the init
structs during boot, hence simplifying the replacement of host-provided
page-table by the one the hypervisor will create for itself.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/arm.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fc4c95dd2d26..2d1e7ef69c04 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1383,22 +1383,18 @@ static int kvm_init_vector_slots(void)
 	return 0;
 }
 
-static void cpu_init_hyp_mode(void)
+static void cpu_prepare_hyp_mode(int cpu)
 {
-	struct kvm_nvhe_init_params *params = this_cpu_ptr_nvhe_sym(kvm_init_params);
-	struct arm_smccc_res res;
+	struct kvm_nvhe_init_params *params = per_cpu_ptr_nvhe_sym(kvm_init_params, cpu);
 	unsigned long tcr;
 
-	/* Switch from the HYP stub to our own HYP init vector */
-	__hyp_set_vectors(kvm_get_idmap_vector());
-
 	/*
 	 * Calculate the raw per-cpu offset without a translation from the
 	 * kernel's mapping to the linear mapping, and store it in tpidr_el2
 	 * so that we can use adr_l to access per-cpu variables in EL2.
 	 * Also drop the KASAN tag which gets in the way...
 	 */
-	params->tpidr_el2 = (unsigned long)kasan_reset_tag(this_cpu_ptr_nvhe_sym(__per_cpu_start)) -
+	params->tpidr_el2 = (unsigned long)kasan_reset_tag(per_cpu_ptr_nvhe_sym(__per_cpu_start, cpu)) -
 			    (unsigned long)kvm_ksym_ref(CHOOSE_NVHE_SYM(__per_cpu_start));
 
 	params->mair_el2 = read_sysreg(mair_el1);
@@ -1422,7 +1418,7 @@ static void cpu_init_hyp_mode(void)
 	tcr |= (idmap_t0sz & GENMASK(TCR_TxSZ_WIDTH - 1, 0)) << TCR_T0SZ_OFFSET;
 	params->tcr_el2 = tcr;
 
-	params->stack_hyp_va = kern_hyp_va(__this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE);
+	params->stack_hyp_va = kern_hyp_va(per_cpu(kvm_arm_hyp_stack_page, cpu) + PAGE_SIZE);
 	params->pgd_pa = kvm_mmu_get_httbr();
 
 	/*
@@ -1430,6 +1426,15 @@ static void cpu_init_hyp_mode(void)
 	 * be read while the MMU is off.
 	 */
 	kvm_flush_dcache_to_poc(params, sizeof(*params));
+}
+
+static void cpu_init_hyp_mode(void)
+{
+	struct kvm_nvhe_init_params *params;
+	struct arm_smccc_res res;
+
+	/* Switch from the HYP stub to our own HYP init vector */
+	__hyp_set_vectors(kvm_get_idmap_vector());
 
 	/*
 	 * Call initialization code, and switch to the full blown HYP code.
@@ -1438,6 +1443,7 @@ static void cpu_init_hyp_mode(void)
 	 * cpus_have_const_cap() wrapper.
 	 */
 	BUG_ON(!system_capabilities_finalized());
+	params = this_cpu_ptr_nvhe_sym(kvm_init_params);
 	arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init), virt_to_phys(params), &res);
 	WARN_ON(res.a0 != SMCCC_RET_SUCCESS);
 
@@ -1785,19 +1791,19 @@ static int init_hyp_mode(void)
 		}
 	}
 
-	/*
-	 * Map Hyp percpu pages
-	 */
 	for_each_possible_cpu(cpu) {
 		char *percpu_begin = (char *)kvm_arm_hyp_percpu_base[cpu];
 		char *percpu_end = percpu_begin + nvhe_percpu_size();
 
+		/* Map Hyp percpu pages */
 		err = create_hyp_mappings(percpu_begin, percpu_end, PAGE_HYP);
-
 		if (err) {
 			kvm_err("Cannot map hyp percpu region\n");
 			goto out_err;
 		}
+
+		/* Prepare the CPU initialization parameters */
+		cpu_prepare_hyp_mode(cpu);
 	}
 
 	if (is_protected_kvm_enabled()) {
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 05/34] KVM: arm64: Avoid free_page() in page-table allocator
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (3 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 04/34] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
                   ` (28 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Currently, the KVM page-table allocator uses a mix of put_page() and
free_page() calls depending on the context even though page-allocation
is always achieved using variants of __get_free_page().

Make the code consistent by using put_page() throughout, and reduce the
memory management API surface used by the page-table code. This will
ease factoring out page-allocation from pgtable.c, which is a
pre-requisite to creating page-tables at EL2.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 4d177ce1d536..81fe032f34d1 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -413,7 +413,7 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
 static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			   enum kvm_pgtable_walk_flags flag, void * const arg)
 {
-	free_page((unsigned long)kvm_pte_follow(*ptep));
+	put_page(virt_to_page(kvm_pte_follow(*ptep)));
 	return 0;
 }
 
@@ -425,7 +425,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 	};
 
 	WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
-	free_page((unsigned long)pgt->pgd);
+	put_page(virt_to_page(pgt->pgd));
 	pgt->pgd = NULL;
 }
 
@@ -577,7 +577,7 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
 	if (!data->anchor)
 		return 0;
 
-	free_page((unsigned long)kvm_pte_follow(*ptep));
+	put_page(virt_to_page(kvm_pte_follow(*ptep)));
 	put_page(virt_to_page(ptep));
 
 	if (data->anchor == ptep) {
@@ -700,7 +700,7 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	}
 
 	if (childp)
-		free_page((unsigned long)childp);
+		put_page(virt_to_page(childp));
 
 	return 0;
 }
@@ -897,7 +897,7 @@ static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	put_page(virt_to_page(ptep));
 
 	if (kvm_pte_table(pte, level))
-		free_page((unsigned long)kvm_pte_follow(pte));
+		put_page(virt_to_page(kvm_pte_follow(pte)));
 
 	return 0;
 }
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (4 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 05/34] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 16:09   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 07/34] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
                   ` (27 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In preparation for enabling the creation of page-tables at EL2, factor
all memory allocation out of the page-table code, hence making it
re-usable with any compatible memory allocator.

No functional changes intended.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 41 +++++++++++-
 arch/arm64/kvm/hyp/pgtable.c         | 98 +++++++++++++++++-----------
 arch/arm64/kvm/mmu.c                 | 66 ++++++++++++++++++-
 3 files changed, 163 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 8886d43cfb11..bbe840e430cb 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -13,17 +13,50 @@
 
 typedef u64 kvm_pte_t;
 
+/**
+ * struct kvm_pgtable_mm_ops - Memory management callbacks.
+ * @zalloc_page:	Allocate a single zeroed memory page. The @arg parameter
+ *			can be used by the walker to pass a memcache. The
+ *			initial refcount of the page is 1.
+ * @zalloc_pages_exact:	Allocate an exact number of zeroed memory pages. The
+ *			@size parameter is in bytes, and is rounded-up to the
+ *			next page boundary. The resulting allocation is
+ *			physically contiguous.
+ * @free_pages_exact:	Free an exact number of memory pages previously
+ *			allocated by zalloc_pages_exact.
+ * @get_page:		Increment the refcount on a page.
+ * @put_page:		Decrement the refcount on a page. When the refcount
+ *			reaches 0 the page is automatically freed.
+ * @page_count:		Return the refcount of a page.
+ * @phys_to_virt:	Convert a physical address into a virtual address mapped
+ *			in the current context.
+ * @virt_to_phys:	Convert a virtual address mapped in the current context
+ *			into a physical address.
+ */
+struct kvm_pgtable_mm_ops {
+	void*		(*zalloc_page)(void *arg);
+	void*		(*zalloc_pages_exact)(size_t size);
+	void		(*free_pages_exact)(void *addr, size_t size);
+	void		(*get_page)(void *addr);
+	void		(*put_page)(void *addr);
+	int		(*page_count)(void *addr);
+	void*		(*phys_to_virt)(phys_addr_t phys);
+	phys_addr_t	(*virt_to_phys)(void *addr);
+};
+
 /**
  * struct kvm_pgtable - KVM page-table.
  * @ia_bits:		Maximum input address size, in bits.
  * @start_level:	Level at which the page-table walk starts.
  * @pgd:		Pointer to the first top-level entry of the page-table.
+ * @mm_ops:		Memory management callbacks.
  * @mmu:		Stage-2 KVM MMU struct. Unused for stage-1 page-tables.
  */
 struct kvm_pgtable {
 	u32					ia_bits;
 	u32					start_level;
 	kvm_pte_t				*pgd;
+	struct kvm_pgtable_mm_ops		*mm_ops;
 
 	/* Stage-2 only */
 	struct kvm_s2_mmu			*mmu;
@@ -86,10 +119,12 @@ struct kvm_pgtable_walker {
  * kvm_pgtable_hyp_init() - Initialise a hypervisor stage-1 page-table.
  * @pgt:	Uninitialised page-table structure to initialise.
  * @va_bits:	Maximum virtual address bits.
+ * @mm_ops:	Memory management callbacks.
  *
  * Return: 0 on success, negative error code on failure.
  */
-int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits);
+int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
+			 struct kvm_pgtable_mm_ops *mm_ops);
 
 /**
  * kvm_pgtable_hyp_destroy() - Destroy an unused hypervisor stage-1 page-table.
@@ -126,10 +161,12 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
  * kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
  * @pgt:	Uninitialised page-table structure to initialise.
  * @kvm:	KVM structure representing the guest virtual machine.
+ * @mm_ops:	Memory management callbacks.
  *
  * Return: 0 on success, negative error code on failure.
  */
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm);
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+			    struct kvm_pgtable_mm_ops *mm_ops);
 
 /**
  * kvm_pgtable_stage2_destroy() - Destroy an unused guest stage-2 page-table.
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 81fe032f34d1..b975a67d1f85 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -152,9 +152,9 @@ static kvm_pte_t kvm_phys_to_pte(u64 pa)
 	return pte;
 }
 
-static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte)
+static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte, struct kvm_pgtable_mm_ops *mm_ops)
 {
-	return __va(kvm_pte_to_phys(pte));
+	return mm_ops->phys_to_virt(kvm_pte_to_phys(pte));
 }
 
 static void kvm_set_invalid_pte(kvm_pte_t *ptep)
@@ -163,9 +163,10 @@ static void kvm_set_invalid_pte(kvm_pte_t *ptep)
 	WRITE_ONCE(*ptep, pte & ~KVM_PTE_VALID);
 }
 
-static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp)
+static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp,
+			      struct kvm_pgtable_mm_ops *mm_ops)
 {
-	kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(__pa(childp));
+	kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp));
 
 	pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE);
 	pte |= KVM_PTE_VALID;
@@ -227,7 +228,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
 		goto out;
 	}
 
-	childp = kvm_pte_follow(pte);
+	childp = kvm_pte_follow(pte, data->pgt->mm_ops);
 	ret = __kvm_pgtable_walk(data, childp, level + 1);
 	if (ret)
 		goto out;
@@ -302,8 +303,9 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
 }
 
 struct hyp_map_data {
-	u64		phys;
-	kvm_pte_t	attr;
+	u64				phys;
+	kvm_pte_t			attr;
+	struct kvm_pgtable_mm_ops	*mm_ops;
 };
 
 static int hyp_map_set_prot_attr(enum kvm_pgtable_prot prot,
@@ -358,6 +360,8 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			  enum kvm_pgtable_walk_flags flag, void * const arg)
 {
 	kvm_pte_t *childp;
+	struct hyp_map_data *data = arg;
+	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
 
 	if (hyp_map_walker_try_leaf(addr, end, level, ptep, arg))
 		return 0;
@@ -365,11 +369,11 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
 		return -EINVAL;
 
-	childp = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL);
+	childp = (kvm_pte_t *)mm_ops->zalloc_page(NULL);
 	if (!childp)
 		return -ENOMEM;
 
-	kvm_set_table_pte(ptep, childp);
+	kvm_set_table_pte(ptep, childp, mm_ops);
 	return 0;
 }
 
@@ -379,6 +383,7 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
 	int ret;
 	struct hyp_map_data map_data = {
 		.phys	= ALIGN_DOWN(phys, PAGE_SIZE),
+		.mm_ops	= pgt->mm_ops,
 	};
 	struct kvm_pgtable_walker walker = {
 		.cb	= hyp_map_walker,
@@ -396,16 +401,18 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
 	return ret;
 }
 
-int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
+int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
+			 struct kvm_pgtable_mm_ops *mm_ops)
 {
 	u64 levels = ARM64_HW_PGTABLE_LEVELS(va_bits);
 
-	pgt->pgd = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL);
+	pgt->pgd = (kvm_pte_t *)mm_ops->zalloc_page(NULL);
 	if (!pgt->pgd)
 		return -ENOMEM;
 
 	pgt->ia_bits		= va_bits;
 	pgt->start_level	= KVM_PGTABLE_MAX_LEVELS - levels;
+	pgt->mm_ops		= mm_ops;
 	pgt->mmu		= NULL;
 	return 0;
 }
@@ -413,7 +420,9 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
 static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			   enum kvm_pgtable_walk_flags flag, void * const arg)
 {
-	put_page(virt_to_page(kvm_pte_follow(*ptep)));
+	struct kvm_pgtable_mm_ops *mm_ops = arg;
+
+	mm_ops->put_page((void *)kvm_pte_follow(*ptep, mm_ops));
 	return 0;
 }
 
@@ -422,10 +431,11 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 	struct kvm_pgtable_walker walker = {
 		.cb	= hyp_free_walker,
 		.flags	= KVM_PGTABLE_WALK_TABLE_POST,
+		.arg	= pgt->mm_ops,
 	};
 
 	WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
-	put_page(virt_to_page(pgt->pgd));
+	pgt->mm_ops->put_page(pgt->pgd);
 	pgt->pgd = NULL;
 }
 
@@ -437,6 +447,8 @@ struct stage2_map_data {
 
 	struct kvm_s2_mmu		*mmu;
 	struct kvm_mmu_memory_cache	*memcache;
+
+	struct kvm_pgtable_mm_ops	*mm_ops;
 };
 
 static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
@@ -470,7 +482,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 {
 	kvm_pte_t new, old = *ptep;
 	u64 granule = kvm_granule_size(level), phys = data->phys;
-	struct page *page = virt_to_page(ptep);
+	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
 
 	if (!kvm_block_mapping_supported(addr, end, phys, level))
 		return -E2BIG;
@@ -492,11 +504,11 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 		 */
 		kvm_set_invalid_pte(ptep);
 		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
-		put_page(page);
+		mm_ops->put_page(ptep);
 	}
 
 	smp_store_release(ptep, new);
-	get_page(page);
+	mm_ops->get_page(ptep);
 	data->phys += granule;
 	return 0;
 }
@@ -526,13 +538,13 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
 static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 				struct stage2_map_data *data)
 {
-	int ret;
+	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
 	kvm_pte_t *childp, pte = *ptep;
-	struct page *page = virt_to_page(ptep);
+	int ret;
 
 	if (data->anchor) {
 		if (kvm_pte_valid(pte))
-			put_page(page);
+			mm_ops->put_page(ptep);
 
 		return 0;
 	}
@@ -547,7 +559,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	if (!data->memcache)
 		return -ENOMEM;
 
-	childp = kvm_mmu_memory_cache_alloc(data->memcache);
+	childp = mm_ops->zalloc_page(data->memcache);
 	if (!childp)
 		return -ENOMEM;
 
@@ -559,11 +571,11 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	if (kvm_pte_valid(pte)) {
 		kvm_set_invalid_pte(ptep);
 		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
-		put_page(page);
+		mm_ops->put_page(ptep);
 	}
 
-	kvm_set_table_pte(ptep, childp);
-	get_page(page);
+	kvm_set_table_pte(ptep, childp, mm_ops);
+	mm_ops->get_page(ptep);
 
 	return 0;
 }
@@ -572,13 +584,14 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
 				      kvm_pte_t *ptep,
 				      struct stage2_map_data *data)
 {
+	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
 	int ret = 0;
 
 	if (!data->anchor)
 		return 0;
 
-	put_page(virt_to_page(kvm_pte_follow(*ptep)));
-	put_page(virt_to_page(ptep));
+	mm_ops->put_page(kvm_pte_follow(*ptep, mm_ops));
+	mm_ops->put_page(ptep);
 
 	if (data->anchor == ptep) {
 		data->anchor = NULL;
@@ -633,6 +646,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.phys		= ALIGN_DOWN(phys, PAGE_SIZE),
 		.mmu		= pgt->mmu,
 		.memcache	= mc,
+		.mm_ops		= pgt->mm_ops,
 	};
 	struct kvm_pgtable_walker walker = {
 		.cb		= stage2_map_walker,
@@ -669,7 +683,9 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			       enum kvm_pgtable_walk_flags flag,
 			       void * const arg)
 {
-	struct kvm_s2_mmu *mmu = arg;
+	struct kvm_pgtable *pgt = arg;
+	struct kvm_s2_mmu *mmu = pgt->mmu;
+	struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
 	kvm_pte_t pte = *ptep, *childp = NULL;
 	bool need_flush = false;
 
@@ -677,9 +693,9 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 		return 0;
 
 	if (kvm_pte_table(pte, level)) {
-		childp = kvm_pte_follow(pte);
+		childp = kvm_pte_follow(pte, mm_ops);
 
-		if (page_count(virt_to_page(childp)) != 1)
+		if (mm_ops->page_count(childp) != 1)
 			return 0;
 	} else if (stage2_pte_cacheable(pte)) {
 		need_flush = true;
@@ -692,15 +708,15 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	 */
 	kvm_set_invalid_pte(ptep);
 	kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, addr, level);
-	put_page(virt_to_page(ptep));
+	mm_ops->put_page(ptep);
 
 	if (need_flush) {
-		stage2_flush_dcache(kvm_pte_follow(pte),
+		stage2_flush_dcache(kvm_pte_follow(pte, mm_ops),
 				    kvm_granule_size(level));
 	}
 
 	if (childp)
-		put_page(virt_to_page(childp));
+		mm_ops->put_page(childp);
 
 	return 0;
 }
@@ -709,7 +725,7 @@ int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
 {
 	struct kvm_pgtable_walker walker = {
 		.cb	= stage2_unmap_walker,
-		.arg	= pgt->mmu,
+		.arg	= pgt,
 		.flags	= KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
 	};
 
@@ -841,12 +857,13 @@ static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			       enum kvm_pgtable_walk_flags flag,
 			       void * const arg)
 {
+	struct kvm_pgtable_mm_ops *mm_ops = arg;
 	kvm_pte_t pte = *ptep;
 
 	if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pte))
 		return 0;
 
-	stage2_flush_dcache(kvm_pte_follow(pte), kvm_granule_size(level));
+	stage2_flush_dcache(kvm_pte_follow(pte, mm_ops), kvm_granule_size(level));
 	return 0;
 }
 
@@ -855,6 +872,7 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	struct kvm_pgtable_walker walker = {
 		.cb	= stage2_flush_walker,
 		.flags	= KVM_PGTABLE_WALK_LEAF,
+		.arg	= pgt->mm_ops,
 	};
 
 	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
@@ -863,7 +881,8 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	return kvm_pgtable_walk(pgt, addr, size, &walker);
 }
 
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+			    struct kvm_pgtable_mm_ops *mm_ops)
 {
 	size_t pgd_sz;
 	u64 vtcr = kvm->arch.vtcr;
@@ -872,12 +891,13 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm)
 	u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
 
 	pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
-	pgt->pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	pgt->pgd = mm_ops->zalloc_pages_exact(pgd_sz);
 	if (!pgt->pgd)
 		return -ENOMEM;
 
 	pgt->ia_bits		= ia_bits;
 	pgt->start_level	= start_level;
+	pgt->mm_ops		= mm_ops;
 	pgt->mmu		= &kvm->arch.mmu;
 
 	/* Ensure zeroed PGD pages are visible to the hardware walker */
@@ -889,15 +909,16 @@ static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			      enum kvm_pgtable_walk_flags flag,
 			      void * const arg)
 {
+	struct kvm_pgtable_mm_ops *mm_ops = arg;
 	kvm_pte_t pte = *ptep;
 
 	if (!kvm_pte_valid(pte))
 		return 0;
 
-	put_page(virt_to_page(ptep));
+	mm_ops->put_page(ptep);
 
 	if (kvm_pte_table(pte, level))
-		put_page(virt_to_page(kvm_pte_follow(pte)));
+		mm_ops->put_page(kvm_pte_follow(pte, mm_ops));
 
 	return 0;
 }
@@ -909,10 +930,11 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
 		.cb	= stage2_free_walker,
 		.flags	= KVM_PGTABLE_WALK_LEAF |
 			  KVM_PGTABLE_WALK_TABLE_POST,
+		.arg	= pgt->mm_ops,
 	};
 
 	WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
 	pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level) * PAGE_SIZE;
-	free_pages_exact(pgt->pgd, pgd_sz);
+	pgt->mm_ops->free_pages_exact(pgt->pgd, pgd_sz);
 	pgt->pgd = NULL;
 }
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 77cb2d28f2a4..4d41d7838d53 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -88,6 +88,44 @@ static bool kvm_is_device_pfn(unsigned long pfn)
 	return !pfn_valid(pfn);
 }
 
+static void *stage2_memcache_zalloc_page(void *arg)
+{
+	struct kvm_mmu_memory_cache *mc = arg;
+
+	/* Allocated with __GFP_ZERO, so no need to zero */
+	return kvm_mmu_memory_cache_alloc(mc);
+}
+
+static void *kvm_host_zalloc_pages_exact(size_t size)
+{
+	return alloc_pages_exact(size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+}
+
+static void kvm_host_get_page(void *addr)
+{
+	get_page(virt_to_page(addr));
+}
+
+static void kvm_host_put_page(void *addr)
+{
+	put_page(virt_to_page(addr));
+}
+
+static int kvm_host_page_count(void *addr)
+{
+	return page_count(virt_to_page(addr));
+}
+
+static phys_addr_t kvm_host_pa(void *addr)
+{
+	return __pa(addr);
+}
+
+static void *kvm_host_va(phys_addr_t phys)
+{
+	return __va(phys);
+}
+
 /*
  * Unmapping vs dcache management:
  *
@@ -351,6 +389,17 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
 	return 0;
 }
 
+static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
+	.zalloc_page		= stage2_memcache_zalloc_page,
+	.zalloc_pages_exact	= kvm_host_zalloc_pages_exact,
+	.free_pages_exact	= free_pages_exact,
+	.get_page		= kvm_host_get_page,
+	.put_page		= kvm_host_put_page,
+	.page_count		= kvm_host_page_count,
+	.phys_to_virt		= kvm_host_va,
+	.virt_to_phys		= kvm_host_pa,
+};
+
 /**
  * kvm_init_stage2_mmu - Initialise a S2 MMU strucrure
  * @kvm:	The pointer to the KVM structure
@@ -374,7 +423,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
 	if (!pgt)
 		return -ENOMEM;
 
-	err = kvm_pgtable_stage2_init(pgt, kvm);
+	err = kvm_pgtable_stage2_init(pgt, kvm, &kvm_s2_mm_ops);
 	if (err)
 		goto out_free_pgtable;
 
@@ -1208,6 +1257,19 @@ static int kvm_map_idmap_text(void)
 	return err;
 }
 
+static void *kvm_hyp_zalloc_page(void *arg)
+{
+	return (void *)get_zeroed_page(GFP_KERNEL);
+}
+
+static struct kvm_pgtable_mm_ops kvm_hyp_mm_ops = {
+	.zalloc_page		= kvm_hyp_zalloc_page,
+	.get_page		= kvm_host_get_page,
+	.put_page		= kvm_host_put_page,
+	.phys_to_virt		= kvm_host_va,
+	.virt_to_phys		= kvm_host_pa,
+};
+
 int kvm_mmu_init(void)
 {
 	int err;
@@ -1251,7 +1313,7 @@ int kvm_mmu_init(void)
 		goto out;
 	}
 
-	err = kvm_pgtable_hyp_init(hyp_pgtable, hyp_va_bits);
+	err = kvm_pgtable_hyp_init(hyp_pgtable, hyp_va_bits, &kvm_hyp_mm_ops);
 	if (err)
 		goto out_free_pgtable;
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 07/34] KVM: arm64: Introduce a BSS section for use at Hyp
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (5 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 08/34] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
                   ` (26 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Currently, the hyp code cannot make full use of a bss, as the kernel
section is mapped read-only.

While this mapping could simply be changed to read-write, it would
intermingle even more the hyp and kernel state than they currently are.
Instead, introduce a __hyp_bss section, that uses reserved pages, and
create the appropriate RW hyp mappings during KVM init.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/sections.h |  1 +
 arch/arm64/kernel/vmlinux.lds.S   | 52 ++++++++++++++++++++-----------
 arch/arm64/kvm/arm.c              | 14 ++++++++-
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S |  1 +
 4 files changed, 49 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
index 2f36b16a5b5d..e4ad9db53af1 100644
--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -13,6 +13,7 @@ extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
 extern char __hyp_text_start[], __hyp_text_end[];
 extern char __hyp_rodata_start[], __hyp_rodata_end[];
 extern char __hyp_reloc_begin[], __hyp_reloc_end[];
+extern char __hyp_bss_start[], __hyp_bss_end[];
 extern char __idmap_text_start[], __idmap_text_end[];
 extern char __initdata_begin[], __initdata_end[];
 extern char __inittext_begin[], __inittext_end[];
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 7eea7888bb02..e96173ce211b 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -5,24 +5,7 @@
  * Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
  */
 
-#define RO_EXCEPTION_TABLE_ALIGN	8
-#define RUNTIME_DISCARD_EXIT
-
-#include <asm-generic/vmlinux.lds.h>
-#include <asm/cache.h>
 #include <asm/hyp_image.h>
-#include <asm/kernel-pgtable.h>
-#include <asm/memory.h>
-#include <asm/page.h>
-
-#include "image.h"
-
-OUTPUT_ARCH(aarch64)
-ENTRY(_text)
-
-jiffies = jiffies_64;
-
-
 #ifdef CONFIG_KVM
 #define HYPERVISOR_EXTABLE					\
 	. = ALIGN(SZ_8);					\
@@ -51,13 +34,43 @@ jiffies = jiffies_64;
 		__hyp_reloc_end = .;				\
 	}
 
+#define BSS_FIRST_SECTIONS					\
+	__hyp_bss_start = .;					\
+	*(HYP_SECTION_NAME(.bss))				\
+	. = ALIGN(PAGE_SIZE);					\
+	__hyp_bss_end = .;
+
+/*
+ * We require that __hyp_bss_start and __bss_start are aligned, and enforce it
+ * with an assertion. But the BSS_SECTION macro places an empty .sbss section
+ * between them, which can in some cases cause the linker to misalign them. To
+ * work around the issue, force a page alignment for __bss_start.
+ */
+#define SBSS_ALIGN			PAGE_SIZE
 #else /* CONFIG_KVM */
 #define HYPERVISOR_EXTABLE
 #define HYPERVISOR_DATA_SECTIONS
 #define HYPERVISOR_PERCPU_SECTION
 #define HYPERVISOR_RELOC_SECTION
+#define SBSS_ALIGN			0
 #endif
 
+#define RO_EXCEPTION_TABLE_ALIGN	8
+#define RUNTIME_DISCARD_EXIT
+
+#include <asm-generic/vmlinux.lds.h>
+#include <asm/cache.h>
+#include <asm/kernel-pgtable.h>
+#include <asm/memory.h>
+#include <asm/page.h>
+
+#include "image.h"
+
+OUTPUT_ARCH(aarch64)
+ENTRY(_text)
+
+jiffies = jiffies_64;
+
 #define HYPERVISOR_TEXT					\
 	/*						\
 	 * Align to 4 KB so that			\
@@ -276,7 +289,7 @@ SECTIONS
 	__pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
 	_edata = .;
 
-	BSS_SECTION(0, 0, 0)
+	BSS_SECTION(SBSS_ALIGN, 0, 0)
 
 	. = ALIGN(PAGE_SIZE);
 	init_pg_dir = .;
@@ -324,6 +337,9 @@ ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1))
 ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,
 	"Entry trampoline text too big")
 #endif
+#ifdef CONFIG_KVM
+ASSERT(__hyp_bss_start == __bss_start, "HYP and Host BSS are misaligned")
+#endif
 /*
  * If padding is applied before .head.text, virt<->phys conversions will fail.
  */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2d1e7ef69c04..3f8bcf8db036 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1770,7 +1770,19 @@ static int init_hyp_mode(void)
 		goto out_err;
 	}
 
-	err = create_hyp_mappings(kvm_ksym_ref(__bss_start),
+	/*
+	 * .hyp.bss is guaranteed to be placed at the beginning of the .bss
+	 * section thanks to an assertion in the linker script. Map it RW and
+	 * the rest of .bss RO.
+	 */
+	err = create_hyp_mappings(kvm_ksym_ref(__hyp_bss_start),
+				  kvm_ksym_ref(__hyp_bss_end), PAGE_HYP);
+	if (err) {
+		kvm_err("Cannot map hyp bss section: %d\n", err);
+		goto out_err;
+	}
+
+	err = create_hyp_mappings(kvm_ksym_ref(__hyp_bss_end),
 				  kvm_ksym_ref(__bss_stop), PAGE_HYP_RO);
 	if (err) {
 		kvm_err("Cannot map bss section\n");
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
index cd119d82d8e3..f4562f417d3f 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -25,4 +25,5 @@ SECTIONS {
 	BEGIN_HYP_SECTION(.data..percpu)
 		PERCPU_INPUT(L1_CACHE_BYTES)
 	END_HYP_SECTION
+	HYP_SECTION(.bss)
 }
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 08/34] KVM: arm64: Make kvm_call_hyp() a function call at Hyp
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (6 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 07/34] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 09/34] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
                   ` (25 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

kvm_call_hyp() has some logic to issue a function call or a hypercall
depending on the EL at which the kernel is running. However, all the
code compiled under __KVM_NVHE_HYPERVISOR__ is guaranteed to only run
at EL2 which allows us to simplify.

Add ifdefery to kvm_host.h to simplify kvm_call_hyp() in .hyp.text.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_host.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3d10e6527f7d..06ca4828005f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -591,6 +591,7 @@ int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
 void kvm_arm_halt_guest(struct kvm *kvm);
 void kvm_arm_resume_guest(struct kvm *kvm);
 
+#ifndef __KVM_NVHE_HYPERVISOR__
 #define kvm_call_hyp_nvhe(f, ...)						\
 	({								\
 		struct arm_smccc_res res;				\
@@ -630,6 +631,11 @@ void kvm_arm_resume_guest(struct kvm *kvm);
 									\
 		ret;							\
 	})
+#else /* __KVM_NVHE_HYPERVISOR__ */
+#define kvm_call_hyp(f, ...) f(__VA_ARGS__)
+#define kvm_call_hyp_ret(f, ...) f(__VA_ARGS__)
+#define kvm_call_hyp_nvhe(f, ...) f(__VA_ARGS__)
+#endif /* __KVM_NVHE_HYPERVISOR__ */
 
 void force_vm_exit(const cpumask_t *mask);
 void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 09/34] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (7 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 08/34] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 10/34] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
                   ` (24 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to allow the usage of code shared by the host and the hyp in
static inline library functions, allow the usage of kvm_nvhe_sym() at
EL2 by defaulting to the raw symbol name.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/hyp_image.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
index 78cd77990c9c..b4b3076a76fb 100644
--- a/arch/arm64/include/asm/hyp_image.h
+++ b/arch/arm64/include/asm/hyp_image.h
@@ -10,11 +10,15 @@
 #define __HYP_CONCAT(a, b)	a ## b
 #define HYP_CONCAT(a, b)	__HYP_CONCAT(a, b)
 
+#ifndef __KVM_NVHE_HYPERVISOR__
 /*
  * KVM nVHE code has its own symbol namespace prefixed with __kvm_nvhe_,
  * to separate it from the kernel proper.
  */
 #define kvm_nvhe_sym(sym)	__kvm_nvhe_##sym
+#else
+#define kvm_nvhe_sym(sym)	sym
+#endif
 
 #ifdef LINKER_SCRIPT
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 10/34] KVM: arm64: Introduce an early Hyp page allocator
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (8 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 09/34] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
                   ` (23 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

With nVHE, the host currently creates all stage 1 hypervisor mappings at
EL1 during boot, installs them at EL2, and extends them as required
(e.g. when creating a new VM). But in a world where the host is no
longer trusted, it cannot have full control over the code mapped in the
hypervisor.

In preparation for enabling the hypervisor to create its own stage 1
mappings during boot, introduce an early page allocator, with minimal
functionality. This allocator is designed to be used only during early
bootstrap of the hyp code when memory protection is enabled, which will
then switch to using a full-fledged page allocator after init.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/include/nvhe/early_alloc.h | 14 +++++
 arch/arm64/kvm/hyp/include/nvhe/memory.h      | 24 +++++++++
 arch/arm64/kvm/hyp/nvhe/Makefile              |  2 +-
 arch/arm64/kvm/hyp/nvhe/early_alloc.c         | 54 +++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/psci-relay.c          |  4 +-
 5 files changed, 94 insertions(+), 4 deletions(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/early_alloc.h
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/memory.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/early_alloc.c

diff --git a/arch/arm64/kvm/hyp/include/nvhe/early_alloc.h b/arch/arm64/kvm/hyp/include/nvhe/early_alloc.h
new file mode 100644
index 000000000000..dc61aaa56f31
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/early_alloc.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __KVM_HYP_EARLY_ALLOC_H
+#define __KVM_HYP_EARLY_ALLOC_H
+
+#include <asm/kvm_pgtable.h>
+
+void hyp_early_alloc_init(void *virt, unsigned long size);
+unsigned long hyp_early_alloc_nr_used_pages(void);
+void *hyp_early_alloc_page(void *arg);
+void *hyp_early_alloc_contig(unsigned int nr_pages);
+
+extern struct kvm_pgtable_mm_ops hyp_early_alloc_mm_ops;
+
+#endif /* __KVM_HYP_EARLY_ALLOC_H */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
new file mode 100644
index 000000000000..3e49eaa7e682
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __KVM_HYP_MEMORY_H
+#define __KVM_HYP_MEMORY_H
+
+#include <asm/page.h>
+
+#include <linux/types.h>
+
+extern s64 hyp_physvirt_offset;
+
+#define __hyp_pa(virt)	((phys_addr_t)(virt) + hyp_physvirt_offset)
+#define __hyp_va(phys)	((void *)((phys_addr_t)(phys) - hyp_physvirt_offset))
+
+static inline void *hyp_phys_to_virt(phys_addr_t phys)
+{
+	return __hyp_va(phys);
+}
+
+static inline phys_addr_t hyp_virt_to_phys(void *addr)
+{
+	return __hyp_pa(addr);
+}
+
+#endif /* __KVM_HYP_MEMORY_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index bc98f8e3d1da..24ff99e2eac5 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -13,7 +13,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
 lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
-	 hyp-main.o hyp-smp.o psci-relay.o
+	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
 obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/early_alloc.c b/arch/arm64/kvm/hyp/nvhe/early_alloc.c
new file mode 100644
index 000000000000..1306c430ab87
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/early_alloc.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <asm/kvm_pgtable.h>
+
+#include <nvhe/early_alloc.h>
+#include <nvhe/memory.h>
+
+struct kvm_pgtable_mm_ops hyp_early_alloc_mm_ops;
+s64 __ro_after_init hyp_physvirt_offset;
+
+static unsigned long base;
+static unsigned long end;
+static unsigned long cur;
+
+unsigned long hyp_early_alloc_nr_used_pages(void)
+{
+	return (cur - base) >> PAGE_SHIFT;
+}
+
+void *hyp_early_alloc_contig(unsigned int nr_pages)
+{
+	unsigned long size = (nr_pages << PAGE_SHIFT);
+	void *ret = (void *)cur;
+
+	if (!nr_pages)
+		return NULL;
+
+	if (end - cur < size)
+		return NULL;
+
+	cur += size;
+	memset(ret, 0, size);
+
+	return ret;
+}
+
+void *hyp_early_alloc_page(void *arg)
+{
+	return hyp_early_alloc_contig(1);
+}
+
+void hyp_early_alloc_init(void *virt, unsigned long size)
+{
+	base = cur = (unsigned long)virt;
+	end = base + size;
+
+	hyp_early_alloc_mm_ops.zalloc_page = hyp_early_alloc_page;
+	hyp_early_alloc_mm_ops.phys_to_virt = hyp_phys_to_virt;
+	hyp_early_alloc_mm_ops.virt_to_phys = hyp_virt_to_phys;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index 63de71c0481e..08508783ec3d 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -11,6 +11,7 @@
 #include <linux/kvm_host.h>
 #include <uapi/linux/psci.h>
 
+#include <nvhe/memory.h>
 #include <nvhe/trap_handler.h>
 
 void kvm_hyp_cpu_entry(unsigned long r0);
@@ -20,9 +21,6 @@ void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
 
 /* Config options set by the host. */
 struct kvm_host_psci_config __ro_after_init kvm_host_psci_config;
-s64 __ro_after_init hyp_physvirt_offset;
-
-#define __hyp_pa(x) ((phys_addr_t)((x)) + hyp_physvirt_offset)
 
 #define INVALID_CPU_ID	UINT_MAX
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (9 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 10/34] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 16:11   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
                   ` (22 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to use the kernel list library at EL2, introduce stubs for the
CONFIG_DEBUG_LIST out-of-lines calls.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/nvhe/Makefile |  2 +-
 arch/arm64/kvm/hyp/nvhe/stub.c   | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kvm/hyp/nvhe/stub.c

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 24ff99e2eac5..144da72ad510 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -13,7 +13,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
 lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
-	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o
+	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
 obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/stub.c b/arch/arm64/kvm/hyp/nvhe/stub.c
new file mode 100644
index 000000000000..c0aa6bbfd79d
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/stub.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Stubs for out-of-line function calls caused by re-using kernel
+ * infrastructure at EL2.
+ *
+ * Copyright (C) 2020 - Google LLC
+ */
+
+#include <linux/list.h>
+
+#ifdef CONFIG_DEBUG_LIST
+bool __list_add_valid(struct list_head *new, struct list_head *prev,
+		      struct list_head *next)
+{
+		return true;
+}
+
+bool __list_del_entry_valid(struct list_head *entry)
+{
+		return true;
+}
+#endif
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (10 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 16:14   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
                   ` (21 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

When memory protection is enabled, the hyp code will require a basic
form of memory management in order to allocate and free memory pages at
EL2. This is needed for various use-cases, including the creation of hyp
mappings or the allocation of stage 2 page tables.

To address these use-case, introduce a simple memory allocator in the
hyp code. The allocator is designed as a conventional 'buddy allocator',
working with a page granularity. It allows to allocate and free
physically contiguous pages from memory 'pools', with a guaranteed order
alignment in the PA space. Each page in a memory pool is associated
with a struct hyp_page which holds the page's metadata, including its
refcount, as well as its current order, hence mimicking the kernel's
buddy system in the GFP infrastructure. The hyp_page metadata are made
accessible through a hyp_vmemmap, following the concept of
SPARSE_VMEMMAP in the kernel.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/include/nvhe/gfp.h    |  68 ++++++++
 arch/arm64/kvm/hyp/include/nvhe/memory.h |  28 ++++
 arch/arm64/kvm/hyp/nvhe/Makefile         |   2 +-
 arch/arm64/kvm/hyp/nvhe/page_alloc.c     | 195 +++++++++++++++++++++++
 4 files changed, 292 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/gfp.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/page_alloc.c

diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
new file mode 100644
index 000000000000..55b3f0ce5bc8
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __KVM_HYP_GFP_H
+#define __KVM_HYP_GFP_H
+
+#include <linux/list.h>
+
+#include <nvhe/memory.h>
+#include <nvhe/spinlock.h>
+
+#define HYP_NO_ORDER	UINT_MAX
+
+struct hyp_pool {
+	/*
+	 * Spinlock protecting concurrent changes to the memory pool as well as
+	 * the struct hyp_page of the pool's pages until we have a proper atomic
+	 * API at EL2.
+	 */
+	hyp_spinlock_t lock;
+	struct list_head free_area[MAX_ORDER];
+	phys_addr_t range_start;
+	phys_addr_t range_end;
+	unsigned int max_order;
+};
+
+static inline void hyp_page_ref_inc(struct hyp_page *p)
+{
+	struct hyp_pool *pool = hyp_page_to_pool(p);
+
+	hyp_spin_lock(&pool->lock);
+	p->refcount++;
+	hyp_spin_unlock(&pool->lock);
+}
+
+static inline int hyp_page_ref_dec_and_test(struct hyp_page *p)
+{
+	struct hyp_pool *pool = hyp_page_to_pool(p);
+	int ret;
+
+	hyp_spin_lock(&pool->lock);
+	p->refcount--;
+	ret = (p->refcount == 0);
+	hyp_spin_unlock(&pool->lock);
+
+	return ret;
+}
+
+static inline void hyp_set_page_refcounted(struct hyp_page *p)
+{
+	struct hyp_pool *pool = hyp_page_to_pool(p);
+
+	hyp_spin_lock(&pool->lock);
+	if (p->refcount) {
+		hyp_spin_unlock(&pool->lock);
+		hyp_panic();
+	}
+	p->refcount = 1;
+	hyp_spin_unlock(&pool->lock);
+}
+
+/* Allocation */
+void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order);
+void hyp_get_page(void *addr);
+void hyp_put_page(void *addr);
+
+/* Used pages cannot be freed */
+int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages,
+		  unsigned int reserved_pages);
+#endif /* __KVM_HYP_GFP_H */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 3e49eaa7e682..d2fb307c5952 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -6,7 +6,17 @@
 
 #include <linux/types.h>
 
+struct hyp_pool;
+struct hyp_page {
+	unsigned int refcount;
+	unsigned int order;
+	struct hyp_pool *pool;
+	struct list_head node;
+};
+
 extern s64 hyp_physvirt_offset;
+extern u64 __hyp_vmemmap;
+#define hyp_vmemmap ((struct hyp_page *)__hyp_vmemmap)
 
 #define __hyp_pa(virt)	((phys_addr_t)(virt) + hyp_physvirt_offset)
 #define __hyp_va(phys)	((void *)((phys_addr_t)(phys) - hyp_physvirt_offset))
@@ -21,4 +31,22 @@ static inline phys_addr_t hyp_virt_to_phys(void *addr)
 	return __hyp_pa(addr);
 }
 
+#define hyp_phys_to_pfn(phys)	((phys) >> PAGE_SHIFT)
+#define hyp_pfn_to_phys(pfn)	((phys_addr_t)((pfn) << PAGE_SHIFT))
+#define hyp_phys_to_page(phys)	(&hyp_vmemmap[hyp_phys_to_pfn(phys)])
+#define hyp_virt_to_page(virt)	hyp_phys_to_page(__hyp_pa(virt))
+#define hyp_virt_to_pfn(virt)	hyp_phys_to_pfn(__hyp_pa(virt))
+
+#define hyp_page_to_pfn(page)	((struct hyp_page *)(page) - hyp_vmemmap)
+#define hyp_page_to_phys(page)  hyp_pfn_to_phys((hyp_page_to_pfn(page)))
+#define hyp_page_to_virt(page)	__hyp_va(hyp_page_to_phys(page))
+#define hyp_page_to_pool(page)	(((struct hyp_page *)page)->pool)
+
+static inline int hyp_page_count(void *addr)
+{
+	struct hyp_page *p = hyp_virt_to_page(addr);
+
+	return p->refcount;
+}
+
 #endif /* __KVM_HYP_MEMORY_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 144da72ad510..6894a917f290 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -13,7 +13,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
 lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
-	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o
+	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
 obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
new file mode 100644
index 000000000000..237e03bf0cb1
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <asm/kvm_hyp.h>
+#include <nvhe/gfp.h>
+
+u64 __hyp_vmemmap;
+
+/*
+ * Index the hyp_vmemmap to find a potential buddy page, but make no assumption
+ * about its current state.
+ *
+ * Example buddy-tree for a 4-pages physically contiguous pool:
+ *
+ *                 o : Page 3
+ *                /
+ *               o-o : Page 2
+ *              /
+ *             /   o : Page 1
+ *            /   /
+ *           o---o-o : Page 0
+ *    Order  2   1 0
+ *
+ * Example of requests on this pool:
+ *   __find_buddy_nocheck(pool, page 0, order 0) => page 1
+ *   __find_buddy_nocheck(pool, page 0, order 1) => page 2
+ *   __find_buddy_nocheck(pool, page 1, order 0) => page 0
+ *   __find_buddy_nocheck(pool, page 2, order 0) => page 3
+ */
+static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
+					     struct hyp_page *p,
+					     unsigned int order)
+{
+	phys_addr_t addr = hyp_page_to_phys(p);
+
+	addr ^= (PAGE_SIZE << order);
+
+	/*
+	 * Don't return a page outside the pool range -- it belongs to
+	 * something else and may not be mapped in hyp_vmemmap.
+	 */
+	if (addr < pool->range_start || addr >= pool->range_end)
+		return NULL;
+
+	return hyp_phys_to_page(addr);
+}
+
+/* Find a buddy page currently available for allocation */
+static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool,
+					   struct hyp_page *p,
+					   unsigned int order)
+{
+	struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order);
+
+	if (!buddy || buddy->order != order || list_empty(&buddy->node))
+		return NULL;
+
+	return buddy;
+
+}
+
+static void __hyp_attach_page(struct hyp_pool *pool,
+			      struct hyp_page *p)
+{
+	unsigned int order = p->order;
+	struct hyp_page *buddy;
+
+	memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order);
+
+	/*
+	 * Only the first struct hyp_page of a high-order page (otherwise known
+	 * as the 'head') should have p->order set. The non-head pages should
+	 * have p->order = HYP_NO_ORDER. Here @p may no longer be the head
+	 * after coallescing, so make sure to mark it HYP_NO_ORDER proactively.
+	 */
+	p->order = HYP_NO_ORDER;
+	for (; (order + 1) < pool->max_order; order++) {
+		buddy = __find_buddy_avail(pool, p, order);
+		if (!buddy)
+			break;
+
+		/* Take the buddy out of its list, and coallesce with @p */
+		list_del_init(&buddy->node);
+		buddy->order = HYP_NO_ORDER;
+		p = min(p, buddy);
+	}
+
+	/* Mark the new head, and insert it */
+	p->order = order;
+	list_add_tail(&p->node, &pool->free_area[order]);
+}
+
+static void hyp_attach_page(struct hyp_page *p)
+{
+	struct hyp_pool *pool = hyp_page_to_pool(p);
+
+	hyp_spin_lock(&pool->lock);
+	__hyp_attach_page(pool, p);
+	hyp_spin_unlock(&pool->lock);
+}
+
+static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
+					   struct hyp_page *p,
+					   unsigned int order)
+{
+	struct hyp_page *buddy;
+
+	list_del_init(&p->node);
+	while (p->order > order) {
+		/*
+		 * The buddy of order n - 1 currently has HYP_NO_ORDER as it
+		 * is covered by a higher-level page (whose head is @p). Use
+		 * __find_buddy_nocheck() to find it and inject it in the
+		 * free_list[n - 1], effectively splitting @p in half.
+		 */
+		p->order--;
+		buddy = __find_buddy_nocheck(pool, p, p->order);
+		buddy->order = p->order;
+		list_add_tail(&buddy->node, &pool->free_area[buddy->order]);
+	}
+
+	return p;
+}
+
+void hyp_put_page(void *addr)
+{
+	struct hyp_page *p = hyp_virt_to_page(addr);
+
+	if (hyp_page_ref_dec_and_test(p))
+		hyp_attach_page(p);
+}
+
+void hyp_get_page(void *addr)
+{
+	struct hyp_page *p = hyp_virt_to_page(addr);
+
+	hyp_page_ref_inc(p);
+}
+
+void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order)
+{
+	unsigned int i = order;
+	struct hyp_page *p;
+
+	hyp_spin_lock(&pool->lock);
+
+	/* Look for a high-enough-order page */
+	while (i < pool->max_order && list_empty(&pool->free_area[i]))
+		i++;
+	if (i >= pool->max_order) {
+		hyp_spin_unlock(&pool->lock);
+		return NULL;
+	}
+
+	/* Extract it from the tree at the right order */
+	p = list_first_entry(&pool->free_area[i], struct hyp_page, node);
+	p = __hyp_extract_page(pool, p, order);
+
+	hyp_spin_unlock(&pool->lock);
+	hyp_set_page_refcounted(p);
+
+	return hyp_page_to_virt(p);
+}
+
+int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages,
+		  unsigned int reserved_pages)
+{
+	phys_addr_t phys = hyp_pfn_to_phys(pfn);
+	struct hyp_page *p;
+	int i;
+
+	hyp_spin_lock_init(&pool->lock);
+	pool->max_order = min(MAX_ORDER, get_order(nr_pages << PAGE_SHIFT));
+	for (i = 0; i < pool->max_order; i++)
+		INIT_LIST_HEAD(&pool->free_area[i]);
+	pool->range_start = phys;
+	pool->range_end = phys + (nr_pages << PAGE_SHIFT);
+
+	/* Init the vmemmap portion */
+	p = hyp_phys_to_page(phys);
+	memset(p, 0, sizeof(*p) * nr_pages);
+	for (i = 0; i < nr_pages; i++) {
+		p[i].pool = pool;
+		INIT_LIST_HEAD(&p[i].node);
+	}
+
+	/* Attach the unused pages to the buddy tree */
+	for (i = reserved_pages; i < nr_pages; i++)
+		__hyp_attach_page(pool, &p[i]);
+
+	return 0;
+}
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (11 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 19:36   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 14/34] KVM: arm64: Factor out vector address calculation Quentin Perret
                   ` (20 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Introduce the infrastructure in KVM enabling to copy CPU feature
registers into EL2-owned data-structures, to allow reading sanitised
values directly at EL2 in nVHE.

Given that only a subset of these features are being read by the
hypervisor, the ones that need to be copied are to be listed under
<asm/kvm_cpufeature.h> together with the name of the nVHE variable that
will hold the copy.

While at it, introduce the first user of this infrastructure by
implementing __flush_dcache_area at EL2, which needs
arm64_ftr_reg_ctrel0.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/cpufeature.h     |  1 +
 arch/arm64/include/asm/kvm_cpufeature.h | 17 +++++++++++++++++
 arch/arm64/include/asm/kvm_host.h       |  4 ++++
 arch/arm64/kernel/cpufeature.c          | 13 +++++++++++++
 arch/arm64/kvm/hyp/nvhe/Makefile        |  3 ++-
 arch/arm64/kvm/hyp/nvhe/cache.S         | 13 +++++++++++++
 arch/arm64/kvm/hyp/nvhe/cpufeature.c    |  8 ++++++++
 arch/arm64/kvm/sys_regs.c               | 21 +++++++++++++++++++++
 8 files changed, 79 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S
 create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 61177bac49fa..a85cea2cac57 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -607,6 +607,7 @@ void check_local_cpu_capabilities(void);
 
 u64 read_sanitised_ftr_reg(u32 id);
 u64 __read_sysreg_by_encoding(u32 sys_id);
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst);
 
 static inline bool cpu_supports_mixed_endian_el0(void)
 {
diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h
new file mode 100644
index 000000000000..d34f85cba358
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <asm/cpufeature.h>
+
+#ifndef KVM_HYP_CPU_FTR_REG
+#if defined(__KVM_NVHE_HYPERVISOR__)
+#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg name;
+#else
+#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name);
+#endif
+#endif
+
+KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 06ca4828005f..459ee557f87c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -751,9 +751,13 @@ void kvm_clr_pmu_events(u32 clr);
 
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
+
+void setup_kvm_el2_caps(void);
 #else
 static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
 static inline void kvm_clr_pmu_events(u32 clr) {}
+
+static inline void setup_kvm_el2_caps(void) {}
 #endif
 
 void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 066030717a4c..f2d8b479ff74 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1154,6 +1154,18 @@ u64 read_sanitised_ftr_reg(u32 id)
 }
 EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
 
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
+{
+	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
+
+	if (!regp)
+		return -EINVAL;
+
+	memcpy(dst, regp, sizeof(*regp));
+
+	return 0;
+}
+
 #define read_sysreg_case(r)	\
 	case r:		val = read_sysreg_s(r); break;
 
@@ -2773,6 +2785,7 @@ void __init setup_cpu_features(void)
 
 	setup_system_capabilities();
 	setup_elf_hwcaps(arm64_elf_hwcaps);
+	setup_kvm_el2_caps();
 
 	if (system_supports_32bit_el0())
 		setup_elf_hwcaps(compat_elf_hwcaps);
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 6894a917f290..0033591553fc 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -13,7 +13,8 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
 lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
-	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o
+	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \
+	 cache.o cpufeature.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
 obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S
new file mode 100644
index 000000000000..36cef6915428
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/cache.S
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Code copied from arch/arm64/mm/cache.S.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/alternative.h>
+
+SYM_FUNC_START_PI(__flush_dcache_area)
+	dcache_by_line_op civac, sy, x0, x1, x2, x3
+	ret
+SYM_FUNC_END_PI(__flush_dcache_area)
diff --git a/arch/arm64/kvm/hyp/nvhe/cpufeature.c b/arch/arm64/kvm/hyp/nvhe/cpufeature.c
new file mode 100644
index 000000000000..a887508f996f
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/cpufeature.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#define KVM_HYP_CPU_FTR_REG(id, name) struct arm64_ftr_reg name;
+#include <asm/kvm_cpufeature.h>
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4f2f1e3145de..84be93df52fa 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -21,6 +21,7 @@
 #include <asm/debug-monitors.h>
 #include <asm/esr.h>
 #include <asm/kvm_arm.h>
+#include <asm/kvm_cpufeature.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
@@ -2775,3 +2776,23 @@ void kvm_sys_reg_table_init(void)
 	/* Clear all higher bits. */
 	cache_levels &= (1 << (i*3))-1;
 }
+
+#undef KVM_HYP_CPU_FTR_REG
+#define KVM_HYP_CPU_FTR_REG(id, name) \
+	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
+struct __ftr_reg_copy_entry {
+	u32			sys_id;
+	struct arm64_ftr_reg	*dst;
+} hyp_ftr_regs[] __initdata = {
+	#include <asm/kvm_cpufeature.h>
+};
+
+void __init setup_kvm_el2_caps(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {
+		WARN(copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst),
+		     "%u feature register not found\n", hyp_ftr_regs[i].sys_id);
+	}
+}
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 14/34] KVM: arm64: Factor out vector address calculation
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (12 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro Quentin Perret
                   ` (19 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to re-map the guest vectors at EL2 when pKVM is enabled,
refactor __kvm_vector_slot2idx() and kvm_init_vector_slot() to move all
the address calculation logic in a static inline function.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_mmu.h | 8 ++++++++
 arch/arm64/kvm/arm.c             | 9 +--------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 90873851f677..5c42ec023cc7 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -168,6 +168,14 @@ phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
 int kvm_mmu_init(void);
 
+static inline void *__kvm_vector_slot2addr(void *base,
+					   enum arm64_hyp_spectre_vector slot)
+{
+	int idx = slot - (slot != HYP_VECTOR_DIRECT);
+
+	return base + (idx * SZ_2K);
+}
+
 struct kvm;
 
 #define kvm_flush_dcache_to_poc(a,l)	__flush_dcache_area((a), (l))
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3f8bcf8db036..26e573cdede3 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1345,16 +1345,9 @@ static unsigned long nvhe_percpu_order(void)
 /* A lookup table holding the hypervisor VA for each vector slot */
 static void *hyp_spectre_vector_selector[BP_HARDEN_EL2_SLOTS];
 
-static int __kvm_vector_slot2idx(enum arm64_hyp_spectre_vector slot)
-{
-	return slot - (slot != HYP_VECTOR_DIRECT);
-}
-
 static void kvm_init_vector_slot(void *base, enum arm64_hyp_spectre_vector slot)
 {
-	int idx = __kvm_vector_slot2idx(slot);
-
-	hyp_spectre_vector_selector[slot] = base + (idx * SZ_2K);
+	hyp_spectre_vector_selector[slot] = __kvm_vector_slot2addr(base, slot);
 }
 
 static int kvm_init_vector_slots(void)
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (13 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 14/34] KVM: arm64: Factor out vector address calculation Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 16:22   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2 Quentin Perret
                   ` (18 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

We will soon need to turn the EL2 stage 1 MMU on and off in nVHE
protected mode, so refactor the set_sctlr_el1 macro to make it usable
for that purpose.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/assembler.h | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index ca31594d3d6c..fb651c1f26e9 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -676,11 +676,11 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 	.endm
 
 /*
- * Set SCTLR_EL1 to the passed value, and invalidate the local icache
+ * Set SCTLR_ELx to the @reg value, and invalidate the local icache
  * in the process. This is called when setting the MMU on.
  */
-.macro set_sctlr_el1, reg
-	msr	sctlr_el1, \reg
+.macro set_sctlr, sreg, reg
+	msr	\sreg, \reg
 	isb
 	/*
 	 * Invalidate the local I-cache so that any instructions fetched
@@ -692,6 +692,14 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 	isb
 .endm
 
+.macro set_sctlr_el1, reg
+	set_sctlr sctlr_el1, \reg
+.endm
+
+.macro set_sctlr_el2, reg
+	set_sctlr sctlr_el2, \reg
+.endm
+
 /*
  * Check whether to yield to another runnable task from kernel mode NEON code
  * (which runs with preemption disabled).
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (14 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 16:21   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation " Quentin Perret
                   ` (17 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

When memory protection is enabled, the EL2 code needs the ability to
create and manage its own page-table. To do so, introduce a new set of
hypercalls to bootstrap a memory management system at EL2.

This leads to the following boot flow in nVHE Protected mode:

 1. the host allocates memory for the hypervisor very early on, using
    the memblock API;

 2. the host creates a set of stage 1 page-table for EL2, installs the
    EL2 vectors, and issues the __pkvm_init hypercall;

 3. during __pkvm_init, the hypervisor re-creates its stage 1 page-table
    and stores it in the memory pool provided by the host;

 4. the hypervisor then extends its stage 1 mappings to include a
    vmemmap in the EL2 VA space, hence allowing to use the buddy
    allocator introduced in a previous patch;

 5. the hypervisor jumps back in the idmap page, switches from the
    host-provided page-table to the new one, and wraps up its
    initialization by enabling the new allocator, before returning to
    the host.

 6. the host can free the now unused page-table created for EL2, and
    will now need to issue hypercalls to make changes to the EL2 stage 1
    mappings instead of modifying them directly.

Note that for the sake of simplifying the review, this patch focuses on
the hypervisor side of things. In other words, this only implements the
new hypercalls, but does not make use of them from the host yet. The
host-side changes will follow in a subsequent patch.

Credits to Will for __pkvm_init_switch_pgd.

Co-authored-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_asm.h     |   4 +
 arch/arm64/include/asm/kvm_host.h    |   7 +
 arch/arm64/include/asm/kvm_hyp.h     |   8 ++
 arch/arm64/include/asm/kvm_pgtable.h |   2 +
 arch/arm64/kernel/image-vars.h       |  16 +++
 arch/arm64/kvm/hyp/Makefile          |   2 +-
 arch/arm64/kvm/hyp/include/nvhe/mm.h |  71 ++++++++++
 arch/arm64/kvm/hyp/nvhe/Makefile     |   4 +-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S   |  27 ++++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c   |  49 +++++++
 arch/arm64/kvm/hyp/nvhe/mm.c         | 173 +++++++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/setup.c      | 197 +++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/pgtable.c         |   2 -
 arch/arm64/kvm/hyp/reserved_mem.c    |  92 +++++++++++++
 arch/arm64/mm/init.c                 |   3 +
 15 files changed, 652 insertions(+), 5 deletions(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mm.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/mm.c
 create mode 100644 arch/arm64/kvm/hyp/nvhe/setup.c
 create mode 100644 arch/arm64/kvm/hyp/reserved_mem.c

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 22d933e9b59e..db20a9477870 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -57,6 +57,10 @@
 #define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2		12
 #define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs		13
 #define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs		14
+#define __KVM_HOST_SMCCC_FUNC___pkvm_init			15
+#define __KVM_HOST_SMCCC_FUNC___pkvm_create_mappings		16
+#define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping	17
+#define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector		18
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 459ee557f87c..b9d45a1f8538 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -781,5 +781,12 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
 	(test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features))
 
 int kvm_trng_call(struct kvm_vcpu *vcpu);
+#ifdef CONFIG_KVM
+extern phys_addr_t hyp_mem_base;
+extern phys_addr_t hyp_mem_size;
+void __init kvm_hyp_reserve(void);
+#else
+static inline void kvm_hyp_reserve(void) { }
+#endif
 
 #endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index c0450828378b..ae55351b99a4 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -100,4 +100,12 @@ void __noreturn hyp_panic(void);
 void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
 #endif
 
+#ifdef __KVM_NVHE_HYPERVISOR__
+void __pkvm_init_switch_pgd(phys_addr_t phys, unsigned long size,
+			    phys_addr_t pgd, void *sp, void *cont_fn);
+int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
+		unsigned long *per_cpu_base, u32 hyp_va_bits);
+void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
+#endif
+
 #endif /* __ARM64_KVM_HYP_H__ */
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index bbe840e430cb..bf7a3cc49420 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -11,6 +11,8 @@
 #include <linux/kvm_host.h>
 #include <linux/types.h>
 
+#define KVM_PGTABLE_MAX_LEVELS		4U
+
 typedef u64 kvm_pte_t;
 
 /**
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 4eb7a15c8b60..940c378fa837 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -115,6 +115,22 @@ KVM_NVHE_ALIAS_HYP(__memcpy, __pi_memcpy);
 KVM_NVHE_ALIAS_HYP(__memset, __pi_memset);
 #endif
 
+/* Kernel memory sections */
+KVM_NVHE_ALIAS(__start_rodata);
+KVM_NVHE_ALIAS(__end_rodata);
+KVM_NVHE_ALIAS(__bss_start);
+KVM_NVHE_ALIAS(__bss_stop);
+
+/* Hyp memory sections */
+KVM_NVHE_ALIAS(__hyp_idmap_text_start);
+KVM_NVHE_ALIAS(__hyp_idmap_text_end);
+KVM_NVHE_ALIAS(__hyp_text_start);
+KVM_NVHE_ALIAS(__hyp_text_end);
+KVM_NVHE_ALIAS(__hyp_bss_start);
+KVM_NVHE_ALIAS(__hyp_bss_end);
+KVM_NVHE_ALIAS(__hyp_rodata_start);
+KVM_NVHE_ALIAS(__hyp_rodata_end);
+
 #endif /* CONFIG_KVM */
 
 #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 687598e41b21..b726332eec49 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile
@@ -10,4 +10,4 @@ subdir-ccflags-y := -I$(incdir)				\
 		    -DDISABLE_BRANCH_PROFILING		\
 		    $(DISABLE_STACKLEAK_PLUGIN)
 
-obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o
+obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o reserved_mem.o
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
new file mode 100644
index 000000000000..ac0f7fcffd08
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __KVM_HYP_MM_H
+#define __KVM_HYP_MM_H
+
+#include <asm/kvm_pgtable.h>
+#include <asm/spectre.h>
+#include <linux/memblock.h>
+#include <linux/types.h>
+
+#include <nvhe/memory.h>
+#include <nvhe/spinlock.h>
+
+#define HYP_MEMBLOCK_REGIONS 128
+extern struct memblock_region kvm_nvhe_sym(hyp_memory)[];
+extern unsigned int kvm_nvhe_sym(hyp_memblock_nr);
+extern struct kvm_pgtable pkvm_pgtable;
+extern hyp_spinlock_t pkvm_pgd_lock;
+extern struct hyp_pool hpool;
+extern u64 __io_map_base;
+
+int hyp_create_idmap(u32 hyp_va_bits);
+int hyp_map_vectors(void);
+int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back);
+int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot);
+int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
+int __pkvm_create_mappings(unsigned long start, unsigned long size,
+			   unsigned long phys, enum kvm_pgtable_prot prot);
+unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
+					    enum kvm_pgtable_prot prot);
+
+static inline void hyp_vmemmap_range(phys_addr_t phys, unsigned long size,
+				     unsigned long *start, unsigned long *end)
+{
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	struct hyp_page *p = hyp_phys_to_page(phys);
+
+	*start = (unsigned long)p;
+	*end = *start + nr_pages * sizeof(struct hyp_page);
+	*start = ALIGN_DOWN(*start, PAGE_SIZE);
+	*end = ALIGN(*end, PAGE_SIZE);
+}
+
+static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
+{
+	unsigned long total = 0, i;
+
+	/* Provision the worst case scenario */
+	for (i = 0; i < KVM_PGTABLE_MAX_LEVELS; i++) {
+		nr_pages = DIV_ROUND_UP(nr_pages, PTRS_PER_PTE);
+		total += nr_pages;
+	}
+
+	return total;
+}
+
+static inline unsigned long hyp_s1_pgtable_pages(void)
+{
+	unsigned long res = 0, i;
+
+	/* Cover all of memory with page-granularity */
+	for (i = 0; i < kvm_nvhe_sym(hyp_memblock_nr); i++) {
+		struct memblock_region *reg = &kvm_nvhe_sym(hyp_memory)[i];
+		res += __hyp_pgtable_max_pages(reg->size >> PAGE_SHIFT);
+	}
+
+	/* Allow 1 GiB for private mappings */
+	res += __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
+
+	return res;
+}
+#endif /* __KVM_HYP_MM_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 0033591553fc..e204ea77ab27 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -14,9 +14,9 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
 	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \
-	 cache.o cpufeature.o
+	 cache.o cpufeature.o setup.o mm.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
-	 ../fpsimd.o ../hyp-entry.o ../exception.o
+	 ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
 obj-y += $(lib-objs)
 
 ##
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index c631e29fb001..a2b8b6a84cbd 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -244,4 +244,31 @@ alternative_else_nop_endif
 
 SYM_CODE_END(__kvm_handle_stub_hvc)
 
+SYM_FUNC_START(__pkvm_init_switch_pgd)
+	/* Turn the MMU off */
+	pre_disable_mmu_workaround
+	mrs	x2, sctlr_el2
+	bic	x3, x2, #SCTLR_ELx_M
+	msr	sctlr_el2, x3
+	isb
+
+	tlbi	alle2
+
+	/* Install the new pgtables */
+	ldr	x3, [x0, #NVHE_INIT_PGD_PA]
+	phys_to_ttbr x4, x3
+alternative_if ARM64_HAS_CNP
+	orr	x4, x4, #TTBR_CNP_BIT
+alternative_else_nop_endif
+	msr	ttbr0_el2, x4
+
+	/* Set the new stack pointer */
+	ldr	x0, [x0, #NVHE_INIT_STACK_HYP_VA]
+	mov	sp, x0
+
+	/* And turn the MMU back on! */
+	set_sctlr_el2	x2
+	ret	x1
+SYM_FUNC_END(__pkvm_init_switch_pgd)
+
 	.popsection
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index f012f8665ecc..ae6503c9be15 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -6,12 +6,14 @@
 
 #include <hyp/switch.h>
 
+#include <asm/pgtable-types.h>
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_host.h>
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 
+#include <nvhe/mm.h>
 #include <nvhe/trap_handler.h>
 
 DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
@@ -106,6 +108,49 @@ static void handle___vgic_v3_restore_aprs(struct kvm_cpu_context *host_ctxt)
 	__vgic_v3_restore_aprs(kern_hyp_va(cpu_if));
 }
 
+static void handle___pkvm_init(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
+	DECLARE_REG(unsigned long, size, host_ctxt, 2);
+	DECLARE_REG(unsigned long, nr_cpus, host_ctxt, 3);
+	DECLARE_REG(unsigned long *, per_cpu_base, host_ctxt, 4);
+	DECLARE_REG(u32, hyp_va_bits, host_ctxt, 5);
+
+	/*
+	 * __pkvm_init() will return only if an error occurred, otherwise it
+	 * will tail-call in __pkvm_init_finalise() which will have to deal
+	 * with the host context directly.
+	 */
+	cpu_reg(host_ctxt, 1) = __pkvm_init(phys, size, nr_cpus, per_cpu_base,
+					    hyp_va_bits);
+}
+
+static void handle___pkvm_cpu_set_vector(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(enum arm64_hyp_spectre_vector, slot, host_ctxt, 1);
+
+	cpu_reg(host_ctxt, 1) = pkvm_cpu_set_vector(slot);
+}
+
+static void handle___pkvm_create_mappings(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(unsigned long, start, host_ctxt, 1);
+	DECLARE_REG(unsigned long, size, host_ctxt, 2);
+	DECLARE_REG(unsigned long, phys, host_ctxt, 3);
+	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 4);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_create_mappings(start, size, phys, prot);
+}
+
+static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
+	DECLARE_REG(size_t, size, host_ctxt, 2);
+	DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 3);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_create_private_mapping(phys, size, prot);
+}
+
 typedef void (*hcall_t)(struct kvm_cpu_context *);
 
 #define HANDLE_FUNC(x)	[__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
@@ -125,6 +170,10 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__kvm_get_mdcr_el2),
 	HANDLE_FUNC(__vgic_v3_save_aprs),
 	HANDLE_FUNC(__vgic_v3_restore_aprs),
+	HANDLE_FUNC(__pkvm_init),
+	HANDLE_FUNC(__pkvm_cpu_set_vector),
+	HANDLE_FUNC(__pkvm_create_mappings),
+	HANDLE_FUNC(__pkvm_create_private_mapping),
 };
 
 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
new file mode 100644
index 000000000000..a8efdf0f9003
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_pgtable.h>
+#include <asm/spectre.h>
+
+#include <nvhe/early_alloc.h>
+#include <nvhe/gfp.h>
+#include <nvhe/memory.h>
+#include <nvhe/mm.h>
+#include <nvhe/spinlock.h>
+
+struct kvm_pgtable pkvm_pgtable;
+hyp_spinlock_t pkvm_pgd_lock;
+u64 __io_map_base;
+
+struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
+unsigned int hyp_memblock_nr;
+
+int __pkvm_create_mappings(unsigned long start, unsigned long size,
+			  unsigned long phys, enum kvm_pgtable_prot prot)
+{
+	int err;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+	err = kvm_pgtable_hyp_map(&pkvm_pgtable, start, size, phys, prot);
+	hyp_spin_unlock(&pkvm_pgd_lock);
+
+	return err;
+}
+
+unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
+					    enum kvm_pgtable_prot prot)
+{
+	unsigned long addr;
+	int err;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+
+	size = PAGE_ALIGN(size + offset_in_page(phys));
+	addr = __io_map_base;
+	__io_map_base += size;
+
+	/* Are we overflowing on the vmemmap ? */
+	if (__io_map_base > __hyp_vmemmap) {
+		__io_map_base -= size;
+		addr = (unsigned long)ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	err = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, size, phys, prot);
+	if (err) {
+		addr = (unsigned long)ERR_PTR(err);
+		goto out;
+	}
+
+	addr = addr + offset_in_page(phys);
+out:
+	hyp_spin_unlock(&pkvm_pgd_lock);
+
+	return addr;
+}
+
+int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
+{
+	unsigned long start = (unsigned long)from;
+	unsigned long end = (unsigned long)to;
+	unsigned long virt_addr;
+	phys_addr_t phys;
+
+	start = start & PAGE_MASK;
+	end = PAGE_ALIGN(end);
+
+	for (virt_addr = start; virt_addr < end; virt_addr += PAGE_SIZE) {
+		int err;
+
+		phys = hyp_virt_to_phys((void *)virt_addr);
+		err = __pkvm_create_mappings(virt_addr, PAGE_SIZE, phys, prot);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back)
+{
+	unsigned long start, end;
+
+	hyp_vmemmap_range(phys, size, &start, &end);
+
+	return __pkvm_create_mappings(start, end - start, back, PAGE_HYP);
+}
+
+static void *__hyp_bp_vect_base;
+int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot)
+{
+	void *vector;
+
+	switch (slot) {
+	case HYP_VECTOR_DIRECT: {
+		vector = __kvm_hyp_vector;
+		break;
+	}
+	case HYP_VECTOR_SPECTRE_DIRECT: {
+		vector = __bp_harden_hyp_vecs;
+		break;
+	}
+	case HYP_VECTOR_INDIRECT:
+	case HYP_VECTOR_SPECTRE_INDIRECT: {
+		vector = (void *)__hyp_bp_vect_base;
+		break;
+	}
+	default:
+		return -EINVAL;
+	}
+
+	vector = __kvm_vector_slot2addr(vector, slot);
+	*this_cpu_ptr(&kvm_hyp_vector) = (unsigned long)vector;
+
+	return 0;
+}
+
+int hyp_map_vectors(void)
+{
+	phys_addr_t phys;
+	void *bp_base;
+
+	if (!cpus_have_const_cap(ARM64_SPECTRE_V3A))
+		return 0;
+
+	phys = __hyp_pa(__bp_harden_hyp_vecs);
+	bp_base = (void *)__pkvm_create_private_mapping(phys,
+							__BP_HARDEN_HYP_VECS_SZ,
+							PAGE_HYP_EXEC);
+	if (IS_ERR_OR_NULL(bp_base))
+		return PTR_ERR(bp_base);
+
+	__hyp_bp_vect_base = bp_base;
+
+	return 0;
+}
+
+int hyp_create_idmap(u32 hyp_va_bits)
+{
+	unsigned long start, end;
+
+	start = hyp_virt_to_phys((void *)__hyp_idmap_text_start);
+	start = ALIGN_DOWN(start, PAGE_SIZE);
+
+	end = hyp_virt_to_phys((void *)__hyp_idmap_text_end);
+	end = ALIGN(end, PAGE_SIZE);
+
+	/*
+	 * One half of the VA space is reserved to linearly map portions of
+	 * memory -- see va_layout.c for more details. The other half of the VA
+	 * space contains the trampoline page, and needs some care. Split that
+	 * second half in two and find the quarter of VA space not conflicting
+	 * with the idmap to place the IOs and the vmemmap. IOs use the lower
+	 * half of the quarter and the vmemmap the upper half.
+	 */
+	__io_map_base = start & BIT(hyp_va_bits - 2);
+	__io_map_base ^= BIT(hyp_va_bits - 2);
+	__hyp_vmemmap = __io_map_base | BIT(hyp_va_bits - 3);
+
+	return __pkvm_create_mappings(start, end - start, start, PAGE_HYP_EXEC);
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
new file mode 100644
index 000000000000..1e8bcd8b0299
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_pgtable.h>
+
+#include <nvhe/early_alloc.h>
+#include <nvhe/gfp.h>
+#include <nvhe/memory.h>
+#include <nvhe/mm.h>
+#include <nvhe/trap_handler.h>
+
+struct hyp_pool hpool;
+struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
+unsigned long hyp_nr_cpus;
+
+#define hyp_percpu_size ((unsigned long)__per_cpu_end - \
+			 (unsigned long)__per_cpu_start)
+
+static void *vmemmap_base;
+static void *hyp_pgt_base;
+
+static int divide_memory_pool(void *virt, unsigned long size)
+{
+	unsigned long vstart, vend, nr_pages;
+
+	hyp_early_alloc_init(virt, size);
+
+	hyp_vmemmap_range(__hyp_pa(virt), size, &vstart, &vend);
+	nr_pages = (vend - vstart) >> PAGE_SHIFT;
+	vmemmap_base = hyp_early_alloc_contig(nr_pages);
+	if (!vmemmap_base)
+		return -ENOMEM;
+
+	nr_pages = hyp_s1_pgtable_pages();
+	hyp_pgt_base = hyp_early_alloc_contig(nr_pages);
+	if (!hyp_pgt_base)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
+				 unsigned long *per_cpu_base,
+				 u32 hyp_va_bits)
+{
+	void *start, *end, *virt = hyp_phys_to_virt(phys);
+	unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT;
+	int ret, i;
+
+	/* Recreate the hyp page-table using the early page allocator */
+	hyp_early_alloc_init(hyp_pgt_base, pgt_size);
+	ret = kvm_pgtable_hyp_init(&pkvm_pgtable, hyp_va_bits,
+				   &hyp_early_alloc_mm_ops);
+	if (ret)
+		return ret;
+
+	ret = hyp_create_idmap(hyp_va_bits);
+	if (ret)
+		return ret;
+
+	ret = hyp_map_vectors();
+	if (ret)
+		return ret;
+
+	ret = hyp_back_vmemmap(phys, size, hyp_virt_to_phys(vmemmap_base));
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(__hyp_text_start, __hyp_text_end, PAGE_HYP_EXEC);
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(__start_rodata, __end_rodata, PAGE_HYP_RO);
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(__hyp_rodata_start, __hyp_rodata_end, PAGE_HYP_RO);
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(__hyp_bss_start, __hyp_bss_end, PAGE_HYP);
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(__hyp_bss_end, __bss_stop, PAGE_HYP_RO);
+	if (ret)
+		return ret;
+
+	ret = pkvm_create_mappings(virt, virt + size, PAGE_HYP);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < hyp_nr_cpus; i++) {
+		start = (void *)kern_hyp_va(per_cpu_base[i]);
+		end = start + PAGE_ALIGN(hyp_percpu_size);
+		ret = pkvm_create_mappings(start, end, PAGE_HYP);
+		if (ret)
+			return ret;
+
+		end = (void *)per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va;
+		start = end - PAGE_SIZE;
+		ret = pkvm_create_mappings(start, end, PAGE_HYP);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static void update_nvhe_init_params(void)
+{
+	struct kvm_nvhe_init_params *params;
+	unsigned long i;
+
+	for (i = 0; i < hyp_nr_cpus; i++) {
+		params = per_cpu_ptr(&kvm_init_params, i);
+		params->pgd_pa = __hyp_pa(pkvm_pgtable.pgd);
+		__flush_dcache_area(params, sizeof(*params));
+	}
+}
+
+static void *hyp_zalloc_hyp_page(void *arg)
+{
+	return hyp_alloc_pages(&hpool, 0);
+}
+
+void __noreturn __pkvm_init_finalise(void)
+{
+	struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
+	struct kvm_cpu_context *host_ctxt = &host_data->host_ctxt;
+	unsigned long nr_pages, reserved_pages, pfn;
+	int ret;
+
+	/* Now that the vmemmap is backed, install the full-fledged allocator */
+	pfn = hyp_virt_to_pfn(hyp_pgt_base);
+	nr_pages = hyp_s1_pgtable_pages();
+	reserved_pages = hyp_early_alloc_nr_used_pages();
+	ret = hyp_pool_init(&hpool, pfn, nr_pages, reserved_pages);
+	if (ret)
+		goto out;
+
+	pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
+		.zalloc_page = hyp_zalloc_hyp_page,
+		.phys_to_virt = hyp_phys_to_virt,
+		.virt_to_phys = hyp_virt_to_phys,
+		.get_page = hyp_get_page,
+		.put_page = hyp_put_page,
+	};
+	pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;
+
+out:
+	/*
+	 * We tail-called to here from handle___pkvm_init() and will not return,
+	 * so make sure to propagate the return value to the host.
+	 */
+	cpu_reg(host_ctxt, 1) = ret;
+
+	__host_enter(host_ctxt);
+}
+
+int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
+		unsigned long *per_cpu_base, u32 hyp_va_bits)
+{
+	struct kvm_nvhe_init_params *params;
+	void *virt = hyp_phys_to_virt(phys);
+	void (*fn)(phys_addr_t params_pa, void *finalize_fn_va);
+	int ret;
+
+	if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size))
+		return -EINVAL;
+
+	hyp_spin_lock_init(&pkvm_pgd_lock);
+	hyp_nr_cpus = nr_cpus;
+
+	ret = divide_memory_pool(virt, size);
+	if (ret)
+		return ret;
+
+	ret = recreate_hyp_mappings(phys, size, per_cpu_base, hyp_va_bits);
+	if (ret)
+		return ret;
+
+	update_nvhe_init_params();
+
+	/* Jump in the idmap page to switch to the new page-tables */
+	params = this_cpu_ptr(&kvm_init_params);
+	fn = (typeof(fn))__hyp_pa(__pkvm_init_switch_pgd);
+	fn(__hyp_pa(params), __pkvm_init_finalise);
+
+	unreachable();
+}
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index b975a67d1f85..7ce0969203e8 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -10,8 +10,6 @@
 #include <linux/bitfield.h>
 #include <asm/kvm_pgtable.h>
 
-#define KVM_PGTABLE_MAX_LEVELS		4U
-
 #define KVM_PTE_VALID			BIT(0)
 
 #define KVM_PTE_TYPE			BIT(1)
diff --git a/arch/arm64/kvm/hyp/reserved_mem.c b/arch/arm64/kvm/hyp/reserved_mem.c
new file mode 100644
index 000000000000..9bc6a6d27904
--- /dev/null
+++ b/arch/arm64/kvm/hyp/reserved_mem.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/memblock.h>
+
+#include <asm/kvm_host.h>
+
+#include <nvhe/memory.h>
+#include <nvhe/mm.h>
+
+static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory);
+static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr);
+
+phys_addr_t hyp_mem_base;
+phys_addr_t hyp_mem_size;
+
+static int __init register_memblock_regions(void)
+{
+	struct memblock_region *reg;
+
+	for_each_mem_region(reg) {
+		if (*hyp_memblock_nr_ptr >= HYP_MEMBLOCK_REGIONS)
+			return -ENOMEM;
+
+		hyp_memory[*hyp_memblock_nr_ptr] = *reg;
+		(*hyp_memblock_nr_ptr)++;
+	}
+
+	return 0;
+}
+
+void __init kvm_hyp_reserve(void)
+{
+	u64 nr_pages, prev, hyp_mem_pages = 0;
+	int ret;
+
+	if (!is_hyp_mode_available() || is_kernel_in_hyp_mode())
+		return;
+
+	if (kvm_get_mode() != KVM_MODE_PROTECTED)
+		return;
+
+	ret = register_memblock_regions();
+	if (ret) {
+		*hyp_memblock_nr_ptr = 0;
+		kvm_err("Failed to register hyp memblocks: %d\n", ret);
+		return;
+	}
+
+	hyp_mem_pages += hyp_s1_pgtable_pages();
+
+	/*
+	 * The hyp_vmemmap needs to be backed by pages, but these pages
+	 * themselves need to be present in the vmemmap, so compute the number
+	 * of pages needed by looking for a fixed point.
+	 */
+	nr_pages = 0;
+	do {
+		prev = nr_pages;
+		nr_pages = hyp_mem_pages + prev;
+		nr_pages = DIV_ROUND_UP(nr_pages * sizeof(struct hyp_page), PAGE_SIZE);
+		nr_pages += __hyp_pgtable_max_pages(nr_pages);
+	} while (nr_pages != prev);
+	hyp_mem_pages += nr_pages;
+
+	/*
+	 * Try to allocate a PMD-aligned region to reduce TLB pressure once
+	 * this is unmapped from the host stage-2, and fallback to PAGE_SIZE.
+	 */
+	hyp_mem_size = hyp_mem_pages << PAGE_SHIFT;
+	hyp_mem_base = memblock_find_in_range(0, memblock_end_of_DRAM(),
+					      ALIGN(hyp_mem_size, PMD_SIZE),
+					      PMD_SIZE);
+	if (!hyp_mem_base)
+		hyp_mem_base = memblock_find_in_range(0, memblock_end_of_DRAM(),
+						      hyp_mem_size, PAGE_SIZE);
+	else
+		hyp_mem_size = ALIGN(hyp_mem_size, PMD_SIZE);
+
+	if (!hyp_mem_base) {
+		kvm_err("Failed to reserve hyp memory\n");
+		return;
+	}
+	memblock_reserve(hyp_mem_base, hyp_mem_size);
+
+	kvm_info("Reserved %lld MiB at 0x%llx\n", hyp_mem_size >> 20,
+		 hyp_mem_base);
+}
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 0ace5e68efba..2b1b41b1ff9b 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -35,6 +35,7 @@
 #include <asm/fixmap.h>
 #include <asm/kasan.h>
 #include <asm/kernel-pgtable.h>
+#include <asm/kvm_host.h>
 #include <asm/memory.h>
 #include <asm/numa.h>
 #include <asm/sections.h>
@@ -429,6 +430,8 @@ void __init bootmem_init(void)
 
 	dma_pernuma_cma_reserve();
 
+	kvm_hyp_reserve();
+
 	/*
 	 * sparse_init() tries to allocate memory from memblock, so must be
 	 * done after the fixed reservations
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation at EL2
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (15 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2 Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 17:28   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 18/34] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
                   ` (16 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Previous commits have introduced infrastructure to enable the EL2 code
to manage its own stage 1 mappings. However, this was preliminary work,
and none of it is currently in use.

Put all of this together by elevating the mapping creation at EL2 when
memory protection is enabled. In this case, the host kernel running
at EL1 still creates _temporary_ EL2 mappings, only used while
initializing the hypervisor, but frees them right after.

As such, all calls to create_hyp_mappings() after kvm init has finished
turn into hypercalls, as the host now has no 'legal' way to modify the
hypevisor page tables directly.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_mmu.h |  2 +-
 arch/arm64/kvm/arm.c             | 87 +++++++++++++++++++++++++++++---
 arch/arm64/kvm/mmu.c             | 43 ++++++++++++++--
 3 files changed, 120 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 5c42ec023cc7..ce02a4052dcf 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -166,7 +166,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu);
 
 phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
-int kvm_mmu_init(void);
+int kvm_mmu_init(u32 *hyp_va_bits);
 
 static inline void *__kvm_vector_slot2addr(void *base,
 					   enum arm64_hyp_spectre_vector slot)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 26e573cdede3..7d62211109d9 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1421,7 +1421,7 @@ static void cpu_prepare_hyp_mode(int cpu)
 	kvm_flush_dcache_to_poc(params, sizeof(*params));
 }
 
-static void cpu_init_hyp_mode(void)
+static void hyp_install_host_vector(void)
 {
 	struct kvm_nvhe_init_params *params;
 	struct arm_smccc_res res;
@@ -1439,6 +1439,11 @@ static void cpu_init_hyp_mode(void)
 	params = this_cpu_ptr_nvhe_sym(kvm_init_params);
 	arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init), virt_to_phys(params), &res);
 	WARN_ON(res.a0 != SMCCC_RET_SUCCESS);
+}
+
+static void cpu_init_hyp_mode(void)
+{
+	hyp_install_host_vector();
 
 	/*
 	 * Disabling SSBD on a non-VHE system requires us to enable SSBS
@@ -1481,7 +1486,10 @@ static void cpu_set_hyp_vector(void)
 	struct bp_hardening_data *data = this_cpu_ptr(&bp_hardening_data);
 	void *vector = hyp_spectre_vector_selector[data->slot];
 
-	*this_cpu_ptr_hyp_sym(kvm_hyp_vector) = (unsigned long)vector;
+	if (!is_protected_kvm_enabled())
+		*this_cpu_ptr_hyp_sym(kvm_hyp_vector) = (unsigned long)vector;
+	else
+		kvm_call_hyp_nvhe(__pkvm_cpu_set_vector, data->slot);
 }
 
 static void cpu_hyp_reinit(void)
@@ -1489,13 +1497,14 @@ static void cpu_hyp_reinit(void)
 	kvm_init_host_cpu_context(&this_cpu_ptr_hyp_sym(kvm_host_data)->host_ctxt);
 
 	cpu_hyp_reset();
-	cpu_set_hyp_vector();
 
 	if (is_kernel_in_hyp_mode())
 		kvm_timer_init_vhe();
 	else
 		cpu_init_hyp_mode();
 
+	cpu_set_hyp_vector();
+
 	kvm_arm_init_debug();
 
 	if (vgic_present)
@@ -1691,18 +1700,59 @@ static void teardown_hyp_mode(void)
 	}
 }
 
+static int do_pkvm_init(u32 hyp_va_bits)
+{
+	void *per_cpu_base = kvm_ksym_ref(kvm_arm_hyp_percpu_base);
+	int ret;
+
+	preempt_disable();
+	hyp_install_host_vector();
+	ret = kvm_call_hyp_nvhe(__pkvm_init, hyp_mem_base, hyp_mem_size,
+				num_possible_cpus(), kern_hyp_va(per_cpu_base),
+				hyp_va_bits);
+	preempt_enable();
+
+	return ret;
+}
+
+static int kvm_hyp_init_protection(u32 hyp_va_bits)
+{
+	void *addr = phys_to_virt(hyp_mem_base);
+	int ret;
+
+	ret = create_hyp_mappings(addr, addr + hyp_mem_size, PAGE_HYP);
+	if (ret)
+		return ret;
+
+	ret = do_pkvm_init(hyp_va_bits);
+	if (ret)
+		return ret;
+
+	free_hyp_pgds();
+
+	return 0;
+}
+
 /**
  * Inits Hyp-mode on all online CPUs
  */
 static int init_hyp_mode(void)
 {
+	u32 hyp_va_bits;
 	int cpu;
-	int err = 0;
+	int err = -ENOMEM;
+
+	/*
+	 * The protected Hyp-mode cannot be initialized if the memory pool
+	 * allocation has failed.
+	 */
+	if (is_protected_kvm_enabled() && !hyp_mem_base)
+		goto out_err;
 
 	/*
 	 * Allocate Hyp PGD and setup Hyp identity mapping
 	 */
-	err = kvm_mmu_init();
+	err = kvm_mmu_init(&hyp_va_bits);
 	if (err)
 		goto out_err;
 
@@ -1818,6 +1868,14 @@ static int init_hyp_mode(void)
 			goto out_err;
 	}
 
+	if (is_protected_kvm_enabled()) {
+		err = kvm_hyp_init_protection(hyp_va_bits);
+		if (err) {
+			kvm_err("Failed to init hyp memory protection\n");
+			goto out_err;
+		}
+	}
+
 	return 0;
 
 out_err:
@@ -1826,6 +1884,16 @@ static int init_hyp_mode(void)
 	return err;
 }
 
+static int finalize_hyp_mode(void)
+{
+	if (!is_protected_kvm_enabled())
+		return 0;
+
+	static_branch_enable(&kvm_protected_mode_initialized);
+
+	return 0;
+}
+
 static void check_kvm_target_cpu(void *ret)
 {
 	*(int *)ret = kvm_target_cpu();
@@ -1942,8 +2010,15 @@ int kvm_arch_init(void *opaque)
 	if (err)
 		goto out_hyp;
 
+	if (!in_hyp_mode) {
+		err = finalize_hyp_mode();
+		if (err) {
+			kvm_err("Failed to finalize Hyp protection\n");
+			goto out_hyp;
+		}
+	}
+
 	if (is_protected_kvm_enabled()) {
-		static_branch_enable(&kvm_protected_mode_initialized);
 		kvm_info("Protected nVHE mode initialized successfully\n");
 	} else if (in_hyp_mode) {
 		kvm_info("VHE mode initialized successfully\n");
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 4d41d7838d53..9d331bf262d2 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -221,15 +221,39 @@ void free_hyp_pgds(void)
 	if (hyp_pgtable) {
 		kvm_pgtable_hyp_destroy(hyp_pgtable);
 		kfree(hyp_pgtable);
+		hyp_pgtable = NULL;
 	}
 	mutex_unlock(&kvm_hyp_pgd_mutex);
 }
 
+static bool kvm_host_owns_hyp_mappings(void)
+{
+	if (static_branch_likely(&kvm_protected_mode_initialized))
+		return false;
+
+	/*
+	 * This can happen at boot time when __create_hyp_mappings() is called
+	 * after the hyp protection has been enabled, but the static key has
+	 * not been flipped yet.
+	 */
+	if (!hyp_pgtable && is_protected_kvm_enabled())
+		return false;
+
+	WARN_ON(!hyp_pgtable);
+
+	return true;
+}
+
 static int __create_hyp_mappings(unsigned long start, unsigned long size,
 				 unsigned long phys, enum kvm_pgtable_prot prot)
 {
 	int err;
 
+	if (!kvm_host_owns_hyp_mappings()) {
+		return kvm_call_hyp_nvhe(__pkvm_create_mappings,
+					 start, size, phys, prot);
+	}
+
 	mutex_lock(&kvm_hyp_pgd_mutex);
 	err = kvm_pgtable_hyp_map(hyp_pgtable, start, size, phys, prot);
 	mutex_unlock(&kvm_hyp_pgd_mutex);
@@ -291,6 +315,16 @@ static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
 	unsigned long base;
 	int ret = 0;
 
+	if (!kvm_host_owns_hyp_mappings()) {
+		base = kvm_call_hyp_nvhe(__pkvm_create_private_mapping,
+					 phys_addr, size, prot);
+		if (IS_ERR_OR_NULL((void *)base))
+			return PTR_ERR((void *)base);
+		*haddr = base;
+
+		return 0;
+	}
+
 	mutex_lock(&kvm_hyp_pgd_mutex);
 
 	/*
@@ -1270,10 +1304,9 @@ static struct kvm_pgtable_mm_ops kvm_hyp_mm_ops = {
 	.virt_to_phys		= kvm_host_pa,
 };
 
-int kvm_mmu_init(void)
+int kvm_mmu_init(u32 *hyp_va_bits)
 {
 	int err;
-	u32 hyp_va_bits;
 
 	hyp_idmap_start = __pa_symbol(__hyp_idmap_text_start);
 	hyp_idmap_start = ALIGN_DOWN(hyp_idmap_start, PAGE_SIZE);
@@ -1287,8 +1320,8 @@ int kvm_mmu_init(void)
 	 */
 	BUG_ON((hyp_idmap_start ^ (hyp_idmap_end - 1)) & PAGE_MASK);
 
-	hyp_va_bits = 64 - ((idmap_t0sz & TCR_T0SZ_MASK) >> TCR_T0SZ_OFFSET);
-	kvm_debug("Using %u-bit virtual addresses at EL2\n", hyp_va_bits);
+	*hyp_va_bits = 64 - ((idmap_t0sz & TCR_T0SZ_MASK) >> TCR_T0SZ_OFFSET);
+	kvm_debug("Using %u-bit virtual addresses at EL2\n", *hyp_va_bits);
 	kvm_debug("IDMAP page: %lx\n", hyp_idmap_start);
 	kvm_debug("HYP VA range: %lx:%lx\n",
 		  kern_hyp_va(PAGE_OFFSET),
@@ -1313,7 +1346,7 @@ int kvm_mmu_init(void)
 		goto out;
 	}
 
-	err = kvm_pgtable_hyp_init(hyp_pgtable, hyp_va_bits, &kvm_hyp_mm_ops);
+	err = kvm_pgtable_hyp_init(hyp_pgtable, *hyp_va_bits, &kvm_hyp_mm_ops);
 	if (err)
 		goto out_free_pgtable;
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 18/34] KVM: arm64: Use kvm_arch for stage 2 pgtable
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (16 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation " Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 19/34] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
                   ` (15 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to make use of the stage 2 pgtable code for the host stage 2,
use struct kvm_arch in lieu of struct kvm as the host will have the
former but not the latter.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 5 +++--
 arch/arm64/kvm/hyp/pgtable.c         | 6 +++---
 arch/arm64/kvm/mmu.c                 | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index bf7a3cc49420..7945ec87eaec 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -162,12 +162,13 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
 /**
  * kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
  * @pgt:	Uninitialised page-table structure to initialise.
- * @kvm:	KVM structure representing the guest virtual machine.
+ * @arch:	Arch-specific KVM structure representing the guest virtual
+ *		machine.
  * @mm_ops:	Memory management callbacks.
  *
  * Return: 0 on success, negative error code on failure.
  */
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_arch *arch,
 			    struct kvm_pgtable_mm_ops *mm_ops);
 
 /**
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 7ce0969203e8..3d79c8094cdd 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -879,11 +879,11 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	return kvm_pgtable_walk(pgt, addr, size, &walker);
 }
 
-int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
+int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_arch *arch,
 			    struct kvm_pgtable_mm_ops *mm_ops)
 {
 	size_t pgd_sz;
-	u64 vtcr = kvm->arch.vtcr;
+	u64 vtcr = arch->vtcr;
 	u32 ia_bits = VTCR_EL2_IPA(vtcr);
 	u32 sl0 = FIELD_GET(VTCR_EL2_SL0_MASK, vtcr);
 	u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
@@ -896,7 +896,7 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm,
 	pgt->ia_bits		= ia_bits;
 	pgt->start_level	= start_level;
 	pgt->mm_ops		= mm_ops;
-	pgt->mmu		= &kvm->arch.mmu;
+	pgt->mmu		= &arch->mmu;
 
 	/* Ensure zeroed PGD pages are visible to the hardware walker */
 	dsb(ishst);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 9d331bf262d2..41f9c03cbcc3 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -457,7 +457,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
 	if (!pgt)
 		return -ENOMEM;
 
-	err = kvm_pgtable_stage2_init(pgt, kvm, &kvm_s2_mm_ops);
+	err = kvm_pgtable_stage2_init(pgt, &kvm->arch, &kvm_s2_mm_ops);
 	if (err)
 		goto out_free_pgtable;
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 19/34] KVM: arm64: Use kvm_arch in kvm_s2_mmu
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (17 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 18/34] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 20/34] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
                   ` (14 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to make use of the stage 2 pgtable code for the host stage 2,
change kvm_s2_mmu to use a kvm_arch pointer in lieu of the kvm pointer,
as the host will have the former but not the latter.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_host.h | 2 +-
 arch/arm64/include/asm/kvm_mmu.h  | 6 +++++-
 arch/arm64/kvm/mmu.c              | 8 ++++----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b9d45a1f8538..90565782ce3e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -94,7 +94,7 @@ struct kvm_s2_mmu {
 	/* The last vcpu id that ran on each physical CPU */
 	int __percpu *last_vcpu_ran;
 
-	struct kvm *kvm;
+	struct kvm_arch *arch;
 };
 
 struct kvm_arch_memory_slot {
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index ce02a4052dcf..6f743e20cb06 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -272,7 +272,7 @@ static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
  */
 static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
 {
-	write_sysreg(kern_hyp_va(mmu->kvm)->arch.vtcr, vtcr_el2);
+	write_sysreg(kern_hyp_va(mmu->arch)->vtcr, vtcr_el2);
 	write_sysreg(kvm_get_vttbr(mmu), vttbr_el2);
 
 	/*
@@ -283,5 +283,9 @@ static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 }
 
+static inline struct kvm *kvm_s2_mmu_to_kvm(struct kvm_s2_mmu *mmu)
+{
+	return container_of(mmu->arch, struct kvm, arch);
+}
 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 41f9c03cbcc3..3257cadfab24 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -165,7 +165,7 @@ static void *kvm_host_va(phys_addr_t phys)
 static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size,
 				 bool may_block)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	phys_addr_t end = start + size;
 
 	assert_spin_locked(&kvm->mmu_lock);
@@ -470,7 +470,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
 	for_each_possible_cpu(cpu)
 		*per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;
 
-	mmu->kvm = kvm;
+	mmu->arch = &kvm->arch;
 	mmu->pgt = pgt;
 	mmu->pgd_phys = __pa(pgt->pgd);
 	mmu->vmid.vmid_gen = 0;
@@ -552,7 +552,7 @@ void stage2_unmap_vm(struct kvm *kvm)
 
 void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	struct kvm_pgtable *pgt = NULL;
 
 	spin_lock(&kvm->mmu_lock);
@@ -621,7 +621,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
  */
 static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
 {
-	struct kvm *kvm = mmu->kvm;
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
 	stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_wrprotect);
 }
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 20/34] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (18 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 19/34] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 21/34] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
                   ` (13 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Move the registers relevant to host stage 2 enablement to
kvm_nvhe_init_params to prepare the ground for enabling it in later
patches.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_asm.h   |  3 +++
 arch/arm64/kernel/asm-offsets.c    |  3 +++
 arch/arm64/kvm/arm.c               |  5 +++++
 arch/arm64/kvm/hyp/nvhe/hyp-init.S | 14 +++++++++-----
 arch/arm64/kvm/hyp/nvhe/switch.c   |  5 +----
 5 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index db20a9477870..6dce860f8bca 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -158,6 +158,9 @@ struct kvm_nvhe_init_params {
 	unsigned long tpidr_el2;
 	unsigned long stack_hyp_va;
 	phys_addr_t pgd_pa;
+	unsigned long hcr_el2;
+	unsigned long vttbr;
+	unsigned long vtcr;
 };
 
 /* Translate a kernel address @ptr into its equivalent linear mapping */
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index a36e2fc330d4..8930b42f6418 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -120,6 +120,9 @@ int main(void)
   DEFINE(NVHE_INIT_TPIDR_EL2,	offsetof(struct kvm_nvhe_init_params, tpidr_el2));
   DEFINE(NVHE_INIT_STACK_HYP_VA,	offsetof(struct kvm_nvhe_init_params, stack_hyp_va));
   DEFINE(NVHE_INIT_PGD_PA,	offsetof(struct kvm_nvhe_init_params, pgd_pa));
+  DEFINE(NVHE_INIT_HCR_EL2,	offsetof(struct kvm_nvhe_init_params, hcr_el2));
+  DEFINE(NVHE_INIT_VTTBR,	offsetof(struct kvm_nvhe_init_params, vttbr));
+  DEFINE(NVHE_INIT_VTCR,	offsetof(struct kvm_nvhe_init_params, vtcr));
 #endif
 #ifdef CONFIG_CPU_PM
   DEFINE(CPU_CTX_SP,		offsetof(struct cpu_suspend_ctx, sp));
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7d62211109d9..d474eec606a3 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1413,6 +1413,11 @@ static void cpu_prepare_hyp_mode(int cpu)
 
 	params->stack_hyp_va = kern_hyp_va(per_cpu(kvm_arm_hyp_stack_page, cpu) + PAGE_SIZE);
 	params->pgd_pa = kvm_mmu_get_httbr();
+	if (is_protected_kvm_enabled())
+		params->hcr_el2 = HCR_HOST_NVHE_PROTECTED_FLAGS;
+	else
+		params->hcr_el2 = HCR_HOST_NVHE_FLAGS;
+	params->vttbr = params->vtcr = 0;
 
 	/*
 	 * Flush the init params from the data cache because the struct will
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index a2b8b6a84cbd..a50ad9e9fc05 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -83,11 +83,6 @@ SYM_CODE_END(__kvm_hyp_init)
  * x0: struct kvm_nvhe_init_params PA
  */
 SYM_CODE_START_LOCAL(___kvm_hyp_init)
-alternative_if ARM64_KVM_PROTECTED_MODE
-	mov_q	x1, HCR_HOST_NVHE_PROTECTED_FLAGS
-	msr	hcr_el2, x1
-alternative_else_nop_endif
-
 	ldr	x1, [x0, #NVHE_INIT_TPIDR_EL2]
 	msr	tpidr_el2, x1
 
@@ -97,6 +92,15 @@ alternative_else_nop_endif
 	ldr	x1, [x0, #NVHE_INIT_MAIR_EL2]
 	msr	mair_el2, x1
 
+	ldr	x1, [x0, #NVHE_INIT_HCR_EL2]
+	msr	hcr_el2, x1
+
+	ldr	x1, [x0, #NVHE_INIT_VTTBR]
+	msr	vttbr_el2, x1
+
+	ldr	x1, [x0, #NVHE_INIT_VTCR]
+	msr	vtcr_el2, x1
+
 	ldr	x1, [x0, #NVHE_INIT_PGD_PA]
 	phys_to_ttbr x2, x1
 alternative_if ARM64_HAS_CNP
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index f3d0e9eca56c..979a76cdf9fb 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -97,10 +97,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 	mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
 
 	write_sysreg(mdcr_el2, mdcr_el2);
-	if (is_protected_kvm_enabled())
-		write_sysreg(HCR_HOST_NVHE_PROTECTED_FLAGS, hcr_el2);
-	else
-		write_sysreg(HCR_HOST_NVHE_FLAGS, hcr_el2);
+	write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
 	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
 	write_sysreg(__kvm_hyp_host_vector, vbar_el2);
 }
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 21/34] KVM: arm64: Refactor kvm_arm_setup_stage2()
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (19 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 20/34] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 22/34] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
                   ` (12 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to re-use some of the stage 2 setup code at EL2, factor parts
of kvm_arm_setup_stage2() out into separate functions.

No functional change intended.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 26 +++++++++++++++++
 arch/arm64/kvm/hyp/pgtable.c         | 32 +++++++++++++++++++++
 arch/arm64/kvm/reset.c               | 42 +++-------------------------
 3 files changed, 62 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 7945ec87eaec..9cdc198ea6b4 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -13,6 +13,16 @@
 
 #define KVM_PGTABLE_MAX_LEVELS		4U
 
+static inline u64 kvm_get_parange(u64 mmfr0)
+{
+	u64 parange = cpuid_feature_extract_unsigned_field(mmfr0,
+				ID_AA64MMFR0_PARANGE_SHIFT);
+	if (parange > ID_AA64MMFR0_PARANGE_MAX)
+		parange = ID_AA64MMFR0_PARANGE_MAX;
+
+	return parange;
+}
+
 typedef u64 kvm_pte_t;
 
 /**
@@ -159,6 +169,22 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt);
 int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys,
 			enum kvm_pgtable_prot prot);
 
+/**
+ * kvm_get_vtcr() - Helper to construct VTCR_EL2
+ * @mmfr0:	Sanitized value of SYS_ID_AA64MMFR0_EL1 register.
+ * @mmfr1:	Sanitized value of SYS_ID_AA64MMFR1_EL1 register.
+ * @phys_shfit:	Value to set in VTCR_EL2.T0SZ.
+ *
+ * The VTCR value is common across all the physical CPUs on the system.
+ * We use system wide sanitised values to fill in different fields,
+ * except for Hardware Management of Access Flags. HA Flag is set
+ * unconditionally on all CPUs, as it is safe to run with or without
+ * the feature and the bit is RES0 on CPUs that don't support it.
+ *
+ * Return: VTCR_EL2 value
+ */
+u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift);
+
 /**
  * kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
  * @pgt:	Uninitialised page-table structure to initialise.
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 3d79c8094cdd..296675e5600d 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -9,6 +9,7 @@
 
 #include <linux/bitfield.h>
 #include <asm/kvm_pgtable.h>
+#include <asm/stage2_pgtable.h>
 
 #define KVM_PTE_VALID			BIT(0)
 
@@ -449,6 +450,37 @@ struct stage2_map_data {
 	struct kvm_pgtable_mm_ops	*mm_ops;
 };
 
+u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
+{
+	u64 vtcr = VTCR_EL2_FLAGS;
+	u8 lvls;
+
+	vtcr |= kvm_get_parange(mmfr0) << VTCR_EL2_PS_SHIFT;
+	vtcr |= VTCR_EL2_T0SZ(phys_shift);
+	/*
+	 * Use a minimum 2 level page table to prevent splitting
+	 * host PMD huge pages at stage2.
+	 */
+	lvls = stage2_pgtable_levels(phys_shift);
+	if (lvls < 2)
+		lvls = 2;
+	vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);
+
+	/*
+	 * Enable the Hardware Access Flag management, unconditionally
+	 * on all CPUs. The features is RES0 on CPUs without the support
+	 * and must be ignored by the CPUs.
+	 */
+	vtcr |= VTCR_EL2_HA;
+
+	/* Set the vmid bits */
+	vtcr |= (get_vmid_bits(mmfr1) == 16) ?
+		VTCR_EL2_VS_16BIT :
+		VTCR_EL2_VS_8BIT;
+
+	return vtcr;
+}
+
 static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
 				    struct stage2_map_data *data)
 {
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 47f3f035f3ea..6aae118c960a 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -332,19 +332,10 @@ int kvm_set_ipa_limit(void)
 	return 0;
 }
 
-/*
- * Configure the VTCR_EL2 for this VM. The VTCR value is common
- * across all the physical CPUs on the system. We use system wide
- * sanitised values to fill in different fields, except for Hardware
- * Management of Access Flags. HA Flag is set unconditionally on
- * all CPUs, as it is safe to run with or without the feature and
- * the bit is RES0 on CPUs that don't support it.
- */
 int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
 {
-	u64 vtcr = VTCR_EL2_FLAGS, mmfr0;
-	u32 parange, phys_shift;
-	u8 lvls;
+	u64 mmfr0, mmfr1;
+	u32 phys_shift;
 
 	if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
 		return -EINVAL;
@@ -359,33 +350,8 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
 	}
 
 	mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
-	parange = cpuid_feature_extract_unsigned_field(mmfr0,
-				ID_AA64MMFR0_PARANGE_SHIFT);
-	if (parange > ID_AA64MMFR0_PARANGE_MAX)
-		parange = ID_AA64MMFR0_PARANGE_MAX;
-	vtcr |= parange << VTCR_EL2_PS_SHIFT;
-
-	vtcr |= VTCR_EL2_T0SZ(phys_shift);
-	/*
-	 * Use a minimum 2 level page table to prevent splitting
-	 * host PMD huge pages at stage2.
-	 */
-	lvls = stage2_pgtable_levels(phys_shift);
-	if (lvls < 2)
-		lvls = 2;
-	vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);
-
-	/*
-	 * Enable the Hardware Access Flag management, unconditionally
-	 * on all CPUs. The features is RES0 on CPUs without the support
-	 * and must be ignored by the CPUs.
-	 */
-	vtcr |= VTCR_EL2_HA;
+	mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
+	kvm->arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);
 
-	/* Set the vmid bits */
-	vtcr |= (kvm_get_vmid_bits() == 16) ?
-		VTCR_EL2_VS_16BIT :
-		VTCR_EL2_VS_8BIT;
-	kvm->arch.vtcr = vtcr;
 	return 0;
 }
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 22/34] KVM: arm64: Refactor __load_guest_stage2()
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (20 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 21/34] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 23/34] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
                   ` (11 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Refactor __load_guest_stage2() to introduce __load_stage2() which will
be re-used when loading the host stage 2.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_mmu.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 6f743e20cb06..9d64fa73ee67 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -270,9 +270,9 @@ static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)
  * Must be called from hyp code running at EL2 with an updated VTTBR
  * and interrupts disabled.
  */
-static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
+static __always_inline void __load_stage2(struct kvm_s2_mmu *mmu, unsigned long vtcr)
 {
-	write_sysreg(kern_hyp_va(mmu->arch)->vtcr, vtcr_el2);
+	write_sysreg(vtcr, vtcr_el2);
 	write_sysreg(kvm_get_vttbr(mmu), vttbr_el2);
 
 	/*
@@ -283,6 +283,11 @@ static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 }
 
+static __always_inline void __load_guest_stage2(struct kvm_s2_mmu *mmu)
+{
+	__load_stage2(mmu, kern_hyp_va(mmu->arch)->vtcr);
+}
+
 static inline struct kvm *kvm_s2_mmu_to_kvm(struct kvm_s2_mmu *mmu)
 {
 	return container_of(mmu->arch, struct kvm, arch);
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 23/34] KVM: arm64: Refactor __populate_fault_info()
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (21 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 22/34] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 24/34] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
                   ` (10 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Refactor __populate_fault_info() to introduce __get_fault_info() which
will be used once the host is wrapped in a stage 2.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/include/hyp/switch.h | 34 +++++++++++++------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 6c1f51f25eb3..40c274da5a7c 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -160,19 +160,9 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
 	return true;
 }
 
-static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
+static inline bool __get_fault_info(u64 esr, struct kvm_vcpu_fault_info *fault)
 {
-	u8 ec;
-	u64 esr;
-	u64 hpfar, far;
-
-	esr = vcpu->arch.fault.esr_el2;
-	ec = ESR_ELx_EC(esr);
-
-	if (ec != ESR_ELx_EC_DABT_LOW && ec != ESR_ELx_EC_IABT_LOW)
-		return true;
-
-	far = read_sysreg_el2(SYS_FAR);
+	fault->far_el2 = read_sysreg_el2(SYS_FAR);
 
 	/*
 	 * The HPFAR can be invalid if the stage 2 fault did not
@@ -188,17 +178,29 @@ static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
 	if (!(esr & ESR_ELx_S1PTW) &&
 	    (cpus_have_final_cap(ARM64_WORKAROUND_834220) ||
 	     (esr & ESR_ELx_FSC_TYPE) == FSC_PERM)) {
-		if (!__translate_far_to_hpfar(far, &hpfar))
+		if (!__translate_far_to_hpfar(fault->far_el2, &fault->hpfar_el2))
 			return false;
 	} else {
-		hpfar = read_sysreg(hpfar_el2);
+		fault->hpfar_el2 = read_sysreg(hpfar_el2);
 	}
 
-	vcpu->arch.fault.far_el2 = far;
-	vcpu->arch.fault.hpfar_el2 = hpfar;
 	return true;
 }
 
+static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
+{
+	u8 ec;
+	u64 esr;
+
+	esr = vcpu->arch.fault.esr_el2;
+	ec = ESR_ELx_EC(esr);
+
+	if (ec != ESR_ELx_EC_DABT_LOW && ec != ESR_ELx_EC_IABT_LOW)
+		return true;
+
+	return __get_fault_info(esr, &vcpu->arch.fault);
+}
+
 /* Check for an FPSIMD/SVE trap and handle as appropriate */
 static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 {
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 24/34] KVM: arm64: Make memcache anonymous in pgtable allocator
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (22 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 23/34] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 25/34] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
                   ` (9 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

The current stage2 page-table allocator uses a memcache to get
pre-allocated pages when it needs any. To allow re-using this code at
EL2 which uses a concept of memory pools, make the memcache argument of
kvm_pgtable_stage2_map() anonymous, and let the mm_ops zalloc_page()
callbacks use it the way they need to.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 6 +++---
 arch/arm64/kvm/hyp/pgtable.c         | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 9cdc198ea6b4..4ae19247837b 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -213,8 +213,8 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  * @size:	Size of the mapping.
  * @phys:	Physical address of the memory to map.
  * @prot:	Permissions and attributes for the mapping.
- * @mc:		Cache of pre-allocated GFP_PGTABLE_USER memory from which to
- *		allocate page-table pages.
+ * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
+ *		page-table pages.
  *
  * The offset of @addr within a page is ignored, @size is rounded-up to
  * the next page boundary and @phys is rounded-down to the previous page
@@ -236,7 +236,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  */
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   struct kvm_mmu_memory_cache *mc);
+			   void *mc);
 
 /**
  * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 296675e5600d..bdd6e3d4eeb6 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -445,7 +445,7 @@ struct stage2_map_data {
 	kvm_pte_t			*anchor;
 
 	struct kvm_s2_mmu		*mmu;
-	struct kvm_mmu_memory_cache	*memcache;
+	void				*memcache;
 
 	struct kvm_pgtable_mm_ops	*mm_ops;
 };
@@ -669,7 +669,7 @@ static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   struct kvm_mmu_memory_cache *mc)
+			   void *mc)
 {
 	int ret;
 	struct stage2_map_data map_data = {
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 25/34] KVM: arm64: Reserve memory for host stage 2
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (23 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 24/34] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 26/34] KVM: arm64: Sort the hypervisor memblocks Quentin Perret
                   ` (8 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Extend the memory pool allocated for the hypervisor to include enough
pages to map all of memory at page granularity for the host stage 2.
While at it, also reserve some memory for device mappings.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/include/nvhe/mm.h | 27 ++++++++++++++++++++++++++-
 arch/arm64/kvm/hyp/nvhe/setup.c      | 12 ++++++++++++
 arch/arm64/kvm/hyp/reserved_mem.c    |  2 ++
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
index ac0f7fcffd08..0095f6289742 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
@@ -53,7 +53,7 @@ static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
 	return total;
 }
 
-static inline unsigned long hyp_s1_pgtable_pages(void)
+static inline unsigned long __hyp_pgtable_total_pages(void)
 {
 	unsigned long res = 0, i;
 
@@ -63,9 +63,34 @@ static inline unsigned long hyp_s1_pgtable_pages(void)
 		res += __hyp_pgtable_max_pages(reg->size >> PAGE_SHIFT);
 	}
 
+	return res;
+}
+
+static inline unsigned long hyp_s1_pgtable_pages(void)
+{
+	unsigned long res;
+
+	res = __hyp_pgtable_total_pages();
+
 	/* Allow 1 GiB for private mappings */
 	res += __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
 
 	return res;
 }
+
+static inline unsigned long host_s2_mem_pgtable_pages(void)
+{
+	/*
+	 * Include an extra 16 pages to safely upper-bound the worst case of
+	 * concatenated pgds.
+	 */
+	return __hyp_pgtable_total_pages() + 16;
+}
+
+static inline unsigned long host_s2_dev_pgtable_pages(void)
+{
+	/* Allow 1 GiB for MMIO mappings */
+	return __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
+}
+
 #endif /* __KVM_HYP_MM_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 1e8bcd8b0299..c1a3e7e0ebbc 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -24,6 +24,8 @@ unsigned long hyp_nr_cpus;
 
 static void *vmemmap_base;
 static void *hyp_pgt_base;
+static void *host_s2_mem_pgt_base;
+static void *host_s2_dev_pgt_base;
 
 static int divide_memory_pool(void *virt, unsigned long size)
 {
@@ -42,6 +44,16 @@ static int divide_memory_pool(void *virt, unsigned long size)
 	if (!hyp_pgt_base)
 		return -ENOMEM;
 
+	nr_pages = host_s2_mem_pgtable_pages();
+	host_s2_mem_pgt_base = hyp_early_alloc_contig(nr_pages);
+	if (!host_s2_mem_pgt_base)
+		return -ENOMEM;
+
+	nr_pages = host_s2_dev_pgtable_pages();
+	host_s2_dev_pgt_base = hyp_early_alloc_contig(nr_pages);
+	if (!host_s2_dev_pgt_base)
+		return -ENOMEM;
+
 	return 0;
 }
 
diff --git a/arch/arm64/kvm/hyp/reserved_mem.c b/arch/arm64/kvm/hyp/reserved_mem.c
index 9bc6a6d27904..fd42705a3c26 100644
--- a/arch/arm64/kvm/hyp/reserved_mem.c
+++ b/arch/arm64/kvm/hyp/reserved_mem.c
@@ -52,6 +52,8 @@ void __init kvm_hyp_reserve(void)
 	}
 
 	hyp_mem_pages += hyp_s1_pgtable_pages();
+	hyp_mem_pages += host_s2_mem_pgtable_pages();
+	hyp_mem_pages += host_s2_dev_pgtable_pages();
 
 	/*
 	 * The hyp_vmemmap needs to be backed by pages, but these pages
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 26/34] KVM: arm64: Sort the hypervisor memblocks
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (24 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 25/34] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs Quentin Perret
                   ` (7 subsequent siblings)
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

We will soon need to check if a Physical Address belongs to a memblock
at EL2, so make sure to sort them so this can be done efficiently.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/reserved_mem.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/arm64/kvm/hyp/reserved_mem.c b/arch/arm64/kvm/hyp/reserved_mem.c
index fd42705a3c26..83ca23ac259b 100644
--- a/arch/arm64/kvm/hyp/reserved_mem.c
+++ b/arch/arm64/kvm/hyp/reserved_mem.c
@@ -6,6 +6,7 @@
 
 #include <linux/kvm_host.h>
 #include <linux/memblock.h>
+#include <linux/sort.h>
 
 #include <asm/kvm_host.h>
 
@@ -18,6 +19,23 @@ static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr);
 phys_addr_t hyp_mem_base;
 phys_addr_t hyp_mem_size;
 
+static int cmp_hyp_memblock(const void *p1, const void *p2)
+{
+	const struct memblock_region *r1 = p1;
+	const struct memblock_region *r2 = p2;
+
+	return r1->base < r2->base ? -1 : (r1->base > r2->base);
+}
+
+static void __init sort_memblock_regions(void)
+{
+	sort(hyp_memory,
+	     *hyp_memblock_nr_ptr,
+	     sizeof(struct memblock_region),
+	     cmp_hyp_memblock,
+	     NULL);
+}
+
 static int __init register_memblock_regions(void)
 {
 	struct memblock_region *reg;
@@ -29,6 +47,7 @@ static int __init register_memblock_regions(void)
 		hyp_memory[*hyp_memblock_nr_ptr] = *reg;
 		(*hyp_memblock_nr_ptr)++;
 	}
+	sort_memblock_regions();
 
 	return 0;
 }
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (25 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 26/34] KVM: arm64: Sort the hypervisor memblocks Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 17:33   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership Quentin Perret
                   ` (6 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

kvm_set_invalid_pte() currently only clears bit 0 from a PTE because
stage2_map_walk_table_post() needs to be able to follow the anchor. In
preparation for re-using bits 63-02 from invalid PTEs, make sure to zero
it entirely by ensuring to cache the anchor's child upfront.

Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index bdd6e3d4eeb6..f37b4179b880 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -156,10 +156,9 @@ static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte, struct kvm_pgtable_mm_ops *mm_op
 	return mm_ops->phys_to_virt(kvm_pte_to_phys(pte));
 }
 
-static void kvm_set_invalid_pte(kvm_pte_t *ptep)
+static void kvm_clear_pte(kvm_pte_t *ptep)
 {
-	kvm_pte_t pte = *ptep;
-	WRITE_ONCE(*ptep, pte & ~KVM_PTE_VALID);
+	WRITE_ONCE(*ptep, 0);
 }
 
 static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp,
@@ -443,6 +442,7 @@ struct stage2_map_data {
 	kvm_pte_t			attr;
 
 	kvm_pte_t			*anchor;
+	kvm_pte_t			*childp;
 
 	struct kvm_s2_mmu		*mmu;
 	void				*memcache;
@@ -532,7 +532,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 		 * There's an existing different valid leaf entry, so perform
 		 * break-before-make.
 		 */
-		kvm_set_invalid_pte(ptep);
+		kvm_clear_pte(ptep);
 		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
 		mm_ops->put_page(ptep);
 	}
@@ -553,7 +553,8 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
 	if (!kvm_block_mapping_supported(addr, end, data->phys, level))
 		return 0;
 
-	kvm_set_invalid_pte(ptep);
+	data->childp = kvm_pte_follow(*ptep, data->mm_ops);
+	kvm_clear_pte(ptep);
 
 	/*
 	 * Invalidate the whole stage-2, as we may have numerous leaf
@@ -599,7 +600,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	 * will be mapped lazily.
 	 */
 	if (kvm_pte_valid(pte)) {
-		kvm_set_invalid_pte(ptep);
+		kvm_clear_pte(ptep);
 		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
 		mm_ops->put_page(ptep);
 	}
@@ -615,19 +616,24 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
 				      struct stage2_map_data *data)
 {
 	struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
+	kvm_pte_t *childp;
 	int ret = 0;
 
 	if (!data->anchor)
 		return 0;
 
-	mm_ops->put_page(kvm_pte_follow(*ptep, mm_ops));
-	mm_ops->put_page(ptep);
-
 	if (data->anchor == ptep) {
+		childp = data->childp;
 		data->anchor = NULL;
+		data->childp = NULL;
 		ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
+	} else {
+		childp = kvm_pte_follow(*ptep, mm_ops);
 	}
 
+	mm_ops->put_page(childp);
+	mm_ops->put_page(ptep);
+
 	return ret;
 }
 
@@ -736,7 +742,7 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	 * block entry and rely on the remaining portions being faulted
 	 * back lazily.
 	 */
-	kvm_set_invalid_pte(ptep);
+	kvm_clear_pte(ptep);
 	kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, addr, level);
 	mm_ops->put_page(ptep);
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (26 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 18:38   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr() Quentin Perret
                   ` (5 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

As the host stage 2 will be identity mapped, all the .hyp memory regions
and/or memory pages donated to protected guestis will have to marked
invalid in the host stage 2 page-table. At the same time, the hypervisor
will need a way to track the ownership of each physical page to ensure
memory sharing or donation between entities (host, guests, hypervisor) is
legal.

In order to enable this tracking at EL2, let's use the host stage 2
page-table itself. The idea is to use the top bits of invalid mappings
to store the unique identifier of the page owner. The page-table owner
(the host) gets identifier 0 such that, at boot time, it owns the entire
IPA space as the pgd starts zeroed.

Provide kvm_pgtable_stage2_set_owner() which allows to modify the
ownership of pages in the host stage 2. It re-uses most of the map()
logic, but ends up creating invalid mappings instead. This impacts
how we do refcount as we now need to count invalid mappings when they
are used for ownership tracking.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 21 +++++++
 arch/arm64/kvm/hyp/pgtable.c         | 92 ++++++++++++++++++++++++----
 2 files changed, 101 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 4ae19247837b..b09af4612656 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -238,6 +238,27 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
 			   void *mc);
 
+/**
+ * kvm_pgtable_stage2_set_owner() - Annotate invalid mappings with metadata
+ *				    encoding the ownership of a page in the
+ *				    IPA space.
+ * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
+ * @addr:	Intermediate physical address at which to place the annotation.
+ * @size:	Size of the IPA range to annotate.
+ * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
+ *		page-table pages.
+ * @owner_id:	Unique identifier for the owner of the page.
+ *
+ * The page-table owner has identifier 0. This function can be used to mark
+ * portions of the IPA space as owned by other entities. When a stage 2 is used
+ * with identity-mappings, these annotations allow to use the page-table data
+ * structure as a simple rmap.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				 void *mc, u32 owner_id);
+
 /**
  * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
  * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index f37b4179b880..e4670b639726 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -48,6 +48,8 @@
 					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
+#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)
+
 struct kvm_pgtable_walk_data {
 	struct kvm_pgtable		*pgt;
 	struct kvm_pgtable_walker	*walker;
@@ -186,6 +188,11 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level)
 	return pte;
 }
 
+static kvm_pte_t kvm_init_invalid_leaf_owner(u32 owner_id)
+{
+	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
+}
+
 static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
 				  u32 level, kvm_pte_t *ptep,
 				  enum kvm_pgtable_walk_flags flag)
@@ -440,6 +447,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 struct stage2_map_data {
 	u64				phys;
 	kvm_pte_t			attr;
+	u32				owner_id;
 
 	kvm_pte_t			*anchor;
 	kvm_pte_t			*childp;
@@ -506,6 +514,24 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
 	return 0;
 }
 
+static bool stage2_is_permission_change(kvm_pte_t old, kvm_pte_t new)
+{
+	if (!kvm_pte_valid(old) || !kvm_pte_valid(new))
+		return false;
+
+	return !((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS));
+}
+
+static bool stage2_pte_is_counted(kvm_pte_t pte)
+{
+	/*
+	 * The refcount tracks valid entries as well as invalid entries if they
+	 * encode ownership of a page to another entity than the page-table
+	 * owner, whose id is 0.
+	 */
+	return !!pte;
+}
+
 static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 				      kvm_pte_t *ptep,
 				      struct stage2_map_data *data)
@@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 	if (!kvm_block_mapping_supported(addr, end, phys, level))
 		return -E2BIG;
 
-	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
-	if (kvm_pte_valid(old)) {
+	if (kvm_pte_valid(data->attr))
+		new = kvm_init_valid_leaf_pte(phys, data->attr, level);
+	else
+		new = kvm_init_invalid_leaf_owner(data->owner_id);
+
+	if (stage2_pte_is_counted(old)) {
 		/*
 		 * Skip updating the PTE if we are trying to recreate the exact
 		 * same mapping or only change the access permissions. Instead,
 		 * the vCPU will exit one more time from guest if still needed
 		 * and then go through the path of relaxing permissions.
 		 */
-		if (!((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS)))
+		if (stage2_is_permission_change(old, new))
 			return -EAGAIN;
 
 		/*
-		 * There's an existing different valid leaf entry, so perform
-		 * break-before-make.
+		 * Clear the existing PTE, and perform break-before-make with
+		 * TLB maintenance if it was valid.
 		 */
 		kvm_clear_pte(ptep);
-		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
+		if (kvm_pte_valid(old)) {
+			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr,
+				     level);
+		}
 		mm_ops->put_page(ptep);
 	}
 
 	smp_store_release(ptep, new);
-	mm_ops->get_page(ptep);
+	if (stage2_pte_is_counted(new))
+		mm_ops->get_page(ptep);
 	data->phys += granule;
 	return 0;
 }
@@ -574,7 +608,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	int ret;
 
 	if (data->anchor) {
-		if (kvm_pte_valid(pte))
+		if (stage2_pte_is_counted(pte))
 			mm_ops->put_page(ptep);
 
 		return 0;
@@ -599,9 +633,10 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	 * a table. Accesses beyond 'end' that fall within the new table
 	 * will be mapped lazily.
 	 */
-	if (kvm_pte_valid(pte)) {
+	if (stage2_pte_is_counted(pte)) {
 		kvm_clear_pte(ptep);
-		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
+		if (kvm_pte_valid(pte))
+			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
 		mm_ops->put_page(ptep);
 	}
 
@@ -683,6 +718,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.mmu		= pgt->mmu,
 		.memcache	= mc,
 		.mm_ops		= pgt->mm_ops,
+		.owner_id	= 0,
 	};
 	struct kvm_pgtable_walker walker = {
 		.cb		= stage2_map_walker,
@@ -696,6 +732,33 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	if (ret)
 		return ret;
 
+	/* Set the valid flag to distinguish with the set_owner() path. */
+	map_data.attr |= KVM_PTE_VALID;
+
+	ret = kvm_pgtable_walk(pgt, addr, size, &walker);
+	dsb(ishst);
+	return ret;
+}
+
+int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				 void *mc, u32 owner_id)
+{
+	int ret;
+	struct stage2_map_data map_data = {
+		.mmu		= pgt->mmu,
+		.memcache	= mc,
+		.mm_ops		= pgt->mm_ops,
+		.owner_id	= owner_id,
+		.attr		= 0,
+	};
+	struct kvm_pgtable_walker walker = {
+		.cb		= stage2_map_walker,
+		.flags		= KVM_PGTABLE_WALK_TABLE_PRE |
+				  KVM_PGTABLE_WALK_LEAF |
+				  KVM_PGTABLE_WALK_TABLE_POST,
+		.arg		= &map_data,
+	};
+
 	ret = kvm_pgtable_walk(pgt, addr, size, &walker);
 	dsb(ishst);
 	return ret;
@@ -725,8 +788,13 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	kvm_pte_t pte = *ptep, *childp = NULL;
 	bool need_flush = false;
 
-	if (!kvm_pte_valid(pte))
+	if (!kvm_pte_valid(pte)) {
+		if (stage2_pte_is_counted(pte)) {
+			kvm_clear_pte(ptep);
+			mm_ops->put_page(ptep);
+		}
 		return 0;
+	}
 
 	if (kvm_pte_table(pte, level)) {
 		childp = kvm_pte_follow(pte, mm_ops);
@@ -948,7 +1016,7 @@ static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	struct kvm_pgtable_mm_ops *mm_ops = arg;
 	kvm_pte_t pte = *ptep;
 
-	if (!kvm_pte_valid(pte))
+	if (!stage2_pte_is_counted(pte))
 		return 0;
 
 	mm_ops->put_page(ptep);
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr()
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (27 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 18:48   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range() Quentin Perret
                   ` (4 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

In order to ease its re-use in other code paths, refactor
stage2_map_set_prot_attr() to not depend on a stage2_map_data struct.
No functional change intended.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index e4670b639726..c16e0306dd9a 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -489,8 +489,7 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
 	return vtcr;
 }
 
-static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
-				    struct stage2_map_data *data)
+static int stage2_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
 {
 	bool device = prot & KVM_PGTABLE_PROT_DEVICE;
 	kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :
@@ -510,7 +509,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
 
 	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
 	attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
-	data->attr = attr;
+	*ptep = attr;
+
 	return 0;
 }
 
@@ -728,7 +728,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.arg		= &map_data,
 	};
 
-	ret = stage2_map_set_prot_attr(prot, &map_data);
+	ret = stage2_set_prot_attr(prot, &map_data.attr);
 	if (ret)
 		return ret;
 
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range()
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (28 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr() Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 19:04   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
                   ` (3 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

Since the host stage 2 will be identity mapped, and since it will own
most of memory, it would preferable for performance to try and use large
block mappings whenever that is possible. To ease this, introduce a new
helper in the KVM page-table code which allows to search for large
ranges of available IPA space. This will be used in the host memory
abort path to greedily idmap large portion of the PA space.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 30 ++++++++++
 arch/arm64/kvm/hyp/pgtable.c         | 90 +++++++++++++++++++++++++++-
 2 files changed, 117 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index b09af4612656..477bf10c48a9 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -94,6 +94,16 @@ enum kvm_pgtable_prot {
 #define PAGE_HYP_RO		(KVM_PGTABLE_PROT_R)
 #define PAGE_HYP_DEVICE		(PAGE_HYP | KVM_PGTABLE_PROT_DEVICE)
 
+/**
+ * struct kvm_mem_range - Range of Intermediate Physical Addresses
+ * @start:	Start of the range.
+ * @end:	End of the range.
+ */
+struct kvm_mem_range {
+	u64 start;
+	u64 end;
+};
+
 /**
  * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk.
  * @KVM_PGTABLE_WALK_LEAF:		Visit leaf entries, including invalid
@@ -398,4 +408,24 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size);
 int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		     struct kvm_pgtable_walker *walker);
 
+/**
+ * kvm_pgtable_stage2_find_range() - Find a range of Intermediate Physical
+ *				     Addresses with compatible permission
+ *				     attributes.
+ * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
+ * @addr:	Address that must be covered by the range.
+ * @prot:	Protection attributes that the range must be compatible with.
+ * @range:	Range structure used to limit the search space at call time and
+ *		that will hold the result.
+ *
+ * The offset of @addr within a page is ignored. An existing mapping is defined
+ * as compatible with @prot if it is invalid and not owned by another entity, or
+ * if its permission attributes are strictly similar to @prot and it has no
+ * software bits set.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
+				  enum kvm_pgtable_prot prot,
+				  struct kvm_mem_range *range);
 #endif	/* __ARM64_KVM_PGTABLE_H__ */
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index c16e0306dd9a..f20287bb3e41 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -48,6 +48,8 @@
 					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
+#define KVM_PTE_LEAF_ATTR_S2_RES	GENMASK(58, 55)
+
 #define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)
 
 struct kvm_pgtable_walk_data {
@@ -69,10 +71,8 @@ static u64 kvm_granule_size(u32 level)
 	return BIT(kvm_granule_shift(level));
 }
 
-static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
+static bool kvm_level_support_block_mappings(u32 level)
 {
-	u64 granule = kvm_granule_size(level);
-
 	/*
 	 * Reject invalid block mappings and don't bother with 4TB mappings for
 	 * 52-bit PAs.
@@ -80,6 +80,16 @@ static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
 	if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1))
 		return false;
 
+	return true;
+}
+
+static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
+{
+	u64 granule = kvm_granule_size(level);
+
+	if (!kvm_level_support_block_mappings(level))
+		return false;
+
 	if (granule > (end - addr))
 		return false;
 
@@ -1042,3 +1052,77 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
 	pgt->mm_ops->free_pages_exact(pgt->pgd, pgd_sz);
 	pgt->pgd = NULL;
 }
+
+#define KVM_PTE_LEAF_S2_COMPAT_MASK	(KVM_PTE_LEAF_ATTR_S2_PERMS | \
+					 KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | \
+					 KVM_PTE_LEAF_ATTR_S2_RES)
+
+static int stage2_check_permission_walker(u64 addr, u64 end, u32 level,
+					  kvm_pte_t *ptep,
+					  enum kvm_pgtable_walk_flags flag,
+					  void * const arg)
+{
+	kvm_pte_t old_attr, pte = *ptep, *new_attr = arg;
+
+	/*
+	 * Compatible mappings are either invalid and owned by the page-table
+	 * owner (whose id is 0), or valid with matching permission attributes.
+	 */
+	if (kvm_pte_valid(pte)) {
+		old_attr = pte & KVM_PTE_LEAF_S2_COMPAT_MASK;
+		if (old_attr != *new_attr)
+			return -EEXIST;
+	} else if (pte) {
+		return -EEXIST;
+	}
+
+	return 0;
+}
+
+int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
+				  enum kvm_pgtable_prot prot,
+				  struct kvm_mem_range *range)
+{
+	kvm_pte_t attr;
+	struct kvm_pgtable_walker check_perm_walker = {
+		.cb		= stage2_check_permission_walker,
+		.flags		= KVM_PGTABLE_WALK_LEAF,
+		.arg		= &attr,
+	};
+	u64 granule, start, end;
+	u32 level;
+	int ret;
+
+	ret = stage2_set_prot_attr(prot, &attr);
+	if (ret)
+		return ret;
+	attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;
+
+	for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
+		granule = kvm_granule_size(level);
+		start = ALIGN_DOWN(addr, granule);
+		end = start + granule;
+
+		if (!kvm_level_support_block_mappings(level))
+			continue;
+
+		if (start < range->start || range->end < end)
+			continue;
+
+		/*
+		 * Check the presence of existing mappings with incompatible
+		 * permissions within the current block range, and try one level
+		 * deeper if one is found.
+		 */
+		ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
+		if (ret != -EEXIST)
+			break;
+	}
+
+	if (!ret) {
+		range->start = start;
+		range->end = end;
+	}
+
+	return ret;
+}
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (29 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range() Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 19:09   ` Will Deacon
  2021-03-10 17:57 ` [PATCH v4 32/34] KVM: arm64: Page-align the .hyp sections Quentin Perret
                   ` (2 subsequent siblings)
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

When KVM runs in protected nVHE mode, make use of a stage 2 page-table
to give the hypervisor some control over the host memory accesses. The
host stage 2 is created lazily using large block mappings if possible,
and will default to page mappings in absence of a better solution.

From this point on, memory accesses from the host to protected memory
regions (e.g. marked PROT_NONE) are fatal and lead to hyp_panic().

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_asm.h              |   1 +
 arch/arm64/include/asm/kvm_cpufeature.h       |   2 +
 arch/arm64/kernel/image-vars.h                |   3 +
 arch/arm64/kvm/arm.c                          |  10 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  34 +++
 arch/arm64/kvm/hyp/nvhe/Makefile              |   2 +-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S            |   1 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  11 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 246 ++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/setup.c               |   5 +
 arch/arm64/kvm/hyp/nvhe/switch.c              |   7 +-
 arch/arm64/kvm/hyp/nvhe/tlb.c                 |   4 +-
 12 files changed, 319 insertions(+), 7 deletions(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 6dce860f8bca..b127af02bd45 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -61,6 +61,7 @@
 #define __KVM_HOST_SMCCC_FUNC___pkvm_create_mappings		16
 #define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping	17
 #define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector		18
+#define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize		19
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h
index d34f85cba358..74043a149322 100644
--- a/arch/arm64/include/asm/kvm_cpufeature.h
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -15,3 +15,5 @@
 #endif
 
 KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
+KVM_HYP_CPU_FTR_REG(SYS_ID_AA64MMFR0_EL1, arm64_ftr_reg_id_aa64mmfr0_el1)
+KVM_HYP_CPU_FTR_REG(SYS_ID_AA64MMFR1_EL1, arm64_ftr_reg_id_aa64mmfr1_el1)
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 940c378fa837..d5dc2b792651 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -131,6 +131,9 @@ KVM_NVHE_ALIAS(__hyp_bss_end);
 KVM_NVHE_ALIAS(__hyp_rodata_start);
 KVM_NVHE_ALIAS(__hyp_rodata_end);
 
+/* pKVM static key */
+KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
+
 #endif /* CONFIG_KVM */
 
 #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index d474eec606a3..7e6a81079652 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1889,12 +1889,22 @@ static int init_hyp_mode(void)
 	return err;
 }
 
+void _kvm_host_prot_finalize(void *discard)
+{
+	WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize));
+}
+
 static int finalize_hyp_mode(void)
 {
 	if (!is_protected_kvm_enabled())
 		return 0;
 
+	/*
+	 * Flip the static key upfront as that may no longer be possible
+	 * once the host stage 2 is installed.
+	 */
 	static_branch_enable(&kvm_protected_mode_initialized);
+	on_each_cpu(_kvm_host_prot_finalize, NULL, 1);
 
 	return 0;
 }
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
new file mode 100644
index 000000000000..d293cb328cc4
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#ifndef __KVM_NVHE_MEM_PROTECT__
+#define __KVM_NVHE_MEM_PROTECT__
+#include <linux/kvm_host.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_pgtable.h>
+#include <asm/virt.h>
+#include <nvhe/spinlock.h>
+
+struct host_kvm {
+	struct kvm_arch arch;
+	struct kvm_pgtable pgt;
+	struct kvm_pgtable_mm_ops mm_ops;
+	hyp_spinlock_t lock;
+};
+extern struct host_kvm host_kvm;
+
+int __pkvm_prot_finalize(void);
+int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool);
+void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
+
+static __always_inline void __load_host_stage2(void)
+{
+	if (static_branch_likely(&kvm_protected_mode_initialized))
+		__load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
+	else
+		write_sysreg(0, vttbr_el2);
+}
+#endif /* __KVM_NVHE_MEM_PROTECT__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index e204ea77ab27..ce49795324a7 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -14,7 +14,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
 	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \
-	 cache.o cpufeature.o setup.o mm.o
+	 cache.o cpufeature.o setup.o mm.o mem_protect.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
 obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index a50ad9e9fc05..c164045af238 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -119,6 +119,7 @@ alternative_else_nop_endif
 
 	/* Invalidate the stale TLBs from Bootloader */
 	tlbi	alle2
+	tlbi	vmalls12e1
 	dsb	sy
 
 	/*
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index ae6503c9be15..f47028d3fd0a 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -13,6 +13,7 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 
+#include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
 #include <nvhe/trap_handler.h>
 
@@ -151,6 +152,10 @@ static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ct
 	cpu_reg(host_ctxt, 1) = __pkvm_create_private_mapping(phys, size, prot);
 }
 
+static void handle___pkvm_prot_finalize(struct kvm_cpu_context *host_ctxt)
+{
+	cpu_reg(host_ctxt, 1) = __pkvm_prot_finalize();
+}
 typedef void (*hcall_t)(struct kvm_cpu_context *);
 
 #define HANDLE_FUNC(x)	[__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
@@ -174,6 +179,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_cpu_set_vector),
 	HANDLE_FUNC(__pkvm_create_mappings),
 	HANDLE_FUNC(__pkvm_create_private_mapping),
+	HANDLE_FUNC(__pkvm_prot_finalize),
 };
 
 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
@@ -226,6 +232,11 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
 	case ESR_ELx_EC_SMC64:
 		handle_host_smc(host_ctxt);
 		break;
+	case ESR_ELx_EC_IABT_LOW:
+		fallthrough;
+	case ESR_ELx_EC_DABT_LOW:
+		handle_host_mem_abort(host_ctxt);
+		break;
 	default:
 		hyp_panic();
 	}
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
new file mode 100644
index 000000000000..5c88a325e6fc
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@google.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_cpufeature.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_pgtable.h>
+#include <asm/stage2_pgtable.h>
+
+#include <hyp/switch.h>
+
+#include <nvhe/gfp.h>
+#include <nvhe/memory.h>
+#include <nvhe/mem_protect.h>
+#include <nvhe/mm.h>
+
+extern unsigned long hyp_nr_cpus;
+struct host_kvm host_kvm;
+
+struct hyp_pool host_s2_mem;
+struct hyp_pool host_s2_dev;
+
+static void *host_s2_zalloc_pages_exact(size_t size)
+{
+	return hyp_alloc_pages(&host_s2_mem, get_order(size));
+}
+
+static void *host_s2_zalloc_page(void *pool)
+{
+	return hyp_alloc_pages(pool, 0);
+}
+
+static int prepare_s2_pools(void *mem_pgt_pool, void *dev_pgt_pool)
+{
+	unsigned long nr_pages, pfn;
+	int ret;
+
+	pfn = hyp_virt_to_pfn(mem_pgt_pool);
+	nr_pages = host_s2_mem_pgtable_pages();
+	ret = hyp_pool_init(&host_s2_mem, pfn, nr_pages, 0);
+	if (ret)
+		return ret;
+
+	pfn = hyp_virt_to_pfn(dev_pgt_pool);
+	nr_pages = host_s2_dev_pgtable_pages();
+	ret = hyp_pool_init(&host_s2_dev, pfn, nr_pages, 0);
+	if (ret)
+		return ret;
+
+	host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
+		.zalloc_pages_exact = host_s2_zalloc_pages_exact,
+		.zalloc_page = host_s2_zalloc_page,
+		.phys_to_virt = hyp_phys_to_virt,
+		.virt_to_phys = hyp_virt_to_phys,
+		.page_count = hyp_page_count,
+		.get_page = hyp_get_page,
+		.put_page = hyp_put_page,
+	};
+
+	return 0;
+}
+
+static void prepare_host_vtcr(void)
+{
+	u32 parange, phys_shift;
+	u64 mmfr0, mmfr1;
+
+	mmfr0 = arm64_ftr_reg_id_aa64mmfr0_el1.sys_val;
+	mmfr1 = arm64_ftr_reg_id_aa64mmfr1_el1.sys_val;
+
+	/* The host stage 2 is id-mapped, so use parange for T0SZ */
+	parange = kvm_get_parange(mmfr0);
+	phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
+
+	host_kvm.arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);
+}
+
+int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool)
+{
+	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
+	int ret;
+
+	prepare_host_vtcr();
+	hyp_spin_lock_init(&host_kvm.lock);
+
+	ret = prepare_s2_pools(mem_pgt_pool, dev_pgt_pool);
+	if (ret)
+		return ret;
+
+	ret = kvm_pgtable_stage2_init(&host_kvm.pgt, &host_kvm.arch,
+				      &host_kvm.mm_ops);
+	if (ret)
+		return ret;
+
+	mmu->pgd_phys = __hyp_pa(host_kvm.pgt.pgd);
+	mmu->arch = &host_kvm.arch;
+	mmu->pgt = &host_kvm.pgt;
+	mmu->vmid.vmid_gen = 0;
+	mmu->vmid.vmid = 0;
+
+	return 0;
+}
+
+int __pkvm_prot_finalize(void)
+{
+	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
+	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
+
+	params->vttbr = kvm_get_vttbr(mmu);
+	params->vtcr = host_kvm.arch.vtcr;
+	params->hcr_el2 |= HCR_VM;
+	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
+		params->hcr_el2 |= HCR_FWB;
+	kvm_flush_dcache_to_poc(params, sizeof(*params));
+
+	write_sysreg(params->hcr_el2, hcr_el2);
+	__load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
+
+	/*
+	 * Make sure to have an ISB before the TLB maintenance below but only
+	 * when __load_stage2() doesn't include one already.
+	 */
+	asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT));
+
+	/* Invalidate stale HCR bits that may be cached in TLBs */
+	__tlbi(vmalls12e1);
+	dsb(nsh);
+	isb();
+
+	return 0;
+}
+
+static int host_stage2_unmap_dev_all(void)
+{
+	struct kvm_pgtable *pgt = &host_kvm.pgt;
+	struct memblock_region *reg;
+	u64 addr = 0;
+	int i, ret;
+
+	/* Unmap all non-memory regions to recycle the pages */
+	for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) {
+		reg = &hyp_memory[i];
+		ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr);
+		if (ret)
+			return ret;
+	}
+	return kvm_pgtable_stage2_unmap(pgt, addr, BIT(pgt->ia_bits) - addr);
+}
+
+static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
+{
+	int cur, left = 0, right = hyp_memblock_nr;
+	struct memblock_region *reg;
+	phys_addr_t end;
+
+	range->start = 0;
+	range->end = ULONG_MAX;
+
+	/* The list of memblock regions is sorted, binary search it */
+	while (left < right) {
+		cur = (left + right) >> 1;
+		reg = &hyp_memory[cur];
+		end = reg->base + reg->size;
+		if (addr < reg->base) {
+			right = cur;
+			range->end = reg->base;
+		} else if (addr >= end) {
+			left = cur + 1;
+			range->start = end;
+		} else {
+			range->start = reg->base;
+			range->end = end;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static inline int __host_stage2_idmap(u64 start, u64 end,
+				      enum kvm_pgtable_prot prot,
+				      struct hyp_pool *pool)
+{
+	return kvm_pgtable_stage2_map(&host_kvm.pgt, start, end - start, start,
+				      prot, pool);
+}
+
+static int host_stage2_idmap(u64 addr)
+{
+	enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;
+	struct kvm_mem_range range;
+	bool is_memory = find_mem_range(addr, &range);
+	struct hyp_pool *pool = is_memory ? &host_s2_mem : &host_s2_dev;
+	int ret;
+
+	if (is_memory)
+		prot |= KVM_PGTABLE_PROT_X;
+
+	hyp_spin_lock(&host_kvm.lock);
+	ret = kvm_pgtable_stage2_find_range(&host_kvm.pgt, addr, prot, &range);
+	if (ret)
+		goto unlock;
+
+	ret = __host_stage2_idmap(range.start, range.end, prot, pool);
+	if (is_memory || ret != -ENOMEM)
+		goto unlock;
+
+	/*
+	 * host_s2_mem has been provided with enough pages to cover all of
+	 * memory with page granularity, so we should never hit the ENOMEM case.
+	 * However, it is difficult to know how much of the MMIO range we will
+	 * need to cover upfront, so we may need to 'recycle' the pages if we
+	 * run out.
+	 */
+	ret = host_stage2_unmap_dev_all();
+	if (ret)
+		goto unlock;
+
+	ret = __host_stage2_idmap(range.start, range.end, prot, pool);
+
+unlock:
+	hyp_spin_unlock(&host_kvm.lock);
+
+	return ret;
+}
+
+void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
+{
+	struct kvm_vcpu_fault_info fault;
+	u64 esr, addr;
+	int ret = 0;
+
+	esr = read_sysreg_el2(SYS_ESR);
+	if (!__get_fault_info(esr, &fault))
+		hyp_panic();
+
+	addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
+	ret = host_stage2_idmap(addr);
+	if (ret && ret != -EAGAIN)
+		hyp_panic();
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index c1a3e7e0ebbc..7488f53b0aa2 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -12,6 +12,7 @@
 #include <nvhe/early_alloc.h>
 #include <nvhe/gfp.h>
 #include <nvhe/memory.h>
+#include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
 #include <nvhe/trap_handler.h>
 
@@ -157,6 +158,10 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
+	ret = kvm_host_prepare_stage2(host_s2_mem_pgt_base, host_s2_dev_pgt_base);
+	if (ret)
+		goto out;
+
 	pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
 		.zalloc_page = hyp_zalloc_hyp_page,
 		.phys_to_virt = hyp_phys_to_virt,
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 979a76cdf9fb..31bc1a843bf8 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -28,6 +28,8 @@
 #include <asm/processor.h>
 #include <asm/thread_info.h>
 
+#include <nvhe/mem_protect.h>
+
 /* Non-VHE specific context */
 DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
 DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
@@ -102,11 +104,6 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 	write_sysreg(__kvm_hyp_host_vector, vbar_el2);
 }
 
-static void __load_host_stage2(void)
-{
-	write_sysreg(0, vttbr_el2);
-}
-
 /* Save VGICv3 state on non-VHE systems */
 static void __hyp_vgic_save_state(struct kvm_vcpu *vcpu)
 {
diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c
index fbde89a2c6e8..255a23a1b2db 100644
--- a/arch/arm64/kvm/hyp/nvhe/tlb.c
+++ b/arch/arm64/kvm/hyp/nvhe/tlb.c
@@ -8,6 +8,8 @@
 #include <asm/kvm_mmu.h>
 #include <asm/tlbflush.h>
 
+#include <nvhe/mem_protect.h>
+
 struct tlb_inv_context {
 	u64		tcr;
 };
@@ -43,7 +45,7 @@ static void __tlb_switch_to_guest(struct kvm_s2_mmu *mmu,
 
 static void __tlb_switch_to_host(struct tlb_inv_context *cxt)
 {
-	write_sysreg(0, vttbr_el2);
+	__load_host_stage2();
 
 	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
 		/* Ensure write of the host VMID */
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 32/34] KVM: arm64: Page-align the .hyp sections
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (30 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 33/34] KVM: arm64: Disable PMU support in protected mode Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host Quentin Perret
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

We will soon unmap the .hyp sections from the host stage 2 in Protected
nVHE mode, which obviously works with at least page granularity, so make
sure to align them correctly.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kernel/vmlinux.lds.S | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e96173ce211b..709d2c433c5e 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -15,9 +15,11 @@
 
 #define HYPERVISOR_DATA_SECTIONS				\
 	HYP_SECTION_NAME(.rodata) : {				\
+		. = ALIGN(PAGE_SIZE);				\
 		__hyp_rodata_start = .;				\
 		*(HYP_SECTION_NAME(.data..ro_after_init))	\
 		*(HYP_SECTION_NAME(.rodata))			\
+		. = ALIGN(PAGE_SIZE);				\
 		__hyp_rodata_end = .;				\
 	}
 
@@ -72,21 +74,14 @@ ENTRY(_text)
 jiffies = jiffies_64;
 
 #define HYPERVISOR_TEXT					\
-	/*						\
-	 * Align to 4 KB so that			\
-	 * a) the HYP vector table is at its minimum	\
-	 *    alignment of 2048 bytes			\
-	 * b) the HYP init code will not cross a page	\
-	 *    boundary if its size does not exceed	\
-	 *    4 KB (see related ASSERT() below)		\
-	 */						\
-	. = ALIGN(SZ_4K);				\
+	. = ALIGN(PAGE_SIZE);				\
 	__hyp_idmap_text_start = .;			\
 	*(.hyp.idmap.text)				\
 	__hyp_idmap_text_end = .;			\
 	__hyp_text_start = .;				\
 	*(.hyp.text)					\
 	HYPERVISOR_EXTABLE				\
+	. = ALIGN(PAGE_SIZE);				\
 	__hyp_text_end = .;
 
 #define IDMAP_TEXT					\
@@ -322,11 +317,12 @@ SECTIONS
 #include "image-vars.h"
 
 /*
- * The HYP init code and ID map text can't be longer than a page each,
- * and should not cross a page boundary.
+ * The HYP init code and ID map text can't be longer than a page each. The
+ * former is page-aligned, but the latter may not be with 16K or 64K pages, so
+ * it should also not cross a page boundary.
  */
-ASSERT(__hyp_idmap_text_end - (__hyp_idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
-	"HYP init code too big or misaligned")
+ASSERT(__hyp_idmap_text_end - __hyp_idmap_text_start <= PAGE_SIZE,
+	"HYP init code too big")
 ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
 	"ID map text too big or misaligned")
 #ifdef CONFIG_HIBERNATION
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 33/34] KVM: arm64: Disable PMU support in protected mode
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (31 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 32/34] KVM: arm64: Page-align the .hyp sections Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-10 17:57 ` [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host Quentin Perret
  33 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

The host currently writes directly in EL2 per-CPU data sections from
the PMU code when running in nVHE. In preparation for unmapping the EL2
sections from the host stage 2, disable PMU support in protected mode as
we currently do not have a use-case for it.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/kvm/perf.c | 3 ++-
 arch/arm64/kvm/pmu.c  | 8 ++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index 739164324afe..8f860ae56bb7 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -55,7 +55,8 @@ int kvm_perf_init(void)
 	 * hardware performance counters. This could ensure the presence of
 	 * a physical PMU and CONFIG_PERF_EVENT is selected.
 	 */
-	if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0)
+	if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0
+				       && !is_protected_kvm_enabled())
 		static_branch_enable(&kvm_arm_pmu_available);
 
 	return perf_register_guest_info_callbacks(&kvm_guest_cbs);
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index faf32a44ba04..03a6c1f4a09a 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -33,7 +33,7 @@ void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
 {
 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
-	if (!ctx || !kvm_pmu_switch_needed(attr))
+	if (!kvm_arm_support_pmu_v3() || !ctx || !kvm_pmu_switch_needed(attr))
 		return;
 
 	if (!attr->exclude_host)
@@ -49,7 +49,7 @@ void kvm_clr_pmu_events(u32 clr)
 {
 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
-	if (!ctx)
+	if (!kvm_arm_support_pmu_v3() || !ctx)
 		return;
 
 	ctx->pmu_events.events_host &= ~clr;
@@ -172,7 +172,7 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
 	struct kvm_host_data *host;
 	u32 events_guest, events_host;
 
-	if (!has_vhe())
+	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
 	preempt_disable();
@@ -193,7 +193,7 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
 	struct kvm_host_data *host;
 	u32 events_guest, events_host;
 
-	if (!has_vhe())
+	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
 	host = this_cpu_ptr_hyp_sym(kvm_host_data);
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host
  2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
                   ` (32 preceding siblings ...)
  2021-03-10 17:57 ` [PATCH v4 33/34] KVM: arm64: Disable PMU support in protected mode Quentin Perret
@ 2021-03-10 17:57 ` Quentin Perret
  2021-03-11 19:17   ` Will Deacon
  33 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-10 17:57 UTC (permalink / raw)
  To: catalin.marinas, will, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose
  Cc: android-kvm, linux-kernel, kernel-team, kvmarm, linux-arm-kernel,
	tabba, mark.rutland, dbrazdil, mate.toth-pal, seanjc, qperret,
	robh+dt, ardb

When KVM runs in nVHE protected mode, use the host stage 2 to unmap the
hypervisor sections by marking them as owned by the hypervisor itself.
The long-term goal is to ensure the EL2 code can remain robust
regardless of the host's state, so this starts by making sure the host
cannot e.g. write to the .hyp sections directly.

Signed-off-by: Quentin Perret <qperret@google.com>
---
 arch/arm64/include/asm/kvm_asm.h              |  1 +
 arch/arm64/kvm/arm.c                          | 46 +++++++++++++++++++
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  9 ++++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 33 +++++++++++++
 5 files changed, 91 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index b127af02bd45..d468c4b37190 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -62,6 +62,7 @@
 #define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping	17
 #define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector		18
 #define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize		19
+#define __KVM_HOST_SMCCC_FUNC___pkvm_mark_hyp			20
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7e6a81079652..d6baf76d4747 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1894,11 +1894,57 @@ void _kvm_host_prot_finalize(void *discard)
 	WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize));
 }
 
+static inline int pkvm_mark_hyp(phys_addr_t start, phys_addr_t end)
+{
+	return kvm_call_hyp_nvhe(__pkvm_mark_hyp, start, end);
+}
+
+#define pkvm_mark_hyp_section(__section)		\
+	pkvm_mark_hyp(__pa_symbol(__section##_start),	\
+			__pa_symbol(__section##_end))
+
 static int finalize_hyp_mode(void)
 {
+	int cpu, ret;
+
 	if (!is_protected_kvm_enabled())
 		return 0;
 
+	ret = pkvm_mark_hyp_section(__hyp_idmap_text);
+	if (ret)
+		return ret;
+
+	ret = pkvm_mark_hyp_section(__hyp_text);
+	if (ret)
+		return ret;
+
+	ret = pkvm_mark_hyp_section(__hyp_rodata);
+	if (ret)
+		return ret;
+
+	ret = pkvm_mark_hyp_section(__hyp_bss);
+	if (ret)
+		return ret;
+
+	ret = pkvm_mark_hyp(hyp_mem_base, hyp_mem_base + hyp_mem_size);
+	if (ret)
+		return ret;
+
+	for_each_possible_cpu(cpu) {
+		phys_addr_t start = virt_to_phys((void *)kvm_arm_hyp_percpu_base[cpu]);
+		phys_addr_t end = start + (PAGE_SIZE << nvhe_percpu_order());
+
+		ret = pkvm_mark_hyp(start, end);
+		if (ret)
+			return ret;
+
+		start = virt_to_phys((void *)per_cpu(kvm_arm_hyp_stack_page, cpu));
+		end = start + PAGE_SIZE;
+		ret = pkvm_mark_hyp(start, end);
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 * Flip the static key upfront as that may no longer be possible
 	 * once the host stage 2 is installed.
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index d293cb328cc4..42d81ec739fa 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -21,6 +21,8 @@ struct host_kvm {
 extern struct host_kvm host_kvm;
 
 int __pkvm_prot_finalize(void);
+int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end);
+
 int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool);
 void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
 
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index f47028d3fd0a..3df33d4de4a1 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -156,6 +156,14 @@ static void handle___pkvm_prot_finalize(struct kvm_cpu_context *host_ctxt)
 {
 	cpu_reg(host_ctxt, 1) = __pkvm_prot_finalize();
 }
+
+static void handle___pkvm_mark_hyp(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(phys_addr_t, start, host_ctxt, 1);
+	DECLARE_REG(phys_addr_t, end, host_ctxt, 2);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_mark_hyp(start, end);
+}
 typedef void (*hcall_t)(struct kvm_cpu_context *);
 
 #define HANDLE_FUNC(x)	[__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
@@ -180,6 +188,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_create_mappings),
 	HANDLE_FUNC(__pkvm_create_private_mapping),
 	HANDLE_FUNC(__pkvm_prot_finalize),
+	HANDLE_FUNC(__pkvm_mark_hyp),
 };
 
 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 5c88a325e6fc..fffa432ce3eb 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -25,6 +25,8 @@ struct host_kvm host_kvm;
 struct hyp_pool host_s2_mem;
 struct hyp_pool host_s2_dev;
 
+static const u32 pkvm_hyp_id = 0xffffffff;
+
 static void *host_s2_zalloc_pages_exact(size_t size)
 {
 	return hyp_alloc_pages(&host_s2_mem, get_order(size));
@@ -182,6 +184,18 @@ static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 	return false;
 }
 
+static bool range_is_memory(u64 start, u64 end)
+{
+	struct kvm_mem_range r1, r2;
+
+	if (!find_mem_range(start, &r1) || !find_mem_range(end, &r2))
+		return false;
+	if (r1.start != r2.start)
+		return false;
+
+	return true;
+}
+
 static inline int __host_stage2_idmap(u64 start, u64 end,
 				      enum kvm_pgtable_prot prot,
 				      struct hyp_pool *pool)
@@ -229,6 +243,25 @@ static int host_stage2_idmap(u64 addr)
 	return ret;
 }
 
+int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end)
+{
+	int ret;
+
+	/*
+	 * host_stage2_unmap_dev_all() currently relies on MMIO mappings being
+	 * non-persistent, so don't allow changing page ownership in MMIO range.
+	 */
+	if (!range_is_memory(start, end))
+		return -EINVAL;
+
+	hyp_spin_lock(&host_kvm.lock);
+	ret = kvm_pgtable_stage2_set_owner(&host_kvm.pgt, start, end - start,
+					   &host_s2_mem, pkvm_hyp_id);
+	hyp_spin_unlock(&host_kvm.lock);
+
+	return ret != -EAGAIN ? ret : 0;
+}
+
 void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 {
 	struct kvm_vcpu_fault_info fault;
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c
  2021-03-10 17:57 ` [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
@ 2021-03-11 16:09   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 16:09 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:23PM +0000, Quentin Perret wrote:
> In preparation for enabling the creation of page-tables at EL2, factor
> all memory allocation out of the page-table code, hence making it
> re-usable with any compatible memory allocator.
> 
> No functional changes intended.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_pgtable.h | 41 +++++++++++-
>  arch/arm64/kvm/hyp/pgtable.c         | 98 +++++++++++++++++-----------
>  arch/arm64/kvm/mmu.c                 | 66 ++++++++++++++++++-
>  3 files changed, 163 insertions(+), 42 deletions(-)

Thanks, looks good to me now:

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp
  2021-03-10 17:57 ` [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
@ 2021-03-11 16:11   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 16:11 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:28PM +0000, Quentin Perret wrote:
> In order to use the kernel list library at EL2, introduce stubs for the
> CONFIG_DEBUG_LIST out-of-lines calls.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/Makefile |  2 +-
>  arch/arm64/kvm/hyp/nvhe/stub.c   | 22 ++++++++++++++++++++++
>  2 files changed, 23 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/stub.c
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index 24ff99e2eac5..144da72ad510 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -13,7 +13,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
>  lib-objs := $(addprefix ../../../lib/, $(lib-objs))
>  
>  obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
> -	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o
> +	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o
>  obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
>  	 ../fpsimd.o ../hyp-entry.o ../exception.o
>  obj-y += $(lib-objs)
> diff --git a/arch/arm64/kvm/hyp/nvhe/stub.c b/arch/arm64/kvm/hyp/nvhe/stub.c
> new file mode 100644
> index 000000000000..c0aa6bbfd79d
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/stub.c
> @@ -0,0 +1,22 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Stubs for out-of-line function calls caused by re-using kernel
> + * infrastructure at EL2.
> + *
> + * Copyright (C) 2020 - Google LLC
> + */
> +
> +#include <linux/list.h>
> +
> +#ifdef CONFIG_DEBUG_LIST
> +bool __list_add_valid(struct list_head *new, struct list_head *prev,
> +		      struct list_head *next)
> +{
> +		return true;
> +}
> +
> +bool __list_del_entry_valid(struct list_head *entry)
> +{
> +		return true;
> +}
> +#endif

This isn't any worse than disabling DEBUG_LIST for the EL2 object, so as
an initial implementation:

Acked-by: Will Deacon <will@kernel.org>

but we really should have the debug list checks on (probably
unconditionally) for the EL2 code in my opinion.

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator
  2021-03-10 17:57 ` [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
@ 2021-03-11 16:14   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 16:14 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:29PM +0000, Quentin Perret wrote:
> When memory protection is enabled, the hyp code will require a basic
> form of memory management in order to allocate and free memory pages at
> EL2. This is needed for various use-cases, including the creation of hyp
> mappings or the allocation of stage 2 page tables.
> 
> To address these use-case, introduce a simple memory allocator in the
> hyp code. The allocator is designed as a conventional 'buddy allocator',
> working with a page granularity. It allows to allocate and free
> physically contiguous pages from memory 'pools', with a guaranteed order
> alignment in the PA space. Each page in a memory pool is associated
> with a struct hyp_page which holds the page's metadata, including its
> refcount, as well as its current order, hence mimicking the kernel's
> buddy system in the GFP infrastructure. The hyp_page metadata are made
> accessible through a hyp_vmemmap, following the concept of
> SPARSE_VMEMMAP in the kernel.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/gfp.h    |  68 ++++++++
>  arch/arm64/kvm/hyp/include/nvhe/memory.h |  28 ++++
>  arch/arm64/kvm/hyp/nvhe/Makefile         |   2 +-
>  arch/arm64/kvm/hyp/nvhe/page_alloc.c     | 195 +++++++++++++++++++++++
>  4 files changed, 292 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/kvm/hyp/include/nvhe/gfp.h
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/page_alloc.c

Eventually, we can replace the refcount with refcount_t, but for now this
looks pretty good:

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2
  2021-03-10 17:57 ` [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2 Quentin Perret
@ 2021-03-11 16:21   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 16:21 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:33PM +0000, Quentin Perret wrote:
> When memory protection is enabled, the EL2 code needs the ability to
> create and manage its own page-table. To do so, introduce a new set of
> hypercalls to bootstrap a memory management system at EL2.
> 
> This leads to the following boot flow in nVHE Protected mode:
> 
>  1. the host allocates memory for the hypervisor very early on, using
>     the memblock API;
> 
>  2. the host creates a set of stage 1 page-table for EL2, installs the
>     EL2 vectors, and issues the __pkvm_init hypercall;
> 
>  3. during __pkvm_init, the hypervisor re-creates its stage 1 page-table
>     and stores it in the memory pool provided by the host;
> 
>  4. the hypervisor then extends its stage 1 mappings to include a
>     vmemmap in the EL2 VA space, hence allowing to use the buddy
>     allocator introduced in a previous patch;
> 
>  5. the hypervisor jumps back in the idmap page, switches from the
>     host-provided page-table to the new one, and wraps up its
>     initialization by enabling the new allocator, before returning to
>     the host.
> 
>  6. the host can free the now unused page-table created for EL2, and
>     will now need to issue hypercalls to make changes to the EL2 stage 1
>     mappings instead of modifying them directly.
> 
> Note that for the sake of simplifying the review, this patch focuses on
> the hypervisor side of things. In other words, this only implements the
> new hypercalls, but does not make use of them from the host yet. The
> host-side changes will follow in a subsequent patch.
> 
> Credits to Will for __pkvm_init_switch_pgd.
> 
> Co-authored-by: Will Deacon <will@kernel.org>
> Signed-off-by: Will Deacon <will@kernel.org>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h     |   4 +
>  arch/arm64/include/asm/kvm_host.h    |   7 +
>  arch/arm64/include/asm/kvm_hyp.h     |   8 ++
>  arch/arm64/include/asm/kvm_pgtable.h |   2 +
>  arch/arm64/kernel/image-vars.h       |  16 +++
>  arch/arm64/kvm/hyp/Makefile          |   2 +-
>  arch/arm64/kvm/hyp/include/nvhe/mm.h |  71 ++++++++++
>  arch/arm64/kvm/hyp/nvhe/Makefile     |   4 +-
>  arch/arm64/kvm/hyp/nvhe/hyp-init.S   |  27 ++++
>  arch/arm64/kvm/hyp/nvhe/hyp-main.c   |  49 +++++++
>  arch/arm64/kvm/hyp/nvhe/mm.c         | 173 +++++++++++++++++++++++
>  arch/arm64/kvm/hyp/nvhe/setup.c      | 197 +++++++++++++++++++++++++++
>  arch/arm64/kvm/hyp/pgtable.c         |   2 -
>  arch/arm64/kvm/hyp/reserved_mem.c    |  92 +++++++++++++
>  arch/arm64/mm/init.c                 |   3 +
>  15 files changed, 652 insertions(+), 5 deletions(-)
>  create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mm.h
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/mm.c
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/setup.c
>  create mode 100644 arch/arm64/kvm/hyp/reserved_mem.c

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro
  2021-03-10 17:57 ` [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro Quentin Perret
@ 2021-03-11 16:22   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 16:22 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:32PM +0000, Quentin Perret wrote:
> We will soon need to turn the EL2 stage 1 MMU on and off in nVHE
> protected mode, so refactor the set_sctlr_el1 macro to make it usable
> for that purpose.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/assembler.h | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation at EL2
  2021-03-10 17:57 ` [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation " Quentin Perret
@ 2021-03-11 17:28   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 17:28 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:34PM +0000, Quentin Perret wrote:
> Previous commits have introduced infrastructure to enable the EL2 code
> to manage its own stage 1 mappings. However, this was preliminary work,
> and none of it is currently in use.
> 
> Put all of this together by elevating the mapping creation at EL2 when
> memory protection is enabled. In this case, the host kernel running
> at EL1 still creates _temporary_ EL2 mappings, only used while
> initializing the hypervisor, but frees them right after.
> 
> As such, all calls to create_hyp_mappings() after kvm init has finished
> turn into hypercalls, as the host now has no 'legal' way to modify the
> hypevisor page tables directly.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_mmu.h |  2 +-
>  arch/arm64/kvm/arm.c             | 87 +++++++++++++++++++++++++++++---
>  arch/arm64/kvm/mmu.c             | 43 ++++++++++++++--
>  3 files changed, 120 insertions(+), 12 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs
  2021-03-10 17:57 ` [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs Quentin Perret
@ 2021-03-11 17:33   ` Will Deacon
  2021-03-12  9:15     ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-11 17:33 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:44PM +0000, Quentin Perret wrote:
> kvm_set_invalid_pte() currently only clears bit 0 from a PTE because
> stage2_map_walk_table_post() needs to be able to follow the anchor. In
> preparation for re-using bits 63-02 from invalid PTEs, make sure to zero

Why do you exclude bit 1 from this range?

> it entirely by ensuring to cache the anchor's child upfront.
> 
> Suggested-by: Will Deacon <will@kernel.org>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/pgtable.c | 26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)

For the patch:

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-10 17:57 ` [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership Quentin Perret
@ 2021-03-11 18:38   ` Will Deacon
  2021-03-12  6:23     ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-11 18:38 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:45PM +0000, Quentin Perret wrote:
> As the host stage 2 will be identity mapped, all the .hyp memory regions
> and/or memory pages donated to protected guestis will have to marked
> invalid in the host stage 2 page-table. At the same time, the hypervisor
> will need a way to track the ownership of each physical page to ensure
> memory sharing or donation between entities (host, guests, hypervisor) is
> legal.
> 
> In order to enable this tracking at EL2, let's use the host stage 2
> page-table itself. The idea is to use the top bits of invalid mappings
> to store the unique identifier of the page owner. The page-table owner
> (the host) gets identifier 0 such that, at boot time, it owns the entire
> IPA space as the pgd starts zeroed.
> 
> Provide kvm_pgtable_stage2_set_owner() which allows to modify the
> ownership of pages in the host stage 2. It re-uses most of the map()
> logic, but ends up creating invalid mappings instead. This impacts
> how we do refcount as we now need to count invalid mappings when they
> are used for ownership tracking.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_pgtable.h | 21 +++++++
>  arch/arm64/kvm/hyp/pgtable.c         | 92 ++++++++++++++++++++++++----
>  2 files changed, 101 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index 4ae19247837b..b09af4612656 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -238,6 +238,27 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
>  			   u64 phys, enum kvm_pgtable_prot prot,
>  			   void *mc);
>  
> +/**
> + * kvm_pgtable_stage2_set_owner() - Annotate invalid mappings with metadata
> + *				    encoding the ownership of a page in the
> + *				    IPA space.
> + * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> + * @addr:	Intermediate physical address at which to place the annotation.

This confused me a bit, as the annotation is stored in the page-table, not
at the memory identified by @addr. How about:

  "Base intermediate physical address to annotate"

> + * @size:	Size of the IPA range to annotate.

  "Size of the annotated range"

> + * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
> + *		page-table pages.
> + * @owner_id:	Unique identifier for the owner of the page.
> + *
> + * The page-table owner has identifier 0.

Perhaps, "By default, all page-tables are owned by identifier 0"

> + *
> + * Return: 0 on success, negative error code on failure.
> + */
> +int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> +				 void *mc, u32 owner_id);

Is there a need for the owner_id to be 32-bit rather than e.g. 16-bit? Just
strikes me that it might be difficult to recover these bits in future if we
give them out freely now.

> +
>  /**
>   * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
>   * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index f37b4179b880..e4670b639726 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -48,6 +48,8 @@
>  					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
>  					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
>  
> +#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)

Ah, so that '02' earlier was a typo for '32'.

> +
>  struct kvm_pgtable_walk_data {
>  	struct kvm_pgtable		*pgt;
>  	struct kvm_pgtable_walker	*walker;
> @@ -186,6 +188,11 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level)
>  	return pte;
>  }
>  
> +static kvm_pte_t kvm_init_invalid_leaf_owner(u32 owner_id)
> +{
> +	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
> +}
> +
>  static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
>  				  u32 level, kvm_pte_t *ptep,
>  				  enum kvm_pgtable_walk_flags flag)
> @@ -440,6 +447,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
>  struct stage2_map_data {
>  	u64				phys;
>  	kvm_pte_t			attr;
> +	u32				owner_id;
>  
>  	kvm_pte_t			*anchor;
>  	kvm_pte_t			*childp;
> @@ -506,6 +514,24 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
>  	return 0;
>  }
>  
> +static bool stage2_is_permission_change(kvm_pte_t old, kvm_pte_t new)
> +{
> +	if (!kvm_pte_valid(old) || !kvm_pte_valid(new))
> +		return false;
> +
> +	return !((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS));
> +}

This new name throws me, because it will return true if old == new.

> +static bool stage2_pte_is_counted(kvm_pte_t pte)
> +{
> +	/*
> +	 * The refcount tracks valid entries as well as invalid entries if they
> +	 * encode ownership of a page to another entity than the page-table
> +	 * owner, whose id is 0.
> +	 */
> +	return !!pte;
> +}
> +
>  static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
>  				      kvm_pte_t *ptep,
>  				      struct stage2_map_data *data)
> @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
>  	if (!kvm_block_mapping_supported(addr, end, phys, level))
>  		return -E2BIG;
>  
> -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> -	if (kvm_pte_valid(old)) {
> +	if (kvm_pte_valid(data->attr))

This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
is intended to correspond directly to the lower/upper attributes of the
descriptor as per the architecture, so tagging the valid bit in there is
pretty grotty. However, I can see the significant advantage in being able
to re-use the stage2_map_walker functionality, so about instead of nobbling
attr, you set phys to something invalid instead, e.g.:

	#define KVM_PHYS_SET_OWNER	(-1ULL)

> +		new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> +	else
> +		new = kvm_init_invalid_leaf_owner(data->owner_id);
> +
> +	if (stage2_pte_is_counted(old)) {
>  		/*
>  		 * Skip updating the PTE if we are trying to recreate the exact
>  		 * same mapping or only change the access permissions. Instead,
>  		 * the vCPU will exit one more time from guest if still needed
>  		 * and then go through the path of relaxing permissions.
>  		 */
> -		if (!((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS)))
> +		if (stage2_is_permission_change(old, new))
>  			return -EAGAIN;
>  
>  		/*
> -		 * There's an existing different valid leaf entry, so perform
> -		 * break-before-make.
> +		 * Clear the existing PTE, and perform break-before-make with
> +		 * TLB maintenance if it was valid.
>  		 */
>  		kvm_clear_pte(ptep);
> -		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
> +		if (kvm_pte_valid(old)) {
> +			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr,
> +				     level);
> +		}

Why do you clear the pte unconditionally here? I think you can move that
into the 'if' as well.

>  		mm_ops->put_page(ptep);
>  	}
>  
>  	smp_store_release(ptep, new);
> -	mm_ops->get_page(ptep);
> +	if (stage2_pte_is_counted(new))
> +		mm_ops->get_page(ptep);
>  	data->phys += granule;
>  	return 0;
>  }
> @@ -574,7 +608,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
>  	int ret;
>  
>  	if (data->anchor) {
> -		if (kvm_pte_valid(pte))
> +		if (stage2_pte_is_counted(pte))
>  			mm_ops->put_page(ptep);
>  
>  		return 0;
> @@ -599,9 +633,10 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
>  	 * a table. Accesses beyond 'end' that fall within the new table
>  	 * will be mapped lazily.
>  	 */
> -	if (kvm_pte_valid(pte)) {
> +	if (stage2_pte_is_counted(pte)) {
>  		kvm_clear_pte(ptep);
> -		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
> +		if (kvm_pte_valid(pte))
> +			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);

Same here.

>  		mm_ops->put_page(ptep);
>  	}
>  
> @@ -683,6 +718,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
>  		.mmu		= pgt->mmu,
>  		.memcache	= mc,
>  		.mm_ops		= pgt->mm_ops,
> +		.owner_id	= 0,

Not needed.

>  	};
>  	struct kvm_pgtable_walker walker = {
>  		.cb		= stage2_map_walker,
> @@ -696,6 +732,33 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
>  	if (ret)
>  		return ret;
>  
> +	/* Set the valid flag to distinguish with the set_owner() path. */
> +	map_data.attr |= KVM_PTE_VALID;

(see earlier comments)

> +	ret = kvm_pgtable_walk(pgt, addr, size, &walker);
> +	dsb(ishst);
> +	return ret;
> +}
> +
> +int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> +				 void *mc, u32 owner_id)
> +{
> +	int ret;
> +	struct stage2_map_data map_data = {
> +		.mmu		= pgt->mmu,
> +		.memcache	= mc,
> +		.mm_ops		= pgt->mm_ops,
> +		.owner_id	= owner_id,
> +		.attr		= 0,

Not needed.

> +	};
> +	struct kvm_pgtable_walker walker = {
> +		.cb		= stage2_map_walker,
> +		.flags		= KVM_PGTABLE_WALK_TABLE_PRE |
> +				  KVM_PGTABLE_WALK_LEAF |
> +				  KVM_PGTABLE_WALK_TABLE_POST,

Oh man, now I see why phys is zero -- so that the table callbacks will
put down the largest possible block. That needs a comment because it's
pretty horrible, and also means my idea of using -1 won't help you. Hmm.

Is there ever a reason to use kvm_pgtable_stage2_set_owner() to set an
owner of 0, or should you just use the map/unmap APIs for that? If so,
then maybe the key is simply if owner_id is non-zero, then an invalid
entry is installed?

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr()
  2021-03-10 17:57 ` [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr() Quentin Perret
@ 2021-03-11 18:48   ` Will Deacon
  2021-03-12  5:10     ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-11 18:48 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:46PM +0000, Quentin Perret wrote:
> In order to ease its re-use in other code paths, refactor
> stage2_map_set_prot_attr() to not depend on a stage2_map_data struct.
> No functional change intended.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/pgtable.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index e4670b639726..c16e0306dd9a 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -489,8 +489,7 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
>  	return vtcr;
>  }
>  
> -static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
> -				    struct stage2_map_data *data)
> +static int stage2_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
>  {
>  	bool device = prot & KVM_PGTABLE_PROT_DEVICE;
>  	kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :
> @@ -510,7 +509,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
>  
>  	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
>  	attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
> -	data->attr = attr;
> +	*ptep = attr;
> +
>  	return 0;
>  }
>  
> @@ -728,7 +728,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
>  		.arg		= &map_data,
>  	};
>  
> -	ret = stage2_map_set_prot_attr(prot, &map_data);
> +	ret = stage2_set_prot_attr(prot, &map_data.attr);
>  	if (ret)
>  		return ret;

(nit: this is now different to hyp_map_set_prot_attr() -- can we do the same
thing there, please?)

With that:

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range()
  2021-03-10 17:57 ` [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range() Quentin Perret
@ 2021-03-11 19:04   ` Will Deacon
  2021-03-12  5:32     ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-11 19:04 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:47PM +0000, Quentin Perret wrote:
> Since the host stage 2 will be identity mapped, and since it will own
> most of memory, it would preferable for performance to try and use large
> block mappings whenever that is possible. To ease this, introduce a new
> helper in the KVM page-table code which allows to search for large
> ranges of available IPA space. This will be used in the host memory
> abort path to greedily idmap large portion of the PA space.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_pgtable.h | 30 ++++++++++
>  arch/arm64/kvm/hyp/pgtable.c         | 90 +++++++++++++++++++++++++++-
>  2 files changed, 117 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index b09af4612656..477bf10c48a9 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -94,6 +94,16 @@ enum kvm_pgtable_prot {
>  #define PAGE_HYP_RO		(KVM_PGTABLE_PROT_R)
>  #define PAGE_HYP_DEVICE		(PAGE_HYP | KVM_PGTABLE_PROT_DEVICE)
>  
> +/**
> + * struct kvm_mem_range - Range of Intermediate Physical Addresses
> + * @start:	Start of the range.
> + * @end:	End of the range.
> + */
> +struct kvm_mem_range {
> +	u64 start;
> +	u64 end;
> +};
> +
>  /**
>   * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk.
>   * @KVM_PGTABLE_WALK_LEAF:		Visit leaf entries, including invalid
> @@ -398,4 +408,24 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size);
>  int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
>  		     struct kvm_pgtable_walker *walker);
>  
> +/**
> + * kvm_pgtable_stage2_find_range() - Find a range of Intermediate Physical
> + *				     Addresses with compatible permission
> + *				     attributes.
> + * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> + * @addr:	Address that must be covered by the range.
> + * @prot:	Protection attributes that the range must be compatible with.
> + * @range:	Range structure used to limit the search space at call time and
> + *		that will hold the result.
> + *
> + * The offset of @addr within a page is ignored. An existing mapping is defined
> + * as compatible with @prot if it is invalid and not owned by another entity, or
> + * if its permission attributes are strictly similar to @prot and it has no
> + * software bits set.

nit: I think the 'or' is ambigious here, as it makes it sound like an
invalid entry that _is_ owned by another entity is compatible if the
permissions attribute match. How about:

  | An IPA is compatible with prot iff its corresponding stage-2 page-table
  | entry has default ownership and, if valid, is mapped with protection
  | attributes identical to @prot.

> + *
> + * Return: 0 on success, negative error code on failure.
> + */
> +int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
> +				  enum kvm_pgtable_prot prot,
> +				  struct kvm_mem_range *range);
>  #endif	/* __ARM64_KVM_PGTABLE_H__ */
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index c16e0306dd9a..f20287bb3e41 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -48,6 +48,8 @@
>  					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
>  					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
>  
> +#define KVM_PTE_LEAF_ATTR_S2_RES	GENMASK(58, 55)

Please make this IGN instead of RES, to match the architecture (and because
RES is usually used in the context of RES0 or RES1).

>  #define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)
>  
>  struct kvm_pgtable_walk_data {
> @@ -69,10 +71,8 @@ static u64 kvm_granule_size(u32 level)
>  	return BIT(kvm_granule_shift(level));
>  }
>  
> -static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> +static bool kvm_level_support_block_mappings(u32 level)
>  {
> -	u64 granule = kvm_granule_size(level);
> -
>  	/*
>  	 * Reject invalid block mappings and don't bother with 4TB mappings for
>  	 * 52-bit PAs.
> @@ -80,6 +80,16 @@ static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
>  	if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1))
>  		return false;
>  
> +	return true;

return !(level == 0 || (PAGE_SIZE != SZ_4K && level == 1));

> +static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> +{
> +	u64 granule = kvm_granule_size(level);
> +
> +	if (!kvm_level_support_block_mappings(level))
> +		return false;
> +
>  	if (granule > (end - addr))
>  		return false;
>  
> @@ -1042,3 +1052,77 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
>  	pgt->mm_ops->free_pages_exact(pgt->pgd, pgd_sz);
>  	pgt->pgd = NULL;
>  }
> +
> +#define KVM_PTE_LEAF_S2_COMPAT_MASK	(KVM_PTE_LEAF_ATTR_S2_PERMS | \
> +					 KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | \
> +					 KVM_PTE_LEAF_ATTR_S2_RES)
> +
> +static int stage2_check_permission_walker(u64 addr, u64 end, u32 level,
> +					  kvm_pte_t *ptep,
> +					  enum kvm_pgtable_walk_flags flag,
> +					  void * const arg)
> +{
> +	kvm_pte_t old_attr, pte = *ptep, *new_attr = arg;
> +
> +	/*
> +	 * Compatible mappings are either invalid and owned by the page-table
> +	 * owner (whose id is 0), or valid with matching permission attributes.
> +	 */
> +	if (kvm_pte_valid(pte)) {
> +		old_attr = pte & KVM_PTE_LEAF_S2_COMPAT_MASK;
> +		if (old_attr != *new_attr)
> +			return -EEXIST;
> +	} else if (pte) {
> +		return -EEXIST;
> +	}
> +
> +	return 0;
> +}
> +
> +int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
> +				  enum kvm_pgtable_prot prot,
> +				  struct kvm_mem_range *range)
> +{
> +	kvm_pte_t attr;
> +	struct kvm_pgtable_walker check_perm_walker = {
> +		.cb		= stage2_check_permission_walker,
> +		.flags		= KVM_PGTABLE_WALK_LEAF,
> +		.arg		= &attr,
> +	};
> +	u64 granule, start, end;
> +	u32 level;
> +	int ret;
> +
> +	ret = stage2_set_prot_attr(prot, &attr);
> +	if (ret)
> +		return ret;
> +	attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;
> +
> +	for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
> +		granule = kvm_granule_size(level);
> +		start = ALIGN_DOWN(addr, granule);
> +		end = start + granule;
> +
> +		if (!kvm_level_support_block_mappings(level))
> +			continue;
> +
> +		if (start < range->start || range->end < end)
> +			continue;
> +
> +		/*
> +		 * Check the presence of existing mappings with incompatible
> +		 * permissions within the current block range, and try one level
> +		 * deeper if one is found.
> +		 */
> +		ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
> +		if (ret != -EEXIST)
> +			break;
> +	}

Can you write this as a:

	do {
		...
	} while (level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST);

loop?

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2
  2021-03-10 17:57 ` [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
@ 2021-03-11 19:09   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 19:09 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:48PM +0000, Quentin Perret wrote:
> When KVM runs in protected nVHE mode, make use of a stage 2 page-table
> to give the hypervisor some control over the host memory accesses. The
> host stage 2 is created lazily using large block mappings if possible,
> and will default to page mappings in absence of a better solution.
> 
> From this point on, memory accesses from the host to protected memory
> regions (e.g. marked PROT_NONE) are fatal and lead to hyp_panic().
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h              |   1 +
>  arch/arm64/include/asm/kvm_cpufeature.h       |   2 +
>  arch/arm64/kernel/image-vars.h                |   3 +
>  arch/arm64/kvm/arm.c                          |  10 +
>  arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  34 +++
>  arch/arm64/kvm/hyp/nvhe/Makefile              |   2 +-
>  arch/arm64/kvm/hyp/nvhe/hyp-init.S            |   1 +
>  arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  11 +
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 246 ++++++++++++++++++
>  arch/arm64/kvm/hyp/nvhe/setup.c               |   5 +
>  arch/arm64/kvm/hyp/nvhe/switch.c              |   7 +-
>  arch/arm64/kvm/hyp/nvhe/tlb.c                 |   4 +-
>  12 files changed, 319 insertions(+), 7 deletions(-)
>  create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c

I like this a lot more now, thanks:

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host
  2021-03-10 17:57 ` [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host Quentin Perret
@ 2021-03-11 19:17   ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-11 19:17 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:51PM +0000, Quentin Perret wrote:
> When KVM runs in nVHE protected mode, use the host stage 2 to unmap the
> hypervisor sections by marking them as owned by the hypervisor itself.
> The long-term goal is to ensure the EL2 code can remain robust
> regardless of the host's state, so this starts by making sure the host
> cannot e.g. write to the .hyp sections directly.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h              |  1 +
>  arch/arm64/kvm/arm.c                          | 46 +++++++++++++++++++
>  arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 +
>  arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  9 ++++
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 33 +++++++++++++
>  5 files changed, 91 insertions(+)

Acked-by: Will Deacon <will@kernel.org>

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2
  2021-03-10 17:57 ` [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
@ 2021-03-11 19:36   ` Will Deacon
  2021-03-12  6:34     ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-11 19:36 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Wed, Mar 10, 2021 at 05:57:30PM +0000, Quentin Perret wrote:
> Introduce the infrastructure in KVM enabling to copy CPU feature
> registers into EL2-owned data-structures, to allow reading sanitised
> values directly at EL2 in nVHE.
> 
> Given that only a subset of these features are being read by the
> hypervisor, the ones that need to be copied are to be listed under
> <asm/kvm_cpufeature.h> together with the name of the nVHE variable that
> will hold the copy.
> 
> While at it, introduce the first user of this infrastructure by
> implementing __flush_dcache_area at EL2, which needs
> arm64_ftr_reg_ctrel0.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/cpufeature.h     |  1 +
>  arch/arm64/include/asm/kvm_cpufeature.h | 17 +++++++++++++++++
>  arch/arm64/include/asm/kvm_host.h       |  4 ++++
>  arch/arm64/kernel/cpufeature.c          | 13 +++++++++++++
>  arch/arm64/kvm/hyp/nvhe/Makefile        |  3 ++-
>  arch/arm64/kvm/hyp/nvhe/cache.S         | 13 +++++++++++++
>  arch/arm64/kvm/hyp/nvhe/cpufeature.c    |  8 ++++++++
>  arch/arm64/kvm/sys_regs.c               | 21 +++++++++++++++++++++
>  8 files changed, 79 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c
> 
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 61177bac49fa..a85cea2cac57 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -607,6 +607,7 @@ void check_local_cpu_capabilities(void);
>  
>  u64 read_sanitised_ftr_reg(u32 id);
>  u64 __read_sysreg_by_encoding(u32 sys_id);
> +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst);
>  
>  static inline bool cpu_supports_mixed_endian_el0(void)
>  {
> diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h
> new file mode 100644
> index 000000000000..d34f85cba358
> --- /dev/null
> +++ b/arch/arm64/include/asm/kvm_cpufeature.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 - Google LLC
> + * Author: Quentin Perret <qperret@google.com>
> + */
> +
> +#include <asm/cpufeature.h>
> +
> +#ifndef KVM_HYP_CPU_FTR_REG
> +#if defined(__KVM_NVHE_HYPERVISOR__)
> +#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg name;
> +#else
> +#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name);
> +#endif
> +#endif
> +
> +KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 06ca4828005f..459ee557f87c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -751,9 +751,13 @@ void kvm_clr_pmu_events(u32 clr);
>  
>  void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
>  void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
> +
> +void setup_kvm_el2_caps(void);
>  #else
>  static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
>  static inline void kvm_clr_pmu_events(u32 clr) {}
> +
> +static inline void setup_kvm_el2_caps(void) {}
>  #endif
>  
>  void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 066030717a4c..f2d8b479ff74 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1154,6 +1154,18 @@ u64 read_sanitised_ftr_reg(u32 id)
>  }
>  EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
>  
> +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
> +{
> +	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
> +
> +	if (!regp)
> +		return -EINVAL;
> +
> +	memcpy(dst, regp, sizeof(*regp));

Can you not just use struct assignment here?

> diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S
> new file mode 100644
> index 000000000000..36cef6915428
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/cache.S
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Code copied from arch/arm64/mm/cache.S.
> + */
> +
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +#include <asm/alternative.h>
> +
> +SYM_FUNC_START_PI(__flush_dcache_area)
> +	dcache_by_line_op civac, sy, x0, x1, x2, x3
> +	ret
> +SYM_FUNC_END_PI(__flush_dcache_area)

Separate patch for this? (or fold it into that one really near the start
that introduces some other PI helpers).

> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 4f2f1e3145de..84be93df52fa 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -21,6 +21,7 @@
>  #include <asm/debug-monitors.h>
>  #include <asm/esr.h>
>  #include <asm/kvm_arm.h>
> +#include <asm/kvm_cpufeature.h>
>  #include <asm/kvm_emulate.h>
>  #include <asm/kvm_hyp.h>
>  #include <asm/kvm_mmu.h>
> @@ -2775,3 +2776,23 @@ void kvm_sys_reg_table_init(void)
>  	/* Clear all higher bits. */
>  	cache_levels &= (1 << (i*3))-1;
>  }
> +
> +#undef KVM_HYP_CPU_FTR_REG
> +#define KVM_HYP_CPU_FTR_REG(id, name) \
> +	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
> +struct __ftr_reg_copy_entry {
> +	u32			sys_id;
> +	struct arm64_ftr_reg	*dst;
> +} hyp_ftr_regs[] __initdata = {
> +	#include <asm/kvm_cpufeature.h>
> +};

This looks a bit elaborate to me. Why can't you just spell things out here
like:

#define KVM_HYP_CPU_FTR_REG(id, name) \
	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }

struct __ftr_reg_copy_entry {
	u32			sys_id;
	struct arm64_ftr_reg	*dst;
} hyp_ftr_regs[] __initdata = {
	KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0),
	...
};

and then have the header file be a normal, guarded header which just
declares these things? The id parameter to the macro isn't used there.

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr()
  2021-03-11 18:48   ` Will Deacon
@ 2021-03-12  5:10     ` Quentin Perret
  0 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-12  5:10 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Thursday 11 Mar 2021 at 18:48:36 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:46PM +0000, Quentin Perret wrote:
> > In order to ease its re-use in other code paths, refactor
> > stage2_map_set_prot_attr() to not depend on a stage2_map_data struct.
> > No functional change intended.
> > 
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> >  arch/arm64/kvm/hyp/pgtable.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index e4670b639726..c16e0306dd9a 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -489,8 +489,7 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
> >  	return vtcr;
> >  }
> >  
> > -static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
> > -				    struct stage2_map_data *data)
> > +static int stage2_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
> >  {
> >  	bool device = prot & KVM_PGTABLE_PROT_DEVICE;
> >  	kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) :
> > @@ -510,7 +509,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
> >  
> >  	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
> >  	attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
> > -	data->attr = attr;
> > +	*ptep = attr;
> > +
> >  	return 0;
> >  }
> >  
> > @@ -728,7 +728,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >  		.arg		= &map_data,
> >  	};
> >  
> > -	ret = stage2_map_set_prot_attr(prot, &map_data);
> > +	ret = stage2_set_prot_attr(prot, &map_data.attr);
> >  	if (ret)
> >  		return ret;
> 
> (nit: this is now different to hyp_map_set_prot_attr() -- can we do the same
> thing there, please?)

Will do.

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range()
  2021-03-11 19:04   ` Will Deacon
@ 2021-03-12  5:32     ` Quentin Perret
  2021-03-12  9:40       ` Will Deacon
  0 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-12  5:32 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Thursday 11 Mar 2021 at 19:04:07 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:47PM +0000, Quentin Perret wrote:
> > Since the host stage 2 will be identity mapped, and since it will own
> > most of memory, it would preferable for performance to try and use large
> > block mappings whenever that is possible. To ease this, introduce a new
> > helper in the KVM page-table code which allows to search for large
> > ranges of available IPA space. This will be used in the host memory
> > abort path to greedily idmap large portion of the PA space.
> > 
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> >  arch/arm64/include/asm/kvm_pgtable.h | 30 ++++++++++
> >  arch/arm64/kvm/hyp/pgtable.c         | 90 +++++++++++++++++++++++++++-
> >  2 files changed, 117 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > index b09af4612656..477bf10c48a9 100644
> > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > @@ -94,6 +94,16 @@ enum kvm_pgtable_prot {
> >  #define PAGE_HYP_RO		(KVM_PGTABLE_PROT_R)
> >  #define PAGE_HYP_DEVICE		(PAGE_HYP | KVM_PGTABLE_PROT_DEVICE)
> >  
> > +/**
> > + * struct kvm_mem_range - Range of Intermediate Physical Addresses
> > + * @start:	Start of the range.
> > + * @end:	End of the range.
> > + */
> > +struct kvm_mem_range {
> > +	u64 start;
> > +	u64 end;
> > +};
> > +
> >  /**
> >   * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk.
> >   * @KVM_PGTABLE_WALK_LEAF:		Visit leaf entries, including invalid
> > @@ -398,4 +408,24 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size);
> >  int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >  		     struct kvm_pgtable_walker *walker);
> >  
> > +/**
> > + * kvm_pgtable_stage2_find_range() - Find a range of Intermediate Physical
> > + *				     Addresses with compatible permission
> > + *				     attributes.
> > + * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> > + * @addr:	Address that must be covered by the range.
> > + * @prot:	Protection attributes that the range must be compatible with.
> > + * @range:	Range structure used to limit the search space at call time and
> > + *		that will hold the result.
> > + *
> > + * The offset of @addr within a page is ignored. An existing mapping is defined
> > + * as compatible with @prot if it is invalid and not owned by another entity, or
> > + * if its permission attributes are strictly similar to @prot and it has no
> > + * software bits set.
> 
> nit: I think the 'or' is ambigious here, as it makes it sound like an
> invalid entry that _is_ owned by another entity is compatible if the
> permissions attribute match. How about:
> 
>   | An IPA is compatible with prot iff its corresponding stage-2 page-table
>   | entry has default ownership and, if valid, is mapped with protection
>   | attributes identical to @prot.

Works for me.

> > + *
> > + * Return: 0 on success, negative error code on failure.
> > + */
> > +int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
> > +				  enum kvm_pgtable_prot prot,
> > +				  struct kvm_mem_range *range);
> >  #endif	/* __ARM64_KVM_PGTABLE_H__ */
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index c16e0306dd9a..f20287bb3e41 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -48,6 +48,8 @@
> >  					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
> >  					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
> >  
> > +#define KVM_PTE_LEAF_ATTR_S2_RES	GENMASK(58, 55)
> 
> Please make this IGN instead of RES, to match the architecture (and because
> RES is usually used in the context of RES0 or RES1).

Ack, maybe I'll even say 'IGNORED' in full to match the Arm ARM -- IGN
sounds like an acronym otherwise.

> >  #define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)
> >  
> >  struct kvm_pgtable_walk_data {
> > @@ -69,10 +71,8 @@ static u64 kvm_granule_size(u32 level)
> >  	return BIT(kvm_granule_shift(level));
> >  }
> >  
> > -static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> > +static bool kvm_level_support_block_mappings(u32 level)
> >  {
> > -	u64 granule = kvm_granule_size(level);
> > -
> >  	/*
> >  	 * Reject invalid block mappings and don't bother with 4TB mappings for
> >  	 * 52-bit PAs.
> > @@ -80,6 +80,16 @@ static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> >  	if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1))
> >  		return false;
> >  
> > +	return true;
> 
> return !(level == 0 || (PAGE_SIZE != SZ_4K && level == 1));
> 
> > +static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
> > +{
> > +	u64 granule = kvm_granule_size(level);
> > +
> > +	if (!kvm_level_support_block_mappings(level))
> > +		return false;
> > +
> >  	if (granule > (end - addr))
> >  		return false;
> >  
> > @@ -1042,3 +1052,77 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
> >  	pgt->mm_ops->free_pages_exact(pgt->pgd, pgd_sz);
> >  	pgt->pgd = NULL;
> >  }
> > +
> > +#define KVM_PTE_LEAF_S2_COMPAT_MASK	(KVM_PTE_LEAF_ATTR_S2_PERMS | \
> > +					 KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | \
> > +					 KVM_PTE_LEAF_ATTR_S2_RES)
> > +
> > +static int stage2_check_permission_walker(u64 addr, u64 end, u32 level,
> > +					  kvm_pte_t *ptep,
> > +					  enum kvm_pgtable_walk_flags flag,
> > +					  void * const arg)
> > +{
> > +	kvm_pte_t old_attr, pte = *ptep, *new_attr = arg;
> > +
> > +	/*
> > +	 * Compatible mappings are either invalid and owned by the page-table
> > +	 * owner (whose id is 0), or valid with matching permission attributes.
> > +	 */
> > +	if (kvm_pte_valid(pte)) {
> > +		old_attr = pte & KVM_PTE_LEAF_S2_COMPAT_MASK;
> > +		if (old_attr != *new_attr)
> > +			return -EEXIST;
> > +	} else if (pte) {
> > +		return -EEXIST;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
> > +				  enum kvm_pgtable_prot prot,
> > +				  struct kvm_mem_range *range)
> > +{
> > +	kvm_pte_t attr;
> > +	struct kvm_pgtable_walker check_perm_walker = {
> > +		.cb		= stage2_check_permission_walker,
> > +		.flags		= KVM_PGTABLE_WALK_LEAF,
> > +		.arg		= &attr,
> > +	};
> > +	u64 granule, start, end;
> > +	u32 level;
> > +	int ret;
> > +
> > +	ret = stage2_set_prot_attr(prot, &attr);
> > +	if (ret)
> > +		return ret;
> > +	attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;
> > +
> > +	for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
> > +		granule = kvm_granule_size(level);
> > +		start = ALIGN_DOWN(addr, granule);
> > +		end = start + granule;
> > +
> > +		if (!kvm_level_support_block_mappings(level))
> > +			continue;
> > +
> > +		if (start < range->start || range->end < end)
> > +			continue;
> > +
> > +		/*
> > +		 * Check the presence of existing mappings with incompatible
> > +		 * permissions within the current block range, and try one level
> > +		 * deeper if one is found.
> > +		 */
> > +		ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
> > +		if (ret != -EEXIST)
> > +			break;
> > +	}
> 
> Can you write this as a:
> 
> 	do {
> 		...
> 	} while (level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST);
> 
> loop?

I tried it but found it a little less pretty -- the pre-assignment of
level and the increment at the end make it really feel like a for loop
to me:

--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1098,26 +1098,23 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
                return ret;
        attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;
 
-       for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
+       ret = -EEXIST;
+       level = pgt->start_level;
+       do {
                granule = kvm_granule_size(level);
                start = ALIGN_DOWN(addr, granule);
                end = start + granule;
 
-               if (!kvm_level_support_block_mappings(level))
-                       continue;
-
-               if (start < range->start || range->end < end)
-                       continue;
-
                /*
                 * Check the presence of existing mappings with incompatible
                 * permissions within the current block range, and try one level
                 * deeper if one is found.
                 */
-               ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
-               if (ret != -EEXIST)
-                       break;
-       }
+               if (kvm_level_support_block_mappings(level) && start >= range->start && range->end >= end)
+                       ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
+
+               level++;
+       } while (level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST);
 
        if (!ret) {


I'm guessing you're not a fan of the break case in existing loop?
Another option could be:

--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1098,7 +1098,7 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
                return ret;
        attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;

-       for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
+       for (ret = -EEXIST, level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST; level++) {
                granule = kvm_granule_size(level);
                start = ALIGN_DOWN(addr, granule);
                end = start + granule;
@@ -1115,8 +1115,6 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
                 * deeper if one is found.
                 */
                ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
-               if (ret != -EEXIST)
-                       break;
        }

        if (!ret) {

No strong opinion either way. Thoughts?

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-11 18:38   ` Will Deacon
@ 2021-03-12  6:23     ` Quentin Perret
  2021-03-12  9:32       ` Will Deacon
  0 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-12  6:23 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Thursday 11 Mar 2021 at 18:38:36 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:45PM +0000, Quentin Perret wrote:
> > As the host stage 2 will be identity mapped, all the .hyp memory regions
> > and/or memory pages donated to protected guestis will have to marked
> > invalid in the host stage 2 page-table. At the same time, the hypervisor
> > will need a way to track the ownership of each physical page to ensure
> > memory sharing or donation between entities (host, guests, hypervisor) is
> > legal.
> > 
> > In order to enable this tracking at EL2, let's use the host stage 2
> > page-table itself. The idea is to use the top bits of invalid mappings
> > to store the unique identifier of the page owner. The page-table owner
> > (the host) gets identifier 0 such that, at boot time, it owns the entire
> > IPA space as the pgd starts zeroed.
> > 
> > Provide kvm_pgtable_stage2_set_owner() which allows to modify the
> > ownership of pages in the host stage 2. It re-uses most of the map()
> > logic, but ends up creating invalid mappings instead. This impacts
> > how we do refcount as we now need to count invalid mappings when they
> > are used for ownership tracking.
> > 
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> >  arch/arm64/include/asm/kvm_pgtable.h | 21 +++++++
> >  arch/arm64/kvm/hyp/pgtable.c         | 92 ++++++++++++++++++++++++----
> >  2 files changed, 101 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > index 4ae19247837b..b09af4612656 100644
> > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > @@ -238,6 +238,27 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >  			   u64 phys, enum kvm_pgtable_prot prot,
> >  			   void *mc);
> >  
> > +/**
> > + * kvm_pgtable_stage2_set_owner() - Annotate invalid mappings with metadata
> > + *				    encoding the ownership of a page in the
> > + *				    IPA space.
> > + * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> > + * @addr:	Intermediate physical address at which to place the annotation.
> 
> This confused me a bit, as the annotation is stored in the page-table, not
> at the memory identified by @addr. How about:
> 
>   "Base intermediate physical address to annotate"
> 
> > + * @size:	Size of the IPA range to annotate.
> 
>   "Size of the annotated range"
> 
> > + * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
> > + *		page-table pages.
> > + * @owner_id:	Unique identifier for the owner of the page.
> > + *
> > + * The page-table owner has identifier 0.
> 
> Perhaps, "By default, all page-tables are owned by identifier 0"

Ack all of the above.

> > + *
> > + * Return: 0 on success, negative error code on failure.
> > + */
> > +int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> > +				 void *mc, u32 owner_id);
> 
> Is there a need for the owner_id to be 32-bit rather than e.g. 16-bit? Just
> strikes me that it might be difficult to recover these bits in future if we
> give them out freely now.

I figured we might want to use identifiers that are stable for the
lifetime of protected VMs. I wasn't sure using e.g. VMIDs would be a
better choice here as re-using them will cause a lot of pain for the
host stage 2 pgtable maintenance.

> > +
> >  /**
> >   * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
> >   * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index f37b4179b880..e4670b639726 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -48,6 +48,8 @@
> >  					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
> >  					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
> >  
> > +#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 32)
> 
> Ah, so that '02' earlier was a typo for '32'.
> 
> > +
> >  struct kvm_pgtable_walk_data {
> >  	struct kvm_pgtable		*pgt;
> >  	struct kvm_pgtable_walker	*walker;
> > @@ -186,6 +188,11 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level)
> >  	return pte;
> >  }
> >  
> > +static kvm_pte_t kvm_init_invalid_leaf_owner(u32 owner_id)
> > +{
> > +	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
> > +}
> > +
> >  static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
> >  				  u32 level, kvm_pte_t *ptep,
> >  				  enum kvm_pgtable_walk_flags flag)
> > @@ -440,6 +447,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
> >  struct stage2_map_data {
> >  	u64				phys;
> >  	kvm_pte_t			attr;
> > +	u32				owner_id;
> >  
> >  	kvm_pte_t			*anchor;
> >  	kvm_pte_t			*childp;
> > @@ -506,6 +514,24 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,
> >  	return 0;
> >  }
> >  
> > +static bool stage2_is_permission_change(kvm_pte_t old, kvm_pte_t new)
> > +{
> > +	if (!kvm_pte_valid(old) || !kvm_pte_valid(new))
> > +		return false;
> > +
> > +	return !((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS));
> > +}
> 
> This new name throws me, because it will return true if old == new.

How about I invert it and call it 'stage2_pte_needs_update()' or so?

> > +static bool stage2_pte_is_counted(kvm_pte_t pte)
> > +{
> > +	/*
> > +	 * The refcount tracks valid entries as well as invalid entries if they
> > +	 * encode ownership of a page to another entity than the page-table
> > +	 * owner, whose id is 0.
> > +	 */
> > +	return !!pte;
> > +}
> > +
> >  static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> >  				      kvm_pte_t *ptep,
> >  				      struct stage2_map_data *data)
> > @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> >  	if (!kvm_block_mapping_supported(addr, end, phys, level))
> >  		return -E2BIG;
> >  
> > -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > -	if (kvm_pte_valid(old)) {
> > +	if (kvm_pte_valid(data->attr))
> 
> This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
> is intended to correspond directly to the lower/upper attributes of the
> descriptor as per the architecture, so tagging the valid bit in there is
> pretty grotty. However, I can see the significant advantage in being able
> to re-use the stage2_map_walker functionality, so about instead of nobbling
> attr, you set phys to something invalid instead, e.g.:
> 
> 	#define KVM_PHYS_SET_OWNER	(-1ULL)

That'll confuse kvm_block_mapping_supported() and friends I think, at
least in their current form. If you _really_ don't like this, maybe we
could have an extra 'flags' field in stage2_map_data?

> > +		new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > +	else
> > +		new = kvm_init_invalid_leaf_owner(data->owner_id);
> > +
> > +	if (stage2_pte_is_counted(old)) {
> >  		/*
> >  		 * Skip updating the PTE if we are trying to recreate the exact
> >  		 * same mapping or only change the access permissions. Instead,
> >  		 * the vCPU will exit one more time from guest if still needed
> >  		 * and then go through the path of relaxing permissions.
> >  		 */
> > -		if (!((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS)))
> > +		if (stage2_is_permission_change(old, new))
> >  			return -EAGAIN;
> >  
> >  		/*
> > -		 * There's an existing different valid leaf entry, so perform
> > -		 * break-before-make.
> > +		 * Clear the existing PTE, and perform break-before-make with
> > +		 * TLB maintenance if it was valid.
> >  		 */
> >  		kvm_clear_pte(ptep);
> > -		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
> > +		if (kvm_pte_valid(old)) {
> > +			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr,
> > +				     level);
> > +		}
> 
> Why do you clear the pte unconditionally here? I think you can move that
> into the 'if' as well.

Yep that should work.

> >  		mm_ops->put_page(ptep);
> >  	}
> >  
> >  	smp_store_release(ptep, new);
> > -	mm_ops->get_page(ptep);
> > +	if (stage2_pte_is_counted(new))
> > +		mm_ops->get_page(ptep);
> >  	data->phys += granule;
> >  	return 0;
> >  }
> > @@ -574,7 +608,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
> >  	int ret;
> >  
> >  	if (data->anchor) {
> > -		if (kvm_pte_valid(pte))
> > +		if (stage2_pte_is_counted(pte))
> >  			mm_ops->put_page(ptep);
> >  
> >  		return 0;
> > @@ -599,9 +633,10 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
> >  	 * a table. Accesses beyond 'end' that fall within the new table
> >  	 * will be mapped lazily.
> >  	 */
> > -	if (kvm_pte_valid(pte)) {
> > +	if (stage2_pte_is_counted(pte)) {
> >  		kvm_clear_pte(ptep);
> > -		kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
> > +		if (kvm_pte_valid(pte))
> > +			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level);
> 
> Same here.
> 
> >  		mm_ops->put_page(ptep);
> >  	}
> >  
> > @@ -683,6 +718,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >  		.mmu		= pgt->mmu,
> >  		.memcache	= mc,
> >  		.mm_ops		= pgt->mm_ops,
> > +		.owner_id	= 0,
> 
> Not needed.
> 
> >  	};
> >  	struct kvm_pgtable_walker walker = {
> >  		.cb		= stage2_map_walker,
> > @@ -696,6 +732,33 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> >  	if (ret)
> >  		return ret;
> >  
> > +	/* Set the valid flag to distinguish with the set_owner() path. */
> > +	map_data.attr |= KVM_PTE_VALID;
> 
> (see earlier comments)
> 
> > +	ret = kvm_pgtable_walk(pgt, addr, size, &walker);
> > +	dsb(ishst);
> > +	return ret;
> > +}
> > +
> > +int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> > +				 void *mc, u32 owner_id)
> > +{
> > +	int ret;
> > +	struct stage2_map_data map_data = {
> > +		.mmu		= pgt->mmu,
> > +		.memcache	= mc,
> > +		.mm_ops		= pgt->mm_ops,
> > +		.owner_id	= owner_id,
> > +		.attr		= 0,
> 
> Not needed.
> 
> > +	};
> > +	struct kvm_pgtable_walker walker = {
> > +		.cb		= stage2_map_walker,
> > +		.flags		= KVM_PGTABLE_WALK_TABLE_PRE |
> > +				  KVM_PGTABLE_WALK_LEAF |
> > +				  KVM_PGTABLE_WALK_TABLE_POST,
> 
> Oh man, now I see why phys is zero -- so that the table callbacks will
> put down the largest possible block. That needs a comment because it's
> pretty horrible, and also means my idea of using -1 won't help you. Hmm.

We're creating invalid mappings which by definition don't map to
physical pages (the annotation is purely in the _IPA_ space), so yeah
the best thing to do was to take phys 'out of the way'. Setting it to
e.g. @addr would be quite confusing IMO -- imagine if we ever decide to
annotate the stage 2 of guests one day.

And as you noticed, weird values will also happen to confuse
kvm_block_mapping_supported(), and/or to cause range issues, so 0 seemed
like a reasonable choice.

I'll stick a comment.

> Is there ever a reason to use kvm_pgtable_stage2_set_owner() to set an
> owner of 0, or should you just use the map/unmap APIs for that? If so,
> then maybe the key is simply if owner_id is non-zero, then an invalid
> entry is installed?

I couldn't find a good reason to restrict it, as that wouldn't change
the implementation much anyway. Also, if we added the right CMOs, we
could probably remove the unmap walker and re-express it in terms of
set_owner(0) ... But I suppose that is for later :-)

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2
  2021-03-11 19:36   ` Will Deacon
@ 2021-03-12  6:34     ` Quentin Perret
  2021-03-12  9:25       ` Will Deacon
  0 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-12  6:34 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Thursday 11 Mar 2021 at 19:36:39 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:30PM +0000, Quentin Perret wrote:
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 066030717a4c..f2d8b479ff74 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -1154,6 +1154,18 @@ u64 read_sanitised_ftr_reg(u32 id)
> >  }
> >  EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
> >  
> > +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
> > +{
> > +	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
> > +
> > +	if (!regp)
> > +		return -EINVAL;
> > +
> > +	memcpy(dst, regp, sizeof(*regp));
> 
> Can you not just use struct assignment here?

Sure.

> > diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S
> > new file mode 100644
> > index 000000000000..36cef6915428
> > --- /dev/null
> > +++ b/arch/arm64/kvm/hyp/nvhe/cache.S
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Code copied from arch/arm64/mm/cache.S.
> > + */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/assembler.h>
> > +#include <asm/alternative.h>
> > +
> > +SYM_FUNC_START_PI(__flush_dcache_area)
> > +	dcache_by_line_op civac, sy, x0, x1, x2, x3
> > +	ret
> > +SYM_FUNC_END_PI(__flush_dcache_area)
> 
> Separate patch for this? (or fold it into that one really near the start
> that introduces some other PI helpers).

Right, I guess that'll make reverts and such easier so why not.

> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index 4f2f1e3145de..84be93df52fa 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -21,6 +21,7 @@
> >  #include <asm/debug-monitors.h>
> >  #include <asm/esr.h>
> >  #include <asm/kvm_arm.h>
> > +#include <asm/kvm_cpufeature.h>
> >  #include <asm/kvm_emulate.h>
> >  #include <asm/kvm_hyp.h>
> >  #include <asm/kvm_mmu.h>
> > @@ -2775,3 +2776,23 @@ void kvm_sys_reg_table_init(void)
> >  	/* Clear all higher bits. */
> >  	cache_levels &= (1 << (i*3))-1;
> >  }
> > +
> > +#undef KVM_HYP_CPU_FTR_REG
> > +#define KVM_HYP_CPU_FTR_REG(id, name) \
> > +	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
> > +struct __ftr_reg_copy_entry {
> > +	u32			sys_id;
> > +	struct arm64_ftr_reg	*dst;
> > +} hyp_ftr_regs[] __initdata = {
> > +	#include <asm/kvm_cpufeature.h>
> > +};
> 
> This looks a bit elaborate to me. Why can't you just spell things out here
> like:
> 
> #define KVM_HYP_CPU_FTR_REG(id, name) \
> 	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }
> 
> struct __ftr_reg_copy_entry {
> 	u32			sys_id;
> 	struct arm64_ftr_reg	*dst;
> } hyp_ftr_regs[] __initdata = {
> 	KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0),
> 	...
> };
> 
> and then have the header file be a normal, guarded header which just
> declares these things? The id parameter to the macro isn't used there.

I just tried to reduce the boilerplate as much as possible -- in the
current form you only need to add additional features to the header
it'll 'just work'.

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs
  2021-03-11 17:33   ` Will Deacon
@ 2021-03-12  9:15     ` Quentin Perret
  0 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-12  9:15 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Thursday 11 Mar 2021 at 17:33:38 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:44PM +0000, Quentin Perret wrote:
> > kvm_set_invalid_pte() currently only clears bit 0 from a PTE because
> > stage2_map_walk_table_post() needs to be able to follow the anchor. In
> > preparation for re-using bits 63-02 from invalid PTEs, make sure to zero
> 
> Why do you exclude bit 1 from this range?

Hmm, no good reason really. I wanted to play games with invalid table
mappings at some point, but dropped the idea and forgot to update the
commit message. My bad, I'll fix it up.

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2
  2021-03-12  6:34     ` Quentin Perret
@ 2021-03-12  9:25       ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-12  9:25 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Fri, Mar 12, 2021 at 06:34:09AM +0000, Quentin Perret wrote:
> On Thursday 11 Mar 2021 at 19:36:39 (+0000), Will Deacon wrote:
> > On Wed, Mar 10, 2021 at 05:57:30PM +0000, Quentin Perret wrote:
> > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > > index 4f2f1e3145de..84be93df52fa 100644
> > > --- a/arch/arm64/kvm/sys_regs.c
> > > +++ b/arch/arm64/kvm/sys_regs.c
> > > @@ -21,6 +21,7 @@
> > >  #include <asm/debug-monitors.h>
> > >  #include <asm/esr.h>
> > >  #include <asm/kvm_arm.h>
> > > +#include <asm/kvm_cpufeature.h>
> > >  #include <asm/kvm_emulate.h>
> > >  #include <asm/kvm_hyp.h>
> > >  #include <asm/kvm_mmu.h>
> > > @@ -2775,3 +2776,23 @@ void kvm_sys_reg_table_init(void)
> > >  	/* Clear all higher bits. */
> > >  	cache_levels &= (1 << (i*3))-1;
> > >  }
> > > +
> > > +#undef KVM_HYP_CPU_FTR_REG
> > > +#define KVM_HYP_CPU_FTR_REG(id, name) \
> > > +	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
> > > +struct __ftr_reg_copy_entry {
> > > +	u32			sys_id;
> > > +	struct arm64_ftr_reg	*dst;
> > > +} hyp_ftr_regs[] __initdata = {
> > > +	#include <asm/kvm_cpufeature.h>
> > > +};
> > 
> > This looks a bit elaborate to me. Why can't you just spell things out here
> > like:
> > 
> > #define KVM_HYP_CPU_FTR_REG(id, name) \
> > 	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }
> > 
> > struct __ftr_reg_copy_entry {
> > 	u32			sys_id;
> > 	struct arm64_ftr_reg	*dst;
> > } hyp_ftr_regs[] __initdata = {
> > 	KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0),
> > 	...
> > };
> > 
> > and then have the header file be a normal, guarded header which just
> > declares these things? The id parameter to the macro isn't used there.
> 
> I just tried to reduce the boilerplate as much as possible -- in the
> current form you only need to add additional features to the header
> it'll 'just work'.

I don't really think it's worth it -- people are used to having to add
declarations for things, so keeping it simple should be fine.

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-12  6:23     ` Quentin Perret
@ 2021-03-12  9:32       ` Will Deacon
  2021-03-12 10:13         ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-12  9:32 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Fri, Mar 12, 2021 at 06:23:00AM +0000, Quentin Perret wrote:
> On Thursday 11 Mar 2021 at 18:38:36 (+0000), Will Deacon wrote:
> > On Wed, Mar 10, 2021 at 05:57:45PM +0000, Quentin Perret wrote:
> > > As the host stage 2 will be identity mapped, all the .hyp memory regions
> > > and/or memory pages donated to protected guestis will have to marked
> > > invalid in the host stage 2 page-table. At the same time, the hypervisor
> > > will need a way to track the ownership of each physical page to ensure
> > > memory sharing or donation between entities (host, guests, hypervisor) is
> > > legal.
> > > 
> > > In order to enable this tracking at EL2, let's use the host stage 2
> > > page-table itself. The idea is to use the top bits of invalid mappings
> > > to store the unique identifier of the page owner. The page-table owner
> > > (the host) gets identifier 0 such that, at boot time, it owns the entire
> > > IPA space as the pgd starts zeroed.
> > > 
> > > Provide kvm_pgtable_stage2_set_owner() which allows to modify the
> > > ownership of pages in the host stage 2. It re-uses most of the map()
> > > logic, but ends up creating invalid mappings instead. This impacts
> > > how we do refcount as we now need to count invalid mappings when they
> > > are used for ownership tracking.
> > > 
> > > Signed-off-by: Quentin Perret <qperret@google.com>
> > > ---
> > >  arch/arm64/include/asm/kvm_pgtable.h | 21 +++++++
> > >  arch/arm64/kvm/hyp/pgtable.c         | 92 ++++++++++++++++++++++++----
> > >  2 files changed, 101 insertions(+), 12 deletions(-)
> > > 
> > > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > > index 4ae19247837b..b09af4612656 100644
> > > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > > @@ -238,6 +238,27 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> > >  			   u64 phys, enum kvm_pgtable_prot prot,
> > >  			   void *mc);
> > >  
> > > +/**
> > > + * kvm_pgtable_stage2_set_owner() - Annotate invalid mappings with metadata
> > > + *				    encoding the ownership of a page in the
> > > + *				    IPA space.
> > > + * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init().
> > > + * @addr:	Intermediate physical address at which to place the annotation.
> > 
> > This confused me a bit, as the annotation is stored in the page-table, not
> > at the memory identified by @addr. How about:
> > 
> >   "Base intermediate physical address to annotate"
> > 
> > > + * @size:	Size of the IPA range to annotate.
> > 
> >   "Size of the annotated range"
> > 
> > > + * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
> > > + *		page-table pages.
> > > + * @owner_id:	Unique identifier for the owner of the page.
> > > + *
> > > + * The page-table owner has identifier 0.
> > 
> > Perhaps, "By default, all page-tables are owned by identifier 0"
> 
> Ack all of the above.
> 
> > > + *
> > > + * Return: 0 on success, negative error code on failure.
> > > + */
> > > +int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> > > +				 void *mc, u32 owner_id);
> > 
> > Is there a need for the owner_id to be 32-bit rather than e.g. 16-bit? Just
> > strikes me that it might be difficult to recover these bits in future if we
> > give them out freely now.
> 
> I figured we might want to use identifiers that are stable for the
> lifetime of protected VMs. I wasn't sure using e.g. VMIDs would be a
> better choice here as re-using them will cause a lot of pain for the
> host stage 2 pgtable maintenance.

I'm not saying to use the VMID directly, just that allocating half of the
pte feels a bit OTT given that the state of things after this patch series
is that we're using exactly 1 bit.

> > > @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> > >  	if (!kvm_block_mapping_supported(addr, end, phys, level))
> > >  		return -E2BIG;
> > >  
> > > -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > > -	if (kvm_pte_valid(old)) {
> > > +	if (kvm_pte_valid(data->attr))
> > 
> > This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
> > is intended to correspond directly to the lower/upper attributes of the
> > descriptor as per the architecture, so tagging the valid bit in there is
> > pretty grotty. However, I can see the significant advantage in being able
> > to re-use the stage2_map_walker functionality, so about instead of nobbling
> > attr, you set phys to something invalid instead, e.g.:
> > 
> > 	#define KVM_PHYS_SET_OWNER	(-1ULL)
> 
> That'll confuse kvm_block_mapping_supported() and friends I think, at
> least in their current form. If you _really_ don't like this, maybe we
> could have an extra 'flags' field in stage2_map_data?

I was pondering this last night and I thought of two ways to do it:

1. Add a 'bool valid' and then stick the owner and the phys in a union.
   (yes, you'll need to update the block mapping checks to look at the
    valid flag)

2. Go with my latter suggestion:

> > Is there ever a reason to use kvm_pgtable_stage2_set_owner() to set an
> > owner of 0, or should you just use the map/unmap APIs for that? If so,
> > then maybe the key is simply if owner_id is non-zero, then an invalid
> > entry is installed?
> 
> I couldn't find a good reason to restrict it, as that wouldn't change
> the implementation much anyway. Also, if we added the right CMOs, we
> could probably remove the unmap walker and re-express it in terms of
> set_owner(0) ... But I suppose that is for later :-)

The idea being that if owner is 0, then we install a mapping for phys, but
if owner is !0 then we set the invalid mapping.

(1) is probably the less hacky option... what do you reckon?

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range()
  2021-03-12  5:32     ` Quentin Perret
@ 2021-03-12  9:40       ` Will Deacon
  0 siblings, 0 replies; 59+ messages in thread
From: Will Deacon @ 2021-03-12  9:40 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Fri, Mar 12, 2021 at 05:32:13AM +0000, Quentin Perret wrote:
> On Thursday 11 Mar 2021 at 19:04:07 (+0000), Will Deacon wrote:
> > On Wed, Mar 10, 2021 at 05:57:47PM +0000, Quentin Perret wrote:
> > > +	for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
> > > +		granule = kvm_granule_size(level);
> > > +		start = ALIGN_DOWN(addr, granule);
> > > +		end = start + granule;
> > > +
> > > +		if (!kvm_level_support_block_mappings(level))
> > > +			continue;
> > > +
> > > +		if (start < range->start || range->end < end)
> > > +			continue;
> > > +
> > > +		/*
> > > +		 * Check the presence of existing mappings with incompatible
> > > +		 * permissions within the current block range, and try one level
> > > +		 * deeper if one is found.
> > > +		 */
> > > +		ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker);
> > > +		if (ret != -EEXIST)
> > > +			break;
> > > +	}
> > 
> > Can you write this as a:
> > 
> > 	do {
> > 		...
> > 	} while (level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST);
> > 
> > loop?
> 
> I tried it but found it a little less pretty -- the pre-assignment of
> level and the increment at the end make it really feel like a for loop
> to me:
> 
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -1098,26 +1098,23 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr,
>                 return ret;
>         attr &= KVM_PTE_LEAF_S2_COMPAT_MASK;
>  
> -       for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) {
> +       ret = -EEXIST;
> +       level = pgt->start_level;
> +       do {
>                 granule = kvm_granule_size(level);
>                 start = ALIGN_DOWN(addr, granule);
>                 end = start + granule;
>  
> -               if (!kvm_level_support_block_mappings(level))
> -                       continue;
> -
> -               if (start < range->start || range->end < end)
> -                       continue;

Urgh, yes, sorry, I hadn't appreciated what a mess it causes for these guys.

Stick with the 'for' loop.

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-12  9:32       ` Will Deacon
@ 2021-03-12 10:13         ` Quentin Perret
  2021-03-12 11:18           ` Will Deacon
  0 siblings, 1 reply; 59+ messages in thread
From: Quentin Perret @ 2021-03-12 10:13 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Friday 12 Mar 2021 at 09:32:06 (+0000), Will Deacon wrote:
> I'm not saying to use the VMID directly, just that allocating half of the
> pte feels a bit OTT given that the state of things after this patch series
> is that we're using exactly 1 bit.

Right, and that was the reason for the PROT_NONE approach in the
previous version, but we agreed it'd be worth generalizing to allow for
future use-cases :-)

> > > > @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> > > >  	if (!kvm_block_mapping_supported(addr, end, phys, level))
> > > >  		return -E2BIG;
> > > >  
> > > > -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > > > -	if (kvm_pte_valid(old)) {
> > > > +	if (kvm_pte_valid(data->attr))
> > > 
> > > This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
> > > is intended to correspond directly to the lower/upper attributes of the
> > > descriptor as per the architecture, so tagging the valid bit in there is
> > > pretty grotty. However, I can see the significant advantage in being able
> > > to re-use the stage2_map_walker functionality, so about instead of nobbling
> > > attr, you set phys to something invalid instead, e.g.:
> > > 
> > > 	#define KVM_PHYS_SET_OWNER	(-1ULL)
> > 
> > That'll confuse kvm_block_mapping_supported() and friends I think, at
> > least in their current form. If you _really_ don't like this, maybe we
> > could have an extra 'flags' field in stage2_map_data?
> 
> I was pondering this last night and I thought of two ways to do it:
> 
> 1. Add a 'bool valid' and then stick the owner and the phys in a union.
>    (yes, you'll need to update the block mapping checks to look at the
>     valid flag)

Right, though that is also used for the hyp s1 which doesn't use any of
this ATM. That shouldn't be too bad to change, I'll have a look.

> 2. Go with my latter suggestion:
> 
> > > Is there ever a reason to use kvm_pgtable_stage2_set_owner() to set an
> > > owner of 0, or should you just use the map/unmap APIs for that? If so,
> > > then maybe the key is simply if owner_id is non-zero, then an invalid
> > > entry is installed?
> > 
> > I couldn't find a good reason to restrict it, as that wouldn't change
> > the implementation much anyway. Also, if we added the right CMOs, we
> > could probably remove the unmap walker and re-express it in terms of
> > set_owner(0) ... But I suppose that is for later :-)
> 
> The idea being that if owner is 0, then we install a mapping for phys, but
> if owner is !0 then we set the invalid mapping.

And I could even special-case set_owner(0) by calling unmap under the
hood so the caller doesn't need to care, but it's a bit yuck.

> (1) is probably the less hacky option... what do you reckon?

Agreed, (1) is a bit nicer. I was also considering setting phys = BIT(63)
in the set_owner() path. That makes it obvious it is an invalid PA, and
it should retain the nice alignment properties I need. But I suppose an
explicit flag makes it easier to reason about, so I'll have a go at it.

Thanks,
Quentin

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-12 10:13         ` Quentin Perret
@ 2021-03-12 11:18           ` Will Deacon
  2021-03-12 11:45             ` Quentin Perret
  0 siblings, 1 reply; 59+ messages in thread
From: Will Deacon @ 2021-03-12 11:18 UTC (permalink / raw)
  To: Quentin Perret
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Fri, Mar 12, 2021 at 10:13:26AM +0000, Quentin Perret wrote:
> On Friday 12 Mar 2021 at 09:32:06 (+0000), Will Deacon wrote:
> > I'm not saying to use the VMID directly, just that allocating half of the
> > pte feels a bit OTT given that the state of things after this patch series
> > is that we're using exactly 1 bit.
> 
> Right, and that was the reason for the PROT_NONE approach in the
> previous version, but we agreed it'd be worth generalizing to allow for
> future use-cases :-)

Yeah, just generalising to 32 bits feels like going too far! I dunno,
make it a u8 for now, or define the hypervisor owner ID as 1 and reject
owners greater than that? We can easily extend it later.

> > > > > @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> > > > >  	if (!kvm_block_mapping_supported(addr, end, phys, level))
> > > > >  		return -E2BIG;
> > > > >  
> > > > > -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > > > > -	if (kvm_pte_valid(old)) {
> > > > > +	if (kvm_pte_valid(data->attr))
> > > > 
> > > > This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
> > > > is intended to correspond directly to the lower/upper attributes of the
> > > > descriptor as per the architecture, so tagging the valid bit in there is
> > > > pretty grotty. However, I can see the significant advantage in being able
> > > > to re-use the stage2_map_walker functionality, so about instead of nobbling
> > > > attr, you set phys to something invalid instead, e.g.:
> > > > 
> > > > 	#define KVM_PHYS_SET_OWNER	(-1ULL)
> > > 
> > > That'll confuse kvm_block_mapping_supported() and friends I think, at
> > > least in their current form. If you _really_ don't like this, maybe we
> > > could have an extra 'flags' field in stage2_map_data?
> > 
> > I was pondering this last night and I thought of two ways to do it:
> > 
> > 1. Add a 'bool valid' and then stick the owner and the phys in a union.
> >    (yes, you'll need to update the block mapping checks to look at the
> >     valid flag)
> 
> Right, though that is also used for the hyp s1 which doesn't use any of
> this ATM. That shouldn't be too bad to change, I'll have a look.

Oh, I meant stick the bool in the stage2_map_data so that should be limited
to the stage2 path.

Will

^ permalink raw reply	[flat|nested] 59+ messages in thread

* Re: [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership
  2021-03-12 11:18           ` Will Deacon
@ 2021-03-12 11:45             ` Quentin Perret
  0 siblings, 0 replies; 59+ messages in thread
From: Quentin Perret @ 2021-03-12 11:45 UTC (permalink / raw)
  To: Will Deacon
  Cc: catalin.marinas, maz, james.morse, julien.thierry.kdev,
	suzuki.poulose, android-kvm, linux-kernel, kernel-team, kvmarm,
	linux-arm-kernel, tabba, mark.rutland, dbrazdil, mate.toth-pal,
	seanjc, robh+dt, ardb

On Friday 12 Mar 2021 at 11:18:05 (+0000), Will Deacon wrote:
> On Fri, Mar 12, 2021 at 10:13:26AM +0000, Quentin Perret wrote:
> > On Friday 12 Mar 2021 at 09:32:06 (+0000), Will Deacon wrote:
> > > I'm not saying to use the VMID directly, just that allocating half of the
> > > pte feels a bit OTT given that the state of things after this patch series
> > > is that we're using exactly 1 bit.
> > 
> > Right, and that was the reason for the PROT_NONE approach in the
> > previous version, but we agreed it'd be worth generalizing to allow for
> > future use-cases :-)
> 
> Yeah, just generalising to 32 bits feels like going too far! I dunno,
> make it a u8 for now, or define the hypervisor owner ID as 1 and reject
> owners greater than that? We can easily extend it later.

Alrighty I'll do _both_

> > > > > > @@ -517,28 +543,36 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> > > > > >  	if (!kvm_block_mapping_supported(addr, end, phys, level))
> > > > > >  		return -E2BIG;
> > > > > >  
> > > > > > -	new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> > > > > > -	if (kvm_pte_valid(old)) {
> > > > > > +	if (kvm_pte_valid(data->attr))
> > > > > 
> > > > > This feels like a bit of a hack to me: the 'attr' field in stage2_map_data
> > > > > is intended to correspond directly to the lower/upper attributes of the
> > > > > descriptor as per the architecture, so tagging the valid bit in there is
> > > > > pretty grotty. However, I can see the significant advantage in being able
> > > > > to re-use the stage2_map_walker functionality, so about instead of nobbling
> > > > > attr, you set phys to something invalid instead, e.g.:
> > > > > 
> > > > > 	#define KVM_PHYS_SET_OWNER	(-1ULL)
> > > > 
> > > > That'll confuse kvm_block_mapping_supported() and friends I think, at
> > > > least in their current form. If you _really_ don't like this, maybe we
> > > > could have an extra 'flags' field in stage2_map_data?
> > > 
> > > I was pondering this last night and I thought of two ways to do it:
> > > 
> > > 1. Add a 'bool valid' and then stick the owner and the phys in a union.
> > >    (yes, you'll need to update the block mapping checks to look at the
> > >     valid flag)
> > 
> > Right, though that is also used for the hyp s1 which doesn't use any of
> > this ATM. That shouldn't be too bad to change, I'll have a look.
> 
> Oh, I meant stick the bool in the stage2_map_data so that should be limited
> to the stage2 path.

I mean I still want to use kvm_block_mapping_supported() but ignore the
phys check when it's not valid. I find it ugly to add a 'valid'
parameter to the function itself, so maybe we're better off with just
special casing phys == -1ULL as you first suggested. How much do you hate
the below (totally untested)?

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 8e4599256969..9ec937462fd6 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -71,6 +71,13 @@ static u64 kvm_granule_size(u32 level)
        return BIT(kvm_granule_shift(level));
 }

+#define KVM_PHYS_INVALID (-1ULL)
+
+static bool kvm_phys_is_valid(u64 phys)
+{
+       return phys != KVM_PHYS_INVALID;
+}
+
 static bool kvm_level_support_block_mappings(u32 level)
 {
        /*
@@ -90,7 +97,10 @@ static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level)
        if (granule > (end - addr))
                return false;

-       return IS_ALIGNED(addr, granule) && IS_ALIGNED(phys, granule);
+       if (kvm_phys_is_valid(phys) && !IS_ALIGNED(phys, granule))
+               return false;
+
+       return IS_ALIGNED(addr, granule);
 }

 static u32 kvm_pgtable_idx(struct kvm_pgtable_walk_data *data, u32 level)
@@ -550,7 +560,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
        if (!kvm_block_mapping_supported(addr, end, phys, level))
                return -E2BIG;

-       if (kvm_pte_valid(data->attr))
+       if (kvm_phys_is_valid(phys))
                new = kvm_init_valid_leaf_pte(phys, data->attr, level);
        else
                new = kvm_init_invalid_leaf_owner(data->owner_id);
@@ -580,7 +590,8 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
        smp_store_release(ptep, new);
        if (stage2_pte_is_counted(new))
                mm_ops->get_page(ptep);
-       data->phys += granule;
+       if (kvm_phys_is_valid(phys))
+               data->phys += granule;
        return 0;
 }

@@ -739,9 +750,6 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
        if (ret)
                return ret;

-       /* Set the valid flag to distinguish with the set_owner() path. */
-       map_data.attr |= KVM_PTE_VALID;
-
        ret = kvm_pgtable_walk(pgt, addr, size, &walker);
        dsb(ishst);
        return ret;
@@ -752,6 +760,7 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
 {
        int ret;
        struct stage2_map_data map_data = {
+               .phys           = KVM_PHYS_INVALID,
                .mmu            = pgt->mmu,
                .memcache       = mc,
                .mm_ops         = pgt->mm_ops,




^ permalink raw reply	[flat|nested] 59+ messages in thread

end of thread, other threads:[~2021-03-12 11:46 UTC | newest]

Thread overview: 59+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-10 17:57 [PATCH v4 00/34] KVM: arm64: A stage 2 for the host Quentin Perret
2021-03-10 17:57 ` [PATCH v4 01/34] arm64: lib: Annotate {clear,copy}_page() as position-independent Quentin Perret
2021-03-10 17:57 ` [PATCH v4 02/34] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
2021-03-10 17:57 ` [PATCH v4 03/34] arm64: kvm: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
2021-03-10 17:57 ` [PATCH v4 04/34] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
2021-03-10 17:57 ` [PATCH v4 05/34] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
2021-03-10 17:57 ` [PATCH v4 06/34] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
2021-03-11 16:09   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 07/34] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
2021-03-10 17:57 ` [PATCH v4 08/34] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
2021-03-10 17:57 ` [PATCH v4 09/34] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
2021-03-10 17:57 ` [PATCH v4 10/34] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
2021-03-10 17:57 ` [PATCH v4 11/34] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
2021-03-11 16:11   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 12/34] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
2021-03-11 16:14   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 13/34] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
2021-03-11 19:36   ` Will Deacon
2021-03-12  6:34     ` Quentin Perret
2021-03-12  9:25       ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 14/34] KVM: arm64: Factor out vector address calculation Quentin Perret
2021-03-10 17:57 ` [PATCH v4 15/34] arm64: asm: Provide set_sctlr_el2 macro Quentin Perret
2021-03-11 16:22   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 16/34] KVM: arm64: Prepare the creation of s1 mappings at EL2 Quentin Perret
2021-03-11 16:21   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 17/34] KVM: arm64: Elevate hypervisor mappings creation " Quentin Perret
2021-03-11 17:28   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 18/34] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
2021-03-10 17:57 ` [PATCH v4 19/34] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
2021-03-10 17:57 ` [PATCH v4 20/34] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
2021-03-10 17:57 ` [PATCH v4 21/34] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
2021-03-10 17:57 ` [PATCH v4 22/34] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
2021-03-10 17:57 ` [PATCH v4 23/34] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
2021-03-10 17:57 ` [PATCH v4 24/34] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
2021-03-10 17:57 ` [PATCH v4 25/34] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
2021-03-10 17:57 ` [PATCH v4 26/34] KVM: arm64: Sort the hypervisor memblocks Quentin Perret
2021-03-10 17:57 ` [PATCH v4 27/34] KVM: arm64: Always zero invalid PTEs Quentin Perret
2021-03-11 17:33   ` Will Deacon
2021-03-12  9:15     ` Quentin Perret
2021-03-10 17:57 ` [PATCH v4 28/34] KVM: arm64: Use page-table to track page ownership Quentin Perret
2021-03-11 18:38   ` Will Deacon
2021-03-12  6:23     ` Quentin Perret
2021-03-12  9:32       ` Will Deacon
2021-03-12 10:13         ` Quentin Perret
2021-03-12 11:18           ` Will Deacon
2021-03-12 11:45             ` Quentin Perret
2021-03-10 17:57 ` [PATCH v4 29/34] KVM: arm64: Refactor stage2_map_set_prot_attr() Quentin Perret
2021-03-11 18:48   ` Will Deacon
2021-03-12  5:10     ` Quentin Perret
2021-03-10 17:57 ` [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range() Quentin Perret
2021-03-11 19:04   ` Will Deacon
2021-03-12  5:32     ` Quentin Perret
2021-03-12  9:40       ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 31/34] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
2021-03-11 19:09   ` Will Deacon
2021-03-10 17:57 ` [PATCH v4 32/34] KVM: arm64: Page-align the .hyp sections Quentin Perret
2021-03-10 17:57 ` [PATCH v4 33/34] KVM: arm64: Disable PMU support in protected mode Quentin Perret
2021-03-10 17:57 ` [PATCH v4 34/34] KVM: arm64: Protect the .hyp sections from the host Quentin Perret
2021-03-11 19:17   ` Will Deacon

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).