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From: Joao Martins <joao.m.martins@oracle.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: "Ankur Arora" <ankur.a.arora@oracle.com>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	"Joao Martins" <joao.m.martins@oracle.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org
Subject: [PATCH RFC 23/39] KVM: x86/xen: grant table grow support
Date: Wed, 20 Feb 2019 20:15:53 +0000	[thread overview]
Message-ID: <20190220201609.28290-24-joao.m.martins@oracle.com> (raw)
In-Reply-To: <20190220201609.28290-1-joao.m.martins@oracle.com>

Guests grant tables with core Xen PV devices (xenbus, console) need to
be seeded with a bunch of reserved entries at boot. However, at init,
the grant table is, from a guest perspective, empty and has no frames
backing it. That only happens once the guest does:

 XENMEM_add_to_physmap(idx=N,gfn=M,space=XENMAPSPACE_grant_table)

Which will share the added page with the hypervisor.

The way we handle this then is to seed (from userspace) the initial
frame where we store special entries which reference guest PV ring
pages. These pages are in-turn mapped/unmapped in backend domains
hosting xenstored and xenconsoled.

When the guest initializes its grant tables (with the hypercall listed
above) we copy the entries from the private frame into a "mapped" gfn.
To do this, the userspace VMM handles XENMEM_add_to_physmap hypercall and
the hypervisor grows its grant table. Note that a grant table can only
grow - no shrinking is possible.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 arch/x86/include/asm/kvm_host.h | 16 ++++++++
 arch/x86/kvm/xen.c              | 90 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h        |  5 +++
 3 files changed, 111 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e0cbc0899580..70bb7339ddd4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -860,6 +860,21 @@ struct kvm_hv {
 	atomic_t num_mismatched_vp_indexes;
 };
 
+struct kvm_grant_map {
+	u64 gpa;
+	union {
+		struct {
+
+#define _KVM_GNTMAP_ACTIVE      (15)
+#define KVM_GNTMAP_ACTIVE       (1 << _KVM_GNTMAP_ACTIVE)
+			u16 flags;
+			u16 ref;
+			u32 domid;
+		};
+		u64 fields;
+	};
+};
+
 /* Xen grant table */
 struct kvm_grant_table {
 	u32 nr_frames;
@@ -871,6 +886,7 @@ struct kvm_grant_table {
 	gfn_t *frames_addr;
 	gpa_t initial_addr;
 	struct grant_entry_v1 *initial;
+	struct kvm_grant_map **handle;
 
 	/* maptrack limits */
 	u32 max_mt_frames;
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index b9e6e8f72d87..7266d27db210 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -22,6 +22,12 @@
 
 #include "trace.h"
 
+/* Grant v1 references per 4K page */
+#define GPP_V1 (PAGE_SIZE / sizeof(struct grant_entry_v1))
+
+/* Grant mappings per 4K page */
+#define MPP    (PAGE_SIZE / sizeof(struct kvm_grant_map))
+
 struct evtchnfd {
 	struct eventfd_ctx *ctx;
 	u32 vcpu;
@@ -1158,11 +1164,92 @@ int kvm_xen_gnttab_init(struct kvm *kvm, struct kvm_xen *xen,
 void kvm_xen_gnttab_free(struct kvm_xen *xen)
 {
 	struct kvm_grant_table *gnttab = &xen->gnttab;
+	int i;
+
+	for (i = 0; i < gnttab->nr_frames; i++)
+		put_page(virt_to_page(gnttab->frames[i]));
 
 	kfree(gnttab->frames);
 	kfree(gnttab->frames_addr);
 }
 
+int kvm_xen_gnttab_copy_initial_frame(struct kvm *kvm)
+{
+	struct kvm_grant_table *gnttab = &kvm->arch.xen.gnttab;
+	int idx = 0;
+
+	/* Only meant to copy the first gpa being populated */
+	if (!gnttab->initial_addr || !gnttab->frames[idx])
+		return -EINVAL;
+
+	memcpy(gnttab->frames[idx], gnttab->initial, PAGE_SIZE);
+	return 0;
+}
+
+int kvm_xen_maptrack_grow(struct kvm_xen *xen, u32 target)
+{
+	u32 max_entries = target * GPP_V1;
+	u32 nr_entries = xen->gnttab.nr_mt_frames * MPP;
+	int i, j, err = 0;
+	void *addr;
+
+	for (i = nr_entries, j = xen->gnttab.nr_mt_frames;
+	     i < max_entries; i += MPP, j++) {
+		addr = (void *) get_zeroed_page(GFP_KERNEL);
+		if (!addr) {
+			err = -ENOMEM;
+			break;
+		}
+
+		xen->gnttab.handle[j] = addr;
+	}
+
+	xen->gnttab.nr_mt_frames = j;
+	xen->gnttab.nr_frames = target;
+	return err;
+}
+
+int kvm_xen_gnttab_grow(struct kvm *kvm, struct kvm_xen_gnttab *op)
+{
+	struct kvm_xen *xen = &kvm->arch.xen;
+	struct kvm_grant_table *gnttab = &xen->gnttab;
+	gfn_t *map = gnttab->frames_addr;
+	u64 gfn = op->grow.gfn;
+	u32 idx = op->grow.idx;
+	struct page *page;
+
+	if (idx < gnttab->nr_frames || idx >= gnttab->max_nr_frames)
+		return -EINVAL;
+
+	if (!idx && !gnttab->nr_frames &&
+	    !gnttab->initial) {
+		return -EINVAL;
+	}
+
+	page = gfn_to_page(kvm, gfn);
+	if (is_error_page(page))
+		return -EINVAL;
+
+	map[idx] = gfn;
+
+	gnttab->frames[idx] = page_to_virt(page);
+	if (!idx && !gnttab->nr_frames &&
+	    kvm_xen_gnttab_copy_initial_frame(kvm)) {
+		pr_err("kvm_xen: dom%u: failed to copy initial frame\n",
+			xen->domid);
+		return -EFAULT;
+	}
+
+	if (kvm_xen_maptrack_grow(xen, gnttab->nr_frames + 1)) {
+		pr_warn("kvm_xen: dom%u: cannot grow maptrack\n", xen->domid);
+		return -EFAULT;
+	}
+
+	pr_debug("kvm_xen: dom%u: grant table grow frames:%d/%d\n", xen->domid,
+		 gnttab->nr_frames, gnttab->max_nr_frames);
+	return 0;
+}
+
 int kvm_vm_ioctl_xen_gnttab(struct kvm *kvm, struct kvm_xen_gnttab *op)
 {
 	int r = -EINVAL;
@@ -1174,6 +1261,9 @@ int kvm_vm_ioctl_xen_gnttab(struct kvm *kvm, struct kvm_xen_gnttab *op)
 	case KVM_XEN_GNTTAB_F_INIT:
 		r = kvm_xen_gnttab_init(kvm, &kvm->arch.xen, op, 0);
 		break;
+	case KVM_XEN_GNTTAB_F_GROW:
+		r = kvm_xen_gnttab_grow(kvm, op);
+		break;
 	default:
 		r = -ENOSYS;
 		break;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index e4fb9bc34d61..ff7f7d019472 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1505,6 +1505,7 @@ struct kvm_xen_hvm_attr {
 		} dom;
 		struct kvm_xen_gnttab {
 #define KVM_XEN_GNTTAB_F_INIT		0
+#define KVM_XEN_GNTTAB_F_GROW		(1 << 0)
 			__u32 flags;
 			union {
 				struct {
@@ -1512,6 +1513,10 @@ struct kvm_xen_hvm_attr {
 					__u32 max_maptrack_frames;
 					__u64 initial_frame;
 				} init;
+				struct {
+					__u32 idx;
+					__u64 gfn;
+				} grow;
 				__u32 padding[4];
 			};
 		} gnttab;
-- 
2.11.0


  parent reply	other threads:[~2019-02-20 20:18 UTC|newest]

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-20 20:15 [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 01/39] KVM: x86: fix Xen hypercall page msr handling Joao Martins
2019-02-22  1:30   ` Sean Christopherson
2019-02-22 11:47     ` Joao Martins
2019-02-22 12:51     ` Paolo Bonzini
2020-11-30 10:39       ` David Woodhouse
2020-11-30 11:03         ` Paolo Bonzini
2020-11-30 11:27           ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 02/39] KVM: x86/xen: intercept xen hypercalls if enabled Joao Martins
2019-02-21 18:29   ` Sean Christopherson
2019-02-21 20:56     ` Joao Martins
2019-02-22  0:30       ` Sean Christopherson
2019-02-22 12:50         ` Paolo Bonzini
2020-12-01  9:48   ` David Woodhouse
2020-12-01 11:19     ` David Woodhouse
2020-12-02 11:17       ` Joao Martins
2020-12-02 12:12         ` David Woodhouse
2020-12-02  5:19     ` Ankur Arora
2020-12-02  8:03       ` David Woodhouse
2020-12-02 18:20         ` Ankur Arora
2019-02-20 20:15 ` [PATCH RFC 03/39] KVM: x86/xen: register shared_info page Joao Martins
2020-12-01 13:07   ` David Woodhouse
2020-12-02  0:40     ` Ankur Arora
2020-12-02  1:26       ` David Woodhouse
2020-12-02  5:17         ` Ankur Arora
2020-12-02 10:50           ` Joao Martins
2020-12-02 10:44       ` Joao Martins
2020-12-02 12:20         ` David Woodhouse
2020-12-02 20:32           ` Ankur Arora
2020-12-03 10:16             ` David Woodhouse
2020-12-04 17:30               ` Sean Christopherson
2020-12-02 20:33         ` Ankur Arora
2020-12-12 12:07       ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 04/39] KVM: x86/xen: setup pvclock updates Joao Martins
2019-02-20 20:15 ` [PATCH RFC 05/39] KVM: x86/xen: update wallclock region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 06/39] KVM: x86/xen: register vcpu info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 07/39] KVM: x86/xen: register vcpu time info region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 08/39] KVM: x86/xen: register steal clock Joao Martins
2019-02-20 20:15 ` [PATCH RFC 09/39] KVM: x86: declare Xen HVM guest capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 10/39] KVM: x86/xen: support upcall vector Joao Martins
2020-12-02 11:17   ` David Woodhouse
2020-12-02 13:12     ` Joao Martins
2020-12-02 16:47       ` David Woodhouse
2020-12-02 18:34         ` Joao Martins
2020-12-02 19:02           ` David Woodhouse
2020-12-02 20:12             ` Joao Martins
2020-12-02 20:37               ` David Woodhouse
2020-12-03  1:08             ` Ankur Arora
2020-12-08 16:08             ` David Woodhouse
2020-12-09  6:35               ` Ankur Arora
2020-12-09 10:27                 ` David Woodhouse
2020-12-09 10:51                   ` Joao Martins
2020-12-09 11:39                     ` David Woodhouse
2020-12-09 13:26                       ` Joao Martins
2020-12-09 15:41                         ` David Woodhouse
2020-12-09 16:12                           ` Joao Martins
2021-01-01 14:33           ` David Woodhouse
2021-01-05 12:11             ` Joao Martins
2021-01-05 13:23               ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 11/39] KVM: x86/xen: evtchn signaling via eventfd Joao Martins
2020-11-30  9:41   ` David Woodhouse
2020-11-30 12:17     ` Joao Martins
2020-11-30 12:55       ` David Woodhouse
2020-11-30 15:08         ` Joao Martins
2020-11-30 16:48           ` David Woodhouse
2020-11-30 17:15             ` Joao Martins
2020-11-30 18:01               ` David Woodhouse
2020-11-30 18:41                 ` Joao Martins
2020-11-30 19:04                   ` David Woodhouse
2020-11-30 19:25                     ` Joao Martins
2021-11-23 13:15           ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 12/39] KVM: x86/xen: store virq when assigning evtchn Joao Martins
     [not found]   ` <b750291466f3c89e0a393e48079c087704b217a5.camel@amazon.co.uk>
2022-02-10 12:17     ` Joao Martins
2022-02-10 15:23       ` [EXTERNAL] " David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 13/39] KVM: x86/xen: handle PV timers oneshot mode Joao Martins
2019-02-20 20:15 ` [PATCH RFC 14/39] KVM: x86/xen: handle PV IPI vcpu yield Joao Martins
2019-02-20 20:15 ` [PATCH RFC 15/39] KVM: x86/xen: handle PV spinlocks slowpath Joao Martins
2022-02-08 12:36   ` David Woodhouse
2022-02-10 12:17     ` Joao Martins
2022-02-10 14:11       ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 16/39] KVM: x86: declare Xen HVM evtchn offload capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 17/39] x86/xen: export vcpu_info and shared_info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 18/39] x86/xen: make hypercall_page generic Joao Martins
2019-02-20 20:15 ` [PATCH RFC 19/39] xen/xenbus: xenbus uninit support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 20/39] xen-blkback: module_exit support Joao Martins
2019-02-25 18:57   ` Konrad Rzeszutek Wilk
2019-02-26 11:20     ` Joao Martins
2019-02-20 20:15 ` [PATCH RFC 21/39] KVM: x86/xen: domid allocation Joao Martins
2019-02-20 20:15 ` [PATCH RFC 22/39] KVM: x86/xen: grant table init Joao Martins
2019-02-20 20:15 ` Joao Martins [this message]
2019-02-20 20:15 ` [PATCH RFC 24/39] KVM: x86/xen: backend hypercall support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 25/39] KVM: x86/xen: grant map support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 26/39] KVM: x86/xen: grant unmap support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 27/39] KVM: x86/xen: grant copy support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 28/39] KVM: x86/xen: interdomain evtchn support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 29/39] KVM: x86/xen: evtchn unmask support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 30/39] KVM: x86/xen: add additional evtchn ops Joao Martins
2019-02-20 20:16 ` [PATCH RFC 31/39] xen-shim: introduce shim domain driver Joao Martins
2019-02-20 20:16 ` [PATCH RFC 32/39] xen/balloon: xen_shim_domain() support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 33/39] xen/grant-table: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 34/39] xen/gntdev: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 35/39] xen/xenbus: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 36/39] drivers/xen: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 37/39] xen-netback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 38/39] xen-blkback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 39/39] KVM: x86: declare Xen HVM Dom0 capability Joao Martins
2019-02-20 21:09 ` [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Paolo Bonzini
2019-02-21  0:29   ` Ankur Arora
2019-02-21 11:45   ` Joao Martins
2019-02-22 16:59     ` Paolo Bonzini
2019-03-12 17:14       ` Joao Martins
2019-04-08  6:44         ` Juergen Gross
2019-04-08 10:36           ` Joao Martins
2019-04-08 10:42             ` Juergen Gross
2019-04-08 17:31               ` Joao Martins
2019-04-09  0:35                 ` Stefano Stabellini
2019-04-10  5:50                   ` [Xen-devel] " Ankur Arora
2019-04-10 20:45                     ` Stefano Stabellini
2019-04-09  5:04                 ` Juergen Gross
2019-04-10  6:55                   ` Ankur Arora
2019-04-10  7:14                     ` Juergen Gross
2019-02-20 23:39 ` [Xen-devel] " Marek Marczykowski-Górecki
2019-02-21  0:31   ` Ankur Arora
2019-02-21  7:57   ` Juergen Gross
2019-02-21 12:00     ` Joao Martins
2019-02-21 11:55   ` Joao Martins

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