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From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, kvm@vger.kernel.org, x86@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
	liran.alon@oracle.com, jwadams@google.com,
	alexandre.chartre@oracle.com
Subject: [RFC KVM 17/27] kvm/isolation: improve mapping copy when mapping is already present
Date: Mon, 13 May 2019 16:38:25 +0200	[thread overview]
Message-ID: <1557758315-12667-18-git-send-email-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com>

A mapping can already exist if a buffer was mapped in the KVM
address space, and then the buffer was freed but there was no
request to unmap from the KVM address space. In that case, clear
the existing mapping before mapping the new buffer.

Also if the new mapping is a subset of an already larger mapped
range, then remap the entire larger map.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
 arch/x86/kvm/isolation.c |   67 +++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
index e494a15..539e287 100644
--- a/arch/x86/kvm/isolation.c
+++ b/arch/x86/kvm/isolation.c
@@ -88,6 +88,9 @@ struct mm_struct kvm_mm = {
 DEFINE_STATIC_KEY_FALSE(kvm_isolation_enabled);
 EXPORT_SYMBOL(kvm_isolation_enabled);
 
+static void kvm_clear_mapping(void *ptr, size_t size,
+			      enum page_table_level level);
+
 /*
  * When set to true, KVM #VMExit handlers run in isolated address space
  * which maps only KVM required code and per-VM information instead of
@@ -721,6 +724,7 @@ static int kvm_copy_mapping(void *ptr, size_t size, enum page_table_level level)
 {
 	unsigned long addr = (unsigned long)ptr;
 	unsigned long end = addr + ((unsigned long)size);
+	unsigned long range_addr, range_end;
 	struct kvm_range_mapping *range_mapping;
 	bool subset;
 	int err;
@@ -728,22 +732,77 @@ static int kvm_copy_mapping(void *ptr, size_t size, enum page_table_level level)
 	BUG_ON(current->mm == &kvm_mm);
 	pr_debug("KERNMAP COPY addr=%px size=%lx level=%d\n", ptr, size, level);
 
-	range_mapping = kmalloc(sizeof(struct kvm_range_mapping), GFP_KERNEL);
-	if (!range_mapping)
-		return -ENOMEM;
+	mutex_lock(&kvm_range_mapping_lock);
+
+	/*
+	 * A mapping can already exist if the buffer was mapped and then
+	 * freed but there was no request to unmap it. We might also be
+	 * trying to map a subset of an already mapped buffer.
+	 */
+	range_mapping = kvm_get_range_mapping_locked(ptr, &subset);
+	if (range_mapping) {
+		if (subset) {
+			pr_debug("range %px/%lx/%d is a subset of %px/%lx/%d already mapped, remapping\n",
+				 ptr, size, level, range_mapping->ptr,
+				 range_mapping->size, range_mapping->level);
+			range_addr = (unsigned long)range_mapping->ptr;
+			range_end = range_addr +
+				((unsigned long)range_mapping->size);
+			err = kvm_copy_pgd_range(&kvm_mm, current->mm,
+						 range_addr, range_end,
+						 range_mapping->level);
+			if (end <= range_end) {
+				/*
+				 * We effectively have a subset, fully contained
+				 * in the superset. So we are done.
+				 */
+				mutex_unlock(&kvm_range_mapping_lock);
+				return err;
+			}
+			/*
+			 * The new range is larger than the existing mapped
+			 * range. So we need an extra mapping to map the end
+			 * of the range.
+			 */
+			addr = range_end;
+			range_mapping = NULL;
+			pr_debug("adding extra range %lx-%lx (%d)\n", addr,
+				 end, level);
+		} else {
+			pr_debug("range %px size=%lx level=%d already mapped, clearing\n",
+				 range_mapping->ptr, range_mapping->size,
+				 range_mapping->level);
+			kvm_clear_mapping(range_mapping->ptr,
+					  range_mapping->size,
+					  range_mapping->level);
+			list_del(&range_mapping->list);
+		}
+	}
+
+	if (!range_mapping) {
+		range_mapping = kmalloc(sizeof(struct kvm_range_mapping),
+		    GFP_KERNEL);
+		if (!range_mapping) {
+			mutex_unlock(&kvm_range_mapping_lock);
+			return -ENOMEM;
+		}
+		INIT_LIST_HEAD(&range_mapping->list);
+	}
 
 	err = kvm_copy_pgd_range(&kvm_mm, current->mm, addr, end, level);
 	if (err) {
+		mutex_unlock(&kvm_range_mapping_lock);
 		kfree(range_mapping);
 		return err;
 	}
 
-	INIT_LIST_HEAD(&range_mapping->list);
 	range_mapping->ptr = ptr;
 	range_mapping->size = size;
 	range_mapping->level = level;
 	list_add(&range_mapping->list, &kvm_range_mapping_list);
 
+	mutex_unlock(&kvm_range_mapping_lock);
+
 	return 0;
 }
 
-- 
1.7.1


  parent reply	other threads:[~2019-05-13 14:40 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13 14:38 [RFC KVM 00/27] KVM Address Space Isolation Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 01/27] kernel: Export memory-management symbols required for KVM address space isolation Alexandre Chartre
2019-05-13 15:15   ` Peter Zijlstra
2019-05-13 15:17     ` Liran Alon
2019-05-13 14:38 ` [RFC KVM 02/27] KVM: x86: Introduce address_space_isolation module parameter Alexandre Chartre
2019-05-13 15:46   ` Andy Lutomirski
2019-05-13 15:55     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 03/27] KVM: x86: Introduce KVM separate virtual address space Alexandre Chartre
2019-05-13 15:45   ` Andy Lutomirski
2019-05-13 16:04     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 04/27] KVM: x86: Switch to KVM address space on entry to guest Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 05/27] KVM: x86: Add handler to exit kvm isolation Alexandre Chartre
2019-05-13 15:49   ` Andy Lutomirski
2019-05-13 16:10     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 06/27] KVM: x86: Exit KVM isolation on IRQ entry Alexandre Chartre
2019-05-13 15:51   ` Andy Lutomirski
2019-05-13 16:28     ` Alexandre Chartre
2019-05-13 18:13       ` Andy Lutomirski
2019-05-14  7:07         ` Peter Zijlstra
2019-05-14  7:58           ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 07/27] KVM: x86: Switch to host address space when may access sensitive data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 08/27] KVM: x86: Optimize branches which checks if address space isolation enabled Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 09/27] kvm/isolation: function to track buffers allocated for the KVM page table Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 10/27] kvm/isolation: add KVM page table entry free functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 11/27] kvm/isolation: add KVM page table entry offset functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 12/27] kvm/isolation: add KVM page table entry allocation functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 13/27] kvm/isolation: add KVM page table entry set functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 14/27] kvm/isolation: functions to copy page table entries for a VA range Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 15/27] kvm/isolation: keep track of VA range mapped in KVM address space Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 16/27] kvm/isolation: functions to clear page table entries for a VA range Alexandre Chartre
2019-05-13 14:38 ` Alexandre Chartre [this message]
2019-05-13 14:38 ` [RFC KVM 18/27] kvm/isolation: function to copy page table entries for percpu buffer Alexandre Chartre
2019-05-13 18:18   ` Andy Lutomirski
2019-05-14  7:09     ` Peter Zijlstra
2019-05-14  8:25       ` Alexandre Chartre
2019-05-14  8:34         ` Andy Lutomirski
2019-05-14  9:41           ` Alexandre Chartre
2019-05-14 15:23             ` Andy Lutomirski
2019-05-14 16:24               ` Alexandre Chartre
2019-05-14 17:05                 ` Peter Zijlstra
2019-05-14 18:09                   ` Sean Christopherson
2019-05-14 20:33                     ` Andy Lutomirski
2019-05-14 21:06                       ` Sean Christopherson
2019-05-14 21:55                         ` Andy Lutomirski
2019-05-14 22:38                           ` Sean Christopherson
2019-05-18  0:05                             ` Jonathan Adams
2019-05-14 20:27                   ` Andy Lutomirski
2019-05-13 14:38 ` [RFC KVM 19/27] kvm/isolation: initialize the KVM page table with core mappings Alexandre Chartre
2019-05-13 15:50   ` Dave Hansen
2019-05-13 16:00     ` Andy Lutomirski
2019-05-13 17:00       ` Alexandre Chartre
2019-05-13 16:46     ` Sean Christopherson
2019-05-13 16:47     ` Alexandre Chartre
2019-05-14 10:26       ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 20/27] kvm/isolation: initialize the KVM page table with vmx specific data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 21/27] kvm/isolation: initialize the KVM page table with vmx VM data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 22/27] kvm/isolation: initialize the KVM page table with vmx cpu data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 23/27] kvm/isolation: initialize the KVM page table with the vcpu tasks Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 24/27] kvm/isolation: KVM page fault handler Alexandre Chartre
2019-05-13 15:15   ` Peter Zijlstra
2019-05-13 21:25     ` Liran Alon
2019-05-14  2:02       ` Andy Lutomirski
2019-05-14  7:21         ` Peter Zijlstra
2019-05-14 15:36           ` Alexandre Chartre
2019-05-14 15:43             ` Andy Lutomirski
2019-05-13 16:02   ` Andy Lutomirski
2019-05-13 16:21     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 25/27] kvm/isolation: implement actual KVM isolation enter/exit Alexandre Chartre
2019-05-13 15:16   ` Peter Zijlstra
2019-05-13 16:01   ` Andy Lutomirski
2019-05-13 14:38 ` [RFC KVM 26/27] kvm/isolation: initialize the KVM page table with KVM memslots Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 27/27] kvm/isolation: initialize the KVM page table with KVM buses Alexandre Chartre
2019-05-13 16:42 ` [RFC KVM 00/27] KVM Address Space Isolation Liran Alon
2019-05-13 18:17 ` Andy Lutomirski
2019-05-13 21:08   ` Liran Alon
2019-05-14  2:07     ` Andy Lutomirski
2019-05-14  7:37       ` Peter Zijlstra
2019-05-14 21:32         ` Jan Setje-Eilers
2019-05-14  8:05       ` Liran Alon
2019-05-14  7:29     ` Peter Zijlstra
2019-05-14  7:57       ` Liran Alon
2019-05-14  8:33     ` Alexandre Chartre
2019-05-13 19:31 ` Nakajima, Jun
2019-05-13 21:16   ` Liran Alon
     [not found]     ` <D07C8F51-F2DF-4C8B-AB3B-0DFABD5F4C33@intel.com>
2019-05-13 21:53       ` Liran Alon
2019-05-15 12:52 ` Alexandre Chartre

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