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[PATCH v2 00/11] KVM: x86: track guest page access

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  [PATCH v2 00/11] KVM: x86: track guest page access Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-12-23 12:40 +0100
    [PATCH v2 06/11] KVM: MMU: let page fault handler be aware tracked page Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-12-23 12:40 +0100
    [PATCH v2 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-12-23 12:40 +0100
    [PATCH v2 02/11] KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}_lpage Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-12-23 12:40 +0100
    [PATCH v2 11/11] KVM: MMU: apply page track notifier Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-12-23 12:40 +0100

#1297389 — [PATCH v2 00/11] KVM: x86: track guest page access

Changelog in v2:
- fix a issue that the track memory of memslot is freed if we only move
  the memslot or change the flags of memslot
- do not track the gfn which is not mapped in memslots
- introduce the nolock APIs at the begin of the patchset
- use 'unsigned short' as the track counter to reduce the memory and which
  should be enough for shadow page table and KVMGT

This patchset introduces the feature which allows us to track page
access in guest. Currently, only write access tracking is implemented
in this version.

Four APIs are introduces:
- kvm_page_track_add_page(kvm, gfn, mode), single guest page @gfn is
  added into the track pool of the guest instance represented by @kvm,
  @mode specifies which kind of access on the @gfn is tracked
  
- kvm_page_track_remove_page(kvm, gfn, mode), is the opposed operation
  of kvm_page_track_add_page() which removes @gfn from the tracking pool.
  gfn is no tracked after its last user is gone

- kvm_page_track_register_notifier(kvm, n), register a notifier so that
  the event triggered by page tracking will be received, at that time,
  the callback of n->track_write() will be called

- kvm_page_track_unregister_notifier(kvm, n), does the opposed operation
  of kvm_page_track_register_notifier(), which unlinks the notifier and
  stops receiving the tracked event

The first user of page track is non-leaf shadow page tables as they are
always write protected. It also gains performance improvement because
page track speeds up page fault handler for the tracked pages. The
performance result of kernel building is as followings:

   before           after
real 461.63       real 455.48
user 4529.55      user 4557.88
sys 1995.39       sys 1922.57

Furthermore, it is the infrastructure of other kind of shadow page table,
such as GPU shadow page table introduced in KVMGT (1) and native nested
IOMMU.

This patch can be divided into two parts:
- patch 1 ~ patch 7, implement page tracking
- others patches apply page tracking to non-leaf shadow page table

(1): http://lkml.iu.edu/hypermail/linux/kernel/1510.3/01562.html

Xiao Guangrong (11):
  KVM: MMU: rename has_wrprotected_page to mmu_gfn_lpage_is_disallowed
  KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}_lpage
  KVM: MMU: introduce kvm_mmu_slot_gfn_write_protect
  KVM: page track: add the framework of guest page tracking
  KVM: page track: introduce kvm_page_track_{add,remove}_page
  KVM: MMU: let page fault handler be aware tracked page
  KVM: page track: add notifier support
  KVM: MMU: use page track for non-leaf shadow pages
  KVM: MMU: simplify mmu_need_write_protect
  KVM: MMU: clear write-flooding on the fast path of tracked page
  KVM: MMU: apply page track notifier

 Documentation/virtual/kvm/mmu.txt     |   6 +-
 arch/x86/include/asm/kvm_host.h       |  12 +-
 arch/x86/include/asm/kvm_page_track.h |  67 +++++++++
 arch/x86/kvm/Makefile                 |   3 +-
 arch/x86/kvm/mmu.c                    | 199 ++++++++++++++++++--------
 arch/x86/kvm/mmu.h                    |   5 +
 arch/x86/kvm/page_track.c             | 257 ++++++++++++++++++++++++++++++++++
 arch/x86/kvm/paging_tmpl.h            |   5 +
 arch/x86/kvm/x86.c                    |  27 ++--
 9 files changed, 509 insertions(+), 72 deletions(-)
 create mode 100644 arch/x86/include/asm/kvm_page_track.h
 create mode 100644 arch/x86/kvm/page_track.c

-- 
1.8.3.1

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#1297390 — [PATCH v2 06/11] KVM: MMU: let page fault handler be aware tracked page

The page fault caused by write access on the write tracked page can not
be fixed, it always need to be emulated. page_fault_handle_page_track()
is the fast path we introduce here to skip holding mmu-lock and shadow
page table walking

However, if the page table is not present, it is worth making the page
table entry present and readonly to make the read access happy

mmu_need_write_protect() need to be cooked to avoid page becoming writable
when making page table present or sync/prefetch shadow page table entries

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 arch/x86/include/asm/kvm_page_track.h |  2 ++
 arch/x86/kvm/mmu.c                    | 44 +++++++++++++++++++++++++++++------
 arch/x86/kvm/page_track.c             | 14 +++++++++++
 arch/x86/kvm/paging_tmpl.h            |  3 +++
 4 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index c010124..97ac9c3 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -23,4 +23,6 @@ void kvm_slot_page_track_remove_page_nolock(struct kvm *kvm,
 					    enum kvm_page_track_mode mode);
 void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
 				enum kvm_page_track_mode mode);
+bool kvm_page_track_check_mode(struct kvm_vcpu *vcpu, gfn_t gfn,
+			       enum kvm_page_track_mode mode);
 #endif
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 39809b8..b23f9fc 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -41,6 +41,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/vmx.h>
+#include <asm/kvm_page_track.h>
 
 /*
  * When setting this variable to true it enables Two-Dimensional-Paging
@@ -2456,25 +2457,29 @@ static void kvm_unsync_pages(struct kvm_vcpu *vcpu,  gfn_t gfn)
 	}
 }
 
-static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
-				  bool can_unsync)
+static bool mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
+				   bool can_unsync)
 {
 	struct kvm_mmu_page *s;
 	bool need_unsync = false;
 
+	if (kvm_page_track_check_mode(vcpu, gfn, KVM_PAGE_TRACK_WRITE))
+		return true;
+
 	for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
 		if (!can_unsync)
-			return 1;
+			return true;
 
 		if (s->role.level != PT_PAGE_TABLE_LEVEL)
-			return 1;
+			return true;
 
 		if (!s->unsync)
 			need_unsync = true;
 	}
 	if (need_unsync)
 		kvm_unsync_pages(vcpu, gfn);
-	return 0;
+
+	return false;
 }
 
 static bool kvm_is_mmio_pfn(pfn_t pfn)
@@ -3388,10 +3393,30 @@ int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct)
 }
 EXPORT_SYMBOL_GPL(handle_mmio_page_fault);
 
+static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
+					 u32 error_code, gfn_t gfn)
+{
+	if (unlikely(error_code & PFERR_RSVD_MASK))
+		return false;
+
+	if (!(error_code & PFERR_PRESENT_MASK) ||
+	      !(error_code & PFERR_WRITE_MASK))
+		return false;
+
+	/*
+	 * guest is writing the page which is write tracked which can
+	 * not be fixed by page fault handler.
+	 */
+	if (kvm_page_track_check_mode(vcpu, gfn, KVM_PAGE_TRACK_WRITE))
+		return true;
+
+	return false;
+}
+
 static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
 				u32 error_code, bool prefault)
 {
-	gfn_t gfn;
+	gfn_t gfn = gva >> PAGE_SHIFT;
 	int r;
 
 	pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code);
@@ -3403,13 +3428,15 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
 			return r;
 	}
 
+	if (page_fault_handle_page_track(vcpu, error_code, gfn))
+		return 1;
+
 	r = mmu_topup_memory_caches(vcpu);
 	if (r)
 		return r;
 
 	MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
 
-	gfn = gva >> PAGE_SHIFT;
 
 	return nonpaging_map(vcpu, gva & PAGE_MASK,
 			     error_code, gfn, prefault);
@@ -3493,6 +3520,9 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 			return r;
 	}
 
+	if (page_fault_handle_page_track(vcpu, error_code, gfn))
+		return 1;
+
 	r = mmu_topup_memory_caches(vcpu);
 	if (r)
 		return r;
diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index e17efe9..de9b32f 100644
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -174,3 +174,17 @@ void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
 		spin_unlock(&kvm->mmu_lock);
 	}
 }
+
+/*
+ * check if the corresponding access on the specified guest page is tracked.
+ */
+bool kvm_page_track_check_mode(struct kvm_vcpu *vcpu, gfn_t gfn,
+			       enum kvm_page_track_mode mode)
+{
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+	int index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
+
+	WARN_ON(!check_mode(mode));
+
+	return !!ACCESS_ONCE(slot->arch.gfn_track[mode][index]);
+}
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 91e939b..ac85682 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -735,6 +735,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 		return 0;
 	}
 
+	if (page_fault_handle_page_track(vcpu, error_code, walker.gfn))
+		return 1;
+
 	vcpu->arch.write_fault_to_shadow_pgtable = false;
 
 	is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu,
-- 
1.8.3.1

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#1297392 — [PATCH v2 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page

These two functions are the user APIs:
- kvm_page_track_add_page(): add the page to the tracking pool after
  that later specified access on that page will be tracked

- kvm_page_track_remove_page(): remove the page from the tracking pool,
  the specified access on the page is not tracked after the last user is
  gone

Both of these are called under the protection of kvm->srcu or
kvm->slots_lock

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 arch/x86/include/asm/kvm_page_track.h |  13 ++++
 arch/x86/kvm/page_track.c             | 124 ++++++++++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)

diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index 55200406..c010124 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -10,4 +10,17 @@ void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
 				 struct kvm_memory_slot *dont);
 int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
 				  unsigned long npages);
+
+void
+kvm_slot_page_track_add_page_nolock(struct kvm *kvm,
+				    struct kvm_memory_slot *slot, gfn_t gfn,
+				    enum kvm_page_track_mode mode);
+void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
+			     enum kvm_page_track_mode mode);
+void kvm_slot_page_track_remove_page_nolock(struct kvm *kvm,
+					    struct kvm_memory_slot *slot,
+					    gfn_t gfn,
+					    enum kvm_page_track_mode mode);
+void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
+				enum kvm_page_track_mode mode);
 #endif
diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index 8c396d0..e17efe9 100644
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -50,3 +50,127 @@ track_free:
 	kvm_page_track_free_memslot(slot, NULL);
 	return -ENOMEM;
 }
+
+static bool check_mode(enum kvm_page_track_mode mode)
+{
+	if (mode < 0 || mode >= KVM_PAGE_TRACK_MAX)
+		return false;
+
+	return true;
+}
+
+static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn,
+			     enum kvm_page_track_mode mode, short count)
+{
+	int index;
+	unsigned short val;
+
+	index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
+
+	val = slot->arch.gfn_track[mode][index];
+
+	/* does tracking count wrap? */
+	WARN_ON((count > 0) && (val + count < val));
+	/* the last tracker has already gone? */
+	WARN_ON((count < 0) && (val < !count));
+
+	slot->arch.gfn_track[mode][index] += count;
+}
+
+void
+kvm_slot_page_track_add_page_nolock(struct kvm *kvm,
+				    struct kvm_memory_slot *slot, gfn_t gfn,
+				    enum kvm_page_track_mode mode)
+{
+
+	WARN_ON(!check_mode(mode));
+
+	update_gfn_track(slot, gfn, mode, 1);
+
+	/*
+	 * new track stops large page mapping for the
+	 * tracked page.
+	 */
+	kvm_mmu_gfn_disallow_lpage(slot, gfn);
+
+	if (mode == KVM_PAGE_TRACK_WRITE)
+		if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn))
+			kvm_flush_remote_tlbs(kvm);
+}
+
+/*
+ * add guest page to the tracking pool so that corresponding access on that
+ * page will be intercepted.
+ *
+ * It should be called under the protection of kvm->srcu or kvm->slots_lock
+ *
+ * @kvm: the guest instance we are interested in.
+ * @gfn: the guest page.
+ * @mode: tracking mode, currently only write track is supported.
+ */
+void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
+			     enum kvm_page_track_mode mode)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *slot;
+	int i;
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		slots = __kvm_memslots(kvm, i);
+
+		slot = __gfn_to_memslot(slots, gfn);
+		if (!slot)
+			continue;
+
+		spin_lock(&kvm->mmu_lock);
+		kvm_slot_page_track_add_page_nolock(kvm, slot, gfn, mode);
+		spin_unlock(&kvm->mmu_lock);
+	}
+}
+
+void kvm_slot_page_track_remove_page_nolock(struct kvm *kvm,
+					    struct kvm_memory_slot *slot,
+					    gfn_t gfn,
+					    enum kvm_page_track_mode mode)
+{
+	WARN_ON(!check_mode(mode));
+
+	update_gfn_track(slot, gfn, mode, -1);
+
+	/*
+	 * allow large page mapping for the tracked page
+	 * after the tracker is gone.
+	 */
+	kvm_mmu_gfn_allow_lpage(slot, gfn);
+}
+
+/*
+ * remove the guest page from the tracking pool which stops the interception
+ * of corresponding access on that page. It is the opposed operation of
+ * kvm_page_track_add_page().
+ *
+ * It should be called under the protection of kvm->srcu or kvm->slots_lock
+ *
+ * @kvm: the guest instance we are interested in.
+ * @gfn: the guest page.
+ * @mode: tracking mode, currently only write track is supported.
+ */
+void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
+				enum kvm_page_track_mode mode)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *slot;
+	int i;
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		slots = __kvm_memslots(kvm, i);
+
+		slot = __gfn_to_memslot(slots, gfn);
+		if (!slot)
+			continue;
+
+		spin_lock(&kvm->mmu_lock);
+		kvm_slot_page_track_remove_page_nolock(kvm, slot, gfn, mode);
+		spin_unlock(&kvm->mmu_lock);
+	}
+}
-- 
1.8.3.1

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#1297393 — [PATCH v2 02/11] KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}_lpage

Abstract the common operations from account_shadowed() and
unaccount_shadowed(), then introduce kvm_mmu_gfn_disallow_lpage()
and kvm_mmu_gfn_allow_lpage()

These two functions will be used by page tracking in the later patch

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 arch/x86/kvm/mmu.c | 38 +++++++++++++++++++++++++-------------
 arch/x86/kvm/mmu.h |  3 +++
 2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 61259ff..4b04d13 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -776,21 +776,39 @@ static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn,
 	return &slot->arch.lpage_info[level - 2][idx];
 }
 
+static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot,
+					    gfn_t gfn, int count)
+{
+	struct kvm_lpage_info *linfo;
+	int i;
+
+	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
+		linfo = lpage_info_slot(gfn, slot, i);
+		linfo->disallow_lpage += count;
+		WARN_ON(linfo->disallow_lpage < 0);
+	}
+}
+
+void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	update_gfn_disallow_lpage_count(slot, gfn, 1);
+}
+
+void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	update_gfn_disallow_lpage_count(slot, gfn, -1);
+}
+
 static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *slot;
-	struct kvm_lpage_info *linfo;
 	gfn_t gfn;
-	int i;
 
 	gfn = sp->gfn;
 	slots = kvm_memslots_for_spte_role(kvm, sp->role);
 	slot = __gfn_to_memslot(slots, gfn);
-	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
-		linfo = lpage_info_slot(gfn, slot, i);
-		linfo->disallow_lpage += 1;
-	}
+	kvm_mmu_gfn_disallow_lpage(slot, gfn);
 	kvm->arch.indirect_shadow_pages++;
 }
 
@@ -798,18 +816,12 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *slot;
-	struct kvm_lpage_info *linfo;
 	gfn_t gfn;
-	int i;
 
 	gfn = sp->gfn;
 	slots = kvm_memslots_for_spte_role(kvm, sp->role);
 	slot = __gfn_to_memslot(slots, gfn);
-	for (i = PT_DIRECTORY_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
-		linfo = lpage_info_slot(gfn, slot, i);
-		linfo->disallow_lpage -= 1;
-		WARN_ON(linfo->disallow_lpage < 0);
-	}
+	kvm_mmu_gfn_allow_lpage(slot, gfn);
 	kvm->arch.indirect_shadow_pages--;
 }
 
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 55ffb7b..de92bed 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -174,4 +174,7 @@ static inline bool permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 
 void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
+
+void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
+void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 #endif
-- 
1.8.3.1

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#1297394 — [PATCH v2 11/11] KVM: MMU: apply page track notifier

Register the notifier to receive write track event so that we can update
our shadow page table

It makes kvm_mmu_pte_write() be the callback of the notifier, no function
is changed

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 arch/x86/include/asm/kvm_host.h |  5 +++--
 arch/x86/kvm/mmu.c              | 19 +++++++++++++++++--
 arch/x86/kvm/x86.c              |  4 ++--
 3 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1d2968e..28f5c7d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -671,6 +671,7 @@ struct kvm_arch {
 	 */
 	struct list_head active_mmu_pages;
 	struct list_head zapped_obsolete_pages;
+	struct kvm_page_track_notifier_node mmu_sp_tracker;
 	struct kvm_page_track_notifier_head track_notifier_head;
 
 	struct list_head assigned_dev_head;
@@ -966,6 +967,8 @@ void kvm_mmu_module_exit(void);
 void kvm_mmu_destroy(struct kvm_vcpu *vcpu);
 int kvm_mmu_create(struct kvm_vcpu *vcpu);
 void kvm_mmu_setup(struct kvm_vcpu *vcpu);
+void kvm_mmu_init_vm(struct kvm *kvm);
+void kvm_mmu_uninit_vm(struct kvm *kvm);
 void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
 		u64 dirty_mask, u64 nx_mask, u64 x_mask);
 
@@ -1105,8 +1108,6 @@ void kvm_pic_clear_all(struct kvm_pic *pic, int irq_source_id);
 
 void kvm_inject_nmi(struct kvm_vcpu *vcpu);
 
-void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
-		       const u8 *new, int bytes);
 int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn);
 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
 void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9f6a4ef..a420c43 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4325,8 +4325,8 @@ static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte)
 	return spte;
 }
 
-void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
-		       const u8 *new, int bytes)
+static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
+			      const u8 *new, int bytes)
 {
 	gfn_t gfn = gpa >> PAGE_SHIFT;
 	struct kvm_mmu_page *sp;
@@ -4540,6 +4540,21 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu)
 	init_kvm_mmu(vcpu);
 }
 
+void kvm_mmu_init_vm(struct kvm *kvm)
+{
+	struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
+
+	node->track_write = kvm_mmu_pte_write;
+	kvm_page_track_register_notifier(kvm, node);
+}
+
+void kvm_mmu_uninit_vm(struct kvm *kvm)
+{
+	struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
+
+	kvm_page_track_unregister_notifier(kvm, node);
+}
+
 /* The return value indicates if tlb flush on all vcpus is needed. */
 typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dc43d99..f06a4fc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4330,7 +4330,6 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
 	ret = kvm_vcpu_write_guest(vcpu, gpa, val, bytes);
 	if (ret < 0)
 		return 0;
-	kvm_mmu_pte_write(vcpu, gpa, val, bytes);
 	kvm_page_track_write(vcpu, gpa, val, bytes);
 	return 1;
 }
@@ -4589,7 +4588,6 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 		return X86EMUL_CMPXCHG_FAILED;
 
 	kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT);
-	kvm_mmu_pte_write(vcpu, gpa, new, bytes);
 	kvm_page_track_write(vcpu, gpa, new, bytes);
 
 	return X86EMUL_CONTINUE;
@@ -7700,6 +7698,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
 
 	kvm_page_track_init(kvm);
+	kvm_mmu_init_vm(kvm);
 
 	return 0;
 }
@@ -7827,6 +7826,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kfree(kvm->arch.vioapic);
 	kvm_free_vcpus(kvm);
 	kfree(rcu_dereference_check(kvm->arch.apic_map, 1));
+	kvm_mmu_uninit_vm(kvm);
 }
 
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-- 
1.8.3.1

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