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oos shadow optimizations v2

PATCH In review Marcelo Tosatti 2 participants 6 messages Dec 2, 2008 – Dec 5, 2008

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Marcelo Tosatti

author
#0 lore raw

cover oos shadow optimizations v2

Addressing comments from previous version.

author
#1 lore raw

PATCH 1/4 KVM: MMU: use page array in unsync walk

Instead of invoking the handler directly collect pages into an array so the caller can work with it.

Simplifies TLB flush collapsing.

Signed-off-by Marcelo Tosatti <[email protected]>
arch/x86/kvm/mmu.c +140 -55
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
@@ -908,8 +908,9 @@ static void kvm_mmu_update_unsync_bitmap
 	struct kvm_mmu_page *sp = page_header(__pa(spte));
 
 	index = spte - sp->spt;
-	__set_bit(index, sp->unsync_child_bitmap);
-	sp->unsync_children = 1;
+	if (!__test_and_set_bit(index, sp->unsync_child_bitmap))
+		sp->unsync_children++;
+	WARN_ON(!sp->unsync_children);
 }
 
 static void kvm_mmu_update_parents_unsync(struct kvm_mmu_page *sp)

@@ -936,7 +937,6 @@ static void kvm_mmu_update_parents_unsyn
 
 static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
-	sp->unsync_children = 1;
 	kvm_mmu_update_parents_unsync(sp);
 	return 1;
 }

@@ -967,18 +967,41 @@ static void nonpaging_invlpg(struct kvm_
 {
 }
 
+#define KVM_PAGE_ARRAY_NR 16
+
+struct kvm_mmu_pages {
+	struct mmu_page_and_offset {
+		struct kvm_mmu_page *sp;
+		unsigned int idx;
+	} page[KVM_PAGE_ARRAY_NR];
+	unsigned int nr;
+};
+
 #define for_each_unsync_children(bitmap, idx)		\
 	for (idx = find_first_bit(bitmap, 512);		\
 	     idx < 512;					\
 	     idx = find_next_bit(bitmap, 512, idx+1))
 
-static int mmu_unsync_walk(struct kvm_mmu_page *sp,
-			   struct kvm_unsync_walk *walker)
+int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp,
+		   int idx)
 {
-	int i, ret;
+	int i;
 
-	if (!sp->unsync_children)
-		return 0;
+	if (sp->unsync)
+		for (i=0; i < pvec->nr; i++)
+			if (pvec->page[i].sp == sp)
+				return 0;
+
+	pvec->page[pvec->nr].sp = sp;
+	pvec->page[pvec->nr].idx = idx;
+	pvec->nr++;
+	return (pvec->nr == KVM_PAGE_ARRAY_NR);
+}
+
+static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
+			   struct kvm_mmu_pages *pvec)
+{
+	int i, ret, nr_unsync_leaf = 0;
 
 	for_each_unsync_children(sp->unsync_child_bitmap, i) {
 		u64 ent = sp->spt[i];

@@ -988,17 +1011,22 @@ static int mmu_unsync_walk(struct kvm_mm
 			child = page_header(ent & PT64_BASE_ADDR_MASK);
 
 			if (child->unsync_children) {
-				ret = mmu_unsync_walk(child, walker);
-				if (ret)
+				if (mmu_pages_add(pvec, child, i))
+					return -ENOSPC;
+
+				ret = __mmu_unsync_walk(child, pvec);
+				if (!ret)
+					__clear_bit(i, sp->unsync_child_bitmap);
+				else if (ret > 0)
+					nr_unsync_leaf += ret;
+				else
 					return ret;
-				__clear_bit(i, sp->unsync_child_bitmap);
 			}
 
 			if (child->unsync) {
-				ret = walker->entry(child, walker);
-				__clear_bit(i, sp->unsync_child_bitmap);
-				if (ret)
-					return ret;
+				nr_unsync_leaf++;
+				if (mmu_pages_add(pvec, child, i))
+					return -ENOSPC;
 			}
 		}
 	}

@@ -1006,7 +1034,17 @@ static int mmu_unsync_walk(struct kvm_mm
 	if (find_first_bit(sp->unsync_child_bitmap, 512) == 512)
 		sp->unsync_children = 0;
 
-	return 0;
+	return nr_unsync_leaf;
+}
+
+static int mmu_unsync_walk(struct kvm_mmu_page *sp,
+			   struct kvm_mmu_pages *pvec)
+{
+	if (!sp->unsync_children)
+		return 0;
+
+	mmu_pages_add(pvec, sp, 0);
+	return __mmu_unsync_walk(sp, pvec);
 }
 
 static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)

@@ -1056,30 +1094,81 @@ static int kvm_sync_page(struct kvm_vcpu
 	return 0;
 }
 
-struct sync_walker {
-	struct kvm_vcpu *vcpu;
-	struct kvm_unsync_walk walker;
+struct mmu_page_path {
+	struct kvm_mmu_page *parent[PT64_ROOT_LEVEL-1];
+	unsigned int idx[PT64_ROOT_LEVEL-1];
 };
 
-static int mmu_sync_fn(struct kvm_mmu_page *sp, struct kvm_unsync_walk *walk)
+#define for_each_sp(pvec, sp, parents, i)			\
+		for (i = mmu_pages_next(&pvec, &parents, -1),	\
+			sp = pvec.page[i].sp;			\
+			i < pvec.nr && ({ sp = pvec.page[i].sp; 1;});	\
+			i = mmu_pages_next(&pvec, &parents, i))
+
+int mmu_pages_next(struct kvm_mmu_pages *pvec, struct mmu_page_path *parents,
+		   int i)
 {
-	struct sync_walker *sync_walk = container_of(walk, struct sync_walker,
-						     walker);
-	struct kvm_vcpu *vcpu = sync_walk->vcpu;
+	int n;
+
+	for (n = i+1; n < pvec->nr; n++) {
+		struct kvm_mmu_page *sp = pvec->page[n].sp;
+
+		if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
+			parents->idx[0] = pvec->page[n].idx;
+			return n;
+		}
 
-	kvm_sync_page(vcpu, sp);
-	return (need_resched() || spin_needbreak(&vcpu->kvm->mmu_lock));
+		parents->parent[sp->role.level-2] = sp;
+		parents->idx[sp->role.level-1] = pvec->page[n].idx;
+	}
+
+	return n;
 }
 
-static void mmu_sync_children(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+void mmu_pages_clear_parents(struct mmu_page_path *parents)
 {
-	struct sync_walker walker = {
-		.walker = { .entry = mmu_sync_fn, },
-		.vcpu = vcpu,
-	};
+	struct kvm_mmu_page *sp;
+	unsigned int level = 0;
+
+	do {
+		unsigned int idx = parents->idx[level];
+
+		sp = parents->parent[level];
+		if (!sp)
+			return;
 
-	while (mmu_unsync_walk(sp, &walker.walker))
+		--sp->unsync_children;
+		WARN_ON((int)sp->unsync_children < 0);
+		__clear_bit(idx, sp->unsync_child_bitmap);
+		level++;
+	} while (level < PT64_ROOT_LEVEL-1 && !sp->unsync_children);
+}
+
+static void kvm_mmu_pages_init(struct kvm_mmu_page *parent,
+			       struct mmu_page_path *parents,
+			       struct kvm_mmu_pages *pvec)
+{
+	parents->parent[parent->role.level-1] = NULL;
+	pvec->nr = 0;
+}
+
+static void mmu_sync_children(struct kvm_vcpu *vcpu,
+			      struct kvm_mmu_page *parent)
+{
+	int i;
+	struct kvm_mmu_page *sp;
+	struct mmu_page_path parents;
+	struct kvm_mmu_pages pages;
+
+	kvm_mmu_pages_init(parent, &parents, &pages);
+	while (mmu_unsync_walk(parent, &pages)) {
+		for_each_sp(pages, sp, parents, i) {
+			kvm_sync_page(vcpu, sp);
+			mmu_pages_clear_parents(&parents);
+		}
 		cond_resched_lock(&vcpu->kvm->mmu_lock);
+		kvm_mmu_pages_init(parent, &parents, &pages);
+	}
 }
 
 static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,

@@ -1245,33 +1334,29 @@ static void kvm_mmu_unlink_parents(struc
 	}
 }
 
-struct zap_walker {
-	struct kvm_unsync_walk walker;
-	struct kvm *kvm;
-	int zapped;
-};
-
-static int mmu_zap_fn(struct kvm_mmu_page *sp, struct kvm_unsync_walk *walk)
-{
-	struct zap_walker *zap_walk = container_of(walk, struct zap_walker,
-						     walker);
-	kvm_mmu_zap_page(zap_walk->kvm, sp);
-	zap_walk->zapped = 1;
-	return 0;
-}
-
-static int mmu_zap_unsync_children(struct kvm *kvm, struct kvm_mmu_page *sp)
+static int mmu_zap_unsync_children(struct kvm *kvm,
+				   struct kvm_mmu_page *parent)
 {
-	struct zap_walker walker = {
-		.walker = { .entry = mmu_zap_fn, },
-		.kvm = kvm,
-		.zapped = 0,
-	};
+	int i, zapped = 0;
+	struct mmu_page_path parents;
+	struct kvm_mmu_pages pages;
 
-	if (sp->role.level == PT_PAGE_TABLE_LEVEL)
+	if (parent->role.level == PT_PAGE_TABLE_LEVEL)
 		return 0;
-	mmu_unsync_walk(sp, &walker.walker);
-	return walker.zapped;
+
+	kvm_mmu_pages_init(parent, &parents, &pages);
+	while (mmu_unsync_walk(parent, &pages)) {
+		struct kvm_mmu_page *sp;
+
+		for_each_sp(pages, sp, parents, i) {
+			kvm_mmu_zap_page(kvm, sp);
+			mmu_pages_clear_parents(&parents);
+		}
+		zapped += pages.nr;
+		kvm_mmu_pages_init(parent, &parents, &pages);
+	}
+
+	return zapped;
 }
 
 static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
arch/x86/include/asm/kvm_host.h +1 -1
Index: kvm/arch/x86/include/asm/kvm_host.h
===================================================================
@@ -200,7 +200,7 @@ struct kvm_mmu_page {
 	int multimapped;         /* More than one parent_pte? */
 	int root_count;          /* Currently serving as active root */
 	bool unsync;
-	bool unsync_children;
+	unsigned int unsync_children;
 	union {
 		u64 *parent_pte;               /* !multimapped */
 		struct hlist_head parent_ptes; /* multimapped, kvm_pte_chain */
author
#2 lore raw

PATCH 2/4 KVM: MMU: collapse remote TLB flushes on root sync

In reply to Marcelo Tosatti

Collapse remote TLB flushes on root sync.

kernbench is 2.7% faster on 4-way guest. Improvements have been seen with other loads such as AIM7.

Signed-off-by Marcelo Tosatti <[email protected]>
arch/x86/kvm/mmu.c +14 -5
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
@@ -621,7 +621,7 @@ static u64 *rmap_next(struct kvm *kvm, u
 	return NULL;
 }
 
-static void rmap_write_protect(struct kvm *kvm, u64 gfn)
+static int rmap_write_protect(struct kvm *kvm, u64 gfn)
 {
 	unsigned long *rmapp;
 	u64 *spte;

@@ -667,8 +667,7 @@ static void rmap_write_protect(struct kv
 		spte = rmap_next(kvm, rmapp, spte);
 	}
 
-	if (write_protected)
-		kvm_flush_remote_tlbs(kvm);
+	return write_protected;
 }
 
 static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp)

@@ -1083,7 +1082,8 @@ static int kvm_sync_page(struct kvm_vcpu
 		return 1;
 	}
 
-	rmap_write_protect(vcpu->kvm, sp->gfn);
+	if (rmap_write_protect(vcpu->kvm, sp->gfn))
+		kvm_flush_remote_tlbs(vcpu->kvm);
 	kvm_unlink_unsync_page(vcpu->kvm, sp);
 	if (vcpu->arch.mmu.sync_page(vcpu, sp)) {
 		kvm_mmu_zap_page(vcpu->kvm, sp);

@@ -1162,6 +1162,14 @@ static void mmu_sync_children(struct kvm
 
 	kvm_mmu_pages_init(parent, &parents, &pages);
 	while (mmu_unsync_walk(parent, &pages)) {
+		int protected = 0;
+
+		for_each_sp(pages, sp, parents, i)
+			protected |= rmap_write_protect(vcpu->kvm, sp->gfn);
+
+		if (protected)
+			kvm_flush_remote_tlbs(vcpu->kvm);
+
 		for_each_sp(pages, sp, parents, i) {
 			kvm_sync_page(vcpu, sp);
 			mmu_pages_clear_parents(&parents);

@@ -1226,7 +1234,8 @@ static struct kvm_mmu_page *kvm_mmu_get_
 	sp->role = role;
 	hlist_add_head(&sp->hash_link, bucket);
 	if (!metaphysical) {
-		rmap_write_protect(vcpu->kvm, gfn);
+		if (rmap_write_protect(vcpu->kvm, gfn))
+			kvm_flush_remote_tlbs(vcpu->kvm);
 		account_shadowed(vcpu->kvm, gfn);
 	}
 	if (shadow_trap_nonpresent_pte != shadow_notrap_nonpresent_pte)
author
#3 lore raw

PATCH 3/4 KVM: MMU: skip global pgtables on sync due to cr3 switch

In reply to Marcelo Tosatti

Skip syncing global pages on cr3 switch (but not on cr4/cr0). This is important for Linux 32-bit guests with PAE, where the kmap page is marked as global.

Signed-off-by Marcelo Tosatti <[email protected]>
arch/x86/include/asm/kvm_host.h +6 -0
Index: kvm/arch/x86/include/asm/kvm_host.h
===================================================================
@@ -182,6 +182,8 @@ struct kvm_mmu_page {
 	struct list_head link;
 	struct hlist_node hash_link;
 
+	struct list_head oos_link;
+
 	/*
 	 * The following two entries are used to key the shadow page in the
 	 * hash table.

@@ -200,6 +202,7 @@ struct kvm_mmu_page {
 	int multimapped;         /* More than one parent_pte? */
 	int root_count;          /* Currently serving as active root */
 	bool unsync;
+	bool global;
 	unsigned int unsync_children;
 	union {
 		u64 *parent_pte;               /* !multimapped */

@@ -356,6 +359,7 @@ struct kvm_arch{
 	 */
 	struct list_head active_mmu_pages;
 	struct list_head assigned_dev_head;
+	struct list_head oos_global_pages;
 	struct dmar_domain *intel_iommu_domain;
 	struct kvm_pic *vpic;
 	struct kvm_ioapic *vioapic;

@@ -385,6 +389,7 @@ struct kvm_vm_stat {
 	u32 mmu_recycled;
 	u32 mmu_cache_miss;
 	u32 mmu_unsync;
+	u32 mmu_unsync_global;
 	u32 remote_tlb_flush;
 	u32 lpages;
 };

@@ -603,6 +608,7 @@ void __kvm_mmu_free_some_pages(struct kv
 int kvm_mmu_load(struct kvm_vcpu *vcpu);
 void kvm_mmu_unload(struct kvm_vcpu *vcpu);
 void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu);
+void kvm_mmu_sync_global(struct kvm_vcpu *vcpu);
 
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
arch/x86/kvm/mmu.c +47 -6

121 lines not on this page · raw message

arch/x86/kvm/paging_tmpl.h +6 -4
Index: kvm/arch/x86/kvm/paging_tmpl.h
===================================================================
@@ -274,7 +274,8 @@ static void FNAME(update_pte)(struct kvm
 		return;
 	kvm_get_pfn(pfn);
 	mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
-		     gpte & PT_DIRTY_MASK, NULL, largepage, gpte_to_gfn(gpte),
+		     gpte & PT_DIRTY_MASK, NULL, largepage,
+		     gpte & PT_GLOBAL_MASK, gpte_to_gfn(gpte),
 		     pfn, true);
 }
 

@@ -301,8 +302,9 @@ static int FNAME(shadow_walk_entry)(stru
 		mmu_set_spte(vcpu, sptep, access, gw->pte_access & access,
 			     sw->user_fault, sw->write_fault,
 			     gw->ptes[gw->level-1] & PT_DIRTY_MASK,
-			     sw->ptwrite, sw->largepage, gw->gfn, sw->pfn,
-			     false);
+			     sw->ptwrite, sw->largepage,
+			     gw->ptes[gw->level-1] & PT_GLOBAL_MASK,
+			     gw->gfn, sw->pfn, false);
 		sw->sptep = sptep;
 		return 1;
 	}

@@ -580,7 +582,7 @@ static int FNAME(sync_page)(struct kvm_v
 		nr_present++;
 		pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
 		set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
-			 is_dirty_pte(gpte), 0, gfn,
+			 is_dirty_pte(gpte), 0, gpte & PT_GLOBAL_MASK, gfn,
 			 spte_to_pfn(sp->spt[i]), true, false);
 	}
arch/x86/kvm/x86.c +4 -0
Index: kvm/arch/x86/kvm/x86.c
===================================================================
@@ -104,6 +104,7 @@ struct kvm_stats_debugfs_item debugfs_en
 	{ "mmu_recycled", VM_STAT(mmu_recycled) },
 	{ "mmu_cache_miss", VM_STAT(mmu_cache_miss) },
 	{ "mmu_unsync", VM_STAT(mmu_unsync) },
+	{ "mmu_unsync_global", VM_STAT(mmu_unsync_global) },
 	{ "remote_tlb_flush", VM_STAT(remote_tlb_flush) },
 	{ "largepages", VM_STAT(lpages) },
 	{ NULL }

@@ -315,6 +316,7 @@ void kvm_set_cr0(struct kvm_vcpu *vcpu, 
 	kvm_x86_ops->set_cr0(vcpu, cr0);
 	vcpu->arch.cr0 = cr0;
 
+	kvm_mmu_sync_global(vcpu);
 	kvm_mmu_reset_context(vcpu);
 	return;
 }

@@ -358,6 +360,7 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, 
 	}
 	kvm_x86_ops->set_cr4(vcpu, cr4);
 	vcpu->arch.cr4 = cr4;
+	kvm_mmu_sync_global(vcpu);
 	kvm_mmu_reset_context(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr4);

@@ -4113,6 +4116,7 @@ struct  kvm *kvm_arch_create_vm(void)
 		return ERR_PTR(-ENOMEM);
 
 	INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
+	INIT_LIST_HEAD(&kvm->arch.oos_global_pages);
 	INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
 	/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
author
#4 lore raw

PATCH 4/4 KVM: MMU: prepopulate the shadow on invlpg

In reply to Marcelo Tosatti

If the guest executes invlpg, peek into the pagetable and attempt to prepopulate the shadow entry.

Also stop dirty fault updates from interfering with the fork detector.

2% improvement on RHEL3/AIM7.

Signed-off-by Marcelo Tosatti <[email protected]>
arch/x86/kvm/mmu.c +13 -12
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
@@ -2441,7 +2441,8 @@ static void kvm_mmu_access_page(struct k
 }
 
 void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
-		       const u8 *new, int bytes)
+		       const u8 *new, int bytes,
+		       bool guest_initiated)
 {
 	gfn_t gfn = gpa >> PAGE_SHIFT;
 	struct kvm_mmu_page *sp;

@@ -2467,15 +2468,17 @@ void kvm_mmu_pte_write(struct kvm_vcpu *
 	kvm_mmu_free_some_pages(vcpu);
 	++vcpu->kvm->stat.mmu_pte_write;
 	kvm_mmu_audit(vcpu, "pre pte write");
-	if (gfn == vcpu->arch.last_pt_write_gfn
-	    && !last_updated_pte_accessed(vcpu)) {
-		++vcpu->arch.last_pt_write_count;
-		if (vcpu->arch.last_pt_write_count >= 3)
-			flooded = 1;
-	} else {
-		vcpu->arch.last_pt_write_gfn = gfn;
-		vcpu->arch.last_pt_write_count = 1;
-		vcpu->arch.last_pte_updated = NULL;
+	if (guest_initiated) {
+		if (gfn == vcpu->arch.last_pt_write_gfn
+		    && !last_updated_pte_accessed(vcpu)) {
+			++vcpu->arch.last_pt_write_count;
+			if (vcpu->arch.last_pt_write_count >= 3)
+				flooded = 1;
+		} else {
+			vcpu->arch.last_pt_write_gfn = gfn;
+			vcpu->arch.last_pt_write_count = 1;
+			vcpu->arch.last_pte_updated = NULL;
+		}
 	}
 	index = kvm_page_table_hashfn(gfn);
 	bucket = &vcpu->kvm->arch.mmu_page_hash[index];

@@ -2615,9 +2618,7 @@ EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
 
 void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
 {
-	spin_lock(&vcpu->kvm->mmu_lock);
 	vcpu->arch.mmu.invlpg(vcpu, gva);
-	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_mmu_flush_tlb(vcpu);
 	++vcpu->stat.invlpg;
 }
arch/x86/kvm/paging_tmpl.h +24 -1
Index: kvm/arch/x86/kvm/paging_tmpl.h
===================================================================
@@ -82,6 +82,7 @@ struct shadow_walker {
 	int *ptwrite;
 	pfn_t pfn;
 	u64 *sptep;
+	gpa_t pte_gpa;
 };
 
 static gfn_t gpte_to_gfn(pt_element_t gpte)

@@ -222,7 +223,7 @@ walk:
 		if (ret)
 			goto walk;
 		pte |= PT_DIRTY_MASK;
-		kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)&pte, sizeof(pte));
+		kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)&pte, sizeof(pte), 0);
 		walker->ptes[walker->level - 1] = pte;
 	}
 

@@ -468,8 +469,15 @@ static int FNAME(shadow_invlpg_entry)(st
 				      struct kvm_vcpu *vcpu, u64 addr,
 				      u64 *sptep, int level)
 {
+	struct shadow_walker *sw =
+		container_of(_sw, struct shadow_walker, walker);
 
 	if (level == PT_PAGE_TABLE_LEVEL) {
+		struct kvm_mmu_page *sp = page_header(__pa(sptep));
+
+		sw->pte_gpa = (sp->gfn << PAGE_SHIFT);
+		sw->pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t);
+
 		if (is_shadow_present_pte(*sptep))
 			rmap_remove(vcpu->kvm, sptep);
 		set_shadow_pte(sptep, shadow_trap_nonpresent_pte);

@@ -482,11 +490,26 @@ static int FNAME(shadow_invlpg_entry)(st
 
 static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
 {
+	pt_element_t gpte;
 	struct shadow_walker walker = {
 		.walker = { .entry = FNAME(shadow_invlpg_entry), },
+		.pte_gpa = -1,
 	};
 
+	spin_lock(&vcpu->kvm->mmu_lock);
 	walk_shadow(&walker.walker, vcpu, gva);
+	spin_unlock(&vcpu->kvm->mmu_lock);
+	if (walker.pte_gpa == -1)
+		return;
+	if (kvm_read_guest_atomic(vcpu->kvm, walker.pte_gpa, &gpte,
+				  sizeof(pt_element_t)))
+		return;
+	if (is_present_pte(gpte) && (gpte & PT_ACCESSED_MASK)) {
+		if (mmu_topup_memory_caches(vcpu))
+			return;
+		kvm_mmu_pte_write(vcpu, walker.pte_gpa, (const u8 *)&gpte,
+				  sizeof(pt_element_t), 0);
+	}
 }
 
 static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
arch/x86/kvm/x86.c +1 -1
Index: kvm/arch/x86/kvm/x86.c
===================================================================
@@ -2046,7 +2046,7 @@ int emulator_write_phys(struct kvm_vcpu 
 	ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes);
 	if (ret < 0)
 		return 0;
-	kvm_mmu_pte_write(vcpu, gpa, val, bytes);
+	kvm_mmu_pte_write(vcpu, gpa, val, bytes, 1);
 	return 1;
 }
arch/x86/include/asm/kvm_host.h +2 -1
Index: kvm/arch/x86/include/asm/kvm_host.h
===================================================================
@@ -602,7 +602,8 @@ unsigned long segment_base(u16 selector)
 
 void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu);
 void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
-		       const u8 *new, int bytes);
+		       const u8 *new, int bytes,
+		       bool guest_initiated);
 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
 void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
 int kvm_mmu_load(struct kvm_vcpu *vcpu);
#5 lore raw
In reply to Marcelo Tosatti
Quoted 3 lines · Marcelo Tosatti

Addressing comments from previous version.

All applied, thanks.

Signature · 2 lines
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.