1 files changed, 943 insertions, 171 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 790423c5f23d..c6f972914f08 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -26,7 +26,31 @@
 #include "vmx.h"
 #include "kvm.h"
 
+#undef MMU_DEBUG
+
+#undef AUDIT
+
+#ifdef AUDIT
+static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg);
+#else
+static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) {}
+#endif
+
+#ifdef MMU_DEBUG
+
+#define pgprintk(x...) do { if (dbg) printk(x); } while (0)
+#define rmap_printk(x...) do { if (dbg) printk(x); } while (0)
+
+#else
+
 #define pgprintk(x...) do { } while (0)
+#define rmap_printk(x...) do { } while (0)
+
+#endif
+
+#if defined(MMU_DEBUG) || defined(AUDIT)
+static int dbg = 1;
+#endif
 
 #define ASSERT(x)                                                       \
         if (!(x)) {                                                     \
@@ -34,8 +58,10 @@
                        __FILE__, __LINE__, #x);                         \
         }
 
-#define PT64_ENT_PER_PAGE 512
-#define PT32_ENT_PER_PAGE 1024
+#define PT64_PT_BITS 9
+#define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
+#define PT32_PT_BITS 10
+#define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
 
 #define PT_WRITABLE_SHIFT 1
 
@@ -125,6 +151,13 @@
 #define PT_DIRECTORY_LEVEL 2
 #define PT_PAGE_TABLE_LEVEL 1
 
+#define RMAP_EXT 4
+
+struct kvm_rmap_desc {
+        u64 *shadow_ptes[RMAP_EXT];
+        struct kvm_rmap_desc *more;
+};
+
 static int is_write_protection(struct kvm_vcpu *vcpu)
 {
         return vcpu->cr0 & CR0_WP_MASK;
@@ -150,32 +183,272 @@ static int is_io_pte(unsigned long pte)
         return pte & PT_SHADOW_IO_MARK;
 }
 
+static int is_rmap_pte(u64 pte)
+{
+        return (pte & (PT_WRITABLE_MASK | PT_PRESENT_MASK))
+                == (PT_WRITABLE_MASK | PT_PRESENT_MASK);
+}
+
+static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
+                                  size_t objsize, int min)
+{
+        void *obj;
+
+        if (cache->nobjs >= min)
+                return 0;
+        while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
+                obj = kzalloc(objsize, GFP_NOWAIT);
+                if (!obj)
+                        return -ENOMEM;
+                cache->objects[cache->nobjs++] = obj;
+        }
+        return 0;
+}
+
+static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
+{
+        while (mc->nobjs)
+                kfree(mc->objects[--mc->nobjs]);
+}
+
+static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
+{
+        int r;
+
+        r = mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
+                                   sizeof(struct kvm_pte_chain), 4);
+        if (r)
+                goto out;
+        r = mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
+                                   sizeof(struct kvm_rmap_desc), 1);
+out:
+        return r;
+}
+
+static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
+{
+        mmu_free_memory_cache(&vcpu->mmu_pte_chain_cache);
+        mmu_free_memory_cache(&vcpu->mmu_rmap_desc_cache);
+}
+
+static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc,
+                                    size_t size)
+{
+        void *p;
+
+        BUG_ON(!mc->nobjs);
+        p = mc->objects[--mc->nobjs];
+        memset(p, 0, size);
+        return p;
+}
+
+static void mmu_memory_cache_free(struct kvm_mmu_memory_cache *mc, void *obj)
+{
+        if (mc->nobjs < KVM_NR_MEM_OBJS)
+                mc->objects[mc->nobjs++] = obj;
+        else
+                kfree(obj);
+}
+
+static struct kvm_pte_chain *mmu_alloc_pte_chain(struct kvm_vcpu *vcpu)
+{
+        return mmu_memory_cache_alloc(&vcpu->mmu_pte_chain_cache,
+                                      sizeof(struct kvm_pte_chain));
+}
+
+static void mmu_free_pte_chain(struct kvm_vcpu *vcpu,
+                               struct kvm_pte_chain *pc)
+{
+        mmu_memory_cache_free(&vcpu->mmu_pte_chain_cache, pc);
+}
+
+static struct kvm_rmap_desc *mmu_alloc_rmap_desc(struct kvm_vcpu *vcpu)
+{
+        return mmu_memory_cache_alloc(&vcpu->mmu_rmap_desc_cache,
+                                      sizeof(struct kvm_rmap_desc));
+}
+
+static void mmu_free_rmap_desc(struct kvm_vcpu *vcpu,
+                               struct kvm_rmap_desc *rd)
+{
+        mmu_memory_cache_free(&vcpu->mmu_rmap_desc_cache, rd);
+}
+
+/*
+ * Reverse mapping data structures:
+ *
+ * If page->private bit zero is zero, then page->private points to the
+ * shadow page table entry that points to page_address(page).
+ *
+ * If page->private bit zero is one, (then page->private & ~1) points
+ * to a struct kvm_rmap_desc containing more mappings.
+ */
+static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte)
+{
+        struct page *page;
+        struct kvm_rmap_desc *desc;
+        int i;
+
+        if (!is_rmap_pte(*spte))
+                return;
+        page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
+        if (!page->private) {
+                rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
+                page->private = (unsigned long)spte;
+        } else if (!(page->private & 1)) {
+                rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
+                desc = mmu_alloc_rmap_desc(vcpu);
+                desc->shadow_ptes[0] = (u64 *)page->private;
+                desc->shadow_ptes[1] = spte;
+                page->private = (unsigned long)desc | 1;
+        } else {
+                rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
+                desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
+                while (desc->shadow_ptes[RMAP_EXT-1] && desc->more)
+                        desc = desc->more;
+                if (desc->shadow_ptes[RMAP_EXT-1]) {
+                        desc->more = mmu_alloc_rmap_desc(vcpu);
+                        desc = desc->more;
+                }
+                for (i = 0; desc->shadow_ptes[i]; ++i)
+                        ;
+                desc->shadow_ptes[i] = spte;
+        }
+}
+
+static void rmap_desc_remove_entry(struct kvm_vcpu *vcpu,
+                                   struct page *page,
+                                   struct kvm_rmap_desc *desc,
+                                   int i,
+                                   struct kvm_rmap_desc *prev_desc)
+{
+        int j;
+
+        for (j = RMAP_EXT - 1; !desc->shadow_ptes[j] && j > i; --j)
+                ;
+        desc->shadow_ptes[i] = desc->shadow_ptes[j];
+        desc->shadow_ptes[j] = 0;
+        if (j != 0)
+                return;
+        if (!prev_desc && !desc->more)
+                page->private = (unsigned long)desc->shadow_ptes[0];
+        else
+                if (prev_desc)
+                        prev_desc->more = desc->more;
+                else
+                        page->private = (unsigned long)desc->more | 1;
+        mmu_free_rmap_desc(vcpu, desc);
+}
+
+static void rmap_remove(struct kvm_vcpu *vcpu, u64 *spte)
+{
+        struct page *page;
+        struct kvm_rmap_desc *desc;
+        struct kvm_rmap_desc *prev_desc;
+        int i;
+
+        if (!is_rmap_pte(*spte))
+                return;
+        page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
+        if (!page->private) {
+                printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
+                BUG();
+        } else if (!(page->private & 1)) {
+                rmap_printk("rmap_remove:  %p %llx 1->0\n", spte, *spte);
+                if ((u64 *)page->private != spte) {
+                        printk(KERN_ERR "rmap_remove:  %p %llx 1->BUG\n",
+                               spte, *spte);
+                        BUG();
+                }
+                page->private = 0;
+        } else {
+                rmap_printk("rmap_remove:  %p %llx many->many\n", spte, *spte);
+                desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
+                prev_desc = NULL;
+                while (desc) {
+                        for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i)
+                                if (desc->shadow_ptes[i] == spte) {
+                                        rmap_desc_remove_entry(vcpu, page,
+                                                               desc, i,
+                                                               prev_desc);
+                                        return;
+                                }
+                        prev_desc = desc;
+                        desc = desc->more;
+                }
+                BUG();
+        }
+}
+
+static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
+{
+        struct kvm *kvm = vcpu->kvm;
+        struct page *page;
+        struct kvm_memory_slot *slot;
+        struct kvm_rmap_desc *desc;
+        u64 *spte;
+
+        slot = gfn_to_memslot(kvm, gfn);
+        BUG_ON(!slot);
+        page = gfn_to_page(slot, gfn);
+
+        while (page->private) {
+                if (!(page->private & 1))
+                        spte = (u64 *)page->private;
+                else {
+                        desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
+                        spte = desc->shadow_ptes[0];
+                }
+                BUG_ON(!spte);
+                BUG_ON((*spte & PT64_BASE_ADDR_MASK) !=
+                       page_to_pfn(page) << PAGE_SHIFT);
+                BUG_ON(!(*spte & PT_PRESENT_MASK));
+                BUG_ON(!(*spte & PT_WRITABLE_MASK));
+                rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
+                rmap_remove(vcpu, spte);
+                kvm_arch_ops->tlb_flush(vcpu);
+                *spte &= ~(u64)PT_WRITABLE_MASK;
+        }
+}
+
+static int is_empty_shadow_page(hpa_t page_hpa)
+{
+        u64 *pos;
+        u64 *end;
+
+        for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u64);
+                      pos != end; pos++)
+                if (*pos != 0) {
+                        printk(KERN_ERR "%s: %p %llx\n", __FUNCTION__,
+                               pos, *pos);
+                        return 0;
+                }
+        return 1;
+}
+
 static void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa)
 {
         struct kvm_mmu_page *page_head = page_header(page_hpa);
 
+        ASSERT(is_empty_shadow_page(page_hpa));
         list_del(&page_head->link);
         page_head->page_hpa = page_hpa;
         list_add(&page_head->link, &vcpu->free_pages);
+        ++vcpu->kvm->n_free_mmu_pages;
 }
 
-static int is_empty_shadow_page(hpa_t page_hpa)
+static unsigned kvm_page_table_hashfn(gfn_t gfn)
 {
-        u32 *pos;
-        u32 *end;
-        for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u32);
-                      pos != end; pos++)
-                if (*pos != 0)
-                        return 0;
-        return 1;
+        return gfn;
 }
 
-static hpa_t kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte)
+static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
+                                               u64 *parent_pte)
 {
         struct kvm_mmu_page *page;
 
         if (list_empty(&vcpu->free_pages))
-                return INVALID_PAGE;
+                return NULL;
 
         page = list_entry(vcpu->free_pages.next, struct kvm_mmu_page, link);
         list_del(&page->link);
@@ -183,8 +456,239 @@ static hpa_t kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte)
         ASSERT(is_empty_shadow_page(page->page_hpa));
         page->slot_bitmap = 0;
         page->global = 1;
+        page->multimapped = 0;
         page->parent_pte = parent_pte;
-        return page->page_hpa;
+        --vcpu->kvm->n_free_mmu_pages;
+        return page;
+}
+
+static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
+                                    struct kvm_mmu_page *page, u64 *parent_pte)
+{
+        struct kvm_pte_chain *pte_chain;
+        struct hlist_node *node;
+        int i;
+
+        if (!parent_pte)
+                return;
+        if (!page->multimapped) {
+                u64 *old = page->parent_pte;
+
+                if (!old) {
+                        page->parent_pte = parent_pte;
+                        return;
+                }
+                page->multimapped = 1;
+                pte_chain = mmu_alloc_pte_chain(vcpu);
+                INIT_HLIST_HEAD(&page->parent_ptes);
+                hlist_add_head(&pte_chain->link, &page->parent_ptes);
+                pte_chain->parent_ptes[0] = old;
+        }
+        hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link) {
+                if (pte_chain->parent_ptes[NR_PTE_CHAIN_ENTRIES-1])
+                        continue;
+                for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i)
+                        if (!pte_chain->parent_ptes[i]) {
+                                pte_chain->parent_ptes[i] = parent_pte;
+                                return;
+                        }
+        }
+        pte_chain = mmu_alloc_pte_chain(vcpu);
+        BUG_ON(!pte_chain);
+        hlist_add_head(&pte_chain->link, &page->parent_ptes);
+        pte_chain->parent_ptes[0] = parent_pte;
+}
+
+static void mmu_page_remove_parent_pte(struct kvm_vcpu *vcpu,
+                                       struct kvm_mmu_page *page,
+                                       u64 *parent_pte)
+{
+        struct kvm_pte_chain *pte_chain;
+        struct hlist_node *node;
+        int i;
+
+        if (!page->multimapped) {
+                BUG_ON(page->parent_pte != parent_pte);
+                page->parent_pte = NULL;
+                return;
+        }
+        hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link)
+                for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
+                        if (!pte_chain->parent_ptes[i])
+                                break;
+                        if (pte_chain->parent_ptes[i] != parent_pte)
+                                continue;
+                        while (i + 1 < NR_PTE_CHAIN_ENTRIES
+                                && pte_chain->parent_ptes[i + 1]) {
+                                pte_chain->parent_ptes[i]
+                                        = pte_chain->parent_ptes[i + 1];
+                                ++i;
+                        }
+                        pte_chain->parent_ptes[i] = NULL;
+                        if (i == 0) {
+                                hlist_del(&pte_chain->link);
+                                mmu_free_pte_chain(vcpu, pte_chain);
+                                if (hlist_empty(&page->parent_ptes)) {
+                                        page->multimapped = 0;
+                                        page->parent_pte = NULL;
+                                }
+                        }
+                        return;
+                }
+        BUG();
+}
+
+static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm_vcpu *vcpu,
+                                                gfn_t gfn)
+{
+        unsigned index;
+        struct hlist_head *bucket;
+        struct kvm_mmu_page *page;
+        struct hlist_node *node;
+
+        pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
+        index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
+        bucket = &vcpu->kvm->mmu_page_hash[index];
+        hlist_for_each_entry(page, node, bucket, hash_link)
+                if (page->gfn == gfn && !page->role.metaphysical) {
+                        pgprintk("%s: found role %x\n",
+                                 __FUNCTION__, page->role.word);
+                        return page;
+                }
+        return NULL;
+}
+
+static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
+                                             gfn_t gfn,
+                                             gva_t gaddr,
+                                             unsigned level,
+                                             int metaphysical,
+                                             u64 *parent_pte)
+{
+        union kvm_mmu_page_role role;
+        unsigned index;
+        unsigned quadrant;
+        struct hlist_head *bucket;
+        struct kvm_mmu_page *page;
+        struct hlist_node *node;
+
+        role.word = 0;
+        role.glevels = vcpu->mmu.root_level;
+        role.level = level;
+        role.metaphysical = metaphysical;
+        if (vcpu->mmu.root_level <= PT32_ROOT_LEVEL) {
+                quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
+                quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
+                role.quadrant = quadrant;
+        }
+        pgprintk("%s: looking gfn %lx role %x\n", __FUNCTION__,
+                 gfn, role.word);
+        index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
+        bucket = &vcpu->kvm->mmu_page_hash[index];
+        hlist_for_each_entry(page, node, bucket, hash_link)
+                if (page->gfn == gfn && page->role.word == role.word) {
+                        mmu_page_add_parent_pte(vcpu, page, parent_pte);
+                        pgprintk("%s: found\n", __FUNCTION__);
+                        return page;
+                }
+        page = kvm_mmu_alloc_page(vcpu, parent_pte);
+        if (!page)
+                return page;
+        pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
+        page->gfn = gfn;
+        page->role = role;
+        hlist_add_head(&page->hash_link, bucket);
+        if (!metaphysical)
+                rmap_write_protect(vcpu, gfn);
+        return page;
+}
+
+static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,
+                                         struct kvm_mmu_page *page)
+{
+        unsigned i;
+        u64 *pt;
+        u64 ent;
+
+        pt = __va(page->page_hpa);
+
+        if (page->role.level == PT_PAGE_TABLE_LEVEL) {
+                for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                        if (pt[i] & PT_PRESENT_MASK)
+                                rmap_remove(vcpu, &pt[i]);
+                        pt[i] = 0;
+                }
+                kvm_arch_ops->tlb_flush(vcpu);
+                return;
+        }
+
+        for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                ent = pt[i];
+
+                pt[i] = 0;
+                if (!(ent & PT_PRESENT_MASK))
+                        continue;
+                ent &= PT64_BASE_ADDR_MASK;
+                mmu_page_remove_parent_pte(vcpu, page_header(ent), &pt[i]);
+        }
+}
+
+static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
+                             struct kvm_mmu_page *page,
+                             u64 *parent_pte)
+{
+        mmu_page_remove_parent_pte(vcpu, page, parent_pte);
+}
+
+static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
+                             struct kvm_mmu_page *page)
+{
+        u64 *parent_pte;
+
+        while (page->multimapped || page->parent_pte) {
+                if (!page->multimapped)
+                        parent_pte = page->parent_pte;
+                else {
+                        struct kvm_pte_chain *chain;
+
+                        chain = container_of(page->parent_ptes.first,
+                                             struct kvm_pte_chain, link);
+                        parent_pte = chain->parent_ptes[0];
+                }
+                BUG_ON(!parent_pte);
+                kvm_mmu_put_page(vcpu, page, parent_pte);
+                *parent_pte = 0;
+        }
+        kvm_mmu_page_unlink_children(vcpu, page);
+        if (!page->root_count) {
+                hlist_del(&page->hash_link);
+                kvm_mmu_free_page(vcpu, page->page_hpa);
+        } else {
+                list_del(&page->link);
+                list_add(&page->link, &vcpu->kvm->active_mmu_pages);
+        }
+}
+
+static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+        unsigned index;
+        struct hlist_head *bucket;
+        struct kvm_mmu_page *page;
+        struct hlist_node *node, *n;
+        int r;
+
+        pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
+        r = 0;
+        index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
+        bucket = &vcpu->kvm->mmu_page_hash[index];
+        hlist_for_each_entry_safe(page, node, n, bucket, hash_link)
+                if (page->gfn == gfn && !page->role.metaphysical) {
+                        pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,
+                                 page->role.word);
+                        kvm_mmu_zap_page(vcpu, page);
+                        r = 1;
+                }
+        return r;
 }
 
 static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
@@ -225,35 +729,6 @@ hpa_t gva_to_hpa(struct kvm_vcpu *vcpu, gva_t gva)
         return gpa_to_hpa(vcpu, gpa);
 }
 
-
-static void release_pt_page_64(struct kvm_vcpu *vcpu, hpa_t page_hpa,
-                               int level)
-{
-        ASSERT(vcpu);
-        ASSERT(VALID_PAGE(page_hpa));
-        ASSERT(level <= PT64_ROOT_LEVEL && level > 0);
-
-        if (level == 1)
-                memset(__va(page_hpa), 0, PAGE_SIZE);
-        else {
-                u64 *pos;
-                u64 *end;
-
-                for (pos = __va(page_hpa), end = pos + PT64_ENT_PER_PAGE;
-                     pos != end; pos++) {
-                        u64 current_ent = *pos;
-
-                        *pos = 0;
-                        if (is_present_pte(current_ent))
-                                release_pt_page_64(vcpu,
-                                                  current_ent &
-                                                  PT64_BASE_ADDR_MASK,
-                                                  level - 1);
-                }
-        }
-        kvm_mmu_free_page(vcpu, page_hpa);
-}
-
 static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
 {
 }
@@ -266,52 +741,109 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
         for (; ; level--) {
                 u32 index = PT64_INDEX(v, level);
                 u64 *table;
+                u64 pte;
 
                 ASSERT(VALID_PAGE(table_addr));
                 table = __va(table_addr);
 
                 if (level == 1) {
+                        pte = table[index];
+                        if (is_present_pte(pte) && is_writeble_pte(pte))
+                                return 0;
                         mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
                         page_header_update_slot(vcpu->kvm, table, v);
                         table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
                                                                 PT_USER_MASK;
+                        rmap_add(vcpu, &table[index]);
                         return 0;
                 }
 
                 if (table[index] == 0) {
-                        hpa_t new_table = kvm_mmu_alloc_page(vcpu,
-                                                             &table[index]);
-
-                        if (!VALID_PAGE(new_table)) {
+                        struct kvm_mmu_page *new_table;
+                        gfn_t pseudo_gfn;
+
+                        pseudo_gfn = (v & PT64_DIR_BASE_ADDR_MASK)
+                                >> PAGE_SHIFT;
+                        new_table = kvm_mmu_get_page(vcpu, pseudo_gfn,
+                                                     v, level - 1,
+                                                     1, &table[index]);
+                        if (!new_table) {
                                 pgprintk("nonpaging_map: ENOMEM\n");
                                 return -ENOMEM;
                         }
 
-                        if (level == PT32E_ROOT_LEVEL)
-                                table[index] = new_table | PT_PRESENT_MASK;
-                        else
-                                table[index] = new_table | PT_PRESENT_MASK |
-                                                PT_WRITABLE_MASK | PT_USER_MASK;
+                        table[index] = new_table->page_hpa | PT_PRESENT_MASK
+                                | PT_WRITABLE_MASK | PT_USER_MASK;
                 }
                 table_addr = table[index] & PT64_BASE_ADDR_MASK;
         }
 }
 
-static void nonpaging_flush(struct kvm_vcpu *vcpu)
+static void mmu_free_roots(struct kvm_vcpu *vcpu)
 {
-        hpa_t root = vcpu->mmu.root_hpa;
+        int i;
+        struct kvm_mmu_page *page;
 
-        ++kvm_stat.tlb_flush;
-        pgprintk("nonpaging_flush\n");
-        ASSERT(VALID_PAGE(root));
-        release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
-        root = kvm_mmu_alloc_page(vcpu, NULL);
-        ASSERT(VALID_PAGE(root));
-        vcpu->mmu.root_hpa = root;
-        if (is_paging(vcpu))
-                root |= (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK));
-        kvm_arch_ops->set_cr3(vcpu, root);
-        kvm_arch_ops->tlb_flush(vcpu);
+#ifdef CONFIG_X86_64
+        if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
+                hpa_t root = vcpu->mmu.root_hpa;
+
+                ASSERT(VALID_PAGE(root));
+                page = page_header(root);
+                --page->root_count;
+                vcpu->mmu.root_hpa = INVALID_PAGE;
+                return;
+        }
+#endif
+        for (i = 0; i < 4; ++i) {
+                hpa_t root = vcpu->mmu.pae_root[i];
+
+                ASSERT(VALID_PAGE(root));
+                root &= PT64_BASE_ADDR_MASK;
+                page = page_header(root);
+                --page->root_count;
+                vcpu->mmu.pae_root[i] = INVALID_PAGE;
+        }
+        vcpu->mmu.root_hpa = INVALID_PAGE;
+}
+
+static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
+{
+        int i;
+        gfn_t root_gfn;
+        struct kvm_mmu_page *page;
+
+        root_gfn = vcpu->cr3 >> PAGE_SHIFT;
+
+#ifdef CONFIG_X86_64
+        if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
+                hpa_t root = vcpu->mmu.root_hpa;
+
+                ASSERT(!VALID_PAGE(root));
+                page = kvm_mmu_get_page(vcpu, root_gfn, 0,
+                                        PT64_ROOT_LEVEL, 0, NULL);
+                root = page->page_hpa;
+                ++page->root_count;
+                vcpu->mmu.root_hpa = root;
+                return;
+        }
+#endif
+        for (i = 0; i < 4; ++i) {
+                hpa_t root = vcpu->mmu.pae_root[i];
+
+                ASSERT(!VALID_PAGE(root));
+                if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
+                        root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
+                else if (vcpu->mmu.root_level == 0)
+                        root_gfn = 0;
+                page = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
+                                        PT32_ROOT_LEVEL, !is_paging(vcpu),
+                                        NULL);
+                root = page->page_hpa;
+                ++page->root_count;
+                vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
+        }
+        vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
 }
 
 static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
@@ -322,43 +854,29 @@ static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
 static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
                                u32 error_code)
 {
-        int ret;
         gpa_t addr = gva;
+        hpa_t paddr;
+        int r;
+
+        r = mmu_topup_memory_caches(vcpu);
+        if (r)
+                return r;
 
         ASSERT(vcpu);
         ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
 
-        for (;;) {
-             hpa_t paddr;
-
-             paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
 
-             if (is_error_hpa(paddr))
-                     return 1;
+        paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
 
-             ret = nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
-             if (ret) {
-                     nonpaging_flush(vcpu);
-                     continue;
-             }
-             break;
-        }
-        return ret;
-}
+        if (is_error_hpa(paddr))
+                return 1;
 
-static void nonpaging_inval_page(struct kvm_vcpu *vcpu, gva_t addr)
-{
+        return nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
 }
 
 static void nonpaging_free(struct kvm_vcpu *vcpu)
 {
-        hpa_t root;
-
-        ASSERT(vcpu);
-        root = vcpu->mmu.root_hpa;
-        if (VALID_PAGE(root))
-                release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
-        vcpu->mmu.root_hpa = INVALID_PAGE;
+        mmu_free_roots(vcpu);
 }
 
 static int nonpaging_init_context(struct kvm_vcpu *vcpu)
@@ -367,40 +885,31 @@ static int nonpaging_init_context(struct kvm_vcpu *vcpu)
 
         context->new_cr3 = nonpaging_new_cr3;
         context->page_fault = nonpaging_page_fault;
-        context->inval_page = nonpaging_inval_page;
         context->gva_to_gpa = nonpaging_gva_to_gpa;
         context->free = nonpaging_free;
-        context->root_level = PT32E_ROOT_LEVEL;
+        context->root_level = 0;
         context->shadow_root_level = PT32E_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa);
         return 0;
 }
 
-
 static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
 {
-        struct kvm_mmu_page *page, *npage;
-
-        list_for_each_entry_safe(page, npage, &vcpu->kvm->active_mmu_pages,
-                                 link) {
-                if (page->global)
-                        continue;
-
-                if (!page->parent_pte)
-                        continue;
-
-                *page->parent_pte = 0;
-                release_pt_page_64(vcpu, page->page_hpa, 1);
-        }
         ++kvm_stat.tlb_flush;
         kvm_arch_ops->tlb_flush(vcpu);
 }
 
 static void paging_new_cr3(struct kvm_vcpu *vcpu)
 {
+        pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->cr3);
+        mmu_free_roots(vcpu);
+        if (unlikely(vcpu->kvm->n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES))
+                kvm_mmu_free_some_pages(vcpu);
+        mmu_alloc_roots(vcpu);
         kvm_mmu_flush_tlb(vcpu);
+        kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
 }
 
 static void mark_pagetable_nonglobal(void *shadow_pte)
@@ -412,7 +921,8 @@ static inline void set_pte_common(struct kvm_vcpu *vcpu,
                              u64 *shadow_pte,
                              gpa_t gaddr,
                              int dirty,
-                             u64 access_bits)
+                             u64 access_bits,
+                             gfn_t gfn)
 {
         hpa_t paddr;
 
@@ -420,13 +930,10 @@ static inline void set_pte_common(struct kvm_vcpu *vcpu,
         if (!dirty)
                 access_bits &= ~PT_WRITABLE_MASK;
 
-        if (access_bits & PT_WRITABLE_MASK)
-                mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
+        paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
 
         *shadow_pte |= access_bits;
 
-        paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
-
         if (!(*shadow_pte & PT_GLOBAL_MASK))
                 mark_pagetable_nonglobal(shadow_pte);
 
@@ -434,10 +941,31 @@ static inline void set_pte_common(struct kvm_vcpu *vcpu,
                 *shadow_pte |= gaddr;
                 *shadow_pte |= PT_SHADOW_IO_MARK;
                 *shadow_pte &= ~PT_PRESENT_MASK;
-        } else {
-                *shadow_pte |= paddr;
-                page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
+                return;
+        }
+
+        *shadow_pte |= paddr;
+
+        if (access_bits & PT_WRITABLE_MASK) {
+                struct kvm_mmu_page *shadow;
+
+                shadow = kvm_mmu_lookup_page(vcpu, gfn);
+                if (shadow) {
+                        pgprintk("%s: found shadow page for %lx, marking ro\n",
+                                 __FUNCTION__, gfn);
+                        access_bits &= ~PT_WRITABLE_MASK;
+                        if (is_writeble_pte(*shadow_pte)) {
+                                    *shadow_pte &= ~PT_WRITABLE_MASK;
+                                    kvm_arch_ops->tlb_flush(vcpu);
+                        }
+                }
         }
+
+        if (access_bits & PT_WRITABLE_MASK)
+                mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
+
+        page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
+        rmap_add(vcpu, shadow_pte);
 }
 
 static void inject_page_fault(struct kvm_vcpu *vcpu,
@@ -474,41 +1002,6 @@ static int may_access(u64 pte, int write, int user)
         return 1;
 }
 
-/*
- * Remove a shadow pte.
- */
-static void paging_inval_page(struct kvm_vcpu *vcpu, gva_t addr)
-{
-        hpa_t page_addr = vcpu->mmu.root_hpa;
-        int level = vcpu->mmu.shadow_root_level;
-
-        ++kvm_stat.invlpg;
-
-        for (; ; level--) {
-                u32 index = PT64_INDEX(addr, level);
-                u64 *table = __va(page_addr);
-
-                if (level == PT_PAGE_TABLE_LEVEL ) {
-                        table[index] = 0;
-                        return;
-                }
-
-                if (!is_present_pte(table[index]))
-                        return;
-
-                page_addr = table[index] & PT64_BASE_ADDR_MASK;
-
-                if (level == PT_DIRECTORY_LEVEL &&
-                          (table[index] & PT_SHADOW_PS_MARK)) {
-                        table[index] = 0;
-                        release_pt_page_64(vcpu, page_addr, PT_PAGE_TABLE_LEVEL);
-
-                        kvm_arch_ops->tlb_flush(vcpu);
-                        return;
-                }
-        }
-}
-
 static void paging_free(struct kvm_vcpu *vcpu)
 {
         nonpaging_free(vcpu);
@@ -522,37 +1015,40 @@ static void paging_free(struct kvm_vcpu *vcpu)
 #include "paging_tmpl.h"
 #undef PTTYPE
 
-static int paging64_init_context(struct kvm_vcpu *vcpu)
+static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
 {
         struct kvm_mmu *context = &vcpu->mmu;
 
         ASSERT(is_pae(vcpu));
         context->new_cr3 = paging_new_cr3;
         context->page_fault = paging64_page_fault;
-        context->inval_page = paging_inval_page;
         context->gva_to_gpa = paging64_gva_to_gpa;
         context->free = paging_free;
-        context->root_level = PT64_ROOT_LEVEL;
-        context->shadow_root_level = PT64_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        context->root_level = level;
+        context->shadow_root_level = level;
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
         return 0;
 }
 
+static int paging64_init_context(struct kvm_vcpu *vcpu)
+{
+        return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
+}
+
 static int paging32_init_context(struct kvm_vcpu *vcpu)
 {
         struct kvm_mmu *context = &vcpu->mmu;
 
         context->new_cr3 = paging_new_cr3;
         context->page_fault = paging32_page_fault;
-        context->inval_page = paging_inval_page;
         context->gva_to_gpa = paging32_gva_to_gpa;
         context->free = paging_free;
         context->root_level = PT32_ROOT_LEVEL;
         context->shadow_root_level = PT32E_ROOT_LEVEL;
-        context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
+        mmu_alloc_roots(vcpu);
         ASSERT(VALID_PAGE(context->root_hpa));
         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
@@ -561,14 +1057,7 @@ static int paging32_init_context(struct kvm_vcpu *vcpu)
 
 static int paging32E_init_context(struct kvm_vcpu *vcpu)
 {
-        int ret;
-
-        if ((ret = paging64_init_context(vcpu)))
-                return ret;
-
-        vcpu->mmu.root_level = PT32E_ROOT_LEVEL;
-        vcpu->mmu.shadow_root_level = PT32E_ROOT_LEVEL;
-        return 0;
+        return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
 }
 
 static int init_kvm_mmu(struct kvm_vcpu *vcpu)
@@ -597,41 +1086,161 @@ static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
 
 int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
 {
+        int r;
+
         destroy_kvm_mmu(vcpu);
-        return init_kvm_mmu(vcpu);
+        r = init_kvm_mmu(vcpu);
+        if (r < 0)
+                goto out;
+        r = mmu_topup_memory_caches(vcpu);
+out:
+        return r;
 }
 
-static void free_mmu_pages(struct kvm_vcpu *vcpu)
+void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
 {
-        while (!list_empty(&vcpu->free_pages)) {
+        gfn_t gfn = gpa >> PAGE_SHIFT;
+        struct kvm_mmu_page *page;
+        struct kvm_mmu_page *child;
+        struct hlist_node *node, *n;
+        struct hlist_head *bucket;
+        unsigned index;
+        u64 *spte;
+        u64 pte;
+        unsigned offset = offset_in_page(gpa);
+        unsigned pte_size;
+        unsigned page_offset;
+        unsigned misaligned;
+        int level;
+        int flooded = 0;
+
+        pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
+        if (gfn == vcpu->last_pt_write_gfn) {
+                ++vcpu->last_pt_write_count;
+                if (vcpu->last_pt_write_count >= 3)
+                        flooded = 1;
+        } else {
+                vcpu->last_pt_write_gfn = gfn;
+                vcpu->last_pt_write_count = 1;
+        }
+        index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
+        bucket = &vcpu->kvm->mmu_page_hash[index];
+        hlist_for_each_entry_safe(page, node, n, bucket, hash_link) {
+                if (page->gfn != gfn || page->role.metaphysical)
+                        continue;
+                pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
+                misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
+                if (misaligned || flooded) {
+                        /*
+                         * Misaligned accesses are too much trouble to fix
+                         * up; also, they usually indicate a page is not used
+                         * as a page table.
+                         *
+                         * If we're seeing too many writes to a page,
+                         * it may no longer be a page table, or we may be
+                         * forking, in which case it is better to unmap the
+                         * page.
+                         */
+                        pgprintk("misaligned: gpa %llx bytes %d role %x\n",
+                                 gpa, bytes, page->role.word);
+                        kvm_mmu_zap_page(vcpu, page);
+                        continue;
+                }
+                page_offset = offset;
+                level = page->role.level;
+                if (page->role.glevels == PT32_ROOT_LEVEL) {
+                        page_offset <<= 1;          /* 32->64 */
+                        page_offset &= ~PAGE_MASK;
+                }
+                spte = __va(page->page_hpa);
+                spte += page_offset / sizeof(*spte);
+                pte = *spte;
+                if (is_present_pte(pte)) {
+                        if (level == PT_PAGE_TABLE_LEVEL)
+                                rmap_remove(vcpu, spte);
+                        else {
+                                child = page_header(pte & PT64_BASE_ADDR_MASK);
+                                mmu_page_remove_parent_pte(vcpu, child, spte);
+                        }
+                }
+                *spte = 0;
+        }
+}
+
+void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
+{
+}
+
+int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
+{
+        gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
+
+        return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT);
+}
+
+void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
+{
+        while (vcpu->kvm->n_free_mmu_pages < KVM_REFILL_PAGES) {
                 struct kvm_mmu_page *page;
 
+                page = container_of(vcpu->kvm->active_mmu_pages.prev,
+                                    struct kvm_mmu_page, link);
+                kvm_mmu_zap_page(vcpu, page);
+        }
+}
+EXPORT_SYMBOL_GPL(kvm_mmu_free_some_pages);
+
+static void free_mmu_pages(struct kvm_vcpu *vcpu)
+{
+        struct kvm_mmu_page *page;
+
+        while (!list_empty(&vcpu->kvm->active_mmu_pages)) {
+                page = container_of(vcpu->kvm->active_mmu_pages.next,
+                                    struct kvm_mmu_page, link);
+                kvm_mmu_zap_page(vcpu, page);
+        }
+        while (!list_empty(&vcpu->free_pages)) {
                 page = list_entry(vcpu->free_pages.next,
                                   struct kvm_mmu_page, link);
                 list_del(&page->link);
                 __free_page(pfn_to_page(page->page_hpa >> PAGE_SHIFT));
                 page->page_hpa = INVALID_PAGE;
         }
+        free_page((unsigned long)vcpu->mmu.pae_root);
 }
 
 static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
 {
+        struct page *page;
         int i;
 
         ASSERT(vcpu);
 
         for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
-                struct page *page;
                 struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
 
                 INIT_LIST_HEAD(&page_header->link);
-                if ((page = alloc_page(GFP_KVM_MMU)) == NULL)
+                if ((page = alloc_page(GFP_KERNEL)) == NULL)
                         goto error_1;
                 page->private = (unsigned long)page_header;
                 page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT;
                 memset(__va(page_header->page_hpa), 0, PAGE_SIZE);
                 list_add(&page_header->link, &vcpu->free_pages);
+                ++vcpu->kvm->n_free_mmu_pages;
         }
+
+        /*
+         * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
+         * Therefore we need to allocate shadow page tables in the first
+         * 4GB of memory, which happens to fit the DMA32 zone.
+         */
+        page = alloc_page(GFP_KERNEL | __GFP_DMA32);
+        if (!page)
+                goto error_1;
+        vcpu->mmu.pae_root = page_address(page);
+        for (i = 0; i < 4; ++i)
+                vcpu->mmu.pae_root[i] = INVALID_PAGE;
+
         return 0;
 
 error_1:
@@ -663,10 +1272,12 @@ void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
 
         destroy_kvm_mmu(vcpu);
         free_mmu_pages(vcpu);
+        mmu_free_memory_caches(vcpu);
 }
 
-void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
+void kvm_mmu_slot_remove_write_access(struct kvm_vcpu *vcpu, int slot)
 {
+        struct kvm *kvm = vcpu->kvm;
         struct kvm_mmu_page *page;
 
         list_for_each_entry(page, &kvm->active_mmu_pages, link) {
@@ -679,8 +1290,169 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
                 pt = __va(page->page_hpa);
                 for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
                         /* avoid RMW */
-                        if (pt[i] & PT_WRITABLE_MASK)
+                        if (pt[i] & PT_WRITABLE_MASK) {
+                                rmap_remove(vcpu, &pt[i]);
                                 pt[i] &= ~PT_WRITABLE_MASK;
+                        }
+        }
+}
+
+#ifdef AUDIT
+
+static const char *audit_msg;
+
+static gva_t canonicalize(gva_t gva)
+{
+#ifdef CONFIG_X86_64
+        gva = (long long)(gva << 16) >> 16;
+#endif
+        return gva;
+}
 
+static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
+                                gva_t va, int level)
+{
+        u64 *pt = __va(page_pte & PT64_BASE_ADDR_MASK);
+        int i;
+        gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1));
+
+        for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) {
+                u64 ent = pt[i];
+
+                if (!ent & PT_PRESENT_MASK)
+                        continue;
+
+                va = canonicalize(va);
+                if (level > 1)
+                        audit_mappings_page(vcpu, ent, va, level - 1);
+                else {
+                        gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, va);
+                        hpa_t hpa = gpa_to_hpa(vcpu, gpa);
+
+                        if ((ent & PT_PRESENT_MASK)
+                            && (ent & PT64_BASE_ADDR_MASK) != hpa)
+                                printk(KERN_ERR "audit error: (%s) levels %d"
+                                       " gva %lx gpa %llx hpa %llx ent %llx\n",
+                                       audit_msg, vcpu->mmu.root_level,
+                                       va, gpa, hpa, ent);
+                }
         }
 }
+
+static void audit_mappings(struct kvm_vcpu *vcpu)
+{
+        int i;
+
+        if (vcpu->mmu.root_level == 4)
+                audit_mappings_page(vcpu, vcpu->mmu.root_hpa, 0, 4);
+        else
+                for (i = 0; i < 4; ++i)
+                        if (vcpu->mmu.pae_root[i] & PT_PRESENT_MASK)
+                                audit_mappings_page(vcpu,
+                                                    vcpu->mmu.pae_root[i],
+                                                    i << 30,
+                                                    2);
+}
+
+static int count_rmaps(struct kvm_vcpu *vcpu)
+{
+        int nmaps = 0;
+        int i, j, k;
+
+        for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
+                struct kvm_memory_slot *m = &vcpu->kvm->memslots[i];
+                struct kvm_rmap_desc *d;
+
+                for (j = 0; j < m->npages; ++j) {
+                        struct page *page = m->phys_mem[j];
+
+                        if (!page->private)
+                                continue;
+                        if (!(page->private & 1)) {
+                                ++nmaps;
+                                continue;
+                        }
+                        d = (struct kvm_rmap_desc *)(page->private & ~1ul);
+                        while (d) {
+                                for (k = 0; k < RMAP_EXT; ++k)
+                                        if (d->shadow_ptes[k])
+                                                ++nmaps;
+                                        else
+                                                break;
+                                d = d->more;
+                        }
+                }
+        }
+        return nmaps;
+}
+
+static int count_writable_mappings(struct kvm_vcpu *vcpu)
+{
+        int nmaps = 0;
+        struct kvm_mmu_page *page;
+        int i;
+
+        list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) {
+                u64 *pt = __va(page->page_hpa);
+
+                if (page->role.level != PT_PAGE_TABLE_LEVEL)
+                        continue;
+
+                for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                        u64 ent = pt[i];
+
+                        if (!(ent & PT_PRESENT_MASK))
+                                continue;
+                        if (!(ent & PT_WRITABLE_MASK))
+                                continue;
+                        ++nmaps;
+                }
+        }
+        return nmaps;
+}
+
+static void audit_rmap(struct kvm_vcpu *vcpu)
+{
+        int n_rmap = count_rmaps(vcpu);
+        int n_actual = count_writable_mappings(vcpu);
+
+        if (n_rmap != n_actual)
+                printk(KERN_ERR "%s: (%s) rmap %d actual %d\n",
+                       __FUNCTION__, audit_msg, n_rmap, n_actual);
+}
+
+static void audit_write_protection(struct kvm_vcpu *vcpu)
+{
+        struct kvm_mmu_page *page;
+
+        list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) {
+                hfn_t hfn;
+                struct page *pg;
+
+                if (page->role.metaphysical)
+                        continue;
+
+                hfn = gpa_to_hpa(vcpu, (gpa_t)page->gfn << PAGE_SHIFT)
+                        >> PAGE_SHIFT;
+                pg = pfn_to_page(hfn);
+                if (pg->private)
+                        printk(KERN_ERR "%s: (%s) shadow page has writable"
+                               " mappings: gfn %lx role %x\n",
+                               __FUNCTION__, audit_msg, page->gfn,
+                               page->role.word);
+        }
+}
+
+static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg)
+{
+        int olddbg = dbg;
+
+        dbg = 0;
+        audit_msg = msg;
+        audit_rmap(vcpu);
+        audit_write_protection(vcpu);
+        audit_mappings(vcpu);
+        dbg = olddbg;
+}
+
+#endif