/* * Kernel-based Virtual Machine driver for Linux * * This module enables machines with Intel VT-x extensions to run virtual * machines without emulation or binary translation. * * MMU support * * Copyright (C) 2006 Qumranet, Inc. * * Authors: * Yaniv Kamay * Avi Kivity * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * */ #include "vmx.h" #include "mmu.h" #include #include #include #include #include #include #include #include #include #include #include #include /* * When setting this variable to true it enables Two-Dimensional-Paging * where the hardware walks 2 page tables: * 1. the guest-virtual to guest-physical * 2. while doing 1. it walks guest-physical to host-physical * If the hardware supports that we don't need to do shadow paging. */ bool tdp_enabled = false; #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 #ifndef MMU_DEBUG #define ASSERT(x) do { } while (0) #else #define ASSERT(x) \ if (!(x)) { \ printk(KERN_WARNING "assertion failed %s:%d: %s\n", \ __FILE__, __LINE__, #x); \ } #endif #define PT_FIRST_AVAIL_BITS_SHIFT 9 #define PT64_SECOND_AVAIL_BITS_SHIFT 52 #define VALID_PAGE(x) ((x) != INVALID_PAGE) #define PT64_LEVEL_BITS 9 #define PT64_LEVEL_SHIFT(level) \ (PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS) #define PT64_LEVEL_MASK(level) \ (((1ULL << PT64_LEVEL_BITS) - 1) << PT64_LEVEL_SHIFT(level)) #define PT64_INDEX(address, level)\ (((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1)) #define PT32_LEVEL_BITS 10 #define PT32_LEVEL_SHIFT(level) \ (PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS) #define PT32_LEVEL_MASK(level) \ (((1ULL << PT32_LEVEL_BITS) - 1) << PT32_LEVEL_SHIFT(level)) #define PT32_INDEX(address, level)\ (((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1)) #define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1)) #define PT64_DIR_BASE_ADDR_MASK \ (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1)) #define PT32_BASE_ADDR_MASK PAGE_MASK #define PT32_DIR_BASE_ADDR_MASK \ (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1)) #define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK \ | PT64_NX_MASK) #define PFERR_PRESENT_MASK (1U << 0) #define PFERR_WRITE_MASK (1U << 1) #define PFERR_USER_MASK (1U << 2) #define PFERR_FETCH_MASK (1U << 4) #define PT_DIRECTORY_LEVEL 2 #define PT_PAGE_TABLE_LEVEL 1 #define RMAP_EXT 4 #define ACC_EXEC_MASK 1 #define ACC_WRITE_MASK PT_WRITABLE_MASK #define ACC_USER_MASK PT_USER_MASK #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) struct kvm_pv_mmu_op_buffer { void *ptr; unsigned len; unsigned processed; char buf[512] __aligned(sizeof(long)); }; struct kvm_rmap_desc { u64 *shadow_ptes[RMAP_EXT]; struct kvm_rmap_desc *more; }; static struct kmem_cache *pte_chain_cache; static struct kmem_cache *rmap_desc_cache; static struct kmem_cache *mmu_page_header_cache; static u64 __read_mostly shadow_trap_nonpresent_pte; static u64 __read_mostly shadow_notrap_nonpresent_pte; static u64 __read_mostly shadow_base_present_pte; static u64 __read_mostly shadow_nx_mask; static u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ static u64 __read_mostly shadow_user_mask; static u64 __read_mostly shadow_accessed_mask; static u64 __read_mostly shadow_dirty_mask; void kvm_mmu_set_nonpresent_ptes(u64 trap_pte, u64 notrap_pte) { shadow_trap_nonpresent_pte = trap_pte; shadow_notrap_nonpresent_pte = notrap_pte; } EXPORT_SYMBOL_GPL(kvm_mmu_set_nonpresent_ptes); void kvm_mmu_set_base_ptes(u64 base_pte) { shadow_base_present_pte = base_pte; } EXPORT_SYMBOL_GPL(kvm_mmu_set_base_ptes); void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, u64 dirty_mask, u64 nx_mask, u64 x_mask) { shadow_user_mask = user_mask; shadow_accessed_mask = accessed_mask; shadow_dirty_mask = dirty_mask; shadow_nx_mask = nx_mask; shadow_x_mask = x_mask; } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); static int is_write_protection(struct kvm_vcpu *vcpu) { return vcpu->arch.cr0 & X86_CR0_WP; } static int is_cpuid_PSE36(void) { return 1; } static int is_nx(struct kvm_vcpu *vcpu) { return vcpu->arch.shadow_efer & EFER_NX; } static int is_present_pte(unsigned long pte) { return pte & PT_PRESENT_MASK; } static int is_shadow_present_pte(u64 pte) { return pte != shadow_trap_nonpresent_pte && pte != shadow_notrap_nonpresent_pte; } static int is_large_pte(u64 pte) { return pte & PT_PAGE_SIZE_MASK; } static int is_writeble_pte(unsigned long pte) { return pte & PT_WRITABLE_MASK; } static int is_dirty_pte(unsigned long pte) { return pte & shadow_dirty_mask; } static int is_rmap_pte(u64 pte) { return is_shadow_present_pte(pte); } static pfn_t spte_to_pfn(u64 pte) { return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; } static gfn_t pse36_gfn_delta(u32 gpte) { int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT; return (gpte & PT32_DIR_PSE36_MASK) << shift; } static void set_shadow_pte(u64 *sptep, u64 spte) { #ifdef CONFIG_X86_64 set_64bit((unsigned long *)sptep, spte); #else set_64bit((unsigned long long *)sptep, spte); #endif } static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, struct kmem_cache *base_cache, int min) { void *obj; if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) { obj = kmem_cache_zalloc(base_cache, GFP_KERNEL); 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_cache_page(struct kvm_mmu_memory_cache *cache, int min) { struct page *page; if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) { page = alloc_page(GFP_KERNEL); if (!page) return -ENOMEM; set_page_private(page, 0); cache->objects[cache->nobjs++] = page_address(page); } return 0; } static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc) { while (mc->nobjs) free_page((unsigned long)mc->objects[--mc->nobjs]); } static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu) { int r; r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_chain_cache, pte_chain_cache, 4); if (r) goto out; r = mmu_topup_memory_cache(&vcpu->arch.mmu_rmap_desc_cache, rmap_desc_cache, 1); if (r) goto out; r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8); if (r) goto out; r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, mmu_page_header_cache, 4); out: return r; } static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) { mmu_free_memory_cache(&vcpu->arch.mmu_pte_chain_cache); mmu_free_memory_cache(&vcpu->arch.mmu_rmap_desc_cache); mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache); mmu_free_memory_cache(&vcpu->arch.mmu_page_header_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 struct kvm_pte_chain *mmu_alloc_pte_chain(struct kvm_vcpu *vcpu) { return mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_chain_cache, sizeof(struct kvm_pte_chain)); } static void mmu_free_pte_chain(struct kvm_pte_chain *pc) { kfree(pc); } static struct kvm_rmap_desc *mmu_alloc_rmap_desc(struct kvm_vcpu *vcpu) { return mmu_memory_cache_alloc(&vcpu->arch.mmu_rmap_desc_cache, sizeof(struct kvm_rmap_desc)); } static void mmu_free_rmap_desc(struct kvm_rmap_desc *rd) { kfree(rd); } /* * Return the pointer to the largepage write count for a given * gfn, handling slots that are not large page aligned. */ static int *slot_largepage_idx(gfn_t gfn, struct kvm_memory_slot *slot) { unsigned long idx; idx = (gfn / KVM_PAGES_PER_HPAGE) - (slot->base_gfn / KVM_PAGES_PER_HPAGE); return &slot->lpage_info[idx].write_count; } static void account_shadowed(struct kvm *kvm, gfn_t gfn) { int *write_count; write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn)); *write_count += 1; } static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn) { int *write_count; write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn)); *write_count -= 1; WARN_ON(*write_count < 0); } static int has_wrprotected_page(struct kvm *kvm, gfn_t gfn) { struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); int *largepage_idx; if (slot) { largepage_idx = slot_largepage_idx(gfn, slot); return *largepage_idx; } return 1; } static int host_largepage_backed(struct kvm *kvm, gfn_t gfn) { struct vm_area_struct *vma; unsigned long addr; addr = gfn_to_hva(kvm, gfn); if (kvm_is_error_hva(addr)) return 0; vma = find_vma(current->mm, addr); if (vma && is_vm_hugetlb_page(vma)) return 1; return 0; } static int is_largepage_backed(struct kvm_vcpu *vcpu, gfn_t large_gfn) { struct kvm_memory_slot *slot; if (has_wrprotected_page(vcpu->kvm, large_gfn)) return 0; if (!host_largepage_backed(vcpu->kvm, large_gfn)) return 0; slot = gfn_to_memslot(vcpu->kvm, large_gfn); if (slot && slot->dirty_bitmap) return 0; return 1; } /* * Take gfn and return the reverse mapping to it. * Note: gfn must be unaliased before this function get called */ static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int lpage) { struct kvm_memory_slot *slot; unsigned long idx; slot = gfn_to_memslot(kvm, gfn); if (!lpage) return &slot->rmap[gfn - slot->base_gfn]; idx = (gfn / KVM_PAGES_PER_HPAGE) - (slot->base_gfn / KVM_PAGES_PER_HPAGE); return &slot->lpage_info[idx].rmap_pde; } /* * Reverse mapping data structures: * * If rmapp bit zero is zero, then rmapp point to the shadw page table entry * that points to page_address(page). * * If rmapp bit zero is one, (then rmap & ~1) points to a struct kvm_rmap_desc * containing more mappings. */ static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn, int lpage) { struct kvm_mmu_page *sp; struct kvm_rmap_desc *desc; unsigned long *rmapp; int i; if (!is_rmap_pte(*spte)) return; gfn = unalias_gfn(vcpu->kvm, gfn); sp = page_header(__pa(spte)); sp->gfns[spte - sp->spt] = gfn; rmapp = gfn_to_rmap(vcpu->kvm, gfn, lpage); if (!*rmapp) { rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte); *rmapp = (unsigned long)spte; } else if (!(*rmapp & 1)) { rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte); desc = mmu_alloc_rmap_desc(vcpu); desc->shadow_ptes[0] = (u64 *)*rmapp; desc->shadow_ptes[1] = spte; *rmapp = (unsigned long)desc | 1; } else { rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte); desc = (struct kvm_rmap_desc *)(*rmapp & ~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(unsigned long *rmapp, 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] = NULL; if (j != 0) return; if (!prev_desc && !desc->more) *rmapp = (unsigned long)desc->shadow_ptes[0]; else if (prev_desc) prev_desc->more = desc->more; else *rmapp = (unsigned long)desc->more | 1; mmu_free_rmap_desc(desc); } static void rmap_remove(struct kvm *kvm, u64 *spte) { struct kvm_rmap_desc *desc; struct kvm_rmap_desc *prev_desc; struct kvm_mmu_page *sp; pfn_t pfn; unsigned long *rmapp; int i; if (!is_rmap_pte(*spte)) return; sp = page_header(__pa(spte)); pfn = spte_to_pfn(*spte); if (*spte & shadow_accessed_mask) kvm_set_pfn_accessed(pfn); if (is_writeble_pte(*spte)) kvm_release_pfn_dirty(pfn); else kvm_release_pfn_clean(pfn); rmapp = gfn_to_rmap(kvm, sp->gfns[spte - sp->spt], is_large_pte(*spte)); if (!*rmapp) { printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte); BUG(); } else if (!(*rmapp & 1)) { rmap_printk("rmap_remove: %p %llx 1->0\n", spte, *spte); if ((u64 *)*rmapp != spte) { printk(KERN_ERR "rmap_remove: %p %llx 1->BUG\n", spte, *spte); BUG(); } *rmapp = 0; } else { rmap_printk("rmap_remove: %p %llx many->many\n", spte, *spte); desc = (struct kvm_rmap_desc *)(*rmapp & ~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(rmapp, desc, i, prev_desc); return; } prev_desc = desc; desc = desc->more; } BUG(); } } static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte) { struct kvm_rmap_desc *desc; struct kvm_rmap_desc *prev_desc; u64 *prev_spte; int i; if (!*rmapp) return NULL; else if (!(*rmapp & 1)) { if (!spte) return (u64 *)*rmapp; return NULL; } desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul); prev_desc = NULL; prev_spte = NULL; while (desc) { for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i) { if (prev_spte == spte) return desc->shadow_ptes[i]; prev_spte = desc->shadow_ptes[i]; } desc = desc->more; } return NULL; } static void rmap_write_protect(struct kvm *kvm, u64 gfn) { unsigned long *rmapp; u64 *spte; int write_protected = 0; gfn = unalias_gfn(kvm, gfn); rmapp = gfn_to_rmap(kvm, gfn, 0); spte = rmap_next(kvm, rmapp, NULL); while (spte) { BUG_ON(!spte); BUG_ON(!(*spte & PT_PRESENT_MASK)); rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte); if (is_writeble_pte(*spte)) { set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK); write_protected = 1; } spte = rmap_next(kvm, rmapp, spte); } if (write_protected) { pfn_t pfn; spte = rmap_next(kvm, rmapp, NULL); pfn = spte_to_pfn(*spte); kvm_set_pfn_dirty(pfn); } /* check for huge page mappings */ rmapp = gfn_to_rmap(kvm, gfn, 1); spte = rmap_next(kvm, rmapp, NULL); while (spte) { BUG_ON(!spte); BUG_ON(!(*spte & PT_PRESENT_MASK)); BUG_ON((*spte & (PT_PAGE_SIZE_MASK|PT_PRESENT_MASK)) != (PT_PAGE_SIZE_MASK|PT_PRESENT_MASK)); pgprintk("rmap_write_protect(large): spte %p %llx %lld\n", spte, *spte, gfn); if (is_writeble_pte(*spte)) { rmap_remove(kvm, spte); --kvm->stat.lpages; set_shadow_pte(spte, shadow_trap_nonpresent_pte); spte = NULL; write_protected = 1; } spte = rmap_next(kvm, rmapp, spte); } if (write_protected) kvm_flush_remote_tlbs(kvm); account_shadowed(kvm, gfn); } #ifdef MMU_DEBUG static int is_empty_shadow_page(u64 *spt) { u64 *pos; u64 *end; for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) if (is_shadow_present_pte(*pos)) { printk(KERN_ERR "%s: %p %llx\n", __func__, pos, *pos); return 0; } return 1; } #endif static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp) { ASSERT(is_empty_shadow_page(sp->spt)); list_del(&sp->link); __free_page(virt_to_page(sp->spt)); __free_page(virt_to_page(sp->gfns)); kfree(sp); ++kvm->arch.n_free_mmu_pages; } static unsigned kvm_page_table_hashfn(gfn_t gfn) { return gfn & ((1 << KVM_MMU_HASH_SHIFT) - 1); } static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte) { struct kvm_mmu_page *sp; sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache, sizeof *sp); sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE); sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE); set_page_private(virt_to_page(sp->spt), (unsigned long)sp); list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); ASSERT(is_empty_shadow_page(sp->spt)); sp->slot_bitmap = 0; sp->multimapped = 0; sp->parent_pte = parent_pte; --vcpu->kvm->arch.n_free_mmu_pages; return sp; } static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *parent_pte) { struct kvm_pte_chain *pte_chain; struct hlist_node *node; int i; if (!parent_pte) return; if (!sp->multimapped) { u64 *old = sp->parent_pte; if (!old) { sp->parent_pte = parent_pte; return; } sp->multimapped = 1; pte_chain = mmu_alloc_pte_chain(vcpu); INIT_HLIST_HEAD(&sp->parent_ptes); hlist_add_head(&pte_chain->link, &sp->parent_ptes); pte_chain->parent_ptes[0] = old; } hlist_for_each_entry(pte_chain, node, &sp->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, &sp->parent_ptes); pte_chain->parent_ptes[0] = parent_pte; } static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, u64 *parent_pte) { struct kvm_pte_chain *pte_chain; struct hlist_node *node; int i; if (!sp->multimapped) { BUG_ON(sp->parent_pte != parent_pte); sp->parent_pte = NULL; return; } hlist_for_each_entry(pte_chain, node, &sp->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(pte_chain); if (hlist_empty(&sp->parent_ptes)) { sp->multimapped = 0; sp->parent_pte = NULL; } } return; } BUG(); } static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { int i; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) sp->spt[i] = shadow_trap_nonpresent_pte; } static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn) { unsigned index; struct hlist_head *bucket; struct kvm_mmu_page *sp; struct hlist_node *node; pgprintk("%s: looking for gfn %lx\n", __func__, gfn); index = kvm_page_table_hashfn(gfn); bucket = &kvm->arch.mmu_page_hash[index]; hlist_for_each_entry(sp, node, bucket, hash_link) if (sp->gfn == gfn && !sp->role.metaphysical && !sp->role.invalid) { pgprintk("%s: found role %x\n", __func__, sp->role.word); return sp; } 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, unsigned access, u64 *parent_pte) { union kvm_mmu_page_role role; unsigned index; unsigned quadrant; struct hlist_head *bucket; struct kvm_mmu_page *sp; struct hlist_node *node; role.word = 0; role.glevels = vcpu->arch.mmu.root_level; role.level = level; role.metaphysical = metaphysical; role.access = access; if (vcpu->arch.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", __func__, gfn, role.word); index = kvm_page_table_hashfn(gfn); bucket = &vcpu->kvm->arch.mmu_page_hash[index]; hlist_for_each_entry(sp, node, bucket, hash_link) if (sp->gfn == gfn && sp->role.word == role.word) { mmu_page_add_parent_pte(vcpu, sp, parent_pte); pgprintk("%s: found\n", __func__); return sp; } ++vcpu->kvm->stat.mmu_cache_miss; sp = kvm_mmu_alloc_page(vcpu, parent_pte); if (!sp) return sp; pgprintk("%s: adding gfn %lx role %x\n", __func__, gfn, role.word); sp->gfn = gfn; sp->role = role; hlist_add_head(&sp->hash_link, bucket); if (!metaphysical) rmap_write_protect(vcpu->kvm, gfn); vcpu->arch.mmu.prefetch_page(vcpu, sp); return sp; } static void kvm_mmu_page_unlink_children(struct kvm *kvm, struct kvm_mmu_page *sp) { unsigned i; u64 *pt; u64 ent; pt = sp->spt; if (sp->role.level == PT_PAGE_TABLE_LEVEL) { for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { if (is_shadow_present_pte(pt[i])) rmap_remove(kvm, &pt[i]); pt[i] = shadow_trap_nonpresent_pte; } kvm_flush_remote_tlbs(kvm); return; } for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { ent = pt[i]; if (is_shadow_present_pte(ent)) { if (!is_large_pte(ent)) { ent &= PT64_BASE_ADDR_MASK; mmu_page_remove_parent_pte(page_header(ent), &pt[i]); } else { --kvm->stat.lpages; rmap_remove(kvm, &pt[i]); } } pt[i] = shadow_trap_nonpresent_pte; } kvm_flush_remote_tlbs(kvm); } static void kvm_mmu_put_page(struct kvm_mmu_page *sp, u64 *parent_pte) { mmu_page_remove_parent_pte(sp, parent_pte); } static void kvm_mmu_reset_last_pte_updated(struct kvm *kvm) { int i; for (i = 0; i < KVM_MAX_VCPUS; ++i) if (kvm->vcpus[i]) kvm->vcpus[i]->arch.last_pte_updated = NULL; } static void kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) { u64 *parent_pte; ++kvm->stat.mmu_shadow_zapped; while (sp->multimapped || sp->parent_pte) { if (!sp->multimapped) parent_pte = sp->parent_pte; else { struct kvm_pte_chain *chain; chain = container_of(sp->parent_ptes.first, struct kvm_pte_chain, link); parent_pte = chain->parent_ptes[0]; } BUG_ON(!parent_pte); kvm_mmu_put_page(sp, parent_pte); set_shadow_pte(parent_pte, shadow_trap_nonpresent_pte); } kvm_mmu_page_unlink_children(kvm, sp); if (!sp->root_count) { if (!sp->role.metaphysical) unaccount_shadowed(kvm, sp->gfn); hlist_del(&sp->hash_link); kvm_mmu_free_page(kvm, sp); } else { list_move(&sp->link, &kvm->arch.active_mmu_pages); sp->role.invalid = 1; kvm_reload_remote_mmus(kvm); } kvm_mmu_reset_last_pte_updated(kvm); } /* * Changing the number of mmu pages allocated to the vm * Note: if kvm_nr_mmu_pages is too small, you will get dead lock */ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages) { /* * If we set the number of mmu pages to be smaller be than the * number of actived pages , we must to free some mmu pages before we * change the value */ if ((kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages) > kvm_nr_mmu_pages) { int n_used_mmu_pages = kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages; while (n_used_mmu_pages > kvm_nr_mmu_pages) { struct kvm_mmu_page *page; page = container_of(kvm->arch.active_mmu_pages.prev, struct kvm_mmu_page, link); kvm_mmu_zap_page(kvm, page); n_used_mmu_pages--; } kvm->arch.n_free_mmu_pages = 0; } else kvm->arch.n_free_mmu_pages += kvm_nr_mmu_pages - kvm->arch.n_alloc_mmu_pages; kvm->arch.n_alloc_mmu_pages = kvm_nr_mmu_pages; } static int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) { unsigned index; struct hlist_head *bucket; struct kvm_mmu_page *sp; struct hlist_node *node, *n; int r; pgprintk("%s: looking for gfn %lx\n", __func__, gfn); r = 0; index = kvm_page_table_hashfn(gfn); bucket = &kvm->arch.mmu_page_hash[index]; hlist_for_each_entry_safe(sp, node, n, bucket, hash_link) if (sp->gfn == gfn && !sp->role.metaphysical) { pgprintk("%s: gfn %lx role %x\n", __func__, gfn, sp->role.word); kvm_mmu_zap_page(kvm, sp); r = 1; } return r; } static void mmu_unshadow(struct kvm *kvm, gfn_t gfn) { struct kvm_mmu_page *sp; while ((sp = kvm_mmu_lookup_page(kvm, gfn)) != NULL) { pgprintk("%s: zap %lx %x\n", __func__, gfn, sp->role.word); kvm_mmu_zap_page(kvm, sp); } } static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn) { int slot = memslot_id(kvm, gfn_to_memslot(kvm, gfn)); struct kvm_mmu_page *sp = page_header(__pa(pte)); __set_bit(slot, &sp->slot_bitmap); } struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva) { struct page *page; gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva); if (gpa == UNMAPPED_GVA) return NULL; down_read(¤t->mm->mmap_sem); page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT); up_read(¤t->mm->mmap_sem); return page; } static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, unsigned pt_access, unsigned pte_access, int user_fault, int write_fault, int dirty, int *ptwrite, int largepage, gfn_t gfn, pfn_t pfn, bool speculative) { u64 spte; int was_rmapped = 0; int was_writeble = is_writeble_pte(*shadow_pte); pgprintk("%s: spte %llx access %x write_fault %d" " user_fault %d gfn %lx\n", __func__, *shadow_pte, pt_access, write_fault, user_fault, gfn); if (is_rmap_pte(*shadow_pte)) { /* * If we overwrite a PTE page pointer with a 2MB PMD, unlink * the parent of the now unreachable PTE. */ if (largepage && !is_large_pte(*shadow_pte)) { struct kvm_mmu_page *child; u64 pte = *shadow_pte; child = page_header(pte & PT64_BASE_ADDR_MASK); mmu_page_remove_parent_pte(child, shadow_pte); } else if (pfn != spte_to_pfn(*shadow_pte)) { pgprintk("hfn old %lx new %lx\n", spte_to_pfn(*shadow_pte), pfn); rmap_remove(vcpu->kvm, shadow_pte); } else { if (largepage) was_rmapped = is_large_pte(*shadow_pte); else was_rmapped = 1; } } /* * We don't set the accessed bit, since we sometimes want to see * whether the guest actually used the pte (in order to detect * demand paging). */ spte = shadow_base_present_pte | shadow_dirty_mask; if (!speculative) pte_access |= PT_ACCESSED_MASK; if (!dirty) pte_access &= ~ACC_WRITE_MASK; if (pte_access & ACC_EXEC_MASK) spte |= shadow_x_mask; else spte |= shadow_nx_mask; if (pte_access & ACC_USER_MASK) spte |= shadow_user_mask; if (largepage) spte |= PT_PAGE_SIZE_MASK; spte |= (u64)pfn << PAGE_SHIFT; if ((pte_access & ACC_WRITE_MASK) || (write_fault && !is_write_protection(vcpu) && !user_fault)) { struct kvm_mmu_page *shadow; spte |= PT_WRITABLE_MASK; shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn); if (shadow || (largepage && has_wrprotected_page(vcpu->kvm, gfn))) { pgprintk("%s: found shadow page for %lx, marking ro\n", __func__, gfn); pte_access &= ~ACC_WRITE_MASK; if (is_writeble_pte(spte)) { spte &= ~PT_WRITABLE_MASK; kvm_x86_ops->tlb_flush(vcpu); } if (write_fault) *ptwrite = 1; } } if (pte_access & ACC_WRITE_MASK) mark_page_dirty(vcpu->kvm, gfn); pgprintk("%s: setting spte %llx\n", __func__, spte); pgprintk("instantiating %s PTE (%s) at %d (%llx) addr %llx\n", (spte&PT_PAGE_SIZE_MASK)? "2MB" : "4kB", (spte&PT_WRITABLE_MASK)?"RW":"R", gfn, spte, shadow_pte); set_shadow_pte(shadow_pte, spte); if (!was_rmapped && (spte & PT_PAGE_SIZE_MASK) && (spte & PT_PRESENT_MASK)) ++vcpu->kvm->stat.lpages; page_header_update_slot(vcpu->kvm, shadow_pte, gfn); if (!was_rmapped) { rmap_add(vcpu, shadow_pte, gfn, largepage); if (!is_rmap_pte(*shadow_pte)) kvm_release_pfn_clean(pfn); } else { if (was_writeble) kvm_release_pfn_dirty(pfn); else kvm_release_pfn_clean(pfn); } if (speculative) { vcpu->arch.last_pte_updated = shadow_pte; vcpu->arch.last_pte_gfn = gfn; } } static void nonpaging_new_cr3(struct kvm_vcpu *vcpu) { } static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write, int largepage, gfn_t gfn, pfn_t pfn, int level) { hpa_t table_addr = vcpu->arch.mmu.root_hpa; int pt_write = 0; for (; ; level--) { u32 index = PT64_INDEX(v, level); u64 *table; ASSERT(VALID_PAGE(table_addr)); table = __va(table_addr); if (level == 1) { mmu_set_spte(vcpu, &table[index], ACC_ALL, ACC_ALL, 0, write, 1, &pt_write, 0, gfn, pfn, false); return pt_write; } if (largepage && level == 2) { mmu_set_spte(vcpu, &table[index], ACC_ALL, ACC_ALL, 0, write, 1, &pt_write, 1, gfn, pfn, false); return pt_write; } if (table[index] == shadow_trap_nonpresent_pte) { 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, ACC_ALL, &table[index]); if (!new_table) { pgprintk("nonpaging_map: ENOMEM\n"); kvm_release_pfn_clean(pfn); return -ENOMEM; } table[index] = __pa(new_table->spt) | PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask | shadow_x_mask; } table_addr = table[index] & PT64_BASE_ADDR_MASK; } } static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) { int r; int largepage = 0; pfn_t pfn; down_read(¤t->mm->mmap_sem); if (is_largepage_backed(vcpu, gfn & ~(KVM_PAGES_PER_HPAGE-1))) { gfn &= ~(KVM_PAGES_PER_HPAGE-1); largepage = 1; } pfn = gfn_to_pfn(vcpu->kvm, gfn); up_read(¤t->mm->mmap_sem); /* mmio */ if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); return 1; } spin_lock(&vcpu->kvm->mmu_lock); kvm_mmu_free_some_pages(vcpu); r = __direct_map(vcpu, v, write, largepage, gfn, pfn, PT32E_ROOT_LEVEL); spin_unlock(&vcpu->kvm->mmu_lock); return r; } static void mmu_free_roots(struct kvm_vcpu *vcpu) { int i; struct kvm_mmu_page *sp; if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) return; spin_lock(&vcpu->kvm->mmu_lock); if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) { hpa_t root = vcpu->arch.mmu.root_hpa; sp = page_header(root); --sp->root_count; if (!sp->root_count && sp->role.invalid) kvm_mmu_zap_page(vcpu->kvm, sp); vcpu->arch.mmu.root_hpa = INVALID_PAGE; spin_unlock(&vcpu->kvm->mmu_lock); return; } for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu.pae_root[i]; if (root) { root &= PT64_BASE_ADDR_MASK; sp = page_header(root); --sp->root_count; if (!sp->root_count && sp->role.invalid) kvm_mmu_zap_page(vcpu->kvm, sp); } vcpu->arch.mmu.pae_root[i] = INVALID_PAGE; } spin_unlock(&vcpu->kvm->mmu_lock); vcpu->arch.mmu.root_hpa = INVALID_PAGE; } static void mmu_alloc_roots(struct kvm_vcpu *vcpu) { int i; gfn_t root_gfn; struct kvm_mmu_page *sp; int metaphysical = 0; root_gfn = vcpu->arch.cr3 >> PAGE_SHIFT; if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) { hpa_t root = vcpu->arch.mmu.root_hpa; ASSERT(!VALID_PAGE(root)); if (tdp_enabled) metaphysical = 1; sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL, metaphysical, ACC_ALL, NULL); root = __pa(sp->spt); ++sp->root_count; vcpu->arch.mmu.root_hpa = root; return; } metaphysical = !is_paging(vcpu); if (tdp_enabled) metaphysical = 1; for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu.pae_root[i]; ASSERT(!VALID_PAGE(root)); if (vcpu->arch.mmu.root_level == PT32E_ROOT_LEVEL) { if (!is_present_pte(vcpu->arch.pdptrs[i])) { vcpu->arch.mmu.pae_root[i] = 0; continue; } root_gfn = vcpu->arch.pdptrs[i] >> PAGE_SHIFT; } else if (vcpu->arch.mmu.root_level == 0) root_gfn = 0; sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, metaphysical, ACC_ALL, NULL); root = __pa(sp->spt); ++sp->root_count; vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK; } vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root); } static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr) { return vaddr; } static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code) { gfn_t gfn; int r; pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code); r = mmu_topup_memory_caches(vcpu); if (r) return r; ASSERT(vcpu); ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa)); gfn = gva >> PAGE_SHIFT; return nonpaging_map(vcpu, gva & PAGE_MASK, error_code & PFERR_WRITE_MASK, gfn); } static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code) { pfn_t pfn; int r; int largepage = 0; gfn_t gfn = gpa >> PAGE_SHIFT; ASSERT(vcpu); ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa)); r = mmu_topup_memory_caches(vcpu); if (r) return r; down_read(¤t->mm->mmap_sem); if (is_largepage_backed(vcpu, gfn & ~(KVM_PAGES_PER_HPAGE-1))) { gfn &= ~(KVM_PAGES_PER_HPAGE-1); largepage = 1; } pfn = gfn_to_pfn(vcpu->kvm, gfn); up_read(¤t->mm->mmap_sem); if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); return 1; } spin_lock(&vcpu->kvm->mmu_lock); kvm_mmu_free_some_pages(vcpu); r = __direct_map(vcpu, gpa, error_code & PFERR_WRITE_MASK, largepage, gfn, pfn, kvm_x86_ops->get_tdp_level()); spin_unlock(&vcpu->kvm->mmu_lock); return r; } static void nonpaging_free(struct kvm_vcpu *vcpu) { mmu_free_roots(vcpu); } static int nonpaging_init_context(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = &vcpu->arch.mmu; context->new_cr3 = nonpaging_new_cr3; context->page_fault = nonpaging_page_fault; context->gva_to_gpa = nonpaging_gva_to_gpa; context->free = nonpaging_free; context->prefetch_page = nonpaging_prefetch_page; context->root_level = 0; context->shadow_root_level = PT32E_ROOT_LEVEL; context->root_hpa = INVALID_PAGE; return 0; } void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu) { ++vcpu->stat.tlb_flush; kvm_x86_ops->tlb_flush(vcpu); } static void paging_new_cr3(struct kvm_vcpu *vcpu) { pgprintk("%s: cr3 %lx\n", __func__, vcpu->arch.cr3); mmu_free_roots(vcpu); } static void inject_page_fault(struct kvm_vcpu *vcpu, u64 addr, u32 err_code) { kvm_inject_page_fault(vcpu, addr, err_code); } static void paging_free(struct kvm_vcpu *vcpu) { nonpaging_free(vcpu); } #define PTTYPE 64 #include "paging_tmpl.h" #undef PTTYPE #define PTTYPE 32 #include "paging_tmpl.h" #undef PTTYPE static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level) { struct kvm_mmu *context = &vcpu->arch.mmu; ASSERT(is_pae(vcpu)); context->new_cr3 = paging_new_cr3; context->page_fault = paging64_page_fault; context->gva_to_gpa = paging64_gva_to_gpa; context->prefetch_page = paging64_prefetch_page; context->free = paging_free; context->root_level = level; context->shadow_root_level = level; context->root_hpa = INVALID_PAGE; 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->arch.mmu; context->new_cr3 = paging_new_cr3; context->page_fault = paging32_page_fault; context->gva_to_gpa = paging32_gva_to_gpa; context->free = paging_free; context->prefetch_page = paging32_prefetch_page; context->root_level = PT32_ROOT_LEVEL; context->shadow_root_level = PT32E_ROOT_LEVEL; context->root_hpa = INVALID_PAGE; return 0; } static int paging32E_init_context(struct kvm_vcpu *vcpu) { return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL); } static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = &vcpu->arch.mmu; context->new_cr3 = nonpaging_new_cr3; context->page_fault = tdp_page_fault; context->free = nonpaging_free; context->prefetch_page = nonpaging_prefetch_page; context->shadow_root_level = kvm_x86_ops->get_tdp_level(); context->root_hpa = INVALID_PAGE; if (!is_paging(vcpu)) { context->gva_to_gpa = nonpaging_gva_to_gpa; context->root_level = 0; } else if (is_long_mode(vcpu)) { context->gva_to_gpa = paging64_gva_to_gpa; context->root_level = PT64_ROOT_LEVEL; } else if (is_pae(vcpu)) { context->gva_to_gpa = paging64_gva_to_gpa; context->root_level = PT32E_ROOT_LEVEL; } else { context->gva_to_gpa = paging32_gva_to_gpa; context->root_level = PT32_ROOT_LEVEL; } return 0; } static int init_kvm_softmmu(struct kvm_vcpu *vcpu) { ASSERT(vcpu); ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa)); if (!is_paging(vcpu)) return nonpaging_init_context(vcpu); else if (is_long_mode(vcpu)) return paging64_init_context(vcpu); else if (is_pae(vcpu)) return paging32E_init_context(vcpu); else return paging32_init_context(vcpu); } static int init_kvm_mmu(struct kvm_vcpu *vcpu) { vcpu->arch.update_pte.pfn = bad_pfn; if (tdp_enabled) return init_kvm_tdp_mmu(vcpu); else return init_kvm_softmmu(vcpu); } static void destroy_kvm_mmu(struct kvm_vcpu *vcpu) { ASSERT(vcpu); if (VALID_PAGE(vcpu->arch.mmu.root_hpa)) { vcpu->arch.mmu.free(vcpu); vcpu->arch.mmu.root_hpa = INVALID_PAGE; } } int kvm_mmu_reset_context(struct kvm_vcpu *vcpu) { destroy_kvm_mmu(vcpu); return init_kvm_mmu(vcpu); } EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); int kvm_mmu_load(struct kvm_vcpu *vcpu) { int r; r = mmu_topup_memory_caches(vcpu); if (r) goto out; spin_lock(&vcpu->kvm->mmu_lock); kvm_mmu_free_some_pages(vcpu); mmu_alloc_roots(vcpu); spin_unlock(&vcpu->kvm->mmu_lock); kvm_x86_ops->set_cr3(vcpu, vcpu->arch.mmu.root_hpa); kvm_mmu_flush_tlb(vcpu); out: return r; } EXPORT_SYMBOL_GPL(kvm_mmu_load); void kvm_mmu_unload(struct kvm_vcpu *vcpu) { mmu_free_roots(vcpu); } static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte) { u64 pte; struct kvm_mmu_page *child; pte = *spte; if (is_shadow_present_pte(pte)) { if (sp->role.level == PT_PAGE_TABLE_LEVEL || is_large_pte(pte)) rmap_remove(vcpu->kvm, spte); else { child = page_header(pte & PT64_BASE_ADDR_MASK); mmu_page_remove_parent_pte(child, spte); } } set_shadow_pte(spte, shadow_trap_nonpresent_pte); if (is_large_pte(pte)) --vcpu->kvm->stat.lpages; } static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte, const void *new) { if (sp->role.level != PT_PAGE_TABLE_LEVEL) { if (!vcpu->arch.update_pte.largepage || sp->role.glevels == PT32_ROOT_LEVEL) { ++vcpu->kvm->stat.mmu_pde_zapped; return; } } ++vcpu->kvm->stat.mmu_pte_updated; if (sp->role.glevels == PT32_ROOT_LEVEL) paging32_update_pte(vcpu, sp, spte, new); else paging64_update_pte(vcpu, sp, spte, new); } static bool need_remote_flush(u64 old, u64 new) { if (!is_shadow_present_pte(old)) return false; if (!is_shadow_present_pte(new)) return true; if ((old ^ new) & PT64_BASE_ADDR_MASK) return true; old ^= PT64_NX_MASK; new ^= PT64_NX_MASK; return (old & ~new & PT64_PERM_MASK) != 0; } static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, u64 old, u64 new) { if (need_remote_flush(old, new)) kvm_flush_remote_tlbs(vcpu->kvm); else kvm_mmu_flush_tlb(vcpu); } static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu) { u64 *spte = vcpu->arch.last_pte_updated; return !!(spte && (*spte & shadow_accessed_mask)); } static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes) { gfn_t gfn; int r; u64 gpte = 0; pfn_t pfn; vcpu->arch.update_pte.largepage = 0; if (bytes != 4 && bytes != 8) return; /* * Assume that the pte write on a page table of the same type * as the current vcpu paging mode. This is nearly always true * (might be false while changing modes). Note it is verified later * by update_pte(). */ if (is_pae(vcpu)) { /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ if ((bytes == 4) && (gpa % 4 == 0)) { r = kvm_read_guest(vcpu->kvm, gpa & ~(u64)7, &gpte, 8); if (r) return; memcpy((void *)&gpte + (gpa % 8), new, 4); } else if ((bytes == 8) && (gpa % 8 == 0)) { memcpy((void *)&gpte, new, 8); } } else { if ((bytes == 4) && (gpa % 4 == 0)) memcpy((void *)&gpte, new, 4); } if (!is_present_pte(gpte)) return; gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; down_read(¤t->mm->mmap_sem); if (is_large_pte(gpte) && is_largepage_backed(vcpu, gfn)) { gfn &= ~(KVM_PAGES_PER_HPAGE-1); vcpu->arch.update_pte.largepage = 1; } pfn = gfn_to_pfn(vcpu->kvm, gfn); up_read(¤t->mm->mmap_sem); if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); return; } vcpu->arch.update_pte.gfn = gfn; vcpu->arch.update_pte.pfn = pfn; } static void kvm_mmu_access_page(struct kvm_vcpu *vcpu, gfn_t gfn) { u64 *spte = vcpu->arch.last_pte_updated; if (spte && vcpu->arch.last_pte_gfn == gfn && shadow_accessed_mask && !(*spte & shadow_accessed_mask) && is_shadow_present_pte(*spte)) set_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte); } 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; struct hlist_node *node, *n; struct hlist_head *bucket; unsigned index; u64 entry, gentry; u64 *spte; unsigned offset = offset_in_page(gpa); unsigned pte_size; unsigned page_offset; unsigned misaligned; unsigned quadrant; int level; int flooded = 0; int npte; int r; pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes); spin_lock(&vcpu->kvm->mmu_lock); kvm_mmu_access_page(vcpu, gfn); 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; } index = kvm_page_table_hashfn(gfn); bucket = &vcpu->kvm->arch.mmu_page_hash[index]; hlist_for_each_entry_safe(sp, node, n, bucket, hash_link) { if (sp->gfn != gfn || sp->role.metaphysical) continue; pte_size = sp->role.glevels == PT32_ROOT_LEVEL ? 4 : 8; misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); misaligned |= bytes < 4; 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, sp->role.word); kvm_mmu_zap_page(vcpu->kvm, sp); ++vcpu->kvm->stat.mmu_flooded; continue; } page_offset = offset; level = sp->role.level; npte = 1; if (sp->role.glevels == PT32_ROOT_LEVEL) { page_offset <<= 1; /* 32->64 */ /* * A 32-bit pde maps 4MB while the shadow pdes map * only 2MB. So we need to double the offset again * and zap two pdes instead of one. */ if (level == PT32_ROOT_LEVEL) { page_offset &= ~7; /* kill rounding error */ page_offset <<= 1; npte = 2; } quadrant = page_offset >> PAGE_SHIFT; page_offset &= ~PAGE_MASK; if (quadrant != sp->role.quadrant) continue; } spte = &sp->spt[page_offset / sizeof(*spte)]; if ((gpa & (pte_size - 1)) || (bytes < pte_size)) { gentry = 0; r = kvm_read_guest_atomic(vcpu->kvm, gpa & ~(u64)(pte_size - 1), &gentry, pte_size); new = (const void *)&gentry; if (r < 0) new = NULL; } while (npte--) { entry = *spte; mmu_pte_write_zap_pte(vcpu, sp, spte); if (new) mmu_pte_write_new_pte(vcpu, sp, spte, new); mmu_pte_write_flush_tlb(vcpu, entry, *spte); ++spte; } } kvm_mmu_audit(vcpu, "post pte write"); spin_unlock(&vcpu->kvm->mmu_lock); if (!is_error_pfn(vcpu->arch.update_pte.pfn)) { kvm_release_pfn_clean(vcpu->arch.update_pte.pfn); vcpu->arch.update_pte.pfn = bad_pfn; } } int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) { gpa_t gpa; int r; gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva); spin_lock(&vcpu->kvm->mmu_lock); r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); spin_unlock(&vcpu->kvm->mmu_lock); return r; } void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu) { while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES) { struct kvm_mmu_page *sp; sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev, struct kvm_mmu_page, link); kvm_mmu_zap_page(vcpu->kvm, sp); ++vcpu->kvm->stat.mmu_recycled; } } int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code) { int r; enum emulation_result er; r = vcpu->arch.mmu.page_fault(vcpu, cr2, error_code); if (r < 0) goto out; if (!r) { r = 1; goto out; } r = mmu_topup_memory_caches(vcpu); if (r) goto out; er = emulate_instruction(vcpu, vcpu->run, cr2, error_code, 0); switch (er) { case EMULATE_DONE: return 1; case EMULATE_DO_MMIO: ++vcpu->stat.mmio_exits; return 0; case EMULATE_FAIL: kvm_report_emulation_failure(vcpu, "pagetable"); return 1; default: BUG(); } out: return r; } EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); void kvm_enable_tdp(void) { tdp_enabled = true; } EXPORT_SYMBOL_GPL(kvm_enable_tdp); static void free_mmu_pages(struct kvm_vcpu *vcpu) { struct kvm_mmu_page *sp; while (!list_empty(&vcpu->kvm->arch.active_mmu_pages)) { sp = container_of(vcpu->kvm->arch.active_mmu_pages.next, struct kvm_mmu_page, link); kvm_mmu_zap_page(vcpu->kvm, sp); cond_resched(); } free_page((unsigned long)vcpu->arch.mmu.pae_root); } static int alloc_mmu_pages(struct kvm_vcpu *vcpu) { struct page *page; int i; ASSERT(vcpu); if (vcpu->kvm->arch.n_requested_mmu_pages) vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_requested_mmu_pages; else vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_alloc_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->arch.mmu.pae_root = page_address(page); for (i = 0; i < 4; ++i) vcpu->arch.mmu.pae_root[i] = INVALID_PAGE; return 0; error_1: free_mmu_pages(vcpu); return -ENOMEM; } int kvm_mmu_create(struct kvm_vcpu *vcpu) { ASSERT(vcpu); ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa)); return alloc_mmu_pages(vcpu); } int kvm_mmu_setup(struct kvm_vcpu *vcpu) { ASSERT(vcpu); ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa)); return init_kvm_mmu(vcpu); } void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { ASSERT(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) { struct kvm_mmu_page *sp; list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) { int i; u64 *pt; if (!test_bit(slot, &sp->slot_bitmap)) continue; pt = sp->spt; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) /* avoid RMW */ if (pt[i] & PT_WRITABLE_MASK) pt[i] &= ~PT_WRITABLE_MASK; } } void kvm_mmu_zap_all(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; spin_lock(&kvm->mmu_lock); list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) kvm_mmu_zap_page(kvm, sp); spin_unlock(&kvm->mmu_lock); kvm_flush_remote_tlbs(kvm); } static void kvm_mmu_remove_one_alloc_mmu_page(struct kvm *kvm) { struct kvm_mmu_page *page; page = container_of(kvm->arch.active_mmu_pages.prev, struct kvm_mmu_page, link); kvm_mmu_zap_page(kvm, page); } static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask) { struct kvm *kvm; struct kvm *kvm_freed = NULL; int cache_count = 0; spin_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) { int npages; spin_lock(&kvm->mmu_lock); npages = kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages; cache_count += npages; if (!kvm_freed && nr_to_scan > 0 && npages > 0) { kvm_mmu_remove_one_alloc_mmu_page(kvm); cache_count--; kvm_freed = kvm; } nr_to_scan--; spin_unlock(&kvm->mmu_lock); } if (kvm_freed) list_move_tail(&kvm_freed->vm_list, &vm_list); spin_unlock(&kvm_lock); return cache_count; } static struct shrinker mmu_shrinker = { .shrink = mmu_shrink, .seeks = DEFAULT_SEEKS * 10, }; static void mmu_destroy_caches(void) { if (pte_chain_cache) kmem_cache_destroy(pte_chain_cache); if (rmap_desc_cache) kmem_cache_destroy(rmap_desc_cache); if (mmu_page_header_cache) kmem_cache_destroy(mmu_page_header_cache); } void kvm_mmu_module_exit(void) { mmu_destroy_caches(); unregister_shrinker(&mmu_shrinker); } int kvm_mmu_module_init(void) { pte_chain_cache = kmem_cache_create("kvm_pte_chain", sizeof(struct kvm_pte_chain), 0, 0, NULL); if (!pte_chain_cache) goto nomem; rmap_desc_cache = kmem_cache_create("kvm_rmap_desc", sizeof(struct kvm_rmap_desc), 0, 0, NULL); if (!rmap_desc_cache) goto nomem; mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header", sizeof(struct kvm_mmu_page), 0, 0, NULL); if (!mmu_page_header_cache) goto nomem; register_shrinker(&mmu_shrinker); return 0; nomem: mmu_destroy_caches(); return -ENOMEM; } /* * Caculate mmu pages needed for kvm. */ unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm) { int i; unsigned int nr_mmu_pages; unsigned int nr_pages = 0; for (i = 0; i < kvm->nmemslots; i++) nr_pages += kvm->memslots[i].npages; nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000; nr_mmu_pages = max(nr_mmu_pages, (unsigned int) KVM_MIN_ALLOC_MMU_PAGES); return nr_mmu_pages; } static void *pv_mmu_peek_buffer(struct kvm_pv_mmu_op_buffer *buffer, unsigned len) { if (len > buffer->len) return NULL; return buffer->ptr; } static void *pv_mmu_read_buffer(struct kvm_pv_mmu_op_buffer *buffer, unsigned len) { void *ret; ret = pv_mmu_peek_buffer(buffer, len); if (!ret) return ret; buffer->ptr += len; buffer->len -= len; buffer->processed += len; return ret; } static int kvm_pv_mmu_write(struct kvm_vcpu *vcpu, gpa_t addr, gpa_t value) { int bytes = 8; int r; if (!is_long_mode(vcpu) && !is_pae(vcpu)) bytes = 4; r = mmu_topup_memory_caches(vcpu); if (r) return r; if (!emulator_write_phys(vcpu, addr, &value, bytes)) return -EFAULT; return 1; } static int kvm_pv_mmu_flush_tlb(struct kvm_vcpu *vcpu) { kvm_x86_ops->tlb_flush(vcpu); return 1; } static int kvm_pv_mmu_release_pt(struct kvm_vcpu *vcpu, gpa_t addr) { spin_lock(&vcpu->kvm->mmu_lock); mmu_unshadow(vcpu->kvm, addr >> PAGE_SHIFT); spin_unlock(&vcpu->kvm->mmu_lock); return 1; } static int kvm_pv_mmu_op_one(struct kvm_vcpu *vcpu, struct kvm_pv_mmu_op_buffer *buffer) { struct kvm_mmu_op_header *header; header = pv_mmu_peek_buffer(buffer, sizeof *header); if (!header) return 0; switch (header->op) { case KVM_MMU_OP_WRITE_PTE: { struct kvm_mmu_op_write_pte *wpte; wpte = pv_mmu_read_buffer(buffer, sizeof *wpte); if (!wpte) return 0; return kvm_pv_mmu_write(vcpu, wpte->pte_phys, wpte->pte_val); } case KVM_MMU_OP_FLUSH_TLB: { struct kvm_mmu_op_flush_tlb *ftlb; ftlb = pv_mmu_read_buffer(buffer, sizeof *ftlb); if (!ftlb) return 0; return kvm_pv_mmu_flush_tlb(vcpu); } case KVM_MMU_OP_RELEASE_PT: { struct kvm_mmu_op_release_pt *rpt; rpt = pv_mmu_read_buffer(buffer, sizeof *rpt); if (!rpt) return 0; return kvm_pv_mmu_release_pt(vcpu, rpt->pt_phys); } default: return 0; } } int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes, gpa_t addr, unsigned long *ret) { int r; struct kvm_pv_mmu_op_buffer buffer; buffer.ptr = buffer.buf; buffer.len = min_t(unsigned long, bytes, sizeof buffer.buf); buffer.processed = 0; r = kvm_read_guest(vcpu->kvm, addr, buffer.buf, buffer.len); if (r) goto out; while (buffer.len) { r = kvm_pv_mmu_op_one(vcpu, &buffer); if (r < 0) goto out; if (r == 0) break; } r = 1; out: *ret = buffer.processed; return r; } #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 == shadow_trap_nonpresent_pte) continue; va = canonicalize(va); if (level > 1) { if (ent == shadow_notrap_nonpresent_pte) printk(KERN_ERR "audit: (%s) nontrapping pte" " in nonleaf level: levels %d gva %lx" " level %d pte %llx\n", audit_msg, vcpu->arch.mmu.root_level, va, level, ent); audit_mappings_page(vcpu, ent, va, level - 1); } else { gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, va); hpa_t hpa = (hpa_t)gpa_to_pfn(vcpu, gpa) << PAGE_SHIFT; if (is_shadow_present_pte(ent) && (ent & PT64_BASE_ADDR_MASK) != hpa) printk(KERN_ERR "xx audit error: (%s) levels %d" " gva %lx gpa %llx hpa %llx ent %llx %d\n", audit_msg, vcpu->arch.mmu.root_level, va, gpa, hpa, ent, is_shadow_present_pte(ent)); else if (ent == shadow_notrap_nonpresent_pte && !is_error_hpa(hpa)) printk(KERN_ERR "audit: (%s) notrap shadow," " valid guest gva %lx\n", audit_msg, va); kvm_release_pfn_clean(pfn); } } } static void audit_mappings(struct kvm_vcpu *vcpu) { unsigned i; if (vcpu->arch.mmu.root_level == 4) audit_mappings_page(vcpu, vcpu->arch.mmu.root_hpa, 0, 4); else for (i = 0; i < 4; ++i) if (vcpu->arch.mmu.pae_root[i] & PT_PRESENT_MASK) audit_mappings_page(vcpu, vcpu->arch.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) { unsigned long *rmapp = &m->rmap[j]; if (!*rmapp) continue; if (!(*rmapp & 1)) { ++nmaps; continue; } d = (struct kvm_rmap_desc *)(*rmapp & ~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 *sp; int i; list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) { u64 *pt = sp->spt; if (sp->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", __func__, audit_msg, n_rmap, n_actual); } static void audit_write_protection(struct kvm_vcpu *vcpu) { struct kvm_mmu_page *sp; struct kvm_memory_slot *slot; unsigned long *rmapp; gfn_t gfn; list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) { if (sp->role.metaphysical) continue; slot = gfn_to_memslot(vcpu->kvm, sp->gfn); gfn = unalias_gfn(vcpu->kvm, sp->gfn); rmapp = &slot->rmap[gfn - slot->base_gfn]; if (*rmapp) printk(KERN_ERR "%s: (%s) shadow page has writable" " mappings: gfn %lx role %x\n", __func__, audit_msg, sp->gfn, sp->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