arch/x86/kvm/mmu.h

   1 #ifndef __KVM_X86_MMU_H
   2 #define __KVM_X86_MMU_H
   3
   4 #include <linux/kvm_host.h>
   5 #include "kvm_cache_regs.h"
   6
   7 #define PT64_PT_BITS 9
   8 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
   9 #define PT32_PT_BITS 10
  10 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
  11
  12 #define PT_WRITABLE_SHIFT 1
  13 #define PT_USER_SHIFT 2
  14
  15 #define PT_PRESENT_MASK (1ULL << 0)
  16 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
  17 #define PT_USER_MASK (1ULL << PT_USER_SHIFT)
  18 #define PT_PWT_MASK (1ULL << 3)
  19 #define PT_PCD_MASK (1ULL << 4)
  20 #define PT_ACCESSED_SHIFT 5
  21 #define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT)
  22 #define PT_DIRTY_SHIFT 6
  23 #define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT)
  24 #define PT_PAGE_SIZE_SHIFT 7
  25 #define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
  26 #define PT_PAT_MASK (1ULL << 7)
  27 #define PT_GLOBAL_MASK (1ULL << 8)
  28 #define PT64_NX_SHIFT 63
  29 #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
  30
  31 #define PT_PAT_SHIFT 7
  32 #define PT_DIR_PAT_SHIFT 12
  33 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
  34
  35 #define PT32_DIR_PSE36_SIZE 4
  36 #define PT32_DIR_PSE36_SHIFT 13
  37 #define PT32_DIR_PSE36_MASK \
  38         (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)
  39
  40 #define PT64_ROOT_LEVEL 4
  41 #define PT32_ROOT_LEVEL 2
  42 #define PT32E_ROOT_LEVEL 3
  43
  44 #define PT_PDPE_LEVEL 3
  45 #define PT_DIRECTORY_LEVEL 2
  46 #define PT_PAGE_TABLE_LEVEL 1
  47 #define PT_MAX_HUGEPAGE_LEVEL (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES - 1)
  48
  49 static inline u64 rsvd_bits(int s, int e)
  50 {
  51         return ((1ULL << (e - s + 1)) - 1) << s;
  52 }
  53
  54 void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);
  55
  56 void
  57 reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
  58
  59 /*
  60  * Return values of handle_mmio_page_fault:
  61  * RET_MMIO_PF_EMULATE: it is a real mmio page fault, emulate the instruction
  62  *                      directly.
  63  * RET_MMIO_PF_INVALID: invalid spte is detected then let the real page
  64  *                      fault path update the mmio spte.
  65  * RET_MMIO_PF_RETRY: let CPU fault again on the address.
  66  * RET_MMIO_PF_BUG: a bug was detected (and a WARN was printed).
  67  */
  68 enum {
  69         RET_MMIO_PF_EMULATE = 1,
  70         RET_MMIO_PF_INVALID = 2,
  71         RET_MMIO_PF_RETRY = 0,
  72         RET_MMIO_PF_BUG = -1
  73 };
  74
  75 int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct);
  76 void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
  77 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
  78                              bool accessed_dirty);
  79 bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
  80
  81 static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
  82 {
  83         if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
  84                 return kvm->arch.n_max_mmu_pages -
  85                         kvm->arch.n_used_mmu_pages;
  86
  87         return 0;
  88 }
  89
  90 static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
  91 {
  92         if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE))
  93                 return 0;
  94
  95         return kvm_mmu_load(vcpu);
  96 }
  97
  98 /*
  99  * Currently, we have two sorts of write-protection, a) the first one
 100  * write-protects guest page to sync the guest modification, b) another one is
 101  * used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences
 102  * between these two sorts are:
 103  * 1) the first case clears SPTE_MMU_WRITEABLE bit.
 104  * 2) the first case requires flushing tlb immediately avoiding corrupting
 105  *    shadow page table between all vcpus so it should be in the protection of
 106  *    mmu-lock. And the another case does not need to flush tlb until returning
 107  *    the dirty bitmap to userspace since it only write-protects the page
 108  *    logged in the bitmap, that means the page in the dirty bitmap is not
 109  *    missed, so it can flush tlb out of mmu-lock.
 110  *
 111  * So, there is the problem: the first case can meet the corrupted tlb caused
 112  * by another case which write-protects pages but without flush tlb
 113  * immediately. In order to making the first case be aware this problem we let
 114  * it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit
 115  * is set, it works since another case never touches SPTE_MMU_WRITEABLE bit.
 116  *
 117  * Anyway, whenever a spte is updated (only permission and status bits are
 118  * changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes
 119  * readonly, if that happens, we need to flush tlb. Fortunately,
 120  * mmu_spte_update() has already handled it perfectly.
 121  *
 122  * The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK:
 123  * - if we want to see if it has writable tlb entry or if the spte can be
 124  *   writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most
 125  *   case, otherwise
 126  * - if we fix page fault on the spte or do write-protection by dirty logging,
 127  *   check PT_WRITABLE_MASK.
 128  *
 129  * TODO: introduce APIs to split these two cases.
 130  */
 131 static inline int is_writable_pte(unsigned long pte)
 132 {
 133         return pte & PT_WRITABLE_MASK;
 134 }
 135
 136 static inline bool is_write_protection(struct kvm_vcpu *vcpu)
 137 {
 138         return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
 139 }
 140
 141 /*
 142  * Check if a given access (described through the I/D, W/R and U/S bits of a
 143  * page fault error code pfec) causes a permission fault with the given PTE
 144  * access rights (in ACC_* format).
 145  *
 146  * Return zero if the access does not fault; return the page fault error code
 147  * if the access faults.
 148  */
 149 static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 150                                   unsigned pte_access, unsigned pte_pkey,
 151                                   unsigned pfec)
 152 {
 153         int cpl = kvm_x86_ops->get_cpl(vcpu);
 154         unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
 155
 156         /*
 157          * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.
 158          *
 159          * If CPL = 3, SMAP applies to all supervisor-mode data accesses
 160          * (these are implicit supervisor accesses) regardless of the value
 161          * of EFLAGS.AC.
 162          *
 163          * This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving
 164          * the result in X86_EFLAGS_AC. We then insert it in place of
 165          * the PFERR_RSVD_MASK bit; this bit will always be zero in pfec,
 166          * but it will be one in index if SMAP checks are being overridden.
 167          * It is important to keep this branchless.
 168          */
 169         unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
 170         int index = (pfec >> 1) +
 171                     (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
 172         bool fault = (mmu->permissions[index] >> pte_access) & 1;
 173         u32 errcode = PFERR_PRESENT_MASK;
 174
 175         WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
 176         if (unlikely(mmu->pkru_mask)) {
 177                 u32 pkru_bits, offset;
 178
 179                 /*
 180                 * PKRU defines 32 bits, there are 16 domains and 2
 181                 * attribute bits per domain in pkru.  pte_pkey is the
 182                 * index of the protection domain, so pte_pkey * 2 is
 183                 * is the index of the first bit for the domain.
 184                 */
 185                 pkru_bits = (kvm_read_pkru(vcpu) >> (pte_pkey * 2)) & 3;
 186
 187                 /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
 188                 offset = (pfec & ~1) +
 189                         ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));
 190
 191                 pkru_bits &= mmu->pkru_mask >> offset;
 192                 errcode |= -pkru_bits & PFERR_PK_MASK;
 193                 fault |= (pkru_bits != 0);
 194         }
 195
 196         return -(u32)fault & errcode;
 197 }
 198
 199 void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
 200 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
 201
 202 void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 203 void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 204 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
 205                                     struct kvm_memory_slot *slot, u64 gfn);
 206 int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
 207 #endif