arch/x86/kvm/mmu.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __KVM_X86_MMU_H
   3 #define __KVM_X86_MMU_H
   4
   5 #include <linux/kvm_host.h>
   6 #include "kvm_cache_regs.h"
   7
   8 #define PT64_PT_BITS 9
   9 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
  10 #define PT32_PT_BITS 10
  11 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
  12
  13 #define PT_WRITABLE_SHIFT 1
  14 #define PT_USER_SHIFT 2
  15
  16 #define PT_PRESENT_MASK (1ULL << 0)
  17 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
  18 #define PT_USER_MASK (1ULL << PT_USER_SHIFT)
  19 #define PT_PWT_MASK (1ULL << 3)
  20 #define PT_PCD_MASK (1ULL << 4)
  21 #define PT_ACCESSED_SHIFT 5
  22 #define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT)
  23 #define PT_DIRTY_SHIFT 6
  24 #define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT)
  25 #define PT_PAGE_SIZE_SHIFT 7
  26 #define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
  27 #define PT_PAT_MASK (1ULL << 7)
  28 #define PT_GLOBAL_MASK (1ULL << 8)
  29 #define PT64_NX_SHIFT 63
  30 #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
  31
  32 #define PT_PAT_SHIFT 7
  33 #define PT_DIR_PAT_SHIFT 12
  34 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
  35
  36 #define PT32_DIR_PSE36_SIZE 4
  37 #define PT32_DIR_PSE36_SHIFT 13
  38 #define PT32_DIR_PSE36_MASK \
  39         (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)
  40
  41 #define PT64_ROOT_5LEVEL 5
  42 #define PT64_ROOT_4LEVEL 4
  43 #define PT32_ROOT_LEVEL 2
  44 #define PT32E_ROOT_LEVEL 3
  45
  46 #define PT_PDPE_LEVEL 3
  47 #define PT_DIRECTORY_LEVEL 2
  48 #define PT_PAGE_TABLE_LEVEL 1
  49 #define PT_MAX_HUGEPAGE_LEVEL (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES - 1)
  50
  51 static inline u64 rsvd_bits(int s, int e)
  52 {
  53         if (e < s)
  54                 return 0;
  55
  56         return ((1ULL << (e - s + 1)) - 1) << s;
  57 }
  58
  59 void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);
  60
  61 void
  62 reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
  63
  64 void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
  65 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
  66                              bool accessed_dirty);
  67 bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
  68 int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
  69                                 u64 fault_address, char *insn, int insn_len,
  70                                 bool need_unprotect);
  71
  72 static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
  73 {
  74         if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
  75                 return kvm->arch.n_max_mmu_pages -
  76                         kvm->arch.n_used_mmu_pages;
  77
  78         return 0;
  79 }
  80
  81 static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
  82 {
  83         if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE))
  84                 return 0;
  85
  86         return kvm_mmu_load(vcpu);
  87 }
  88
  89 /*
  90  * Currently, we have two sorts of write-protection, a) the first one
  91  * write-protects guest page to sync the guest modification, b) another one is
  92  * used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences
  93  * between these two sorts are:
  94  * 1) the first case clears SPTE_MMU_WRITEABLE bit.
  95  * 2) the first case requires flushing tlb immediately avoiding corrupting
  96  *    shadow page table between all vcpus so it should be in the protection of
  97  *    mmu-lock. And the another case does not need to flush tlb until returning
  98  *    the dirty bitmap to userspace since it only write-protects the page
  99  *    logged in the bitmap, that means the page in the dirty bitmap is not
 100  *    missed, so it can flush tlb out of mmu-lock.
 101  *
 102  * So, there is the problem: the first case can meet the corrupted tlb caused
 103  * by another case which write-protects pages but without flush tlb
 104  * immediately. In order to making the first case be aware this problem we let
 105  * it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit
 106  * is set, it works since another case never touches SPTE_MMU_WRITEABLE bit.
 107  *
 108  * Anyway, whenever a spte is updated (only permission and status bits are
 109  * changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes
 110  * readonly, if that happens, we need to flush tlb. Fortunately,
 111  * mmu_spte_update() has already handled it perfectly.
 112  *
 113  * The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK:
 114  * - if we want to see if it has writable tlb entry or if the spte can be
 115  *   writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most
 116  *   case, otherwise
 117  * - if we fix page fault on the spte or do write-protection by dirty logging,
 118  *   check PT_WRITABLE_MASK.
 119  *
 120  * TODO: introduce APIs to split these two cases.
 121  */
 122 static inline int is_writable_pte(unsigned long pte)
 123 {
 124         return pte & PT_WRITABLE_MASK;
 125 }
 126
 127 static inline bool is_write_protection(struct kvm_vcpu *vcpu)
 128 {
 129         return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
 130 }
 131
 132 /*
 133  * Check if a given access (described through the I/D, W/R and U/S bits of a
 134  * page fault error code pfec) causes a permission fault with the given PTE
 135  * access rights (in ACC_* format).
 136  *
 137  * Return zero if the access does not fault; return the page fault error code
 138  * if the access faults.
 139  */
 140 static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 141                                   unsigned pte_access, unsigned pte_pkey,
 142                                   unsigned pfec)
 143 {
 144         int cpl = kvm_x86_ops->get_cpl(vcpu);
 145         unsigned long rflags = kvm_x86_ops->get_rflags(vcpu);
 146
 147         /*
 148          * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.
 149          *
 150          * If CPL = 3, SMAP applies to all supervisor-mode data accesses
 151          * (these are implicit supervisor accesses) regardless of the value
 152          * of EFLAGS.AC.
 153          *
 154          * This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving
 155          * the result in X86_EFLAGS_AC. We then insert it in place of
 156          * the PFERR_RSVD_MASK bit; this bit will always be zero in pfec,
 157          * but it will be one in index if SMAP checks are being overridden.
 158          * It is important to keep this branchless.
 159          */
 160         unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC);
 161         int index = (pfec >> 1) +
 162                     (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
 163         bool fault = (mmu->permissions[index] >> pte_access) & 1;
 164         u32 errcode = PFERR_PRESENT_MASK;
 165
 166         WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
 167         if (unlikely(mmu->pkru_mask)) {
 168                 u32 pkru_bits, offset;
 169
 170                 /*
 171                 * PKRU defines 32 bits, there are 16 domains and 2
 172                 * attribute bits per domain in pkru.  pte_pkey is the
 173                 * index of the protection domain, so pte_pkey * 2 is
 174                 * is the index of the first bit for the domain.
 175                 */
 176                 pkru_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
 177
 178                 /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
 179                 offset = (pfec & ~1) +
 180                         ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));
 181
 182                 pkru_bits &= mmu->pkru_mask >> offset;
 183                 errcode |= -pkru_bits & PFERR_PK_MASK;
 184                 fault |= (pkru_bits != 0);
 185         }
 186
 187         return -(u32)fault & errcode;
 188 }
 189
 190 void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
 191 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
 192
 193 void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 194 void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 195 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
 196                                     struct kvm_memory_slot *slot, u64 gfn);
 197 int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
 198 #endif