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 199