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 #include "cpuid.h" 8 9 #define PT64_PT_BITS 9 10 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS) 11 #define PT32_PT_BITS 10 12 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS) 13 14 #define PT_WRITABLE_SHIFT 1 15 #define PT_USER_SHIFT 2 16 17 #define PT_PRESENT_MASK (1ULL << 0) 18 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT) 19 #define PT_USER_MASK (1ULL << PT_USER_SHIFT) 20 #define PT_PWT_MASK (1ULL << 3) 21 #define PT_PCD_MASK (1ULL << 4) 22 #define PT_ACCESSED_SHIFT 5 23 #define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT) 24 #define PT_DIRTY_SHIFT 6 25 #define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT) 26 #define PT_PAGE_SIZE_SHIFT 7 27 #define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT) 28 #define PT_PAT_MASK (1ULL << 7) 29 #define PT_GLOBAL_MASK (1ULL << 8) 30 #define PT64_NX_SHIFT 63 31 #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT) 32 33 #define PT_PAT_SHIFT 7 34 #define PT_DIR_PAT_SHIFT 12 35 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT) 36 37 #define PT32_DIR_PSE36_SIZE 4 38 #define PT32_DIR_PSE36_SHIFT 13 39 #define PT32_DIR_PSE36_MASK \ 40 (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT) 41 42 #define PT64_ROOT_5LEVEL 5 43 #define PT64_ROOT_4LEVEL 4 44 #define PT32_ROOT_LEVEL 2 45 #define PT32E_ROOT_LEVEL 3 46 47 static __always_inline u64 rsvd_bits(int s, int e) 48 { 49 BUILD_BUG_ON(__builtin_constant_p(e) && __builtin_constant_p(s) && e < s); 50 51 if (__builtin_constant_p(e)) 52 BUILD_BUG_ON(e > 63); 53 else 54 e &= 63; 55 56 if (e < s) 57 return 0; 58 59 return ((2ULL << (e - s)) - 1) << s; 60 } 61 62 void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 access_mask); 63 64 void 65 reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context); 66 67 void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots); 68 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer, 69 gpa_t nested_cr3); 70 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, 71 bool accessed_dirty, gpa_t new_eptp); 72 bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu); 73 int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, 74 u64 fault_address, char *insn, int insn_len); 75 76 static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) 77 { 78 if (likely(vcpu->arch.mmu->root_hpa != INVALID_PAGE)) 79 return 0; 80 81 return kvm_mmu_load(vcpu); 82 } 83 84 static inline unsigned long kvm_get_pcid(struct kvm_vcpu *vcpu, gpa_t cr3) 85 { 86 BUILD_BUG_ON((X86_CR3_PCID_MASK & PAGE_MASK) != 0); 87 88 return kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE) 89 ? cr3 & X86_CR3_PCID_MASK 90 : 0; 91 } 92 93 static inline unsigned long kvm_get_active_pcid(struct kvm_vcpu *vcpu) 94 { 95 return kvm_get_pcid(vcpu, kvm_read_cr3(vcpu)); 96 } 97 98 static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu) 99 { 100 u64 root_hpa = vcpu->arch.mmu->root_hpa; 101 102 if (!VALID_PAGE(root_hpa)) 103 return; 104 105 static_call(kvm_x86_load_mmu_pgd)(vcpu, root_hpa | kvm_get_active_pcid(vcpu), 106 vcpu->arch.mmu->shadow_root_level); 107 } 108 109 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, 110 bool prefault); 111 112 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, 113 u32 err, bool prefault) 114 { 115 #ifdef CONFIG_RETPOLINE 116 if (likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault)) 117 return kvm_tdp_page_fault(vcpu, cr2_or_gpa, err, prefault); 118 #endif 119 return vcpu->arch.mmu->page_fault(vcpu, cr2_or_gpa, err, prefault); 120 } 121 122 /* 123 * Currently, we have two sorts of write-protection, a) the first one 124 * write-protects guest page to sync the guest modification, b) another one is 125 * used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences 126 * between these two sorts are: 127 * 1) the first case clears SPTE_MMU_WRITEABLE bit. 128 * 2) the first case requires flushing tlb immediately avoiding corrupting 129 * shadow page table between all vcpus so it should be in the protection of 130 * mmu-lock. And the another case does not need to flush tlb until returning 131 * the dirty bitmap to userspace since it only write-protects the page 132 * logged in the bitmap, that means the page in the dirty bitmap is not 133 * missed, so it can flush tlb out of mmu-lock. 134 * 135 * So, there is the problem: the first case can meet the corrupted tlb caused 136 * by another case which write-protects pages but without flush tlb 137 * immediately. In order to making the first case be aware this problem we let 138 * it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit 139 * is set, it works since another case never touches SPTE_MMU_WRITEABLE bit. 140 * 141 * Anyway, whenever a spte is updated (only permission and status bits are 142 * changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes 143 * readonly, if that happens, we need to flush tlb. Fortunately, 144 * mmu_spte_update() has already handled it perfectly. 145 * 146 * The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK: 147 * - if we want to see if it has writable tlb entry or if the spte can be 148 * writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most 149 * case, otherwise 150 * - if we fix page fault on the spte or do write-protection by dirty logging, 151 * check PT_WRITABLE_MASK. 152 * 153 * TODO: introduce APIs to split these two cases. 154 */ 155 static inline bool is_writable_pte(unsigned long pte) 156 { 157 return pte & PT_WRITABLE_MASK; 158 } 159 160 static inline bool is_write_protection(struct kvm_vcpu *vcpu) 161 { 162 return kvm_read_cr0_bits(vcpu, X86_CR0_WP); 163 } 164 165 /* 166 * Check if a given access (described through the I/D, W/R and U/S bits of a 167 * page fault error code pfec) causes a permission fault with the given PTE 168 * access rights (in ACC_* format). 169 * 170 * Return zero if the access does not fault; return the page fault error code 171 * if the access faults. 172 */ 173 static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, 174 unsigned pte_access, unsigned pte_pkey, 175 unsigned pfec) 176 { 177 int cpl = static_call(kvm_x86_get_cpl)(vcpu); 178 unsigned long rflags = static_call(kvm_x86_get_rflags)(vcpu); 179 180 /* 181 * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1. 182 * 183 * If CPL = 3, SMAP applies to all supervisor-mode data accesses 184 * (these are implicit supervisor accesses) regardless of the value 185 * of EFLAGS.AC. 186 * 187 * This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving 188 * the result in X86_EFLAGS_AC. We then insert it in place of 189 * the PFERR_RSVD_MASK bit; this bit will always be zero in pfec, 190 * but it will be one in index if SMAP checks are being overridden. 191 * It is important to keep this branchless. 192 */ 193 unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC); 194 int index = (pfec >> 1) + 195 (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1)); 196 bool fault = (mmu->permissions[index] >> pte_access) & 1; 197 u32 errcode = PFERR_PRESENT_MASK; 198 199 WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK)); 200 if (unlikely(mmu->pkru_mask)) { 201 u32 pkru_bits, offset; 202 203 /* 204 * PKRU defines 32 bits, there are 16 domains and 2 205 * attribute bits per domain in pkru. pte_pkey is the 206 * index of the protection domain, so pte_pkey * 2 is 207 * is the index of the first bit for the domain. 208 */ 209 pkru_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3; 210 211 /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */ 212 offset = (pfec & ~1) + 213 ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT)); 214 215 pkru_bits &= mmu->pkru_mask >> offset; 216 errcode |= -pkru_bits & PFERR_PK_MASK; 217 fault |= (pkru_bits != 0); 218 } 219 220 return -(u32)fault & errcode; 221 } 222 223 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end); 224 225 int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu); 226 227 int kvm_mmu_post_init_vm(struct kvm *kvm); 228 void kvm_mmu_pre_destroy_vm(struct kvm *kvm); 229 230 #endif 231