1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __KVM_X86_MMU_INTERNAL_H 3 #define __KVM_X86_MMU_INTERNAL_H 4 5 #include <linux/types.h> 6 #include <linux/kvm_host.h> 7 #include <asm/kvm_host.h> 8 9 #undef MMU_DEBUG 10 11 #ifdef MMU_DEBUG 12 extern bool dbg; 13 14 #define pgprintk(x...) do { if (dbg) printk(x); } while (0) 15 #define rmap_printk(fmt, args...) do { if (dbg) printk("%s: " fmt, __func__, ## args); } while (0) 16 #define MMU_WARN_ON(x) WARN_ON(x) 17 #else 18 #define pgprintk(x...) do { } while (0) 19 #define rmap_printk(x...) do { } while (0) 20 #define MMU_WARN_ON(x) do { } while (0) 21 #endif 22 23 /* Page table builder macros common to shadow (host) PTEs and guest PTEs. */ 24 #define __PT_LEVEL_SHIFT(level, bits_per_level) \ 25 (PAGE_SHIFT + ((level) - 1) * (bits_per_level)) 26 #define __PT_INDEX(address, level, bits_per_level) \ 27 (((address) >> __PT_LEVEL_SHIFT(level, bits_per_level)) & ((1 << (bits_per_level)) - 1)) 28 29 #define __PT_LVL_ADDR_MASK(base_addr_mask, level, bits_per_level) \ 30 ((base_addr_mask) & ~((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1)) 31 32 #define __PT_LVL_OFFSET_MASK(base_addr_mask, level, bits_per_level) \ 33 ((base_addr_mask) & ((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1)) 34 35 #define __PT_ENT_PER_PAGE(bits_per_level) (1 << (bits_per_level)) 36 37 /* 38 * Unlike regular MMU roots, PAE "roots", a.k.a. PDPTEs/PDPTRs, have a PRESENT 39 * bit, and thus are guaranteed to be non-zero when valid. And, when a guest 40 * PDPTR is !PRESENT, its corresponding PAE root cannot be set to INVALID_PAGE, 41 * as the CPU would treat that as PRESENT PDPTR with reserved bits set. Use 42 * '0' instead of INVALID_PAGE to indicate an invalid PAE root. 43 */ 44 #define INVALID_PAE_ROOT 0 45 #define IS_VALID_PAE_ROOT(x) (!!(x)) 46 47 typedef u64 __rcu *tdp_ptep_t; 48 49 struct kvm_mmu_page { 50 /* 51 * Note, "link" through "spt" fit in a single 64 byte cache line on 52 * 64-bit kernels, keep it that way unless there's a reason not to. 53 */ 54 struct list_head link; 55 struct hlist_node hash_link; 56 57 bool tdp_mmu_page; 58 bool unsync; 59 u8 mmu_valid_gen; 60 61 /* 62 * The shadow page can't be replaced by an equivalent huge page 63 * because it is being used to map an executable page in the guest 64 * and the NX huge page mitigation is enabled. 65 */ 66 bool nx_huge_page_disallowed; 67 68 /* 69 * The following two entries are used to key the shadow page in the 70 * hash table. 71 */ 72 union kvm_mmu_page_role role; 73 gfn_t gfn; 74 75 u64 *spt; 76 77 /* 78 * Stores the result of the guest translation being shadowed by each 79 * SPTE. KVM shadows two types of guest translations: nGPA -> GPA 80 * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both 81 * cases the result of the translation is a GPA and a set of access 82 * constraints. 83 * 84 * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed 85 * access permissions are stored in the lower bits. Note, for 86 * convenience and uniformity across guests, the access permissions are 87 * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format. 88 */ 89 u64 *shadowed_translation; 90 91 /* Currently serving as active root */ 92 union { 93 int root_count; 94 refcount_t tdp_mmu_root_count; 95 }; 96 unsigned int unsync_children; 97 union { 98 struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */ 99 tdp_ptep_t ptep; 100 }; 101 union { 102 DECLARE_BITMAP(unsync_child_bitmap, 512); 103 struct { 104 struct work_struct tdp_mmu_async_work; 105 void *tdp_mmu_async_data; 106 }; 107 }; 108 109 /* 110 * Tracks shadow pages that, if zapped, would allow KVM to create an NX 111 * huge page. A shadow page will have nx_huge_page_disallowed set but 112 * not be on the list if a huge page is disallowed for other reasons, 113 * e.g. because KVM is shadowing a PTE at the same gfn, the memslot 114 * isn't properly aligned, etc... 115 */ 116 struct list_head possible_nx_huge_page_link; 117 #ifdef CONFIG_X86_32 118 /* 119 * Used out of the mmu-lock to avoid reading spte values while an 120 * update is in progress; see the comments in __get_spte_lockless(). 121 */ 122 int clear_spte_count; 123 #endif 124 125 /* Number of writes since the last time traversal visited this page. */ 126 atomic_t write_flooding_count; 127 128 #ifdef CONFIG_X86_64 129 /* Used for freeing the page asynchronously if it is a TDP MMU page. */ 130 struct rcu_head rcu_head; 131 #endif 132 }; 133 134 extern struct kmem_cache *mmu_page_header_cache; 135 136 static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role) 137 { 138 return role.smm ? 1 : 0; 139 } 140 141 static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) 142 { 143 return kvm_mmu_role_as_id(sp->role); 144 } 145 146 static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp) 147 { 148 /* 149 * When using the EPT page-modification log, the GPAs in the CPU dirty 150 * log would come from L2 rather than L1. Therefore, we need to rely 151 * on write protection to record dirty pages, which bypasses PML, since 152 * writes now result in a vmexit. Note, the check on CPU dirty logging 153 * being enabled is mandatory as the bits used to denote WP-only SPTEs 154 * are reserved for PAE paging (32-bit KVM). 155 */ 156 return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode; 157 } 158 159 static inline gfn_t gfn_round_for_level(gfn_t gfn, int level) 160 { 161 return gfn & -KVM_PAGES_PER_HPAGE(level); 162 } 163 164 int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, 165 gfn_t gfn, bool can_unsync, bool prefetch); 166 167 void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); 168 void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); 169 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, 170 struct kvm_memory_slot *slot, u64 gfn, 171 int min_level); 172 173 void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, 174 gfn_t nr_pages); 175 176 /* Flush the given page (huge or not) of guest memory. */ 177 static inline void kvm_flush_remote_tlbs_gfn(struct kvm *kvm, gfn_t gfn, int level) 178 { 179 kvm_flush_remote_tlbs_range(kvm, gfn_round_for_level(gfn, level), 180 KVM_PAGES_PER_HPAGE(level)); 181 } 182 183 unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); 184 185 extern int nx_huge_pages; 186 static inline bool is_nx_huge_page_enabled(struct kvm *kvm) 187 { 188 return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages; 189 } 190 191 struct kvm_page_fault { 192 /* arguments to kvm_mmu_do_page_fault. */ 193 const gpa_t addr; 194 const u32 error_code; 195 const bool prefetch; 196 197 /* Derived from error_code. */ 198 const bool exec; 199 const bool write; 200 const bool present; 201 const bool rsvd; 202 const bool user; 203 204 /* Derived from mmu and global state. */ 205 const bool is_tdp; 206 const bool nx_huge_page_workaround_enabled; 207 208 /* 209 * Whether a >4KB mapping can be created or is forbidden due to NX 210 * hugepages. 211 */ 212 bool huge_page_disallowed; 213 214 /* 215 * Maximum page size that can be created for this fault; input to 216 * FNAME(fetch), direct_map() and kvm_tdp_mmu_map(). 217 */ 218 u8 max_level; 219 220 /* 221 * Page size that can be created based on the max_level and the 222 * page size used by the host mapping. 223 */ 224 u8 req_level; 225 226 /* 227 * Page size that will be created based on the req_level and 228 * huge_page_disallowed. 229 */ 230 u8 goal_level; 231 232 /* Shifted addr, or result of guest page table walk if addr is a gva. */ 233 gfn_t gfn; 234 235 /* The memslot containing gfn. May be NULL. */ 236 struct kvm_memory_slot *slot; 237 238 /* Outputs of kvm_faultin_pfn. */ 239 unsigned long mmu_seq; 240 kvm_pfn_t pfn; 241 hva_t hva; 242 bool map_writable; 243 244 /* 245 * Indicates the guest is trying to write a gfn that contains one or 246 * more of the PTEs used to translate the write itself, i.e. the access 247 * is changing its own translation in the guest page tables. 248 */ 249 bool write_fault_to_shadow_pgtable; 250 }; 251 252 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); 253 254 /* 255 * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(), 256 * and of course kvm_mmu_do_page_fault(). 257 * 258 * RET_PF_CONTINUE: So far, so good, keep handling the page fault. 259 * RET_PF_RETRY: let CPU fault again on the address. 260 * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. 261 * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. 262 * RET_PF_FIXED: The faulting entry has been fixed. 263 * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. 264 * 265 * Any names added to this enum should be exported to userspace for use in 266 * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h 267 * 268 * Note, all values must be greater than or equal to zero so as not to encroach 269 * on -errno return values. Somewhat arbitrarily use '0' for CONTINUE, which 270 * will allow for efficient machine code when checking for CONTINUE, e.g. 271 * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero. 272 */ 273 enum { 274 RET_PF_CONTINUE = 0, 275 RET_PF_RETRY, 276 RET_PF_EMULATE, 277 RET_PF_INVALID, 278 RET_PF_FIXED, 279 RET_PF_SPURIOUS, 280 }; 281 282 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, 283 u32 err, bool prefetch, int *emulation_type) 284 { 285 struct kvm_page_fault fault = { 286 .addr = cr2_or_gpa, 287 .error_code = err, 288 .exec = err & PFERR_FETCH_MASK, 289 .write = err & PFERR_WRITE_MASK, 290 .present = err & PFERR_PRESENT_MASK, 291 .rsvd = err & PFERR_RSVD_MASK, 292 .user = err & PFERR_USER_MASK, 293 .prefetch = prefetch, 294 .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault), 295 .nx_huge_page_workaround_enabled = 296 is_nx_huge_page_enabled(vcpu->kvm), 297 298 .max_level = KVM_MAX_HUGEPAGE_LEVEL, 299 .req_level = PG_LEVEL_4K, 300 .goal_level = PG_LEVEL_4K, 301 }; 302 int r; 303 304 if (vcpu->arch.mmu->root_role.direct) { 305 fault.gfn = fault.addr >> PAGE_SHIFT; 306 fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn); 307 } 308 309 /* 310 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the 311 * guest perspective and have already been counted at the time of the 312 * original fault. 313 */ 314 if (!prefetch) 315 vcpu->stat.pf_taken++; 316 317 if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp) 318 r = kvm_tdp_page_fault(vcpu, &fault); 319 else 320 r = vcpu->arch.mmu->page_fault(vcpu, &fault); 321 322 if (fault.write_fault_to_shadow_pgtable && emulation_type) 323 *emulation_type |= EMULTYPE_WRITE_PF_TO_SP; 324 325 /* 326 * Similar to above, prefetch faults aren't truly spurious, and the 327 * async #PF path doesn't do emulation. Do count faults that are fixed 328 * by the async #PF handler though, otherwise they'll never be counted. 329 */ 330 if (r == RET_PF_FIXED) 331 vcpu->stat.pf_fixed++; 332 else if (prefetch) 333 ; 334 else if (r == RET_PF_EMULATE) 335 vcpu->stat.pf_emulate++; 336 else if (r == RET_PF_SPURIOUS) 337 vcpu->stat.pf_spurious++; 338 return r; 339 } 340 341 int kvm_mmu_max_mapping_level(struct kvm *kvm, 342 const struct kvm_memory_slot *slot, gfn_t gfn, 343 int max_level); 344 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); 345 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level); 346 347 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); 348 349 void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); 350 void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); 351 352 #endif /* __KVM_X86_MMU_INTERNAL_H */ 353