arch/arm64/include/asm/kvm_mmu.h

   1 /*
   2  * Copyright (C) 2012,2013 - ARM Ltd
   3  * Author: Marc Zyngier <marc.zyngier@arm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef __ARM64_KVM_MMU_H__
  19 #define __ARM64_KVM_MMU_H__
  20
  21 #include <asm/page.h>
  22 #include <asm/memory.h>
  23 #include <asm/cpufeature.h>
  24
  25 /*
  26  * As ARMv8.0 only has the TTBR0_EL2 register, we cannot express
  27  * "negative" addresses. This makes it impossible to directly share
  28  * mappings with the kernel.
  29  *
  30  * Instead, give the HYP mode its own VA region at a fixed offset from
  31  * the kernel by just masking the top bits (which are all ones for a
  32  * kernel address). We need to find out how many bits to mask.
  33  *
  34  * We want to build a set of page tables that cover both parts of the
  35  * idmap (the trampoline page used to initialize EL2), and our normal
  36  * runtime VA space, at the same time.
  37  *
  38  * Given that the kernel uses VA_BITS for its entire address space,
  39  * and that half of that space (VA_BITS - 1) is used for the linear
  40  * mapping, we can also limit the EL2 space to (VA_BITS - 1).
  41  *
  42  * The main question is "Within the VA_BITS space, does EL2 use the
  43  * top or the bottom half of that space to shadow the kernel's linear
  44  * mapping?". As we need to idmap the trampoline page, this is
  45  * determined by the range in which this page lives.
  46  *
  47  * If the page is in the bottom half, we have to use the top half. If
  48  * the page is in the top half, we have to use the bottom half:
  49  *
  50  * T = __pa_symbol(__hyp_idmap_text_start)
  51  * if (T & BIT(VA_BITS - 1))
  52  *      HYP_VA_MIN = 0  //idmap in upper half
  53  * else
  54  *      HYP_VA_MIN = 1 << (VA_BITS - 1)
  55  * HYP_VA_MAX = HYP_VA_MIN + (1 << (VA_BITS - 1)) - 1
  56  *
  57  * This of course assumes that the trampoline page exists within the
  58  * VA_BITS range. If it doesn't, then it means we're in the odd case
  59  * where the kernel idmap (as well as HYP) uses more levels than the
  60  * kernel runtime page tables (as seen when the kernel is configured
  61  * for 4k pages, 39bits VA, and yet memory lives just above that
  62  * limit, forcing the idmap to use 4 levels of page tables while the
  63  * kernel itself only uses 3). In this particular case, it doesn't
  64  * matter which side of VA_BITS we use, as we're guaranteed not to
  65  * conflict with anything.
  66  *
  67  * When using VHE, there are no separate hyp mappings and all KVM
  68  * functionality is already mapped as part of the main kernel
  69  * mappings, and none of this applies in that case.
  70  */
  71
  72 #define HYP_PAGE_OFFSET_HIGH_MASK       ((UL(1) << VA_BITS) - 1)
  73 #define HYP_PAGE_OFFSET_LOW_MASK        ((UL(1) << (VA_BITS - 1)) - 1)
  74
  75 #ifdef __ASSEMBLY__
  76
  77 #include <asm/alternative.h>
  78 #include <asm/cpufeature.h>
  79
  80 /*
  81  * Convert a kernel VA into a HYP VA.
  82  * reg: VA to be converted.
  83  *
  84  * This generates the following sequences:
  85  * - High mask:
  86  *              and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
  87  *              nop
  88  * - Low mask:
  89  *              and x0, x0, #HYP_PAGE_OFFSET_HIGH_MASK
  90  *              and x0, x0, #HYP_PAGE_OFFSET_LOW_MASK
  91  * - VHE:
  92  *              nop
  93  *              nop
  94  *
  95  * The "low mask" version works because the mask is a strict subset of
  96  * the "high mask", hence performing the first mask for nothing.
  97  * Should be completely invisible on any viable CPU.
  98  */
  99 .macro kern_hyp_va      reg
 100 alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
 101         and     \reg, \reg, #HYP_PAGE_OFFSET_HIGH_MASK
 102 alternative_else_nop_endif
 103 alternative_if ARM64_HYP_OFFSET_LOW
 104         and     \reg, \reg, #HYP_PAGE_OFFSET_LOW_MASK
 105 alternative_else_nop_endif
 106 .endm
 107
 108 #else
 109
 110 #include <asm/pgalloc.h>
 111 #include <asm/cache.h>
 112 #include <asm/cacheflush.h>
 113 #include <asm/mmu_context.h>
 114 #include <asm/pgtable.h>
 115
 116 static inline unsigned long __kern_hyp_va(unsigned long v)
 117 {
 118         asm volatile(ALTERNATIVE("and %0, %0, %1",
 119                                  "nop",
 120                                  ARM64_HAS_VIRT_HOST_EXTN)
 121                      : "+r" (v)
 122                      : "i" (HYP_PAGE_OFFSET_HIGH_MASK));
 123         asm volatile(ALTERNATIVE("nop",
 124                                  "and %0, %0, %1",
 125                                  ARM64_HYP_OFFSET_LOW)
 126                      : "+r" (v)
 127                      : "i" (HYP_PAGE_OFFSET_LOW_MASK));
 128         return v;
 129 }
 130
 131 #define kern_hyp_va(v)  ((typeof(v))(__kern_hyp_va((unsigned long)(v))))
 132
 133 /*
 134  * We currently only support a 40bit IPA.
 135  */
 136 #define KVM_PHYS_SHIFT  (40)
 137 #define KVM_PHYS_SIZE   (1UL << KVM_PHYS_SHIFT)
 138 #define KVM_PHYS_MASK   (KVM_PHYS_SIZE - 1UL)
 139
 140 #include <asm/stage2_pgtable.h>
 141
 142 int create_hyp_mappings(void *from, void *to, pgprot_t prot);
 143 int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
 144 void free_hyp_pgds(void);
 145
 146 void stage2_unmap_vm(struct kvm *kvm);
 147 int kvm_alloc_stage2_pgd(struct kvm *kvm);
 148 void kvm_free_stage2_pgd(struct kvm *kvm);
 149 int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 150                           phys_addr_t pa, unsigned long size, bool writable);
 151
 152 int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run);
 153
 154 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
 155
 156 phys_addr_t kvm_mmu_get_httbr(void);
 157 phys_addr_t kvm_get_idmap_vector(void);
 158 int kvm_mmu_init(void);
 159 void kvm_clear_hyp_idmap(void);
 160
 161 #define kvm_set_pte(ptep, pte)          set_pte(ptep, pte)
 162 #define kvm_set_pmd(pmdp, pmd)          set_pmd(pmdp, pmd)
 163
 164 static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
 165 {
 166         pte_val(pte) |= PTE_S2_RDWR;
 167         return pte;
 168 }
 169
 170 static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
 171 {
 172         pmd_val(pmd) |= PMD_S2_RDWR;
 173         return pmd;
 174 }
 175
 176 static inline void kvm_set_s2pte_readonly(pte_t *pte)
 177 {
 178         pteval_t old_pteval, pteval;
 179
 180         pteval = READ_ONCE(pte_val(*pte));
 181         do {
 182                 old_pteval = pteval;
 183                 pteval &= ~PTE_S2_RDWR;
 184                 pteval |= PTE_S2_RDONLY;
 185                 pteval = cmpxchg_relaxed(&pte_val(*pte), old_pteval, pteval);
 186         } while (pteval != old_pteval);
 187 }
 188
 189 static inline bool kvm_s2pte_readonly(pte_t *pte)
 190 {
 191         return (pte_val(*pte) & PTE_S2_RDWR) == PTE_S2_RDONLY;
 192 }
 193
 194 static inline void kvm_set_s2pmd_readonly(pmd_t *pmd)
 195 {
 196         kvm_set_s2pte_readonly((pte_t *)pmd);
 197 }
 198
 199 static inline bool kvm_s2pmd_readonly(pmd_t *pmd)
 200 {
 201         return kvm_s2pte_readonly((pte_t *)pmd);
 202 }
 203
 204 static inline bool kvm_page_empty(void *ptr)
 205 {
 206         struct page *ptr_page = virt_to_page(ptr);
 207         return page_count(ptr_page) == 1;
 208 }
 209
 210 #define hyp_pte_table_empty(ptep) kvm_page_empty(ptep)
 211
 212 #ifdef __PAGETABLE_PMD_FOLDED
 213 #define hyp_pmd_table_empty(pmdp) (0)
 214 #else
 215 #define hyp_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
 216 #endif
 217
 218 #ifdef __PAGETABLE_PUD_FOLDED
 219 #define hyp_pud_table_empty(pudp) (0)
 220 #else
 221 #define hyp_pud_table_empty(pudp) kvm_page_empty(pudp)
 222 #endif
 223
 224 struct kvm;
 225
 226 #define kvm_flush_dcache_to_poc(a,l)    __flush_dcache_area((a), (l))
 227
 228 static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
 229 {
 230         return (vcpu_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
 231 }
 232
 233 static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
 234                                                kvm_pfn_t pfn,
 235                                                unsigned long size)
 236 {
 237         void *va = page_address(pfn_to_page(pfn));
 238
 239         kvm_flush_dcache_to_poc(va, size);
 240
 241         if (icache_is_aliasing()) {
 242                 /* any kind of VIPT cache */
 243                 __flush_icache_all();
 244         } else if (is_kernel_in_hyp_mode() || !icache_is_vpipt()) {
 245                 /* PIPT or VPIPT at EL2 (see comment in __kvm_tlb_flush_vmid_ipa) */
 246                 flush_icache_range((unsigned long)va,
 247                                    (unsigned long)va + size);
 248         }
 249 }
 250
 251 static inline void __kvm_flush_dcache_pte(pte_t pte)
 252 {
 253         struct page *page = pte_page(pte);
 254         kvm_flush_dcache_to_poc(page_address(page), PAGE_SIZE);
 255 }
 256
 257 static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
 258 {
 259         struct page *page = pmd_page(pmd);
 260         kvm_flush_dcache_to_poc(page_address(page), PMD_SIZE);
 261 }
 262
 263 static inline void __kvm_flush_dcache_pud(pud_t pud)
 264 {
 265         struct page *page = pud_page(pud);
 266         kvm_flush_dcache_to_poc(page_address(page), PUD_SIZE);
 267 }
 268
 269 #define kvm_virt_to_phys(x)             __pa_symbol(x)
 270
 271 void kvm_set_way_flush(struct kvm_vcpu *vcpu);
 272 void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
 273
 274 static inline bool __kvm_cpu_uses_extended_idmap(void)
 275 {
 276         return __cpu_uses_extended_idmap();
 277 }
 278
 279 static inline void __kvm_extend_hypmap(pgd_t *boot_hyp_pgd,
 280                                        pgd_t *hyp_pgd,
 281                                        pgd_t *merged_hyp_pgd,
 282                                        unsigned long hyp_idmap_start)
 283 {
 284         int idmap_idx;
 285
 286         /*
 287          * Use the first entry to access the HYP mappings. It is
 288          * guaranteed to be free, otherwise we wouldn't use an
 289          * extended idmap.
 290          */
 291         VM_BUG_ON(pgd_val(merged_hyp_pgd[0]));
 292         merged_hyp_pgd[0] = __pgd(__pa(hyp_pgd) | PMD_TYPE_TABLE);
 293
 294         /*
 295          * Create another extended level entry that points to the boot HYP map,
 296          * which contains an ID mapping of the HYP init code. We essentially
 297          * merge the boot and runtime HYP maps by doing so, but they don't
 298          * overlap anyway, so this is fine.
 299          */
 300         idmap_idx = hyp_idmap_start >> VA_BITS;
 301         VM_BUG_ON(pgd_val(merged_hyp_pgd[idmap_idx]));
 302         merged_hyp_pgd[idmap_idx] = __pgd(__pa(boot_hyp_pgd) | PMD_TYPE_TABLE);
 303 }
 304
 305 static inline unsigned int kvm_get_vmid_bits(void)
 306 {
 307         int reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
 308
 309         return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
 310 }
 311
 312 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
 313 #include <asm/mmu.h>
 314
 315 static inline void *kvm_get_hyp_vector(void)
 316 {
 317         struct bp_hardening_data *data = arm64_get_bp_hardening_data();
 318         void *vect = kvm_ksym_ref(__kvm_hyp_vector);
 319
 320         if (data->fn) {
 321                 vect = __bp_harden_hyp_vecs_start +
 322                        data->hyp_vectors_slot * SZ_2K;
 323
 324                 if (!has_vhe())
 325                         vect = lm_alias(vect);
 326         }
 327
 328         return vect;
 329 }
 330
 331 static inline int kvm_map_vectors(void)
 332 {
 333         return create_hyp_mappings(kvm_ksym_ref(__bp_harden_hyp_vecs_start),
 334                                    kvm_ksym_ref(__bp_harden_hyp_vecs_end),
 335                                    PAGE_HYP_EXEC);
 336 }
 337
 338 #else
 339 static inline void *kvm_get_hyp_vector(void)
 340 {
 341         return kvm_ksym_ref(__kvm_hyp_vector);
 342 }
 343
 344 static inline int kvm_map_vectors(void)
 345 {
 346         return 0;
 347 }
 348 #endif
 349
 350 #endif /* __ASSEMBLY__ */
 351 #endif /* __ARM64_KVM_MMU_H__ */