target/i386/hvf/x86_mmu.c

   1 /*
   2  * Copyright (C) 2016 Veertu Inc,
   3  * Copyright (C) 2017 Google Inc,
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu/osdep.h"
  20 #include "panic.h"
  21 #include "qemu-common.h"
  22 #include "cpu.h"
  23 #include "x86.h"
  24 #include "x86_mmu.h"
  25 #include "vmcs.h"
  26 #include "vmx.h"
  27 #include "exec/address-spaces.h"
  28
  29 #define pte_present(pte) (pte & PT_PRESENT)
  30 #define pte_write_access(pte) (pte & PT_WRITE)
  31 #define pte_user_access(pte) (pte & PT_USER)
  32 #define pte_exec_access(pte) (!(pte & PT_NX))
  33
  34 #define pte_large_page(pte) (pte & PT_PS)
  35 #define pte_global_access(pte) (pte & PT_GLOBAL)
  36
  37 #define PAE_CR3_MASK                (~0x1fllu)
  38 #define LEGACY_CR3_MASK             (0xffffffff)
  39
  40 #define LEGACY_PTE_PAGE_MASK        (0xffffffffllu << 12)
  41 #define PAE_PTE_PAGE_MASK           ((-1llu << 12) & ((1llu << 52) - 1))
  42 #define PAE_PTE_LARGE_PAGE_MASK     ((-1llu << (21)) & ((1llu << 52) - 1))
  43
  44 struct gpt_translation {
  45     target_ulong  gva;
  46     uint64_t gpa;
  47     int    err_code;
  48     uint64_t pte[5];
  49     bool write_access;
  50     bool user_access;
  51     bool exec_access;
  52 };
  53
  54 static int gpt_top_level(struct CPUState *cpu, bool pae)
  55 {
  56     if (!pae) {
  57         return 2;
  58     }
  59     if (x86_is_long_mode(cpu)) {
  60         return 4;
  61     }
  62
  63     return 3;
  64 }
  65
  66 static inline int gpt_entry(target_ulong addr, int level, bool pae)
  67 {
  68     int level_shift = pae ? 9 : 10;
  69     return (addr >> (level_shift * (level - 1) + 12)) & ((1 << level_shift) - 1);
  70 }
  71
  72 static inline int pte_size(bool pae)
  73 {
  74     return pae ? 8 : 4;
  75 }
  76
  77
  78 static bool get_pt_entry(struct CPUState *cpu, struct gpt_translation *pt,
  79                          int level, bool pae)
  80 {
  81     int index;
  82     uint64_t pte = 0;
  83     uint64_t page_mask = pae ? PAE_PTE_PAGE_MASK : LEGACY_PTE_PAGE_MASK;
  84     uint64_t gpa = pt->pte[level] & page_mask;
  85
  86     if (level == 3 && !x86_is_long_mode(cpu)) {
  87         gpa = pt->pte[level];
  88     }
  89
  90     index = gpt_entry(pt->gva, level, pae);
  91     address_space_read(&address_space_memory, gpa + index * pte_size(pae),
  92                        MEMTXATTRS_UNSPECIFIED, &pte, pte_size(pae));
  93
  94     pt->pte[level - 1] = pte;
  95
  96     return true;
  97 }
  98
  99 /* test page table entry */
 100 static bool test_pt_entry(struct CPUState *cpu, struct gpt_translation *pt,
 101                           int level, bool *is_large, bool pae)
 102 {
 103     uint64_t pte = pt->pte[level];
 104
 105     if (pt->write_access) {
 106         pt->err_code |= MMU_PAGE_WT;
 107     }
 108     if (pt->user_access) {
 109         pt->err_code |= MMU_PAGE_US;
 110     }
 111     if (pt->exec_access) {
 112         pt->err_code |= MMU_PAGE_NX;
 113     }
 114
 115     if (!pte_present(pte)) {
 116         return false;
 117     }
 118
 119     if (pae && !x86_is_long_mode(cpu) && 2 == level) {
 120         goto exit;
 121     }
 122
 123     if (1 == level && pte_large_page(pte)) {
 124         pt->err_code |= MMU_PAGE_PT;
 125         *is_large = true;
 126     }
 127     if (!level) {
 128         pt->err_code |= MMU_PAGE_PT;
 129     }
 130
 131     uint32_t cr0 = rvmcs(cpu->hvf_fd, VMCS_GUEST_CR0);
 132     /* check protection */
 133     if (cr0 & CR0_WP) {
 134         if (pt->write_access && !pte_write_access(pte)) {
 135             return false;
 136         }
 137     }
 138
 139     if (pt->user_access && !pte_user_access(pte)) {
 140         return false;
 141     }
 142
 143     if (pae && pt->exec_access && !pte_exec_access(pte)) {
 144         return false;
 145     }
 146
 147 exit:
 148     /* TODO: check reserved bits */
 149     return true;
 150 }
 151
 152 static inline uint64_t pse_pte_to_page(uint64_t pte)
 153 {
 154     return ((pte & 0x1fe000) << 19) | (pte & 0xffc00000);
 155 }
 156
 157 static inline uint64_t large_page_gpa(struct gpt_translation *pt, bool pae)
 158 {
 159     VM_PANIC_ON(!pte_large_page(pt->pte[1]))
 160     /* 2Mb large page  */
 161     if (pae) {
 162         return (pt->pte[1] & PAE_PTE_LARGE_PAGE_MASK) | (pt->gva & 0x1fffff);
 163     }
 164
 165     /* 4Mb large page */
 166     return pse_pte_to_page(pt->pte[1]) | (pt->gva & 0x3fffff);
 167 }
 168
 169
 170
 171 static bool walk_gpt(struct CPUState *cpu, target_ulong addr, int err_code,
 172                      struct gpt_translation *pt, bool pae)
 173 {
 174     int top_level, level;
 175     bool is_large = false;
 176     target_ulong cr3 = rvmcs(cpu->hvf_fd, VMCS_GUEST_CR3);
 177     uint64_t page_mask = pae ? PAE_PTE_PAGE_MASK : LEGACY_PTE_PAGE_MASK;
 178
 179     memset(pt, 0, sizeof(*pt));
 180     top_level = gpt_top_level(cpu, pae);
 181
 182     pt->pte[top_level] = pae ? (cr3 & PAE_CR3_MASK) : (cr3 & LEGACY_CR3_MASK);
 183     pt->gva = addr;
 184     pt->user_access = (err_code & MMU_PAGE_US);
 185     pt->write_access = (err_code & MMU_PAGE_WT);
 186     pt->exec_access = (err_code & MMU_PAGE_NX);
 187
 188     for (level = top_level; level > 0; level--) {
 189         get_pt_entry(cpu, pt, level, pae);
 190
 191         if (!test_pt_entry(cpu, pt, level - 1, &is_large, pae)) {
 192             return false;
 193         }
 194
 195         if (is_large) {
 196             break;
 197         }
 198     }
 199
 200     if (!is_large) {
 201         pt->gpa = (pt->pte[0] & page_mask) | (pt->gva & 0xfff);
 202     } else {
 203         pt->gpa = large_page_gpa(pt, pae);
 204     }
 205
 206     return true;
 207 }
 208
 209
 210 bool mmu_gva_to_gpa(struct CPUState *cpu, target_ulong gva, uint64_t *gpa)
 211 {
 212     bool res;
 213     struct gpt_translation pt;
 214     int err_code = 0;
 215
 216     if (!x86_is_paging_mode(cpu)) {
 217         *gpa = gva;
 218         return true;
 219     }
 220
 221     res = walk_gpt(cpu, gva, err_code, &pt, x86_is_pae_enabled(cpu));
 222     if (res) {
 223         *gpa = pt.gpa;
 224         return true;
 225     }
 226
 227     return false;
 228 }
 229
 230 void vmx_write_mem(struct CPUState *cpu, target_ulong gva, void *data, int bytes)
 231 {
 232     uint64_t gpa;
 233
 234     while (bytes > 0) {
 235         /* copy page */
 236         int copy = MIN(bytes, 0x1000 - (gva & 0xfff));
 237
 238         if (!mmu_gva_to_gpa(cpu, gva, &gpa)) {
 239             VM_PANIC_EX("%s: mmu_gva_to_gpa %llx failed\n", __func__, gva);
 240         } else {
 241             address_space_write(&address_space_memory, gpa,
 242                                 MEMTXATTRS_UNSPECIFIED, data, copy);
 243         }
 244
 245         bytes -= copy;
 246         gva += copy;
 247         data += copy;
 248     }
 249 }
 250
 251 void vmx_read_mem(struct CPUState *cpu, void *data, target_ulong gva, int bytes)
 252 {
 253     uint64_t gpa;
 254
 255     while (bytes > 0) {
 256         /* copy page */
 257         int copy = MIN(bytes, 0x1000 - (gva & 0xfff));
 258
 259         if (!mmu_gva_to_gpa(cpu, gva, &gpa)) {
 260             VM_PANIC_EX("%s: mmu_gva_to_gpa %llx failed\n", __func__, gva);
 261         }
 262         address_space_read(&address_space_memory, gpa, MEMTXATTRS_UNSPECIFIED,
 263                            data, copy);
 264
 265         bytes -= copy;
 266         gva += copy;
 267         data += copy;
 268     }
 269 }