1 /* 2 * Block driver for the various disk image formats used by Bochs 3 * Currently only for "growing" type in read-only mode 4 * 5 * Copyright (c) 2005 Alex Beregszaszi 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 #include "qemu-common.h" 26 #include "block/block_int.h" 27 #include "qemu/module.h" 28 29 /**************************************************************/ 30 31 #define HEADER_MAGIC "Bochs Virtual HD Image" 32 #define HEADER_VERSION 0x00020000 33 #define HEADER_V1 0x00010000 34 #define HEADER_SIZE 512 35 36 #define REDOLOG_TYPE "Redolog" 37 #define GROWING_TYPE "Growing" 38 39 // not allocated: 0xffffffff 40 41 // always little-endian 42 struct bochs_header { 43 char magic[32]; /* "Bochs Virtual HD Image" */ 44 char type[16]; /* "Redolog" */ 45 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 46 uint32_t version; 47 uint32_t header; /* size of header */ 48 49 uint32_t catalog; /* num of entries */ 50 uint32_t bitmap; /* bitmap size */ 51 uint32_t extent; /* extent size */ 52 53 union { 54 struct { 55 uint32_t reserved; /* for ??? */ 56 uint64_t disk; /* disk size */ 57 char padding[HEADER_SIZE - 64 - 20 - 12]; 58 } QEMU_PACKED redolog; 59 struct { 60 uint64_t disk; /* disk size */ 61 char padding[HEADER_SIZE - 64 - 20 - 8]; 62 } QEMU_PACKED redolog_v1; 63 char padding[HEADER_SIZE - 64 - 20]; 64 } extra; 65 } QEMU_PACKED; 66 67 typedef struct BDRVBochsState { 68 CoMutex lock; 69 uint32_t *catalog_bitmap; 70 uint32_t catalog_size; 71 72 uint32_t data_offset; 73 74 uint32_t bitmap_blocks; 75 uint32_t extent_blocks; 76 uint32_t extent_size; 77 } BDRVBochsState; 78 79 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 80 { 81 const struct bochs_header *bochs = (const void *)buf; 82 83 if (buf_size < HEADER_SIZE) 84 return 0; 85 86 if (!strcmp(bochs->magic, HEADER_MAGIC) && 87 !strcmp(bochs->type, REDOLOG_TYPE) && 88 !strcmp(bochs->subtype, GROWING_TYPE) && 89 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 90 (le32_to_cpu(bochs->version) == HEADER_V1))) 91 return 100; 92 93 return 0; 94 } 95 96 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 97 Error **errp) 98 { 99 BDRVBochsState *s = bs->opaque; 100 uint32_t i; 101 struct bochs_header bochs; 102 int ret; 103 104 bs->read_only = 1; // no write support yet 105 106 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)); 107 if (ret < 0) { 108 return ret; 109 } 110 111 if (strcmp(bochs.magic, HEADER_MAGIC) || 112 strcmp(bochs.type, REDOLOG_TYPE) || 113 strcmp(bochs.subtype, GROWING_TYPE) || 114 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 115 (le32_to_cpu(bochs.version) != HEADER_V1))) { 116 error_setg(errp, "Image not in Bochs format"); 117 return -EINVAL; 118 } 119 120 if (le32_to_cpu(bochs.version) == HEADER_V1) { 121 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 122 } else { 123 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 124 } 125 126 /* Limit to 1M entries to avoid unbounded allocation. This is what is 127 * needed for the largest image that bximage can create (~8 TB). */ 128 s->catalog_size = le32_to_cpu(bochs.catalog); 129 if (s->catalog_size > 0x100000) { 130 error_setg(errp, "Catalog size is too large"); 131 return -EFBIG; 132 } 133 134 s->catalog_bitmap = g_malloc(s->catalog_size * 4); 135 136 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap, 137 s->catalog_size * 4); 138 if (ret < 0) { 139 goto fail; 140 } 141 142 for (i = 0; i < s->catalog_size; i++) 143 le32_to_cpus(&s->catalog_bitmap[i]); 144 145 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 146 147 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 148 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 149 150 s->extent_size = le32_to_cpu(bochs.extent); 151 if (s->extent_size < BDRV_SECTOR_SIZE) { 152 /* bximage actually never creates extents smaller than 4k */ 153 error_setg(errp, "Extent size must be at least 512"); 154 ret = -EINVAL; 155 goto fail; 156 } else if (!is_power_of_2(s->extent_size)) { 157 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 158 s->extent_size); 159 ret = -EINVAL; 160 goto fail; 161 } else if (s->extent_size > 0x800000) { 162 error_setg(errp, "Extent size %" PRIu32 " is too large", 163 s->extent_size); 164 ret = -EINVAL; 165 goto fail; 166 } 167 168 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 169 s->extent_size / BDRV_SECTOR_SIZE)) 170 { 171 error_setg(errp, "Catalog size is too small for this disk size"); 172 ret = -EINVAL; 173 goto fail; 174 } 175 176 qemu_co_mutex_init(&s->lock); 177 return 0; 178 179 fail: 180 g_free(s->catalog_bitmap); 181 return ret; 182 } 183 184 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 185 { 186 BDRVBochsState *s = bs->opaque; 187 uint64_t offset = sector_num * 512; 188 uint64_t extent_index, extent_offset, bitmap_offset; 189 char bitmap_entry; 190 int ret; 191 192 // seek to sector 193 extent_index = offset / s->extent_size; 194 extent_offset = (offset % s->extent_size) / 512; 195 196 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 197 return 0; /* not allocated */ 198 } 199 200 bitmap_offset = s->data_offset + 201 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 202 (s->extent_blocks + s->bitmap_blocks)); 203 204 /* read in bitmap for current extent */ 205 ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 206 &bitmap_entry, 1); 207 if (ret < 0) { 208 return ret; 209 } 210 211 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 212 return 0; /* not allocated */ 213 } 214 215 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 216 } 217 218 static int bochs_read(BlockDriverState *bs, int64_t sector_num, 219 uint8_t *buf, int nb_sectors) 220 { 221 int ret; 222 223 while (nb_sectors > 0) { 224 int64_t block_offset = seek_to_sector(bs, sector_num); 225 if (block_offset < 0) { 226 return block_offset; 227 } else if (block_offset > 0) { 228 ret = bdrv_pread(bs->file, block_offset, buf, 512); 229 if (ret < 0) { 230 return ret; 231 } 232 } else { 233 memset(buf, 0, 512); 234 } 235 nb_sectors--; 236 sector_num++; 237 buf += 512; 238 } 239 return 0; 240 } 241 242 static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num, 243 uint8_t *buf, int nb_sectors) 244 { 245 int ret; 246 BDRVBochsState *s = bs->opaque; 247 qemu_co_mutex_lock(&s->lock); 248 ret = bochs_read(bs, sector_num, buf, nb_sectors); 249 qemu_co_mutex_unlock(&s->lock); 250 return ret; 251 } 252 253 static void bochs_close(BlockDriverState *bs) 254 { 255 BDRVBochsState *s = bs->opaque; 256 g_free(s->catalog_bitmap); 257 } 258 259 static BlockDriver bdrv_bochs = { 260 .format_name = "bochs", 261 .instance_size = sizeof(BDRVBochsState), 262 .bdrv_probe = bochs_probe, 263 .bdrv_open = bochs_open, 264 .bdrv_read = bochs_co_read, 265 .bdrv_close = bochs_close, 266 }; 267 268 static void bdrv_bochs_init(void) 269 { 270 bdrv_register(&bdrv_bochs); 271 } 272 273 block_init(bdrv_bochs_init); 274