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/osdep.h" 26 #include "qapi/error.h" 27 #include "qemu-common.h" 28 #include "block/block_int.h" 29 #include "qemu/module.h" 30 #include "qemu/bswap.h" 31 #include "qemu/error-report.h" 32 33 /**************************************************************/ 34 35 #define HEADER_MAGIC "Bochs Virtual HD Image" 36 #define HEADER_VERSION 0x00020000 37 #define HEADER_V1 0x00010000 38 #define HEADER_SIZE 512 39 40 #define REDOLOG_TYPE "Redolog" 41 #define GROWING_TYPE "Growing" 42 43 // not allocated: 0xffffffff 44 45 // always little-endian 46 struct bochs_header { 47 char magic[32]; /* "Bochs Virtual HD Image" */ 48 char type[16]; /* "Redolog" */ 49 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 50 uint32_t version; 51 uint32_t header; /* size of header */ 52 53 uint32_t catalog; /* num of entries */ 54 uint32_t bitmap; /* bitmap size */ 55 uint32_t extent; /* extent size */ 56 57 union { 58 struct { 59 uint32_t reserved; /* for ??? */ 60 uint64_t disk; /* disk size */ 61 char padding[HEADER_SIZE - 64 - 20 - 12]; 62 } QEMU_PACKED redolog; 63 struct { 64 uint64_t disk; /* disk size */ 65 char padding[HEADER_SIZE - 64 - 20 - 8]; 66 } QEMU_PACKED redolog_v1; 67 char padding[HEADER_SIZE - 64 - 20]; 68 } extra; 69 } QEMU_PACKED; 70 71 typedef struct BDRVBochsState { 72 CoMutex lock; 73 uint32_t *catalog_bitmap; 74 uint32_t catalog_size; 75 76 uint32_t data_offset; 77 78 uint32_t bitmap_blocks; 79 uint32_t extent_blocks; 80 uint32_t extent_size; 81 } BDRVBochsState; 82 83 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 84 { 85 const struct bochs_header *bochs = (const void *)buf; 86 87 if (buf_size < HEADER_SIZE) 88 return 0; 89 90 if (!strcmp(bochs->magic, HEADER_MAGIC) && 91 !strcmp(bochs->type, REDOLOG_TYPE) && 92 !strcmp(bochs->subtype, GROWING_TYPE) && 93 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 94 (le32_to_cpu(bochs->version) == HEADER_V1))) 95 return 100; 96 97 return 0; 98 } 99 100 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 101 Error **errp) 102 { 103 BDRVBochsState *s = bs->opaque; 104 uint32_t i; 105 struct bochs_header bochs; 106 int ret; 107 108 /* No write support yet */ 109 ret = bdrv_apply_auto_read_only(bs, NULL, errp); 110 if (ret < 0) { 111 return ret; 112 } 113 114 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, 115 false, errp); 116 if (!bs->file) { 117 return -EINVAL; 118 } 119 120 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)); 121 if (ret < 0) { 122 return ret; 123 } 124 125 if (strcmp(bochs.magic, HEADER_MAGIC) || 126 strcmp(bochs.type, REDOLOG_TYPE) || 127 strcmp(bochs.subtype, GROWING_TYPE) || 128 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 129 (le32_to_cpu(bochs.version) != HEADER_V1))) { 130 error_setg(errp, "Image not in Bochs format"); 131 return -EINVAL; 132 } 133 134 if (le32_to_cpu(bochs.version) == HEADER_V1) { 135 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 136 } else { 137 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 138 } 139 140 /* Limit to 1M entries to avoid unbounded allocation. This is what is 141 * needed for the largest image that bximage can create (~8 TB). */ 142 s->catalog_size = le32_to_cpu(bochs.catalog); 143 if (s->catalog_size > 0x100000) { 144 error_setg(errp, "Catalog size is too large"); 145 return -EFBIG; 146 } 147 148 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 149 if (s->catalog_size && s->catalog_bitmap == NULL) { 150 error_setg(errp, "Could not allocate memory for catalog"); 151 return -ENOMEM; 152 } 153 154 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap, 155 s->catalog_size * 4); 156 if (ret < 0) { 157 goto fail; 158 } 159 160 for (i = 0; i < s->catalog_size; i++) 161 le32_to_cpus(&s->catalog_bitmap[i]); 162 163 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 164 165 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 166 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 167 168 s->extent_size = le32_to_cpu(bochs.extent); 169 if (s->extent_size < BDRV_SECTOR_SIZE) { 170 /* bximage actually never creates extents smaller than 4k */ 171 error_setg(errp, "Extent size must be at least 512"); 172 ret = -EINVAL; 173 goto fail; 174 } else if (!is_power_of_2(s->extent_size)) { 175 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 176 s->extent_size); 177 ret = -EINVAL; 178 goto fail; 179 } else if (s->extent_size > 0x800000) { 180 error_setg(errp, "Extent size %" PRIu32 " is too large", 181 s->extent_size); 182 ret = -EINVAL; 183 goto fail; 184 } 185 186 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 187 s->extent_size / BDRV_SECTOR_SIZE)) 188 { 189 error_setg(errp, "Catalog size is too small for this disk size"); 190 ret = -EINVAL; 191 goto fail; 192 } 193 194 qemu_co_mutex_init(&s->lock); 195 return 0; 196 197 fail: 198 g_free(s->catalog_bitmap); 199 return ret; 200 } 201 202 static void bochs_refresh_limits(BlockDriverState *bs, Error **errp) 203 { 204 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */ 205 } 206 207 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 208 { 209 BDRVBochsState *s = bs->opaque; 210 uint64_t offset = sector_num * 512; 211 uint64_t extent_index, extent_offset, bitmap_offset; 212 char bitmap_entry; 213 int ret; 214 215 // seek to sector 216 extent_index = offset / s->extent_size; 217 extent_offset = (offset % s->extent_size) / 512; 218 219 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 220 return 0; /* not allocated */ 221 } 222 223 bitmap_offset = s->data_offset + 224 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 225 (s->extent_blocks + s->bitmap_blocks)); 226 227 /* read in bitmap for current extent */ 228 ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 229 &bitmap_entry, 1); 230 if (ret < 0) { 231 return ret; 232 } 233 234 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 235 return 0; /* not allocated */ 236 } 237 238 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 239 } 240 241 static int coroutine_fn 242 bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, 243 QEMUIOVector *qiov, int flags) 244 { 245 BDRVBochsState *s = bs->opaque; 246 uint64_t sector_num = offset >> BDRV_SECTOR_BITS; 247 int nb_sectors = bytes >> BDRV_SECTOR_BITS; 248 uint64_t bytes_done = 0; 249 QEMUIOVector local_qiov; 250 int ret; 251 252 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0); 253 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0); 254 255 qemu_iovec_init(&local_qiov, qiov->niov); 256 qemu_co_mutex_lock(&s->lock); 257 258 while (nb_sectors > 0) { 259 int64_t block_offset = seek_to_sector(bs, sector_num); 260 if (block_offset < 0) { 261 ret = block_offset; 262 goto fail; 263 } 264 265 qemu_iovec_reset(&local_qiov); 266 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512); 267 268 if (block_offset > 0) { 269 ret = bdrv_co_preadv(bs->file, block_offset, 512, 270 &local_qiov, 0); 271 if (ret < 0) { 272 goto fail; 273 } 274 } else { 275 qemu_iovec_memset(&local_qiov, 0, 0, 512); 276 } 277 nb_sectors--; 278 sector_num++; 279 bytes_done += 512; 280 } 281 282 ret = 0; 283 fail: 284 qemu_co_mutex_unlock(&s->lock); 285 qemu_iovec_destroy(&local_qiov); 286 287 return ret; 288 } 289 290 static void bochs_close(BlockDriverState *bs) 291 { 292 BDRVBochsState *s = bs->opaque; 293 g_free(s->catalog_bitmap); 294 } 295 296 static BlockDriver bdrv_bochs = { 297 .format_name = "bochs", 298 .instance_size = sizeof(BDRVBochsState), 299 .bdrv_probe = bochs_probe, 300 .bdrv_open = bochs_open, 301 .bdrv_child_perm = bdrv_format_default_perms, 302 .bdrv_refresh_limits = bochs_refresh_limits, 303 .bdrv_co_preadv = bochs_co_preadv, 304 .bdrv_close = bochs_close, 305 }; 306 307 static void bdrv_bochs_init(void) 308 { 309 bdrv_register(&bdrv_bochs); 310 } 311 312 block_init(bdrv_bochs_init); 313