bochs.c (9446B)
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 "block/block_int.h" 28 #include "qemu/module.h" 29 #include "qemu/bswap.h" 30 #include "qemu/error-report.h" 31 32 /**************************************************************/ 33 34 #define HEADER_MAGIC "Bochs Virtual HD Image" 35 #define HEADER_VERSION 0x00020000 36 #define HEADER_V1 0x00010000 37 #define HEADER_SIZE 512 38 39 #define REDOLOG_TYPE "Redolog" 40 #define GROWING_TYPE "Growing" 41 42 // not allocated: 0xffffffff 43 44 // always little-endian 45 struct bochs_header { 46 char magic[32]; /* "Bochs Virtual HD Image" */ 47 char type[16]; /* "Redolog" */ 48 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 49 uint32_t version; 50 uint32_t header; /* size of header */ 51 52 uint32_t catalog; /* num of entries */ 53 uint32_t bitmap; /* bitmap size */ 54 uint32_t extent; /* extent size */ 55 56 union { 57 struct { 58 uint32_t reserved; /* for ??? */ 59 uint64_t disk; /* disk size */ 60 char padding[HEADER_SIZE - 64 - 20 - 12]; 61 } QEMU_PACKED redolog; 62 struct { 63 uint64_t disk; /* disk size */ 64 char padding[HEADER_SIZE - 64 - 20 - 8]; 65 } QEMU_PACKED redolog_v1; 66 char padding[HEADER_SIZE - 64 - 20]; 67 } extra; 68 } QEMU_PACKED; 69 70 typedef struct BDRVBochsState { 71 CoMutex lock; 72 uint32_t *catalog_bitmap; 73 uint32_t catalog_size; 74 75 uint32_t data_offset; 76 77 uint32_t bitmap_blocks; 78 uint32_t extent_blocks; 79 uint32_t extent_size; 80 } BDRVBochsState; 81 82 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 83 { 84 const struct bochs_header *bochs = (const void *)buf; 85 86 if (buf_size < HEADER_SIZE) 87 return 0; 88 89 if (!strcmp(bochs->magic, HEADER_MAGIC) && 90 !strcmp(bochs->type, REDOLOG_TYPE) && 91 !strcmp(bochs->subtype, GROWING_TYPE) && 92 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 93 (le32_to_cpu(bochs->version) == HEADER_V1))) 94 return 100; 95 96 return 0; 97 } 98 99 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 100 Error **errp) 101 { 102 BDRVBochsState *s = bs->opaque; 103 uint32_t i; 104 struct bochs_header bochs; 105 int ret; 106 107 /* No write support yet */ 108 ret = bdrv_apply_auto_read_only(bs, NULL, errp); 109 if (ret < 0) { 110 return ret; 111 } 112 113 ret = bdrv_open_file_child(NULL, options, "file", bs, errp); 114 if (ret < 0) { 115 return ret; 116 } 117 118 ret = bdrv_pread(bs->file, 0, sizeof(bochs), &bochs, 0); 119 if (ret < 0) { 120 return ret; 121 } 122 123 if (strcmp(bochs.magic, HEADER_MAGIC) || 124 strcmp(bochs.type, REDOLOG_TYPE) || 125 strcmp(bochs.subtype, GROWING_TYPE) || 126 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 127 (le32_to_cpu(bochs.version) != HEADER_V1))) { 128 error_setg(errp, "Image not in Bochs format"); 129 return -EINVAL; 130 } 131 132 if (le32_to_cpu(bochs.version) == HEADER_V1) { 133 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 134 } else { 135 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 136 } 137 138 /* Limit to 1M entries to avoid unbounded allocation. This is what is 139 * needed for the largest image that bximage can create (~8 TB). */ 140 s->catalog_size = le32_to_cpu(bochs.catalog); 141 if (s->catalog_size > 0x100000) { 142 error_setg(errp, "Catalog size is too large"); 143 return -EFBIG; 144 } 145 146 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 147 if (s->catalog_size && s->catalog_bitmap == NULL) { 148 error_setg(errp, "Could not allocate memory for catalog"); 149 return -ENOMEM; 150 } 151 152 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_size * 4, 153 s->catalog_bitmap, 0); 154 if (ret < 0) { 155 goto fail; 156 } 157 158 for (i = 0; i < s->catalog_size; i++) 159 le32_to_cpus(&s->catalog_bitmap[i]); 160 161 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 162 163 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 164 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 165 166 s->extent_size = le32_to_cpu(bochs.extent); 167 if (s->extent_size < BDRV_SECTOR_SIZE) { 168 /* bximage actually never creates extents smaller than 4k */ 169 error_setg(errp, "Extent size must be at least 512"); 170 ret = -EINVAL; 171 goto fail; 172 } else if (!is_power_of_2(s->extent_size)) { 173 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 174 s->extent_size); 175 ret = -EINVAL; 176 goto fail; 177 } else if (s->extent_size > 0x800000) { 178 error_setg(errp, "Extent size %" PRIu32 " is too large", 179 s->extent_size); 180 ret = -EINVAL; 181 goto fail; 182 } 183 184 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 185 s->extent_size / BDRV_SECTOR_SIZE)) 186 { 187 error_setg(errp, "Catalog size is too small for this disk size"); 188 ret = -EINVAL; 189 goto fail; 190 } 191 192 qemu_co_mutex_init(&s->lock); 193 return 0; 194 195 fail: 196 g_free(s->catalog_bitmap); 197 return ret; 198 } 199 200 static void bochs_refresh_limits(BlockDriverState *bs, Error **errp) 201 { 202 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */ 203 } 204 205 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 206 { 207 BDRVBochsState *s = bs->opaque; 208 uint64_t offset = sector_num * 512; 209 uint64_t extent_index, extent_offset, bitmap_offset; 210 char bitmap_entry; 211 int ret; 212 213 // seek to sector 214 extent_index = offset / s->extent_size; 215 extent_offset = (offset % s->extent_size) / 512; 216 217 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 218 return 0; /* not allocated */ 219 } 220 221 bitmap_offset = s->data_offset + 222 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 223 (s->extent_blocks + s->bitmap_blocks)); 224 225 /* read in bitmap for current extent */ 226 ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 1, 227 &bitmap_entry, 0); 228 if (ret < 0) { 229 return ret; 230 } 231 232 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 233 return 0; /* not allocated */ 234 } 235 236 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 237 } 238 239 static int coroutine_fn 240 bochs_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 241 QEMUIOVector *qiov, BdrvRequestFlags flags) 242 { 243 BDRVBochsState *s = bs->opaque; 244 uint64_t sector_num = offset >> BDRV_SECTOR_BITS; 245 int nb_sectors = bytes >> BDRV_SECTOR_BITS; 246 uint64_t bytes_done = 0; 247 QEMUIOVector local_qiov; 248 int ret; 249 250 assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); 251 assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); 252 253 qemu_iovec_init(&local_qiov, qiov->niov); 254 qemu_co_mutex_lock(&s->lock); 255 256 while (nb_sectors > 0) { 257 int64_t block_offset = seek_to_sector(bs, sector_num); 258 if (block_offset < 0) { 259 ret = block_offset; 260 goto fail; 261 } 262 263 qemu_iovec_reset(&local_qiov); 264 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512); 265 266 if (block_offset > 0) { 267 ret = bdrv_co_preadv(bs->file, block_offset, 512, 268 &local_qiov, 0); 269 if (ret < 0) { 270 goto fail; 271 } 272 } else { 273 qemu_iovec_memset(&local_qiov, 0, 0, 512); 274 } 275 nb_sectors--; 276 sector_num++; 277 bytes_done += 512; 278 } 279 280 ret = 0; 281 fail: 282 qemu_co_mutex_unlock(&s->lock); 283 qemu_iovec_destroy(&local_qiov); 284 285 return ret; 286 } 287 288 static void bochs_close(BlockDriverState *bs) 289 { 290 BDRVBochsState *s = bs->opaque; 291 g_free(s->catalog_bitmap); 292 } 293 294 static BlockDriver bdrv_bochs = { 295 .format_name = "bochs", 296 .instance_size = sizeof(BDRVBochsState), 297 .bdrv_probe = bochs_probe, 298 .bdrv_open = bochs_open, 299 .bdrv_child_perm = bdrv_default_perms, 300 .bdrv_refresh_limits = bochs_refresh_limits, 301 .bdrv_co_preadv = bochs_co_preadv, 302 .bdrv_close = bochs_close, 303 .is_format = true, 304 }; 305 306 static void bdrv_bochs_init(void) 307 { 308 bdrv_register(&bdrv_bochs); 309 } 310 311 block_init(bdrv_bochs_init);