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 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, 109 false, errp); 110 if (!bs->file) { 111 return -EINVAL; 112 } 113 114 if (!bdrv_is_read_only(bs)) { 115 error_report("Opening bochs images without an explicit read-only=on " 116 "option is deprecated. Future versions will refuse to " 117 "open the image instead of automatically marking the " 118 "image read-only."); 119 ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */ 120 if (ret < 0) { 121 return ret; 122 } 123 } 124 125 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)); 126 if (ret < 0) { 127 return ret; 128 } 129 130 if (strcmp(bochs.magic, HEADER_MAGIC) || 131 strcmp(bochs.type, REDOLOG_TYPE) || 132 strcmp(bochs.subtype, GROWING_TYPE) || 133 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 134 (le32_to_cpu(bochs.version) != HEADER_V1))) { 135 error_setg(errp, "Image not in Bochs format"); 136 return -EINVAL; 137 } 138 139 if (le32_to_cpu(bochs.version) == HEADER_V1) { 140 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 141 } else { 142 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 143 } 144 145 /* Limit to 1M entries to avoid unbounded allocation. This is what is 146 * needed for the largest image that bximage can create (~8 TB). */ 147 s->catalog_size = le32_to_cpu(bochs.catalog); 148 if (s->catalog_size > 0x100000) { 149 error_setg(errp, "Catalog size is too large"); 150 return -EFBIG; 151 } 152 153 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 154 if (s->catalog_size && s->catalog_bitmap == NULL) { 155 error_setg(errp, "Could not allocate memory for catalog"); 156 return -ENOMEM; 157 } 158 159 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap, 160 s->catalog_size * 4); 161 if (ret < 0) { 162 goto fail; 163 } 164 165 for (i = 0; i < s->catalog_size; i++) 166 le32_to_cpus(&s->catalog_bitmap[i]); 167 168 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 169 170 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 171 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 172 173 s->extent_size = le32_to_cpu(bochs.extent); 174 if (s->extent_size < BDRV_SECTOR_SIZE) { 175 /* bximage actually never creates extents smaller than 4k */ 176 error_setg(errp, "Extent size must be at least 512"); 177 ret = -EINVAL; 178 goto fail; 179 } else if (!is_power_of_2(s->extent_size)) { 180 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 181 s->extent_size); 182 ret = -EINVAL; 183 goto fail; 184 } else if (s->extent_size > 0x800000) { 185 error_setg(errp, "Extent size %" PRIu32 " is too large", 186 s->extent_size); 187 ret = -EINVAL; 188 goto fail; 189 } 190 191 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 192 s->extent_size / BDRV_SECTOR_SIZE)) 193 { 194 error_setg(errp, "Catalog size is too small for this disk size"); 195 ret = -EINVAL; 196 goto fail; 197 } 198 199 qemu_co_mutex_init(&s->lock); 200 return 0; 201 202 fail: 203 g_free(s->catalog_bitmap); 204 return ret; 205 } 206 207 static void bochs_refresh_limits(BlockDriverState *bs, Error **errp) 208 { 209 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */ 210 } 211 212 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 213 { 214 BDRVBochsState *s = bs->opaque; 215 uint64_t offset = sector_num * 512; 216 uint64_t extent_index, extent_offset, bitmap_offset; 217 char bitmap_entry; 218 int ret; 219 220 // seek to sector 221 extent_index = offset / s->extent_size; 222 extent_offset = (offset % s->extent_size) / 512; 223 224 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 225 return 0; /* not allocated */ 226 } 227 228 bitmap_offset = s->data_offset + 229 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 230 (s->extent_blocks + s->bitmap_blocks)); 231 232 /* read in bitmap for current extent */ 233 ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 234 &bitmap_entry, 1); 235 if (ret < 0) { 236 return ret; 237 } 238 239 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 240 return 0; /* not allocated */ 241 } 242 243 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 244 } 245 246 static int coroutine_fn 247 bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, 248 QEMUIOVector *qiov, int flags) 249 { 250 BDRVBochsState *s = bs->opaque; 251 uint64_t sector_num = offset >> BDRV_SECTOR_BITS; 252 int nb_sectors = bytes >> BDRV_SECTOR_BITS; 253 uint64_t bytes_done = 0; 254 QEMUIOVector local_qiov; 255 int ret; 256 257 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0); 258 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0); 259 260 qemu_iovec_init(&local_qiov, qiov->niov); 261 qemu_co_mutex_lock(&s->lock); 262 263 while (nb_sectors > 0) { 264 int64_t block_offset = seek_to_sector(bs, sector_num); 265 if (block_offset < 0) { 266 ret = block_offset; 267 goto fail; 268 } 269 270 qemu_iovec_reset(&local_qiov); 271 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512); 272 273 if (block_offset > 0) { 274 ret = bdrv_co_preadv(bs->file, block_offset, 512, 275 &local_qiov, 0); 276 if (ret < 0) { 277 goto fail; 278 } 279 } else { 280 qemu_iovec_memset(&local_qiov, 0, 0, 512); 281 } 282 nb_sectors--; 283 sector_num++; 284 bytes_done += 512; 285 } 286 287 ret = 0; 288 fail: 289 qemu_co_mutex_unlock(&s->lock); 290 qemu_iovec_destroy(&local_qiov); 291 292 return ret; 293 } 294 295 static void bochs_close(BlockDriverState *bs) 296 { 297 BDRVBochsState *s = bs->opaque; 298 g_free(s->catalog_bitmap); 299 } 300 301 static BlockDriver bdrv_bochs = { 302 .format_name = "bochs", 303 .instance_size = sizeof(BDRVBochsState), 304 .bdrv_probe = bochs_probe, 305 .bdrv_open = bochs_open, 306 .bdrv_child_perm = bdrv_format_default_perms, 307 .bdrv_refresh_limits = bochs_refresh_limits, 308 .bdrv_co_preadv = bochs_co_preadv, 309 .bdrv_close = bochs_close, 310 }; 311 312 static void bdrv_bochs_init(void) 313 { 314 bdrv_register(&bdrv_bochs); 315 } 316 317 block_init(bdrv_bochs_init); 318