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 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 bs->read_only = 1; // no write support yet 108 bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */ 109 110 ret = bdrv_pread(bs->file->bs, 0, &bochs, sizeof(bochs)); 111 if (ret < 0) { 112 return ret; 113 } 114 115 if (strcmp(bochs.magic, HEADER_MAGIC) || 116 strcmp(bochs.type, REDOLOG_TYPE) || 117 strcmp(bochs.subtype, GROWING_TYPE) || 118 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 119 (le32_to_cpu(bochs.version) != HEADER_V1))) { 120 error_setg(errp, "Image not in Bochs format"); 121 return -EINVAL; 122 } 123 124 if (le32_to_cpu(bochs.version) == HEADER_V1) { 125 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 126 } else { 127 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 128 } 129 130 /* Limit to 1M entries to avoid unbounded allocation. This is what is 131 * needed for the largest image that bximage can create (~8 TB). */ 132 s->catalog_size = le32_to_cpu(bochs.catalog); 133 if (s->catalog_size > 0x100000) { 134 error_setg(errp, "Catalog size is too large"); 135 return -EFBIG; 136 } 137 138 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 139 if (s->catalog_size && s->catalog_bitmap == NULL) { 140 error_setg(errp, "Could not allocate memory for catalog"); 141 return -ENOMEM; 142 } 143 144 ret = bdrv_pread(bs->file->bs, le32_to_cpu(bochs.header), s->catalog_bitmap, 145 s->catalog_size * 4); 146 if (ret < 0) { 147 goto fail; 148 } 149 150 for (i = 0; i < s->catalog_size; i++) 151 le32_to_cpus(&s->catalog_bitmap[i]); 152 153 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 154 155 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 156 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 157 158 s->extent_size = le32_to_cpu(bochs.extent); 159 if (s->extent_size < BDRV_SECTOR_SIZE) { 160 /* bximage actually never creates extents smaller than 4k */ 161 error_setg(errp, "Extent size must be at least 512"); 162 ret = -EINVAL; 163 goto fail; 164 } else if (!is_power_of_2(s->extent_size)) { 165 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 166 s->extent_size); 167 ret = -EINVAL; 168 goto fail; 169 } else if (s->extent_size > 0x800000) { 170 error_setg(errp, "Extent size %" PRIu32 " is too large", 171 s->extent_size); 172 ret = -EINVAL; 173 goto fail; 174 } 175 176 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 177 s->extent_size / BDRV_SECTOR_SIZE)) 178 { 179 error_setg(errp, "Catalog size is too small for this disk size"); 180 ret = -EINVAL; 181 goto fail; 182 } 183 184 qemu_co_mutex_init(&s->lock); 185 return 0; 186 187 fail: 188 g_free(s->catalog_bitmap); 189 return ret; 190 } 191 192 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 193 { 194 BDRVBochsState *s = bs->opaque; 195 uint64_t offset = sector_num * 512; 196 uint64_t extent_index, extent_offset, bitmap_offset; 197 char bitmap_entry; 198 int ret; 199 200 // seek to sector 201 extent_index = offset / s->extent_size; 202 extent_offset = (offset % s->extent_size) / 512; 203 204 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 205 return 0; /* not allocated */ 206 } 207 208 bitmap_offset = s->data_offset + 209 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 210 (s->extent_blocks + s->bitmap_blocks)); 211 212 /* read in bitmap for current extent */ 213 ret = bdrv_pread(bs->file->bs, bitmap_offset + (extent_offset / 8), 214 &bitmap_entry, 1); 215 if (ret < 0) { 216 return ret; 217 } 218 219 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 220 return 0; /* not allocated */ 221 } 222 223 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 224 } 225 226 static int coroutine_fn 227 bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, 228 QEMUIOVector *qiov, int flags) 229 { 230 BDRVBochsState *s = bs->opaque; 231 uint64_t sector_num = offset >> BDRV_SECTOR_BITS; 232 int nb_sectors = bytes >> BDRV_SECTOR_BITS; 233 uint64_t bytes_done = 0; 234 QEMUIOVector local_qiov; 235 int ret; 236 237 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0); 238 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0); 239 240 qemu_iovec_init(&local_qiov, qiov->niov); 241 qemu_co_mutex_lock(&s->lock); 242 243 while (nb_sectors > 0) { 244 int64_t block_offset = seek_to_sector(bs, sector_num); 245 if (block_offset < 0) { 246 ret = block_offset; 247 goto fail; 248 } 249 250 qemu_iovec_reset(&local_qiov); 251 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512); 252 253 if (block_offset > 0) { 254 ret = bdrv_co_preadv(bs->file->bs, block_offset, 512, 255 &local_qiov, 0); 256 if (ret < 0) { 257 goto fail; 258 } 259 } else { 260 qemu_iovec_memset(&local_qiov, 0, 0, 512); 261 } 262 nb_sectors--; 263 sector_num++; 264 bytes_done += 512; 265 } 266 267 ret = 0; 268 fail: 269 qemu_co_mutex_unlock(&s->lock); 270 qemu_iovec_destroy(&local_qiov); 271 272 return ret; 273 } 274 275 static void bochs_close(BlockDriverState *bs) 276 { 277 BDRVBochsState *s = bs->opaque; 278 g_free(s->catalog_bitmap); 279 } 280 281 static BlockDriver bdrv_bochs = { 282 .format_name = "bochs", 283 .instance_size = sizeof(BDRVBochsState), 284 .bdrv_probe = bochs_probe, 285 .bdrv_open = bochs_open, 286 .bdrv_co_preadv = bochs_co_preadv, 287 .bdrv_close = bochs_close, 288 }; 289 290 static void bdrv_bochs_init(void) 291 { 292 bdrv_register(&bdrv_bochs); 293 } 294 295 block_init(bdrv_bochs_init); 296