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