| 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-io.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 | GLOBAL_STATE_CODE(); |
| 109 | |
| 110 | /* No write support yet */ |
| 111 | bdrv_graph_rdlock_main_loop(); |
| 112 | ret = bdrv_apply_auto_read_only(bs, NULL, errp); |
| 113 | bdrv_graph_rdunlock_main_loop(); |
| 114 | if (ret < 0) { |
| 115 | return ret; |
| 116 | } |
| 117 | |
| 118 | ret = bdrv_open_file_child(NULL, options, "file", bs, errp); |
| 119 | if (ret < 0) { |
| 120 | return ret; |
| 121 | } |
| 122 | |
| 123 | GRAPH_RDLOCK_GUARD_MAINLOOP(); |
| 124 | |
| 125 | ret = bdrv_pread(bs->file, 0, sizeof(bochs), &bochs, 0); |
| 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_size * 4, |
| 160 | s->catalog_bitmap, 0); |
| 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 coroutine_fn GRAPH_RDLOCK |
| 213 | seek_to_sector(BlockDriverState *bs, int64_t sector_num) |
| 214 | { |
| 215 | BDRVBochsState *s = bs->opaque; |
| 216 | uint64_t offset = sector_num * 512; |
| 217 | uint64_t extent_index, extent_offset, bitmap_offset; |
| 218 | char bitmap_entry; |
| 219 | int ret; |
| 220 | |
| 221 | // seek to sector |
| 222 | extent_index = offset / s->extent_size; |
| 223 | extent_offset = (offset % s->extent_size) / 512; |
| 224 | |
| 225 | if (s->catalog_bitmap[extent_index] == 0xffffffff) { |
| 226 | return 0; /* not allocated */ |
| 227 | } |
| 228 | |
| 229 | bitmap_offset = s->data_offset + |
| 230 | (512 * (uint64_t) s->catalog_bitmap[extent_index] * |
| 231 | (s->extent_blocks + s->bitmap_blocks)); |
| 232 | |
| 233 | /* read in bitmap for current extent */ |
| 234 | ret = bdrv_co_pread(bs->file, bitmap_offset + (extent_offset / 8), 1, |
| 235 | &bitmap_entry, 0); |
| 236 | if (ret < 0) { |
| 237 | return ret; |
| 238 | } |
| 239 | |
| 240 | if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { |
| 241 | return 0; /* not allocated */ |
| 242 | } |
| 243 | |
| 244 | return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); |
| 245 | } |
| 246 | |
| 247 | static int coroutine_fn GRAPH_RDLOCK |
| 248 | bochs_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 249 | QEMUIOVector *qiov, BdrvRequestFlags flags) |
| 250 | { |
| 251 | BDRVBochsState *s = bs->opaque; |
| 252 | uint64_t sector_num = offset >> BDRV_SECTOR_BITS; |
| 253 | int nb_sectors = bytes >> BDRV_SECTOR_BITS; |
| 254 | uint64_t bytes_done = 0; |
| 255 | QEMUIOVector local_qiov; |
| 256 | int ret; |
| 257 | |
| 258 | assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); |
| 259 | assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); |
| 260 | |
| 261 | qemu_iovec_init(&local_qiov, qiov->niov); |
| 262 | qemu_co_mutex_lock(&s->lock); |
| 263 | |
| 264 | while (nb_sectors > 0) { |
| 265 | int64_t block_offset = seek_to_sector(bs, sector_num); |
| 266 | if (block_offset < 0) { |
| 267 | ret = block_offset; |
| 268 | goto fail; |
| 269 | } |
| 270 | |
| 271 | qemu_iovec_reset(&local_qiov); |
| 272 | qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512); |
| 273 | |
| 274 | if (block_offset > 0) { |
| 275 | ret = bdrv_co_preadv(bs->file, block_offset, 512, |
| 276 | &local_qiov, 0); |
| 277 | if (ret < 0) { |
| 278 | goto fail; |
| 279 | } |
| 280 | } else { |
| 281 | qemu_iovec_memset(&local_qiov, 0, 0, 512); |
| 282 | } |
| 283 | nb_sectors--; |
| 284 | sector_num++; |
| 285 | bytes_done += 512; |
| 286 | } |
| 287 | |
| 288 | ret = 0; |
| 289 | fail: |
| 290 | qemu_co_mutex_unlock(&s->lock); |
| 291 | qemu_iovec_destroy(&local_qiov); |
| 292 | |
| 293 | return ret; |
| 294 | } |
| 295 | |
| 296 | static void bochs_close(BlockDriverState *bs) |
| 297 | { |
| 298 | BDRVBochsState *s = bs->opaque; |
| 299 | g_free(s->catalog_bitmap); |
| 300 | } |
| 301 | |
| 302 | static BlockDriver bdrv_bochs = { |
| 303 | .format_name = "bochs", |
| 304 | .instance_size = sizeof(BDRVBochsState), |
| 305 | .bdrv_probe = bochs_probe, |
| 306 | .bdrv_open = bochs_open, |
| 307 | .bdrv_child_perm = bdrv_default_perms, |
| 308 | .bdrv_refresh_limits = bochs_refresh_limits, |
| 309 | .bdrv_co_preadv = bochs_co_preadv, |
| 310 | .bdrv_close = bochs_close, |
| 311 | .is_format = true, |
| 312 | }; |
| 313 | |
| 314 | static void bdrv_bochs_init(void) |
| 315 | { |
| 316 | bdrv_register(&bdrv_bochs); |
| 317 | } |
| 318 | |
| 319 | block_init(bdrv_bochs_init); |