1 /* 2 * Block driver for Hyper-V VHDX Images 3 * 4 * Copyright (c) 2013 Red Hat, Inc., 5 * 6 * Authors: 7 * Jeff Cody <jcody@redhat.com> 8 * 9 * This is based on the "VHDX Format Specification v1.00", published 8/25/2012 10 * by Microsoft: 11 * https://www.microsoft.com/en-us/download/details.aspx?id=34750 12 * 13 * This work is licensed under the terms of the GNU LGPL, version 2 or later. 14 * See the COPYING.LIB file in the top-level directory. 15 * 16 */ 17 18 #ifndef BLOCK_VHDX_H 19 #define BLOCK_VHDX_H 20 21 #define KiB (1 * 1024) 22 #define MiB (KiB * 1024) 23 #define GiB (MiB * 1024) 24 #define TiB ((uint64_t) GiB * 1024) 25 26 #define DEFAULT_LOG_SIZE 1048576 /* 1MiB */ 27 /* Structures and fields present in the VHDX file */ 28 29 /* The header section has the following blocks, 30 * each block is 64KB: 31 * 32 * _____________________________________________________________________________ 33 * | File Id. | Header 1 | Header 2 | Region Table | Reserved (768KB) | 34 * |----------|---------------|------------|--------------|--------------------| 35 * | | | | | | 36 * 0.........64KB...........128KB........192KB..........256KB................1MB 37 */ 38 39 #define VHDX_HEADER_BLOCK_SIZE (64 * 1024) 40 41 #define VHDX_FILE_ID_OFFSET 0 42 #define VHDX_HEADER1_OFFSET (VHDX_HEADER_BLOCK_SIZE * 1) 43 #define VHDX_HEADER2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 2) 44 #define VHDX_REGION_TABLE_OFFSET (VHDX_HEADER_BLOCK_SIZE * 3) 45 #define VHDX_REGION_TABLE2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 4) 46 47 #define VHDX_HEADER_SECTION_END (1 * MiB) 48 /* 49 * A note on the use of MS-GUID fields. For more details on the GUID, 50 * please see: https://en.wikipedia.org/wiki/Globally_unique_identifier. 51 * 52 * The VHDX specification only states that these are MS GUIDs, and which 53 * bytes are data1-data4. It makes no mention of what algorithm should be used 54 * to generate the GUID, nor what standard. However, looking at the specified 55 * known GUID fields, it appears the GUIDs are: 56 * Standard/DCE GUID type (noted by 10b in the MSB of byte 0 of .data4) 57 * Random algorithm (noted by 0x4XXX for .data3) 58 */ 59 60 /* ---- HEADER SECTION STRUCTURES ---- */ 61 62 /* These structures are ones that are defined in the VHDX specification 63 * document */ 64 65 #define VHDX_FILE_SIGNATURE 0x656C696678646876ULL /* "vhdxfile" in ASCII */ 66 typedef struct VHDXFileIdentifier { 67 uint64_t signature; /* "vhdxfile" in ASCII */ 68 uint16_t creator[256]; /* optional; utf-16 string to identify 69 the vhdx file creator. Diagnostic 70 only */ 71 } VHDXFileIdentifier; 72 73 74 /* the guid is a 16 byte unique ID - the definition for this used by 75 * Microsoft is not just 16 bytes though - it is a structure that is defined, 76 * so we need to follow it here so that endianness does not trip us up */ 77 78 typedef struct QEMU_PACKED MSGUID { 79 uint32_t data1; 80 uint16_t data2; 81 uint16_t data3; 82 uint8_t data4[8]; 83 } MSGUID; 84 85 #define guid_eq(a, b) \ 86 (memcmp(&(a), &(b), sizeof(MSGUID)) == 0) 87 88 #define VHDX_HEADER_SIZE (4 * 1024) /* although the vhdx_header struct in disk 89 is only 582 bytes, for purposes of crc 90 the header is the first 4KB of the 64KB 91 block */ 92 93 /* The full header is 4KB, although the actual header data is much smaller. 94 * But for the checksum calculation, it is over the entire 4KB structure, 95 * not just the defined portion of it */ 96 #define VHDX_HEADER_SIGNATURE 0x64616568 97 typedef struct QEMU_PACKED VHDXHeader { 98 uint32_t signature; /* "head" in ASCII */ 99 uint32_t checksum; /* CRC-32C hash of the whole header */ 100 uint64_t sequence_number; /* Seq number of this header. Each 101 VHDX file has 2 of these headers, 102 and only the header with the highest 103 sequence number is valid */ 104 MSGUID file_write_guid; /* 128 bit unique identifier. Must be 105 updated to new, unique value before 106 the first modification is made to 107 file */ 108 MSGUID data_write_guid; /* 128 bit unique identifier. Must be 109 updated to new, unique value before 110 the first modification is made to 111 visible data. Visbile data is 112 defined as: 113 - system & user metadata 114 - raw block data 115 - disk size 116 - any change that will 117 cause the virtual disk 118 sector read to differ 119 120 This does not need to change if 121 blocks are re-arranged */ 122 MSGUID log_guid; /* 128 bit unique identifier. If zero, 123 there is no valid log. If non-zero, 124 log entries with this guid are 125 valid. */ 126 uint16_t log_version; /* version of the log format. Must be 127 set to zero */ 128 uint16_t version; /* version of the vhdx file. Currently, 129 only supported version is "1" */ 130 uint32_t log_length; /* length of the log. Must be multiple 131 of 1MB */ 132 uint64_t log_offset; /* byte offset in the file of the log. 133 Must also be a multiple of 1MB */ 134 } VHDXHeader; 135 136 /* Header for the region table block */ 137 #define VHDX_REGION_SIGNATURE 0x69676572 /* "regi" in ASCII */ 138 typedef struct QEMU_PACKED VHDXRegionTableHeader { 139 uint32_t signature; /* "regi" in ASCII */ 140 uint32_t checksum; /* CRC-32C hash of the 64KB table */ 141 uint32_t entry_count; /* number of valid entries */ 142 uint32_t reserved; 143 } VHDXRegionTableHeader; 144 145 /* Individual region table entry. There may be a maximum of 2047 of these 146 * 147 * There are two known region table properties. Both are required. 148 * BAT (block allocation table): 2DC27766F62342009D64115E9BFD4A08 149 * Metadata: 8B7CA20647904B9AB8FE575F050F886E 150 */ 151 #define VHDX_REGION_ENTRY_REQUIRED 0x01 /* if set, parser must understand 152 this entry in order to open 153 file */ 154 typedef struct QEMU_PACKED VHDXRegionTableEntry { 155 MSGUID guid; /* 128-bit unique identifier */ 156 uint64_t file_offset; /* offset of the object in the file. 157 Must be multiple of 1MB */ 158 uint32_t length; /* length, in bytes, of the object */ 159 uint32_t data_bits; 160 } VHDXRegionTableEntry; 161 162 163 /* ---- LOG ENTRY STRUCTURES ---- */ 164 #define VHDX_LOG_MIN_SIZE (1024 * 1024) 165 #define VHDX_LOG_SECTOR_SIZE 4096 166 #define VHDX_LOG_HDR_SIZE 64 167 #define VHDX_LOG_SIGNATURE 0x65676f6c 168 typedef struct QEMU_PACKED VHDXLogEntryHeader { 169 uint32_t signature; /* "loge" in ASCII */ 170 uint32_t checksum; /* CRC-32C hash of the 64KB table */ 171 uint32_t entry_length; /* length in bytes, multiple of 1MB */ 172 uint32_t tail; /* byte offset of first log entry of a 173 seq, where this entry is the last 174 entry */ 175 uint64_t sequence_number; /* incremented with each log entry. 176 May not be zero. */ 177 uint32_t descriptor_count; /* number of descriptors in this log 178 entry, must be >= 0 */ 179 uint32_t reserved; 180 MSGUID log_guid; /* value of the log_guid from 181 vhdx_header. If not found in 182 vhdx_header, it is invalid */ 183 uint64_t flushed_file_offset; /* see spec for full details - this 184 should be vhdx file size in bytes */ 185 uint64_t last_file_offset; /* size in bytes that all allocated 186 file structures fit into */ 187 } VHDXLogEntryHeader; 188 189 #define VHDX_LOG_DESC_SIZE 32 190 #define VHDX_LOG_DESC_SIGNATURE 0x63736564 191 #define VHDX_LOG_ZERO_SIGNATURE 0x6f72657a 192 typedef struct QEMU_PACKED VHDXLogDescriptor { 193 uint32_t signature; /* "zero" or "desc" in ASCII */ 194 union { 195 uint32_t reserved; /* zero desc */ 196 uint32_t trailing_bytes; /* data desc: bytes 4092-4096 of the 197 data sector */ 198 }; 199 union { 200 uint64_t zero_length; /* zero desc: length of the section to 201 zero */ 202 uint64_t leading_bytes; /* data desc: bytes 0-7 of the data 203 sector */ 204 }; 205 uint64_t file_offset; /* file offset to write zeros - multiple 206 of 4kB */ 207 uint64_t sequence_number; /* must match same field in 208 vhdx_log_entry_header */ 209 } VHDXLogDescriptor; 210 211 #define VHDX_LOG_DATA_SIGNATURE 0x61746164 212 typedef struct QEMU_PACKED VHDXLogDataSector { 213 uint32_t data_signature; /* "data" in ASCII */ 214 uint32_t sequence_high; /* 4 MSB of 8 byte sequence_number */ 215 uint8_t data[4084]; /* raw data, bytes 8-4091 (inclusive). 216 see the data descriptor field for the 217 other mising bytes */ 218 uint32_t sequence_low; /* 4 LSB of 8 byte sequence_number */ 219 } VHDXLogDataSector; 220 221 222 223 /* block states - different state values depending on whether it is a 224 * payload block, or a sector block. */ 225 226 #define PAYLOAD_BLOCK_NOT_PRESENT 0 227 #define PAYLOAD_BLOCK_UNDEFINED 1 228 #define PAYLOAD_BLOCK_ZERO 2 229 #define PAYLOAD_BLOCK_UNMAPPED 5 230 #define PAYLOAD_BLOCK_FULLY_PRESENT 6 231 #define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7 232 233 #define SB_BLOCK_NOT_PRESENT 0 234 #define SB_BLOCK_PRESENT 6 235 236 /* per the spec */ 237 #define VHDX_MAX_SECTORS_PER_BLOCK (1 << 23) 238 239 /* upper 44 bits are the file offset in 1MB units lower 3 bits are the state 240 other bits are reserved */ 241 #define VHDX_BAT_STATE_BIT_MASK 0x07 242 #define VHDX_BAT_FILE_OFF_MASK 0xFFFFFFFFFFF00000ULL /* upper 44 bits */ 243 typedef uint64_t VHDXBatEntry; 244 245 /* ---- METADATA REGION STRUCTURES ---- */ 246 247 #define VHDX_METADATA_ENTRY_SIZE 32 248 #define VHDX_METADATA_MAX_ENTRIES 2047 /* not including the header */ 249 #define VHDX_METADATA_TABLE_MAX_SIZE \ 250 (VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1)) 251 #define VHDX_METADATA_SIGNATURE 0x617461646174656DULL /* "metadata" in ASCII */ 252 typedef struct QEMU_PACKED VHDXMetadataTableHeader { 253 uint64_t signature; /* "metadata" in ASCII */ 254 uint16_t reserved; 255 uint16_t entry_count; /* number table entries. <= 2047 */ 256 uint32_t reserved2[5]; 257 } VHDXMetadataTableHeader; 258 259 #define VHDX_META_FLAGS_IS_USER 0x01 /* max 1024 entries */ 260 #define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02 /* virtual disk metadata if set, 261 otherwise file metdata */ 262 #define VHDX_META_FLAGS_IS_REQUIRED 0x04 /* parse must understand this 263 entry to open the file */ 264 typedef struct QEMU_PACKED VHDXMetadataTableEntry { 265 MSGUID item_id; /* 128-bit identifier for metadata */ 266 uint32_t offset; /* byte offset of the metadata. At 267 least 64kB. Relative to start of 268 metadata region */ 269 /* note: if length = 0, so is offset */ 270 uint32_t length; /* length of metadata. <= 1MB. */ 271 uint32_t data_bits; /* least-significant 3 bits are flags, 272 the rest are reserved (see above) */ 273 uint32_t reserved2; 274 } VHDXMetadataTableEntry; 275 276 #define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01 /* Do not change any blocks to 277 be BLOCK_NOT_PRESENT. 278 If set indicates a fixed 279 size VHDX file */ 280 #define VHDX_PARAMS_HAS_PARENT 0x02 /* has parent / backing file */ 281 #define VHDX_BLOCK_SIZE_MIN (1 * MiB) 282 #define VHDX_BLOCK_SIZE_MAX (256 * MiB) 283 typedef struct QEMU_PACKED VHDXFileParameters { 284 uint32_t block_size; /* size of each payload block, always 285 power of 2, <= 256MB and >= 1MB. */ 286 uint32_t data_bits; /* least-significant 2 bits are flags, 287 the rest are reserved (see above) */ 288 } VHDXFileParameters; 289 290 #define VHDX_MAX_IMAGE_SIZE ((uint64_t) 64 * TiB) 291 typedef struct QEMU_PACKED VHDXVirtualDiskSize { 292 uint64_t virtual_disk_size; /* Size of the virtual disk, in bytes. 293 Must be multiple of the sector size, 294 max of 64TB */ 295 } VHDXVirtualDiskSize; 296 297 typedef struct QEMU_PACKED VHDXPage83Data { 298 MSGUID page_83_data; /* unique id for scsi devices that 299 support page 0x83 */ 300 } VHDXPage83Data; 301 302 typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize { 303 uint32_t logical_sector_size; /* virtual disk sector size (in bytes). 304 Can only be 512 or 4096 bytes */ 305 } VHDXVirtualDiskLogicalSectorSize; 306 307 typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize { 308 uint32_t physical_sector_size; /* physical sector size (in bytes). 309 Can only be 512 or 4096 bytes */ 310 } VHDXVirtualDiskPhysicalSectorSize; 311 312 typedef struct QEMU_PACKED VHDXParentLocatorHeader { 313 MSGUID locator_type; /* type of the parent virtual disk. */ 314 uint16_t reserved; 315 uint16_t key_value_count; /* number of key/value pairs for this 316 locator */ 317 } VHDXParentLocatorHeader; 318 319 /* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */ 320 typedef struct QEMU_PACKED VHDXParentLocatorEntry { 321 uint32_t key_offset; /* offset in metadata for key, > 0 */ 322 uint32_t value_offset; /* offset in metadata for value, >0 */ 323 uint16_t key_length; /* length of entry key, > 0 */ 324 uint16_t value_length; /* length of entry value, > 0 */ 325 } VHDXParentLocatorEntry; 326 327 328 /* ----- END VHDX SPECIFICATION STRUCTURES ---- */ 329 330 typedef struct VHDXMetadataEntries { 331 VHDXMetadataTableEntry file_parameters_entry; 332 VHDXMetadataTableEntry virtual_disk_size_entry; 333 VHDXMetadataTableEntry page83_data_entry; 334 VHDXMetadataTableEntry logical_sector_size_entry; 335 VHDXMetadataTableEntry phys_sector_size_entry; 336 VHDXMetadataTableEntry parent_locator_entry; 337 uint16_t present; 338 } VHDXMetadataEntries; 339 340 typedef struct VHDXLogEntries { 341 uint64_t offset; 342 uint64_t length; 343 uint32_t write; 344 uint32_t read; 345 VHDXLogEntryHeader *hdr; 346 void *desc_buffer; 347 uint64_t sequence; 348 uint32_t tail; 349 } VHDXLogEntries; 350 351 typedef struct VHDXRegionEntry { 352 uint64_t start; 353 uint64_t end; 354 QLIST_ENTRY(VHDXRegionEntry) entries; 355 } VHDXRegionEntry; 356 357 typedef struct BDRVVHDXState { 358 CoMutex lock; 359 360 int curr_header; 361 VHDXHeader *headers[2]; 362 363 VHDXRegionTableHeader rt; 364 VHDXRegionTableEntry bat_rt; /* region table for the BAT */ 365 VHDXRegionTableEntry metadata_rt; /* region table for the metadata */ 366 367 VHDXMetadataTableHeader metadata_hdr; 368 VHDXMetadataEntries metadata_entries; 369 370 VHDXFileParameters params; 371 uint32_t block_size; 372 uint32_t block_size_bits; 373 uint32_t sectors_per_block; 374 uint32_t sectors_per_block_bits; 375 376 uint64_t virtual_disk_size; 377 uint32_t logical_sector_size; 378 uint32_t physical_sector_size; 379 380 uint64_t chunk_ratio; 381 uint32_t chunk_ratio_bits; 382 uint32_t logical_sector_size_bits; 383 384 uint32_t bat_entries; 385 VHDXBatEntry *bat; 386 uint64_t bat_offset; 387 388 bool first_visible_write; 389 MSGUID session_guid; 390 391 VHDXLogEntries log; 392 393 VHDXParentLocatorHeader parent_header; 394 VHDXParentLocatorEntry *parent_entries; 395 396 Error *migration_blocker; 397 398 bool log_replayed_on_open; 399 400 QLIST_HEAD(VHDXRegionHead, VHDXRegionEntry) regions; 401 } BDRVVHDXState; 402 403 void vhdx_guid_generate(MSGUID *guid); 404 405 int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw, 406 MSGUID *log_guid); 407 408 uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset); 409 uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size, 410 int crc_offset); 411 412 bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset); 413 414 int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed, 415 Error **errp); 416 417 int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s, 418 void *data, uint32_t length, uint64_t offset); 419 420 static inline void leguid_to_cpus(MSGUID *guid) 421 { 422 le32_to_cpus(&guid->data1); 423 le16_to_cpus(&guid->data2); 424 le16_to_cpus(&guid->data3); 425 } 426 427 static inline void cpu_to_leguids(MSGUID *guid) 428 { 429 cpu_to_le32s(&guid->data1); 430 cpu_to_le16s(&guid->data2); 431 cpu_to_le16s(&guid->data3); 432 } 433 434 void vhdx_header_le_import(VHDXHeader *h); 435 void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h); 436 void vhdx_log_desc_le_import(VHDXLogDescriptor *d); 437 void vhdx_log_desc_le_export(VHDXLogDescriptor *d); 438 void vhdx_log_data_le_import(VHDXLogDataSector *d); 439 void vhdx_log_data_le_export(VHDXLogDataSector *d); 440 void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr); 441 void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr); 442 void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr); 443 void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr); 444 void vhdx_region_entry_le_import(VHDXRegionTableEntry *e); 445 void vhdx_region_entry_le_export(VHDXRegionTableEntry *e); 446 void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr); 447 void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr); 448 void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e); 449 void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e); 450 int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s); 451 452 #endif 453