vhdx.h (19746B)
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#include "qemu/units.h" 21 22#define DEFAULT_LOG_SIZE 1048576 /* 1MiB */ 23/* Note: can't use 1 * MiB, because it's passed to stringify() */ 24 25/* Structures and fields present in the VHDX file */ 26 27/* The header section has the following blocks, 28 * each block is 64KB: 29 * 30 * _____________________________________________________________________________ 31 * | File Id. | Header 1 | Header 2 | Region Table | Reserved (768KB) | 32 * |----------|---------------|------------|--------------|--------------------| 33 * | | | | | | 34 * 0.........64KB...........128KB........192KB..........256KB................1MB 35 */ 36 37#define VHDX_HEADER_BLOCK_SIZE (64 * KiB) 38 39#define VHDX_FILE_ID_OFFSET 0 40#define VHDX_HEADER1_OFFSET (VHDX_HEADER_BLOCK_SIZE * 1) 41#define VHDX_HEADER2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 2) 42#define VHDX_REGION_TABLE_OFFSET (VHDX_HEADER_BLOCK_SIZE * 3) 43#define VHDX_REGION_TABLE2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 4) 44 45#define VHDX_HEADER_SECTION_END (1 * MiB) 46/* 47 * A note on the use of MS-GUID fields. For more details on the GUID, 48 * please see: https://en.wikipedia.org/wiki/Globally_unique_identifier. 49 * 50 * The VHDX specification only states that these are MS GUIDs, and which 51 * bytes are data1-data4. It makes no mention of what algorithm should be used 52 * to generate the GUID, nor what standard. However, looking at the specified 53 * known GUID fields, it appears the GUIDs are: 54 * Standard/DCE GUID type (noted by 10b in the MSB of byte 0 of .data4) 55 * Random algorithm (noted by 0x4XXX for .data3) 56 */ 57 58/* ---- HEADER SECTION STRUCTURES ---- */ 59 60/* These structures are ones that are defined in the VHDX specification 61 * document */ 62 63#define VHDX_FILE_SIGNATURE 0x656C696678646876ULL /* "vhdxfile" in ASCII */ 64typedef struct VHDXFileIdentifier { 65 uint64_t signature; /* "vhdxfile" in ASCII */ 66 uint16_t creator[256]; /* optional; utf-16 string to identify 67 the vhdx file creator. Diagnostic 68 only */ 69} VHDXFileIdentifier; 70 71 72/* the guid is a 16 byte unique ID - the definition for this used by 73 * Microsoft is not just 16 bytes though - it is a structure that is defined, 74 * so we need to follow it here so that endianness does not trip us up */ 75 76typedef struct QEMU_PACKED MSGUID { 77 uint32_t data1; 78 uint16_t data2; 79 uint16_t data3; 80 uint8_t data4[8]; 81} MSGUID; 82 83#define guid_eq(a, b) \ 84 (memcmp(&(a), &(b), sizeof(MSGUID)) == 0) 85 86#define VHDX_HEADER_SIZE (4 * KiB) /* although the vhdx_header struct in disk 87 is only 582 bytes, for purposes of crc 88 the header is the first 4KB of the 64KB 89 block */ 90 91/* The full header is 4KB, although the actual header data is much smaller. 92 * But for the checksum calculation, it is over the entire 4KB structure, 93 * not just the defined portion of it */ 94#define VHDX_HEADER_SIGNATURE 0x64616568 95typedef struct QEMU_PACKED VHDXHeader { 96 uint32_t signature; /* "head" in ASCII */ 97 uint32_t checksum; /* CRC-32C hash of the whole header */ 98 uint64_t sequence_number; /* Seq number of this header. Each 99 VHDX file has 2 of these headers, 100 and only the header with the highest 101 sequence number is valid */ 102 MSGUID file_write_guid; /* 128 bit unique identifier. Must be 103 updated to new, unique value before 104 the first modification is made to 105 file */ 106 MSGUID data_write_guid; /* 128 bit unique identifier. Must be 107 updated to new, unique value before 108 the first modification is made to 109 visible data. Visbile data is 110 defined as: 111 - system & user metadata 112 - raw block data 113 - disk size 114 - any change that will 115 cause the virtual disk 116 sector read to differ 117 118 This does not need to change if 119 blocks are re-arranged */ 120 MSGUID log_guid; /* 128 bit unique identifier. If zero, 121 there is no valid log. If non-zero, 122 log entries with this guid are 123 valid. */ 124 uint16_t log_version; /* version of the log format. Must be 125 set to zero */ 126 uint16_t version; /* version of the vhdx file. Currently, 127 only supported version is "1" */ 128 uint32_t log_length; /* length of the log. Must be multiple 129 of 1MB */ 130 uint64_t log_offset; /* byte offset in the file of the log. 131 Must also be a multiple of 1MB */ 132} VHDXHeader; 133 134/* Header for the region table block */ 135#define VHDX_REGION_SIGNATURE 0x69676572 /* "regi" in ASCII */ 136typedef struct QEMU_PACKED VHDXRegionTableHeader { 137 uint32_t signature; /* "regi" in ASCII */ 138 uint32_t checksum; /* CRC-32C hash of the 64KB table */ 139 uint32_t entry_count; /* number of valid entries */ 140 uint32_t reserved; 141} VHDXRegionTableHeader; 142 143/* Individual region table entry. There may be a maximum of 2047 of these 144 * 145 * There are two known region table properties. Both are required. 146 * BAT (block allocation table): 2DC27766F62342009D64115E9BFD4A08 147 * Metadata: 8B7CA20647904B9AB8FE575F050F886E 148 */ 149#define VHDX_REGION_ENTRY_REQUIRED 0x01 /* if set, parser must understand 150 this entry in order to open 151 file */ 152typedef struct QEMU_PACKED VHDXRegionTableEntry { 153 MSGUID guid; /* 128-bit unique identifier */ 154 uint64_t file_offset; /* offset of the object in the file. 155 Must be multiple of 1MB */ 156 uint32_t length; /* length, in bytes, of the object */ 157 uint32_t data_bits; 158} VHDXRegionTableEntry; 159 160 161/* ---- LOG ENTRY STRUCTURES ---- */ 162#define VHDX_LOG_MIN_SIZE (1 * MiB) 163#define VHDX_LOG_SECTOR_SIZE (4 * KiB) 164#define VHDX_LOG_HDR_SIZE 64 165#define VHDX_LOG_SIGNATURE 0x65676f6c 166typedef struct QEMU_PACKED VHDXLogEntryHeader { 167 uint32_t signature; /* "loge" in ASCII */ 168 uint32_t checksum; /* CRC-32C hash of the 64KB table */ 169 uint32_t entry_length; /* length in bytes, multiple of 1MB */ 170 uint32_t tail; /* byte offset of first log entry of a 171 seq, where this entry is the last 172 entry */ 173 uint64_t sequence_number; /* incremented with each log entry. 174 May not be zero. */ 175 uint32_t descriptor_count; /* number of descriptors in this log 176 entry, must be >= 0 */ 177 uint32_t reserved; 178 MSGUID log_guid; /* value of the log_guid from 179 vhdx_header. If not found in 180 vhdx_header, it is invalid */ 181 uint64_t flushed_file_offset; /* see spec for full details - this 182 should be vhdx file size in bytes */ 183 uint64_t last_file_offset; /* size in bytes that all allocated 184 file structures fit into */ 185} VHDXLogEntryHeader; 186 187#define VHDX_LOG_DESC_SIZE 32 188#define VHDX_LOG_DESC_SIGNATURE 0x63736564 189#define VHDX_LOG_ZERO_SIGNATURE 0x6f72657a 190typedef struct QEMU_PACKED VHDXLogDescriptor { 191 uint32_t signature; /* "zero" or "desc" in ASCII */ 192 union { 193 uint32_t reserved; /* zero desc */ 194 uint32_t trailing_bytes; /* data desc: bytes 4092-4096 of the 195 data sector */ 196 }; 197 union { 198 uint64_t zero_length; /* zero desc: length of the section to 199 zero */ 200 uint64_t leading_bytes; /* data desc: bytes 0-7 of the data 201 sector */ 202 }; 203 uint64_t file_offset; /* file offset to write zeros - multiple 204 of 4kB */ 205 uint64_t sequence_number; /* must match same field in 206 vhdx_log_entry_header */ 207} VHDXLogDescriptor; 208 209#define VHDX_LOG_DATA_SIGNATURE 0x61746164 210typedef struct QEMU_PACKED VHDXLogDataSector { 211 uint32_t data_signature; /* "data" in ASCII */ 212 uint32_t sequence_high; /* 4 MSB of 8 byte sequence_number */ 213 uint8_t data[4084]; /* raw data, bytes 8-4091 (inclusive). 214 see the data descriptor field for the 215 other mising bytes */ 216 uint32_t sequence_low; /* 4 LSB of 8 byte sequence_number */ 217} VHDXLogDataSector; 218 219 220 221/* block states - different state values depending on whether it is a 222 * payload block, or a sector block. */ 223 224#define PAYLOAD_BLOCK_NOT_PRESENT 0 225#define PAYLOAD_BLOCK_UNDEFINED 1 226#define PAYLOAD_BLOCK_ZERO 2 227#define PAYLOAD_BLOCK_UNMAPPED 3 228#define PAYLOAD_BLOCK_UNMAPPED_v095 5 229#define PAYLOAD_BLOCK_FULLY_PRESENT 6 230#define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7 231 232#define SB_BLOCK_NOT_PRESENT 0 233#define SB_BLOCK_PRESENT 6 234 235/* per the spec */ 236#define VHDX_MAX_SECTORS_PER_BLOCK (1 << 23) 237 238/* upper 44 bits are the file offset in 1MB units lower 3 bits are the state 239 other bits are reserved */ 240#define VHDX_BAT_STATE_BIT_MASK 0x07 241#define VHDX_BAT_FILE_OFF_MASK 0xFFFFFFFFFFF00000ULL /* upper 44 bits */ 242typedef uint64_t VHDXBatEntry; 243 244/* ---- METADATA REGION STRUCTURES ---- */ 245 246#define VHDX_METADATA_ENTRY_SIZE 32 247#define VHDX_METADATA_MAX_ENTRIES 2047 /* not including the header */ 248#define VHDX_METADATA_TABLE_MAX_SIZE \ 249 (VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1)) 250#define VHDX_METADATA_SIGNATURE 0x617461646174656DULL /* "metadata" in ASCII */ 251typedef struct QEMU_PACKED VHDXMetadataTableHeader { 252 uint64_t signature; /* "metadata" in ASCII */ 253 uint16_t reserved; 254 uint16_t entry_count; /* number table entries. <= 2047 */ 255 uint32_t reserved2[5]; 256} VHDXMetadataTableHeader; 257 258#define VHDX_META_FLAGS_IS_USER 0x01 /* max 1024 entries */ 259#define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02 /* virtual disk metadata if set, 260 otherwise file metdata */ 261#define VHDX_META_FLAGS_IS_REQUIRED 0x04 /* parse must understand this 262 entry to open the file */ 263typedef struct QEMU_PACKED VHDXMetadataTableEntry { 264 MSGUID item_id; /* 128-bit identifier for metadata */ 265 uint32_t offset; /* byte offset of the metadata. At 266 least 64kB. Relative to start of 267 metadata region */ 268 /* note: if length = 0, so is offset */ 269 uint32_t length; /* length of metadata. <= 1MB. */ 270 uint32_t data_bits; /* least-significant 3 bits are flags, 271 the rest are reserved (see above) */ 272 uint32_t reserved2; 273} VHDXMetadataTableEntry; 274 275#define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01 /* Do not change any blocks to 276 be BLOCK_NOT_PRESENT. 277 If set indicates a fixed 278 size VHDX file */ 279#define VHDX_PARAMS_HAS_PARENT 0x02 /* has parent / backing file */ 280#define VHDX_BLOCK_SIZE_MIN (1 * MiB) 281#define VHDX_BLOCK_SIZE_MAX (256 * MiB) 282typedef struct QEMU_PACKED VHDXFileParameters { 283 uint32_t block_size; /* size of each payload block, always 284 power of 2, <= 256MB and >= 1MB. */ 285 uint32_t data_bits; /* least-significant 2 bits are flags, 286 the rest are reserved (see above) */ 287} VHDXFileParameters; 288 289#define VHDX_MAX_IMAGE_SIZE ((uint64_t) 64 * TiB) 290typedef struct QEMU_PACKED VHDXVirtualDiskSize { 291 uint64_t virtual_disk_size; /* Size of the virtual disk, in bytes. 292 Must be multiple of the sector size, 293 max of 64TB */ 294} VHDXVirtualDiskSize; 295 296typedef struct QEMU_PACKED VHDXPage83Data { 297 MSGUID page_83_data; /* unique id for scsi devices that 298 support page 0x83 */ 299} VHDXPage83Data; 300 301typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize { 302 uint32_t logical_sector_size; /* virtual disk sector size (in bytes). 303 Can only be 512 or 4096 bytes */ 304} VHDXVirtualDiskLogicalSectorSize; 305 306typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize { 307 uint32_t physical_sector_size; /* physical sector size (in bytes). 308 Can only be 512 or 4096 bytes */ 309} VHDXVirtualDiskPhysicalSectorSize; 310 311typedef struct QEMU_PACKED VHDXParentLocatorHeader { 312 MSGUID locator_type; /* type of the parent virtual disk. */ 313 uint16_t reserved; 314 uint16_t key_value_count; /* number of key/value pairs for this 315 locator */ 316} VHDXParentLocatorHeader; 317 318/* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */ 319typedef struct QEMU_PACKED VHDXParentLocatorEntry { 320 uint32_t key_offset; /* offset in metadata for key, > 0 */ 321 uint32_t value_offset; /* offset in metadata for value, >0 */ 322 uint16_t key_length; /* length of entry key, > 0 */ 323 uint16_t value_length; /* length of entry value, > 0 */ 324} VHDXParentLocatorEntry; 325 326 327/* ----- END VHDX SPECIFICATION STRUCTURES ---- */ 328 329typedef struct VHDXMetadataEntries { 330 VHDXMetadataTableEntry file_parameters_entry; 331 VHDXMetadataTableEntry virtual_disk_size_entry; 332 VHDXMetadataTableEntry page83_data_entry; 333 VHDXMetadataTableEntry logical_sector_size_entry; 334 VHDXMetadataTableEntry phys_sector_size_entry; 335 VHDXMetadataTableEntry parent_locator_entry; 336 uint16_t present; 337} VHDXMetadataEntries; 338 339typedef struct VHDXLogEntries { 340 uint64_t offset; 341 uint64_t length; 342 uint32_t write; 343 uint32_t read; 344 VHDXLogEntryHeader *hdr; 345 void *desc_buffer; 346 uint64_t sequence; 347 uint32_t tail; 348} VHDXLogEntries; 349 350typedef struct VHDXRegionEntry { 351 uint64_t start; 352 uint64_t end; 353 QLIST_ENTRY(VHDXRegionEntry) entries; 354} VHDXRegionEntry; 355 356typedef struct BDRVVHDXState { 357 CoMutex lock; 358 359 int curr_header; 360 VHDXHeader *headers[2]; 361 362 VHDXRegionTableHeader rt; 363 VHDXRegionTableEntry bat_rt; /* region table for the BAT */ 364 VHDXRegionTableEntry metadata_rt; /* region table for the metadata */ 365 366 VHDXMetadataTableHeader metadata_hdr; 367 VHDXMetadataEntries metadata_entries; 368 369 VHDXFileParameters params; 370 uint32_t block_size; 371 uint32_t block_size_bits; 372 uint32_t sectors_per_block; 373 uint32_t sectors_per_block_bits; 374 375 uint64_t virtual_disk_size; 376 uint32_t logical_sector_size; 377 uint32_t physical_sector_size; 378 379 uint64_t chunk_ratio; 380 uint32_t chunk_ratio_bits; 381 uint32_t logical_sector_size_bits; 382 383 uint32_t bat_entries; 384 VHDXBatEntry *bat; 385 uint64_t bat_offset; 386 387 bool first_visible_write; 388 MSGUID session_guid; 389 390 VHDXLogEntries log; 391 392 VHDXParentLocatorHeader parent_header; 393 VHDXParentLocatorEntry *parent_entries; 394 395 Error *migration_blocker; 396 397 bool log_replayed_on_open; 398 399 QLIST_HEAD(, VHDXRegionEntry) regions; 400} BDRVVHDXState; 401 402void vhdx_guid_generate(MSGUID *guid); 403 404int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw, 405 MSGUID *log_guid); 406 407uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset); 408uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size, 409 int crc_offset); 410 411bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset); 412 413int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed, 414 Error **errp); 415 416int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s, 417 void *data, uint32_t length, uint64_t offset); 418 419static inline void leguid_to_cpus(MSGUID *guid) 420{ 421 guid->data1 = le32_to_cpu(guid->data1); 422 guid->data2 = le16_to_cpu(guid->data2); 423 guid->data3 = le16_to_cpu(guid->data3); 424} 425 426static inline void cpu_to_leguids(MSGUID *guid) 427{ 428 guid->data1 = cpu_to_le32(guid->data1); 429 guid->data2 = cpu_to_le16(guid->data2); 430 guid->data3 = cpu_to_le16(guid->data3); 431} 432 433void vhdx_header_le_import(VHDXHeader *h); 434void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h); 435void vhdx_log_desc_le_import(VHDXLogDescriptor *d); 436void vhdx_log_desc_le_export(VHDXLogDescriptor *d); 437void vhdx_log_data_le_import(VHDXLogDataSector *d); 438void vhdx_log_data_le_export(VHDXLogDataSector *d); 439void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr); 440void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr); 441void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr); 442void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr); 443void vhdx_region_entry_le_import(VHDXRegionTableEntry *e); 444void vhdx_region_entry_le_export(VHDXRegionTableEntry *e); 445void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr); 446void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr); 447void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e); 448void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e); 449int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s); 450 451#endif