LXR qemu/block/vhdx.h

   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 */
  66typedef 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
  78typedef 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
  97typedef 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 */
 138typedef 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 */
 154typedef 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
 168typedef 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
 192typedef 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
 212typedef 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          3
 230#define PAYLOAD_BLOCK_UNMAPPED_v095     5
 231#define PAYLOAD_BLOCK_FULLY_PRESENT     6
 232#define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7
 233
 234#define SB_BLOCK_NOT_PRESENT    0
 235#define SB_BLOCK_PRESENT        6
 236
 237/* per the spec */
 238#define VHDX_MAX_SECTORS_PER_BLOCK  (1 << 23)
 239
 240/* upper 44 bits are the file offset in 1MB units lower 3 bits are the state
 241   other bits are reserved */
 242#define VHDX_BAT_STATE_BIT_MASK 0x07
 243#define VHDX_BAT_FILE_OFF_MASK  0xFFFFFFFFFFF00000ULL /* upper 44 bits */
 244typedef uint64_t VHDXBatEntry;
 245
 246/* ---- METADATA REGION STRUCTURES ---- */
 247
 248#define VHDX_METADATA_ENTRY_SIZE 32
 249#define VHDX_METADATA_MAX_ENTRIES 2047  /* not including the header */
 250#define VHDX_METADATA_TABLE_MAX_SIZE \
 251    (VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1))
 252#define VHDX_METADATA_SIGNATURE 0x617461646174656DULL  /* "metadata" in ASCII */
 253typedef struct QEMU_PACKED VHDXMetadataTableHeader {
 254    uint64_t    signature;              /* "metadata" in ASCII */
 255    uint16_t    reserved;
 256    uint16_t    entry_count;            /* number table entries. <= 2047 */
 257    uint32_t    reserved2[5];
 258} VHDXMetadataTableHeader;
 259
 260#define VHDX_META_FLAGS_IS_USER         0x01    /* max 1024 entries */
 261#define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02    /* virtual disk metadata if set,
 262                                                   otherwise file metdata */
 263#define VHDX_META_FLAGS_IS_REQUIRED     0x04    /* parse must understand this
 264                                                   entry to open the file */
 265typedef struct QEMU_PACKED VHDXMetadataTableEntry {
 266    MSGUID      item_id;                /* 128-bit identifier for metadata */
 267    uint32_t    offset;                 /* byte offset of the metadata.  At
 268                                           least 64kB.  Relative to start of
 269                                           metadata region */
 270                                        /* note: if length = 0, so is offset */
 271    uint32_t    length;                 /* length of metadata. <= 1MB. */
 272    uint32_t    data_bits;              /* least-significant 3 bits are flags,
 273                                           the rest are reserved (see above) */
 274    uint32_t    reserved2;
 275} VHDXMetadataTableEntry;
 276
 277#define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01   /* Do not change any blocks to
 278                                                   be BLOCK_NOT_PRESENT.
 279                                                   If set indicates a fixed
 280                                                   size VHDX file */
 281#define VHDX_PARAMS_HAS_PARENT           0x02    /* has parent / backing file */
 282#define VHDX_BLOCK_SIZE_MIN             (1   * MiB)
 283#define VHDX_BLOCK_SIZE_MAX             (256 * MiB)
 284typedef struct QEMU_PACKED VHDXFileParameters {
 285    uint32_t    block_size;             /* size of each payload block, always
 286                                           power of 2, <= 256MB and >= 1MB. */
 287    uint32_t data_bits;                 /* least-significant 2 bits are flags,
 288                                           the rest are reserved (see above) */
 289} VHDXFileParameters;
 290
 291#define VHDX_MAX_IMAGE_SIZE  ((uint64_t) 64 * TiB)
 292typedef struct QEMU_PACKED VHDXVirtualDiskSize {
 293    uint64_t    virtual_disk_size;      /* Size of the virtual disk, in bytes.
 294                                           Must be multiple of the sector size,
 295                                           max of 64TB */
 296} VHDXVirtualDiskSize;
 297
 298typedef struct QEMU_PACKED VHDXPage83Data {
 299    MSGUID      page_83_data;           /* unique id for scsi devices that
 300                                           support page 0x83 */
 301} VHDXPage83Data;
 302
 303typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize {
 304    uint32_t    logical_sector_size;    /* virtual disk sector size (in bytes).
 305                                           Can only be 512 or 4096 bytes */
 306} VHDXVirtualDiskLogicalSectorSize;
 307
 308typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize {
 309    uint32_t    physical_sector_size;   /* physical sector size (in bytes).
 310                                           Can only be 512 or 4096 bytes */
 311} VHDXVirtualDiskPhysicalSectorSize;
 312
 313typedef struct QEMU_PACKED VHDXParentLocatorHeader {
 314    MSGUID      locator_type;           /* type of the parent virtual disk. */
 315    uint16_t    reserved;
 316    uint16_t    key_value_count;        /* number of key/value pairs for this
 317                                           locator */
 318} VHDXParentLocatorHeader;
 319
 320/* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */
 321typedef struct QEMU_PACKED VHDXParentLocatorEntry {
 322    uint32_t    key_offset;             /* offset in metadata for key, > 0 */
 323    uint32_t    value_offset;           /* offset in metadata for value, >0 */
 324    uint16_t    key_length;             /* length of entry key, > 0 */
 325    uint16_t    value_length;           /* length of entry value, > 0 */
 326} VHDXParentLocatorEntry;
 327
 328
 329/* ----- END VHDX SPECIFICATION STRUCTURES ---- */
 330
 331typedef struct VHDXMetadataEntries {
 332    VHDXMetadataTableEntry file_parameters_entry;
 333    VHDXMetadataTableEntry virtual_disk_size_entry;
 334    VHDXMetadataTableEntry page83_data_entry;
 335    VHDXMetadataTableEntry logical_sector_size_entry;
 336    VHDXMetadataTableEntry phys_sector_size_entry;
 337    VHDXMetadataTableEntry parent_locator_entry;
 338    uint16_t present;
 339} VHDXMetadataEntries;
 340
 341typedef struct VHDXLogEntries {
 342    uint64_t offset;
 343    uint64_t length;
 344    uint32_t write;
 345    uint32_t read;
 346    VHDXLogEntryHeader *hdr;
 347    void *desc_buffer;
 348    uint64_t sequence;
 349    uint32_t tail;
 350} VHDXLogEntries;
 351
 352typedef struct VHDXRegionEntry {
 353    uint64_t start;
 354    uint64_t end;
 355    QLIST_ENTRY(VHDXRegionEntry) entries;
 356} VHDXRegionEntry;
 357
 358typedef struct BDRVVHDXState {
 359    CoMutex lock;
 360
 361    int curr_header;
 362    VHDXHeader *headers[2];
 363
 364    VHDXRegionTableHeader rt;
 365    VHDXRegionTableEntry bat_rt;         /* region table for the BAT */
 366    VHDXRegionTableEntry metadata_rt;    /* region table for the metadata */
 367
 368    VHDXMetadataTableHeader metadata_hdr;
 369    VHDXMetadataEntries metadata_entries;
 370
 371    VHDXFileParameters params;
 372    uint32_t block_size;
 373    uint32_t block_size_bits;
 374    uint32_t sectors_per_block;
 375    uint32_t sectors_per_block_bits;
 376
 377    uint64_t virtual_disk_size;
 378    uint32_t logical_sector_size;
 379    uint32_t physical_sector_size;
 380
 381    uint64_t chunk_ratio;
 382    uint32_t chunk_ratio_bits;
 383    uint32_t logical_sector_size_bits;
 384
 385    uint32_t bat_entries;
 386    VHDXBatEntry *bat;
 387    uint64_t bat_offset;
 388
 389    bool first_visible_write;
 390    MSGUID session_guid;
 391
 392    VHDXLogEntries log;
 393
 394    VHDXParentLocatorHeader parent_header;
 395    VHDXParentLocatorEntry *parent_entries;
 396
 397    Error *migration_blocker;
 398
 399    bool log_replayed_on_open;
 400
 401    QLIST_HEAD(VHDXRegionHead, VHDXRegionEntry) regions;
 402} BDRVVHDXState;
 403
 404void vhdx_guid_generate(MSGUID *guid);
 405
 406int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
 407                        MSGUID *log_guid);
 408
 409uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset);
 410uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
 411                            int crc_offset);
 412
 413bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset);
 414
 415int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
 416                   Error **errp);
 417
 418int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
 419                             void *data, uint32_t length, uint64_t offset);
 420
 421static inline void leguid_to_cpus(MSGUID *guid)
 422{
 423    le32_to_cpus(&guid->data1);
 424    le16_to_cpus(&guid->data2);
 425    le16_to_cpus(&guid->data3);
 426}
 427
 428static inline void cpu_to_leguids(MSGUID *guid)
 429{
 430    cpu_to_le32s(&guid->data1);
 431    cpu_to_le16s(&guid->data2);
 432    cpu_to_le16s(&guid->data3);
 433}
 434
 435void vhdx_header_le_import(VHDXHeader *h);
 436void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h);
 437void vhdx_log_desc_le_import(VHDXLogDescriptor *d);
 438void vhdx_log_desc_le_export(VHDXLogDescriptor *d);
 439void vhdx_log_data_le_import(VHDXLogDataSector *d);
 440void vhdx_log_data_le_export(VHDXLogDataSector *d);
 441void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
 442void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);
 443void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr);
 444void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr);
 445void vhdx_region_entry_le_import(VHDXRegionTableEntry *e);
 446void vhdx_region_entry_le_export(VHDXRegionTableEntry *e);
 447void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr);
 448void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr);
 449void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e);
 450void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e);
 451int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s);
 452
 453#endif
 454