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#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
 452