aboutsummaryrefslogtreecommitdiff
path: root/block/vhdx.h
blob: b4a12a081e8ea5ead985a859e3e01c780c5a35c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
/*
 * Block driver for Hyper-V VHDX Images
 *
 * Copyright (c) 2013 Red Hat, Inc.,
 *
 * Authors:
 *  Jeff Cody <jcody@redhat.com>
 *
 *  This is based on the "VHDX Format Specification v1.00", published 8/25/2012
 *  by Microsoft:
 *      https://www.microsoft.com/en-us/download/details.aspx?id=34750
 *
 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
 * See the COPYING.LIB file in the top-level directory.
 *
 */

#ifndef BLOCK_VHDX_H
#define BLOCK_VHDX_H

#define KiB              (1 * 1024)
#define MiB            (KiB * 1024)
#define GiB            (MiB * 1024)
#define TiB ((uint64_t) GiB * 1024)

#define DEFAULT_LOG_SIZE 1048576 /* 1MiB */
/* Structures and fields present in the VHDX file */

/* The header section has the following blocks,
 * each block is 64KB:
 *
 * _____________________________________________________________________________
 * | File Id. |   Header 1    | Header 2   | Region Table |  Reserved (768KB)  |
 * |----------|---------------|------------|--------------|--------------------|
 * |          |               |            |              |                    |
 * 0.........64KB...........128KB........192KB..........256KB................1MB
 */

#define VHDX_HEADER_BLOCK_SIZE      (64 * 1024)

#define VHDX_FILE_ID_OFFSET         0
#define VHDX_HEADER1_OFFSET         (VHDX_HEADER_BLOCK_SIZE * 1)
#define VHDX_HEADER2_OFFSET         (VHDX_HEADER_BLOCK_SIZE * 2)
#define VHDX_REGION_TABLE_OFFSET    (VHDX_HEADER_BLOCK_SIZE * 3)
#define VHDX_REGION_TABLE2_OFFSET   (VHDX_HEADER_BLOCK_SIZE * 4)

#define VHDX_HEADER_SECTION_END     (1 * MiB)
/*
 * A note on the use of MS-GUID fields.  For more details on the GUID,
 * please see: https://en.wikipedia.org/wiki/Globally_unique_identifier.
 *
 * The VHDX specification only states that these are MS GUIDs, and which
 * bytes are data1-data4. It makes no mention of what algorithm should be used
 * to generate the GUID, nor what standard.  However, looking at the specified
 * known GUID fields, it appears the GUIDs are:
 *  Standard/DCE GUID type  (noted by 10b in the MSB of byte 0 of .data4)
 *  Random algorithm        (noted by 0x4XXX for .data3)
 */

/* ---- HEADER SECTION STRUCTURES ---- */

/* These structures are ones that are defined in the VHDX specification
 * document */

#define VHDX_FILE_SIGNATURE 0x656C696678646876ULL  /* "vhdxfile" in ASCII */
typedef struct VHDXFileIdentifier {
    uint64_t    signature;              /* "vhdxfile" in ASCII */
    uint16_t    creator[256];           /* optional; utf-16 string to identify
                                           the vhdx file creator.  Diagnostic
                                           only */
} VHDXFileIdentifier;


/* the guid is a 16 byte unique ID - the definition for this used by
 * Microsoft is not just 16 bytes though - it is a structure that is defined,
 * so we need to follow it here so that endianness does not trip us up */

typedef struct QEMU_PACKED MSGUID {
    uint32_t  data1;
    uint16_t  data2;
    uint16_t  data3;
    uint8_t   data4[8];
} MSGUID;

#define guid_eq(a, b) \
    (memcmp(&(a), &(b), sizeof(MSGUID)) == 0)

#define VHDX_HEADER_SIZE (4 * 1024)   /* although the vhdx_header struct in disk
                                         is only 582 bytes, for purposes of crc
                                         the header is the first 4KB of the 64KB
                                         block */

/* The full header is 4KB, although the actual header data is much smaller.
 * But for the checksum calculation, it is over the entire 4KB structure,
 * not just the defined portion of it */
#define VHDX_HEADER_SIGNATURE 0x64616568
typedef struct QEMU_PACKED VHDXHeader {
    uint32_t    signature;              /* "head" in ASCII */
    uint32_t    checksum;               /* CRC-32C hash of the whole header */
    uint64_t    sequence_number;        /* Seq number of this header.  Each
                                           VHDX file has 2 of these headers,
                                           and only the header with the highest
                                           sequence number is valid */
    MSGUID      file_write_guid;        /* 128 bit unique identifier. Must be
                                           updated to new, unique value before
                                           the first modification is made to
                                           file */
    MSGUID      data_write_guid;        /* 128 bit unique identifier. Must be
                                           updated to new, unique value before
                                           the first modification is made to
                                           visible data.   Visbile data is
                                           defined as:
                                                    - system & user metadata
                                                    - raw block data
                                                    - disk size
                                                    - any change that will
                                                      cause the virtual disk
                                                      sector read to differ

                                           This does not need to change if
                                           blocks are re-arranged */
    MSGUID      log_guid;               /* 128 bit unique identifier. If zero,
                                           there is no valid log. If non-zero,
                                           log entries with this guid are
                                           valid. */
    uint16_t    log_version;            /* version of the log format. Must be
                                           set to zero */
    uint16_t    version;                /* version of the vhdx file.  Currently,
                                           only supported version is "1" */
    uint32_t    log_length;             /* length of the log.  Must be multiple
                                           of 1MB */
    uint64_t    log_offset;             /* byte offset in the file of the log.
                                           Must also be a multiple of 1MB */
} VHDXHeader;

/* Header for the region table block */
#define VHDX_REGION_SIGNATURE  0x69676572  /* "regi" in ASCII */
typedef struct QEMU_PACKED VHDXRegionTableHeader {
    uint32_t    signature;              /* "regi" in ASCII */
    uint32_t    checksum;               /* CRC-32C hash of the 64KB table */
    uint32_t    entry_count;            /* number of valid entries */
    uint32_t    reserved;
} VHDXRegionTableHeader;

/* Individual region table entry.  There may be a maximum of 2047 of these
 *
 *  There are two known region table properties.  Both are required.
 *  BAT (block allocation table):  2DC27766F62342009D64115E9BFD4A08
 *  Metadata:                      8B7CA20647904B9AB8FE575F050F886E
 */
#define VHDX_REGION_ENTRY_REQUIRED  0x01    /* if set, parser must understand
                                               this entry in order to open
                                               file */
typedef struct QEMU_PACKED VHDXRegionTableEntry {
    MSGUID      guid;                   /* 128-bit unique identifier */
    uint64_t    file_offset;            /* offset of the object in the file.
                                           Must be multiple of 1MB */
    uint32_t    length;                 /* length, in bytes, of the object */
    uint32_t    data_bits;
} VHDXRegionTableEntry;


/* ---- LOG ENTRY STRUCTURES ---- */
#define VHDX_LOG_MIN_SIZE (1024 * 1024)
#define VHDX_LOG_SECTOR_SIZE 4096
#define VHDX_LOG_HDR_SIZE 64
#define VHDX_LOG_SIGNATURE 0x65676f6c
typedef struct QEMU_PACKED VHDXLogEntryHeader {
    uint32_t    signature;              /* "loge" in ASCII */
    uint32_t    checksum;               /* CRC-32C hash of the 64KB table */
    uint32_t    entry_length;           /* length in bytes, multiple of 1MB */
    uint32_t    tail;                   /* byte offset of first log entry of a
                                           seq, where this entry is the last
                                           entry */
    uint64_t    sequence_number;        /* incremented with each log entry.
                                           May not be zero. */
    uint32_t    descriptor_count;       /* number of descriptors in this log
                                           entry, must be >= 0 */
    uint32_t    reserved;
    MSGUID      log_guid;               /* value of the log_guid from
                                           vhdx_header.  If not found in
                                           vhdx_header, it is invalid */
    uint64_t    flushed_file_offset;    /* see spec for full details - this
                                           should be vhdx file size in bytes */
    uint64_t    last_file_offset;       /* size in bytes that all allocated
                                           file structures fit into */
} VHDXLogEntryHeader;

#define VHDX_LOG_DESC_SIZE 32
#define VHDX_LOG_DESC_SIGNATURE 0x63736564
#define VHDX_LOG_ZERO_SIGNATURE 0x6f72657a
typedef struct QEMU_PACKED VHDXLogDescriptor {
    uint32_t    signature;              /* "zero" or "desc" in ASCII */
    union  {
        uint32_t    reserved;           /* zero desc */
        uint32_t    trailing_bytes;     /* data desc: bytes 4092-4096 of the
                                           data sector */
    };
    union {
        uint64_t    zero_length;        /* zero desc: length of the section to
                                           zero */
        uint64_t    leading_bytes;      /* data desc: bytes 0-7 of the data
                                           sector */
    };
    uint64_t    file_offset;            /* file offset to write zeros - multiple
                                           of 4kB */
    uint64_t    sequence_number;        /* must match same field in
                                           vhdx_log_entry_header */
} VHDXLogDescriptor;

#define VHDX_LOG_DATA_SIGNATURE 0x61746164
typedef struct QEMU_PACKED VHDXLogDataSector {
    uint32_t    data_signature;         /* "data" in ASCII */
    uint32_t    sequence_high;          /* 4 MSB of 8 byte sequence_number */
    uint8_t     data[4084];             /* raw data, bytes 8-4091 (inclusive).
                                           see the data descriptor field for the
                                           other mising bytes */
    uint32_t    sequence_low;           /* 4 LSB of 8 byte sequence_number */
} VHDXLogDataSector;



/* block states - different state values depending on whether it is a
 * payload block, or a sector block. */

#define PAYLOAD_BLOCK_NOT_PRESENT       0
#define PAYLOAD_BLOCK_UNDEFINED         1
#define PAYLOAD_BLOCK_ZERO              2
#define PAYLOAD_BLOCK_UNMAPPED          5
#define PAYLOAD_BLOCK_FULLY_PRESENT     6
#define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7

#define SB_BLOCK_NOT_PRESENT    0
#define SB_BLOCK_PRESENT        6

/* per the spec */
#define VHDX_MAX_SECTORS_PER_BLOCK  (1 << 23)

/* upper 44 bits are the file offset in 1MB units lower 3 bits are the state
   other bits are reserved */
#define VHDX_BAT_STATE_BIT_MASK 0x07
#define VHDX_BAT_FILE_OFF_MASK  0xFFFFFFFFFFF00000ULL /* upper 44 bits */
typedef uint64_t VHDXBatEntry;

/* ---- METADATA REGION STRUCTURES ---- */

#define VHDX_METADATA_ENTRY_SIZE 32
#define VHDX_METADATA_MAX_ENTRIES 2047  /* not including the header */
#define VHDX_METADATA_TABLE_MAX_SIZE \
    (VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1))
#define VHDX_METADATA_SIGNATURE 0x617461646174656DULL  /* "metadata" in ASCII */
typedef struct QEMU_PACKED VHDXMetadataTableHeader {
    uint64_t    signature;              /* "metadata" in ASCII */
    uint16_t    reserved;
    uint16_t    entry_count;            /* number table entries. <= 2047 */
    uint32_t    reserved2[5];
} VHDXMetadataTableHeader;

#define VHDX_META_FLAGS_IS_USER         0x01    /* max 1024 entries */
#define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02    /* virtual disk metadata if set,
                                                   otherwise file metdata */
#define VHDX_META_FLAGS_IS_REQUIRED     0x04    /* parse must understand this
                                                   entry to open the file */
typedef struct QEMU_PACKED VHDXMetadataTableEntry {
    MSGUID      item_id;                /* 128-bit identifier for metadata */
    uint32_t    offset;                 /* byte offset of the metadata.  At
                                           least 64kB.  Relative to start of
                                           metadata region */
                                        /* note: if length = 0, so is offset */
    uint32_t    length;                 /* length of metadata. <= 1MB. */
    uint32_t    data_bits;              /* least-significant 3 bits are flags,
                                           the rest are reserved (see above) */
    uint32_t    reserved2;
} VHDXMetadataTableEntry;

#define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01   /* Do not change any blocks to
                                                   be BLOCK_NOT_PRESENT.
                                                   If set indicates a fixed
                                                   size VHDX file */
#define VHDX_PARAMS_HAS_PARENT           0x02    /* has parent / backing file */
#define VHDX_BLOCK_SIZE_MIN             (1   * MiB)
#define VHDX_BLOCK_SIZE_MAX             (256 * MiB)
typedef struct QEMU_PACKED VHDXFileParameters {
    uint32_t    block_size;             /* size of each payload block, always
                                           power of 2, <= 256MB and >= 1MB. */
    uint32_t data_bits;                 /* least-significant 2 bits are flags,
                                           the rest are reserved (see above) */
} VHDXFileParameters;

#define VHDX_MAX_IMAGE_SIZE  ((uint64_t) 64 * TiB)
typedef struct QEMU_PACKED VHDXVirtualDiskSize {
    uint64_t    virtual_disk_size;      /* Size of the virtual disk, in bytes.
                                           Must be multiple of the sector size,
                                           max of 64TB */
} VHDXVirtualDiskSize;

typedef struct QEMU_PACKED VHDXPage83Data {
    MSGUID      page_83_data;           /* unique id for scsi devices that
                                           support page 0x83 */
} VHDXPage83Data;

typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize {
    uint32_t    logical_sector_size;    /* virtual disk sector size (in bytes).
                                           Can only be 512 or 4096 bytes */
} VHDXVirtualDiskLogicalSectorSize;

typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize {
    uint32_t    physical_sector_size;   /* physical sector size (in bytes).
                                           Can only be 512 or 4096 bytes */
} VHDXVirtualDiskPhysicalSectorSize;

typedef struct QEMU_PACKED VHDXParentLocatorHeader {
    MSGUID      locator_type;           /* type of the parent virtual disk. */
    uint16_t    reserved;
    uint16_t    key_value_count;        /* number of key/value pairs for this
                                           locator */
} VHDXParentLocatorHeader;

/* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */
typedef struct QEMU_PACKED VHDXParentLocatorEntry {
    uint32_t    key_offset;             /* offset in metadata for key, > 0 */
    uint32_t    value_offset;           /* offset in metadata for value, >0 */
    uint16_t    key_length;             /* length of entry key, > 0 */
    uint16_t    value_length;           /* length of entry value, > 0 */
} VHDXParentLocatorEntry;


/* ----- END VHDX SPECIFICATION STRUCTURES ---- */

typedef struct VHDXMetadataEntries {
    VHDXMetadataTableEntry file_parameters_entry;
    VHDXMetadataTableEntry virtual_disk_size_entry;
    VHDXMetadataTableEntry page83_data_entry;
    VHDXMetadataTableEntry logical_sector_size_entry;
    VHDXMetadataTableEntry phys_sector_size_entry;
    VHDXMetadataTableEntry parent_locator_entry;
    uint16_t present;
} VHDXMetadataEntries;

typedef struct VHDXLogEntries {
    uint64_t offset;
    uint64_t length;
    uint32_t write;
    uint32_t read;
    VHDXLogEntryHeader *hdr;
    void *desc_buffer;
    uint64_t sequence;
    uint32_t tail;
} VHDXLogEntries;

typedef struct VHDXRegionEntry {
    uint64_t start;
    uint64_t end;
    QLIST_ENTRY(VHDXRegionEntry) entries;
} VHDXRegionEntry;

typedef struct BDRVVHDXState {
    CoMutex lock;

    int curr_header;
    VHDXHeader *headers[2];

    VHDXRegionTableHeader rt;
    VHDXRegionTableEntry bat_rt;         /* region table for the BAT */
    VHDXRegionTableEntry metadata_rt;    /* region table for the metadata */

    VHDXMetadataTableHeader metadata_hdr;
    VHDXMetadataEntries metadata_entries;

    VHDXFileParameters params;
    uint32_t block_size;
    uint32_t block_size_bits;
    uint32_t sectors_per_block;
    uint32_t sectors_per_block_bits;

    uint64_t virtual_disk_size;
    uint32_t logical_sector_size;
    uint32_t physical_sector_size;

    uint64_t chunk_ratio;
    uint32_t chunk_ratio_bits;
    uint32_t logical_sector_size_bits;

    uint32_t bat_entries;
    VHDXBatEntry *bat;
    uint64_t bat_offset;

    bool first_visible_write;
    MSGUID session_guid;

    VHDXLogEntries log;

    VHDXParentLocatorHeader parent_header;
    VHDXParentLocatorEntry *parent_entries;

    Error *migration_blocker;

    bool log_replayed_on_open;

    QLIST_HEAD(VHDXRegionHead, VHDXRegionEntry) regions;
} BDRVVHDXState;

void vhdx_guid_generate(MSGUID *guid);

int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
                        MSGUID *log_guid);

uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset);
uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
                            int crc_offset);

bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset);

int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
                   Error **errp);

int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
                             void *data, uint32_t length, uint64_t offset);

static inline void leguid_to_cpus(MSGUID *guid)
{
    le32_to_cpus(&guid->data1);
    le16_to_cpus(&guid->data2);
    le16_to_cpus(&guid->data3);
}

static inline void cpu_to_leguids(MSGUID *guid)
{
    cpu_to_le32s(&guid->data1);
    cpu_to_le16s(&guid->data2);
    cpu_to_le16s(&guid->data3);
}

void vhdx_header_le_import(VHDXHeader *h);
void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h);
void vhdx_log_desc_le_import(VHDXLogDescriptor *d);
void vhdx_log_desc_le_export(VHDXLogDescriptor *d);
void vhdx_log_data_le_import(VHDXLogDataSector *d);
void vhdx_log_data_le_export(VHDXLogDataSector *d);
void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);
void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr);
void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr);
void vhdx_region_entry_le_import(VHDXRegionTableEntry *e);
void vhdx_region_entry_le_export(VHDXRegionTableEntry *e);
void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr);
void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr);
void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e);
void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e);
int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s);

#endif