xref: /qemu/block/vhdx.h (revision 65ff757d)
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 */
64 typedef 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 
76 typedef 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
95 typedef 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 */
136 typedef 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 */
152 typedef 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
166 typedef 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
190 typedef 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
210 typedef 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 missing 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 */
242 typedef 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 */
251 typedef 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 metadata */
261 #define VHDX_META_FLAGS_IS_REQUIRED     0x04    /* parse must understand this
262                                                    entry to open the file */
263 typedef 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)
282 typedef 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)
290 typedef 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 
296 typedef struct QEMU_PACKED VHDXPage83Data {
297     MSGUID      page_83_data;           /* unique id for scsi devices that
298                                            support page 0x83 */
299 } VHDXPage83Data;
300 
301 typedef 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 
306 typedef 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 
311 typedef 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 */
319 typedef 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 
329 typedef 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 
339 typedef 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 
350 typedef struct VHDXRegionEntry {
351     uint64_t start;
352     uint64_t end;
353     QLIST_ENTRY(VHDXRegionEntry) entries;
354 } VHDXRegionEntry;
355 
356 typedef 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 
402 void vhdx_guid_generate(MSGUID *guid);
403 
404 int GRAPH_RDLOCK
405 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 GRAPH_RDLOCK
415 vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
416                Error **errp);
417 
418 int coroutine_fn GRAPH_RDLOCK
419 vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
420                          void *data, uint32_t length, uint64_t offset);
421 
leguid_to_cpus(MSGUID * guid)422 static inline void leguid_to_cpus(MSGUID *guid)
423 {
424     guid->data1 = le32_to_cpu(guid->data1);
425     guid->data2 = le16_to_cpu(guid->data2);
426     guid->data3 = le16_to_cpu(guid->data3);
427 }
428 
cpu_to_leguids(MSGUID * guid)429 static inline void cpu_to_leguids(MSGUID *guid)
430 {
431     guid->data1 = cpu_to_le32(guid->data1);
432     guid->data2 = cpu_to_le16(guid->data2);
433     guid->data3 = cpu_to_le16(guid->data3);
434 }
435 
436 void vhdx_header_le_import(VHDXHeader *h);
437 void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h);
438 void vhdx_log_desc_le_import(VHDXLogDescriptor *d);
439 void vhdx_log_desc_le_export(VHDXLogDescriptor *d);
440 void vhdx_log_data_le_import(VHDXLogDataSector *d);
441 void vhdx_log_data_le_export(VHDXLogDataSector *d);
442 void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
443 void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);
444 void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr);
445 void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr);
446 void vhdx_region_entry_le_import(VHDXRegionTableEntry *e);
447 void vhdx_region_entry_le_export(VHDXRegionTableEntry *e);
448 void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr);
449 void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr);
450 void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e);
451 void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e);
452 
453 int GRAPH_RDLOCK
454 vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s);
455 
456 #endif
457