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qemu/block/vhdx.h

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/*
* 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)
/* 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_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
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