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qemu/block/vhdx.c
Jeff Cody 059e2fbbca block: add read-only support to VHDX image format. 
This adds in read-only support to the VHDX image format.  This supports
reads for fixed-size, and dynamic sized VHDX images.

Differencing files are still unsupported.

The image must be opened without BDRV_O_RDWR set, because we do not
yet update the headers.  I.e., pass 'readonly=on' in the drive image
options from the QEMU commandline.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-05-03 10:31:58 +02:00

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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 v0.95", published 4/12/2012
* by Microsoft:
* https://www.microsoft.com/en-us/download/details.aspx?id=29681
*
* 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.
*
*/
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/crc32c.h"
#include "block/vhdx.h"
/* Several metadata and region table data entries are identified by
* guids in a MS-specific GUID format. */
/* ------- Known Region Table GUIDs ---------------------- */
static const MSGUID bat_guid = { .data1 = 0x2dc27766,
.data2 = 0xf623,
.data3 = 0x4200,
.data4 = { 0x9d, 0x64, 0x11, 0x5e,
0x9b, 0xfd, 0x4a, 0x08} };
static const MSGUID metadata_guid = { .data1 = 0x8b7ca206,
.data2 = 0x4790,
.data3 = 0x4b9a,
.data4 = { 0xb8, 0xfe, 0x57, 0x5f,
0x05, 0x0f, 0x88, 0x6e} };
/* ------- Known Metadata Entry GUIDs ---------------------- */
static const MSGUID file_param_guid = { .data1 = 0xcaa16737,
.data2 = 0xfa36,
.data3 = 0x4d43,
.data4 = { 0xb3, 0xb6, 0x33, 0xf0,
0xaa, 0x44, 0xe7, 0x6b} };
static const MSGUID virtual_size_guid = { .data1 = 0x2FA54224,
.data2 = 0xcd1b,
.data3 = 0x4876,
.data4 = { 0xb2, 0x11, 0x5d, 0xbe,
0xd8, 0x3b, 0xf4, 0xb8} };
static const MSGUID page83_guid = { .data1 = 0xbeca12ab,
.data2 = 0xb2e6,
.data3 = 0x4523,
.data4 = { 0x93, 0xef, 0xc3, 0x09,
0xe0, 0x00, 0xc7, 0x46} };
static const MSGUID phys_sector_guid = { .data1 = 0xcda348c7,
.data2 = 0x445d,
.data3 = 0x4471,
.data4 = { 0x9c, 0xc9, 0xe9, 0x88,
0x52, 0x51, 0xc5, 0x56} };
static const MSGUID parent_locator_guid = { .data1 = 0xa8d35f2d,
.data2 = 0xb30b,
.data3 = 0x454d,
.data4 = { 0xab, 0xf7, 0xd3,
0xd8, 0x48, 0x34,
0xab, 0x0c} };
static const MSGUID logical_sector_guid = { .data1 = 0x8141bf1d,
.data2 = 0xa96f,
.data3 = 0x4709,
.data4 = { 0xba, 0x47, 0xf2,
0x33, 0xa8, 0xfa,
0xab, 0x5f} };
/* Each parent type must have a valid GUID; this is for parent images
* of type 'VHDX'. If we were to allow e.g. a QCOW2 parent, we would
* need to make up our own QCOW2 GUID type */
static const MSGUID parent_vhdx_guid = { .data1 = 0xb04aefb7,
.data2 = 0xd19e,
.data3 = 0x4a81,
.data4 = { 0xb7, 0x89, 0x25, 0xb8,
0xe9, 0x44, 0x59, 0x13} };
#define META_FILE_PARAMETER_PRESENT 0x01
#define META_VIRTUAL_DISK_SIZE_PRESENT 0x02
#define META_PAGE_83_PRESENT 0x04
#define META_LOGICAL_SECTOR_SIZE_PRESENT 0x08
#define META_PHYS_SECTOR_SIZE_PRESENT 0x10
#define META_PARENT_LOCATOR_PRESENT 0x20
#define META_ALL_PRESENT \
(META_FILE_PARAMETER_PRESENT | META_VIRTUAL_DISK_SIZE_PRESENT | \
META_PAGE_83_PRESENT | META_LOGICAL_SECTOR_SIZE_PRESENT | \
META_PHYS_SECTOR_SIZE_PRESENT)
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 VHDXSectorInfo {
uint32_t bat_idx; /* BAT entry index */
uint32_t sectors_avail; /* sectors available in payload block */
uint32_t bytes_left; /* bytes left in the block after data to r/w */
uint32_t bytes_avail; /* bytes available in payload block */
uint64_t file_offset; /* absolute offset in bytes, in file */
uint64_t block_offset; /* block offset, in bytes */
} VHDXSectorInfo;
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;
VHDXParentLocatorHeader parent_header;
VHDXParentLocatorEntry *parent_entries;
} BDRVVHDXState;
uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
int crc_offset)
{
uint32_t crc_new;
uint32_t crc_orig;
assert(buf != NULL);
if (crc_offset > 0) {
memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
memset(buf + crc_offset, 0, sizeof(crc_orig));
}
crc_new = crc32c(crc, buf, size);
if (crc_offset > 0) {
memcpy(buf + crc_offset, &crc_orig, sizeof(crc_orig));
}
return crc_new;
}
/* Validates the checksum of the buffer, with an in-place CRC.
*
* Zero is substituted during crc calculation for the original crc field,
* and the crc field is restored afterwards. But the buffer will be modifed
* during the calculation, so this may not be not suitable for multi-threaded
* use.
*
* crc_offset: byte offset in buf of the buffer crc
* buf: buffer pointer
* size: size of buffer (must be > crc_offset+4)
*
* returns true if checksum is valid, false otherwise
*/
bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset)
{
uint32_t crc_orig;
uint32_t crc;
assert(buf != NULL);
assert(size > (crc_offset + 4));
memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
crc_orig = le32_to_cpu(crc_orig);
crc = vhdx_checksum_calc(0xffffffff, buf, size, crc_offset);
return crc == crc_orig;
}
/*
* Per the MS VHDX Specification, for every VHDX file:
* - The header section is fixed size - 1 MB
* - The header section is always the first "object"
* - The first 64KB of the header is the File Identifier
* - The first uint64 (8 bytes) is the VHDX Signature ("vhdxfile")
* - The following 512 bytes constitute a UTF-16 string identifiying the
* software that created the file, and is optional and diagnostic only.
*
* Therefore, we probe by looking for the vhdxfile signature "vhdxfile"
*/
static int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename)
{
if (buf_size >= 8 && !memcmp(buf, "vhdxfile", 8)) {
return 100;
}
return 0;
}
/* All VHDX structures on disk are little endian */
static void vhdx_header_le_import(VHDXHeader *h)
{
assert(h != NULL);
le32_to_cpus(&h->signature);
le32_to_cpus(&h->checksum);
le64_to_cpus(&h->sequence_number);
leguid_to_cpus(&h->file_write_guid);
leguid_to_cpus(&h->data_write_guid);
leguid_to_cpus(&h->log_guid);
le16_to_cpus(&h->log_version);
le16_to_cpus(&h->version);
le32_to_cpus(&h->log_length);
le64_to_cpus(&h->log_offset);
}
/* opens the specified header block from the VHDX file header section */
static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s)
{
int ret = 0;
VHDXHeader *header1;
VHDXHeader *header2;
bool h1_valid = false;
bool h2_valid = false;
uint64_t h1_seq = 0;
uint64_t h2_seq = 0;
uint8_t *buffer;
header1 = qemu_blockalign(bs, sizeof(VHDXHeader));
header2 = qemu_blockalign(bs, sizeof(VHDXHeader));
buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE);
s->headers[0] = header1;
s->headers[1] = header2;
/* We have to read the whole VHDX_HEADER_SIZE instead of
* sizeof(VHDXHeader), because the checksum is over the whole
* region */
ret = bdrv_pread(bs->file, VHDX_HEADER1_OFFSET, buffer, VHDX_HEADER_SIZE);
if (ret < 0) {
goto fail;
}
/* copy over just the relevant portion that we need */
memcpy(header1, buffer, sizeof(VHDXHeader));
vhdx_header_le_import(header1);
if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) &&
!memcmp(&header1->signature, "head", 4) &&
header1->version == 1) {
h1_seq = header1->sequence_number;
h1_valid = true;
}
ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, buffer, VHDX_HEADER_SIZE);
if (ret < 0) {
goto fail;
}
/* copy over just the relevant portion that we need */
memcpy(header2, buffer, sizeof(VHDXHeader));
vhdx_header_le_import(header2);
if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) &&
!memcmp(&header2->signature, "head", 4) &&
header2->version == 1) {
h2_seq = header2->sequence_number;
h2_valid = true;
}
/* If there is only 1 valid header (or no valid headers), we
* don't care what the sequence numbers are */
if (h1_valid && !h2_valid) {
s->curr_header = 0;
} else if (!h1_valid && h2_valid) {
s->curr_header = 1;
} else if (!h1_valid && !h2_valid) {
ret = -EINVAL;
goto fail;
} else {
/* If both headers are valid, then we choose the active one by the
* highest sequence number. If the sequence numbers are equal, that is
* invalid */
if (h1_seq > h2_seq) {
s->curr_header = 0;
} else if (h2_seq > h1_seq) {
s->curr_header = 1;
} else {
ret = -EINVAL;
goto fail;
}
}
ret = 0;
goto exit;
fail:
qerror_report(ERROR_CLASS_GENERIC_ERROR, "No valid VHDX header found");
qemu_vfree(header1);
qemu_vfree(header2);
s->headers[0] = NULL;
s->headers[1] = NULL;
exit:
qemu_vfree(buffer);
return ret;
}
static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s)
{
int ret = 0;
uint8_t *buffer;
int offset = 0;
VHDXRegionTableEntry rt_entry;
uint32_t i;
bool bat_rt_found = false;
bool metadata_rt_found = false;
/* We have to read the whole 64KB block, because the crc32 is over the
* whole block */
buffer = qemu_blockalign(bs, VHDX_HEADER_BLOCK_SIZE);
ret = bdrv_pread(bs->file, VHDX_REGION_TABLE_OFFSET, buffer,
VHDX_HEADER_BLOCK_SIZE);
if (ret < 0) {
goto fail;
}
memcpy(&s->rt, buffer, sizeof(s->rt));
le32_to_cpus(&s->rt.signature);
le32_to_cpus(&s->rt.checksum);
le32_to_cpus(&s->rt.entry_count);
le32_to_cpus(&s->rt.reserved);
offset += sizeof(s->rt);
if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4) ||
memcmp(&s->rt.signature, "regi", 4)) {
ret = -EINVAL;
goto fail;
}
/* Per spec, maximum region table entry count is 2047 */
if (s->rt.entry_count > 2047) {
ret = -EINVAL;
goto fail;
}
for (i = 0; i < s->rt.entry_count; i++) {
memcpy(&rt_entry, buffer + offset, sizeof(rt_entry));
offset += sizeof(rt_entry);
leguid_to_cpus(&rt_entry.guid);
le64_to_cpus(&rt_entry.file_offset);
le32_to_cpus(&rt_entry.length);
le32_to_cpus(&rt_entry.data_bits);
/* see if we recognize the entry */
if (guid_eq(rt_entry.guid, bat_guid)) {
/* must be unique; if we have already found it this is invalid */
if (bat_rt_found) {
ret = -EINVAL;
goto fail;
}
bat_rt_found = true;
s->bat_rt = rt_entry;
continue;
}
if (guid_eq(rt_entry.guid, metadata_guid)) {
/* must be unique; if we have already found it this is invalid */
if (metadata_rt_found) {
ret = -EINVAL;
goto fail;
}
metadata_rt_found = true;
s->metadata_rt = rt_entry;
continue;
}
if (rt_entry.data_bits & VHDX_REGION_ENTRY_REQUIRED) {
/* cannot read vhdx file - required region table entry that
* we do not understand. per spec, we must fail to open */
ret = -ENOTSUP;
goto fail;
}
}
ret = 0;
fail:
qemu_vfree(buffer);
return ret;
}
/* Metadata initial parser
*
* This loads all the metadata entry fields. This may cause additional
* fields to be processed (e.g. parent locator, etc..).
*
* There are 5 Metadata items that are always required:
* - File Parameters (block size, has a parent)
* - Virtual Disk Size (size, in bytes, of the virtual drive)
* - Page 83 Data (scsi page 83 guid)
* - Logical Sector Size (logical sector size in bytes, either 512 or
* 4096. We only support 512 currently)
* - Physical Sector Size (512 or 4096)
*
* Also, if the File Parameters indicate this is a differencing file,
* we must also look for the Parent Locator metadata item.
*/
static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s)
{
int ret = 0;
uint8_t *buffer;
int offset = 0;
uint32_t i = 0;
VHDXMetadataTableEntry md_entry;
buffer = qemu_blockalign(bs, VHDX_METADATA_TABLE_MAX_SIZE);
ret = bdrv_pread(bs->file, s->metadata_rt.file_offset, buffer,
VHDX_METADATA_TABLE_MAX_SIZE);
if (ret < 0) {
goto exit;
}
memcpy(&s->metadata_hdr, buffer, sizeof(s->metadata_hdr));
offset += sizeof(s->metadata_hdr);
le64_to_cpus(&s->metadata_hdr.signature);
le16_to_cpus(&s->metadata_hdr.reserved);
le16_to_cpus(&s->metadata_hdr.entry_count);
if (memcmp(&s->metadata_hdr.signature, "metadata", 8)) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.present = 0;
if ((s->metadata_hdr.entry_count * sizeof(md_entry)) >
(VHDX_METADATA_TABLE_MAX_SIZE - offset)) {
ret = -EINVAL;
goto exit;
}
for (i = 0; i < s->metadata_hdr.entry_count; i++) {
memcpy(&md_entry, buffer + offset, sizeof(md_entry));
offset += sizeof(md_entry);
leguid_to_cpus(&md_entry.item_id);
le32_to_cpus(&md_entry.offset);
le32_to_cpus(&md_entry.length);
le32_to_cpus(&md_entry.data_bits);
le32_to_cpus(&md_entry.reserved2);
if (guid_eq(md_entry.item_id, file_param_guid)) {
if (s->metadata_entries.present & META_FILE_PARAMETER_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.file_parameters_entry = md_entry;
s->metadata_entries.present |= META_FILE_PARAMETER_PRESENT;
continue;
}
if (guid_eq(md_entry.item_id, virtual_size_guid)) {
if (s->metadata_entries.present & META_VIRTUAL_DISK_SIZE_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.virtual_disk_size_entry = md_entry;
s->metadata_entries.present |= META_VIRTUAL_DISK_SIZE_PRESENT;
continue;
}
if (guid_eq(md_entry.item_id, page83_guid)) {
if (s->metadata_entries.present & META_PAGE_83_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.page83_data_entry = md_entry;
s->metadata_entries.present |= META_PAGE_83_PRESENT;
continue;
}
if (guid_eq(md_entry.item_id, logical_sector_guid)) {
if (s->metadata_entries.present &
META_LOGICAL_SECTOR_SIZE_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.logical_sector_size_entry = md_entry;
s->metadata_entries.present |= META_LOGICAL_SECTOR_SIZE_PRESENT;
continue;
}
if (guid_eq(md_entry.item_id, phys_sector_guid)) {
if (s->metadata_entries.present & META_PHYS_SECTOR_SIZE_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.phys_sector_size_entry = md_entry;
s->metadata_entries.present |= META_PHYS_SECTOR_SIZE_PRESENT;
continue;
}
if (guid_eq(md_entry.item_id, parent_locator_guid)) {
if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
ret = -EINVAL;
goto exit;
}
s->metadata_entries.parent_locator_entry = md_entry;
s->metadata_entries.present |= META_PARENT_LOCATOR_PRESENT;
continue;
}
if (md_entry.data_bits & VHDX_META_FLAGS_IS_REQUIRED) {
/* cannot read vhdx file - required region table entry that
* we do not understand. per spec, we must fail to open */
ret = -ENOTSUP;
goto exit;
}
}
if (s->metadata_entries.present != META_ALL_PRESENT) {
ret = -ENOTSUP;
goto exit;
}
ret = bdrv_pread(bs->file,
s->metadata_entries.file_parameters_entry.offset
+ s->metadata_rt.file_offset,
&s->params,
sizeof(s->params));
if (ret < 0) {
goto exit;
}
le32_to_cpus(&s->params.block_size);
le32_to_cpus(&s->params.data_bits);
/* We now have the file parameters, so we can tell if this is a
* differencing file (i.e.. has_parent), is dynamic or fixed
* sized (leave_blocks_allocated), and the block size */
/* The parent locator required iff the file parameters has_parent set */
if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
/* TODO: parse parent locator fields */
ret = -ENOTSUP; /* temp, until differencing files are supported */
goto exit;
} else {
/* if has_parent is set, but there is not parent locator present,
* then that is an invalid combination */
ret = -EINVAL;
goto exit;
}
}
/* determine virtual disk size, logical sector size,
* and phys sector size */
ret = bdrv_pread(bs->file,
s->metadata_entries.virtual_disk_size_entry.offset
+ s->metadata_rt.file_offset,
&s->virtual_disk_size,
sizeof(uint64_t));
if (ret < 0) {
goto exit;
}
ret = bdrv_pread(bs->file,
s->metadata_entries.logical_sector_size_entry.offset
+ s->metadata_rt.file_offset,
&s->logical_sector_size,
sizeof(uint32_t));
if (ret < 0) {
goto exit;
}
ret = bdrv_pread(bs->file,
s->metadata_entries.phys_sector_size_entry.offset
+ s->metadata_rt.file_offset,
&s->physical_sector_size,
sizeof(uint32_t));
if (ret < 0) {
goto exit;
}
le64_to_cpus(&s->virtual_disk_size);
le32_to_cpus(&s->logical_sector_size);
le32_to_cpus(&s->physical_sector_size);
if (s->logical_sector_size == 0 || s->params.block_size == 0) {
ret = -EINVAL;
goto exit;
}
/* both block_size and sector_size are guaranteed powers of 2 */
s->sectors_per_block = s->params.block_size / s->logical_sector_size;
s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
(uint64_t)s->logical_sector_size /
(uint64_t)s->params.block_size;
/* These values are ones we will want to use for division / multiplication
* later on, and they are all guaranteed (per the spec) to be powers of 2,
* so we can take advantage of that for shift operations during
* reads/writes */
if (s->logical_sector_size & (s->logical_sector_size - 1)) {
ret = -EINVAL;
goto exit;
}
if (s->sectors_per_block & (s->sectors_per_block - 1)) {
ret = -EINVAL;
goto exit;
}
if (s->chunk_ratio & (s->chunk_ratio - 1)) {
ret = -EINVAL;
goto exit;
}
s->block_size = s->params.block_size;
if (s->block_size & (s->block_size - 1)) {
ret = -EINVAL;
goto exit;
}
s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size);
s->sectors_per_block_bits = 31 - clz32(s->sectors_per_block);
s->chunk_ratio_bits = 63 - clz64(s->chunk_ratio);
s->block_size_bits = 31 - clz32(s->block_size);
ret = 0;
exit:
qemu_vfree(buffer);
return ret;
}
/* Parse the replay log. Per the VHDX spec, if the log is present
* it must be replayed prior to opening the file, even read-only.
*
* If read-only, we must replay the log in RAM (or refuse to open
* a dirty VHDX file read-only */
static int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s)
{
int ret = 0;
int i;
VHDXHeader *hdr;
hdr = s->headers[s->curr_header];
/* either the log guid, or log length is zero,
* then a replay log is present */
for (i = 0; i < sizeof(hdr->log_guid.data4); i++) {
ret |= hdr->log_guid.data4[i];
}
if (hdr->log_guid.data1 == 0 &&
hdr->log_guid.data2 == 0 &&
hdr->log_guid.data3 == 0 &&
ret == 0) {
goto exit;
}
/* per spec, only log version of 0 is supported */
if (hdr->log_version != 0) {
ret = -EINVAL;
goto exit;
}
if (hdr->log_length == 0) {
goto exit;
}
/* We currently do not support images with logs to replay */
ret = -ENOTSUP;
exit:
return ret;
}
static int vhdx_open(BlockDriverState *bs, QDict *options, int flags)
{
BDRVVHDXState *s = bs->opaque;
int ret = 0;
uint32_t i;
uint64_t signature;
uint32_t data_blocks_cnt, bitmap_blocks_cnt;
s->bat = NULL;
qemu_co_mutex_init(&s->lock);
/* validate the file signature */
ret = bdrv_pread(bs->file, 0, &signature, sizeof(uint64_t));
if (ret < 0) {
goto fail;
}
if (memcmp(&signature, "vhdxfile", 8)) {
ret = -EINVAL;
goto fail;
}
ret = vhdx_parse_header(bs, s);
if (ret) {
goto fail;
}
ret = vhdx_parse_log(bs, s);
if (ret) {
goto fail;
}
ret = vhdx_open_region_tables(bs, s);
if (ret) {
goto fail;
}
ret = vhdx_parse_metadata(bs, s);
if (ret) {
goto fail;
}
s->block_size = s->params.block_size;
/* the VHDX spec dictates that virtual_disk_size is always a multiple of
* logical_sector_size */
bs->total_sectors = s->virtual_disk_size >> s->logical_sector_size_bits;
data_blocks_cnt = s->virtual_disk_size >> s->block_size_bits;
if (s->virtual_disk_size - (data_blocks_cnt << s->block_size_bits)) {
data_blocks_cnt++;
}
bitmap_blocks_cnt = data_blocks_cnt >> s->chunk_ratio_bits;
if (data_blocks_cnt - (bitmap_blocks_cnt << s->chunk_ratio_bits)) {
bitmap_blocks_cnt++;
}
if (s->parent_entries) {
s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1);
} else {
s->bat_entries = data_blocks_cnt +
((data_blocks_cnt - 1) >> s->chunk_ratio_bits);
}
s->bat_offset = s->bat_rt.file_offset;
if (s->bat_entries > s->bat_rt.length / sizeof(VHDXBatEntry)) {
/* BAT allocation is not large enough for all entries */
ret = -EINVAL;
goto fail;
}
s->bat = qemu_blockalign(bs, s->bat_rt.length);
ret = bdrv_pread(bs->file, s->bat_offset, s->bat, s->bat_rt.length);
if (ret < 0) {
goto fail;
}
for (i = 0; i < s->bat_entries; i++) {
le64_to_cpus(&s->bat[i]);
}
if (flags & BDRV_O_RDWR) {
ret = -ENOTSUP;
goto fail;
}
/* TODO: differencing files, write */
return 0;
fail:
qemu_vfree(s->headers[0]);
qemu_vfree(s->headers[1]);
qemu_vfree(s->bat);
qemu_vfree(s->parent_entries);
return ret;
}
static int vhdx_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
return 0;
}
/*
* Perform sector to block offset translations, to get various
* sector and file offsets into the image. See VHDXSectorInfo
*/
static void vhdx_block_translate(BDRVVHDXState *s, int64_t sector_num,
int nb_sectors, VHDXSectorInfo *sinfo)
{
uint32_t block_offset;
sinfo->bat_idx = sector_num >> s->sectors_per_block_bits;
/* effectively a modulo - this gives us the offset into the block
* (in sector sizes) for our sector number */
block_offset = sector_num - (sinfo->bat_idx << s->sectors_per_block_bits);
/* the chunk ratio gives us the interleaving of the sector
* bitmaps, so we need to advance our page block index by the
* sector bitmaps entry number */
sinfo->bat_idx += sinfo->bat_idx >> s->chunk_ratio_bits;
/* the number of sectors we can read/write in this cycle */
sinfo->sectors_avail = s->sectors_per_block - block_offset;
sinfo->bytes_left = sinfo->sectors_avail << s->logical_sector_size_bits;
if (sinfo->sectors_avail > nb_sectors) {
sinfo->sectors_avail = nb_sectors;
}
sinfo->bytes_avail = sinfo->sectors_avail << s->logical_sector_size_bits;
sinfo->file_offset = s->bat[sinfo->bat_idx] >> VHDX_BAT_FILE_OFF_BITS;
sinfo->block_offset = block_offset << s->logical_sector_size_bits;
/* The file offset must be past the header section, so must be > 0 */
if (sinfo->file_offset == 0) {
return;
}
/* block offset is the offset in vhdx logical sectors, in
* the payload data block. Convert that to a byte offset
* in the block, and add in the payload data block offset
* in the file, in bytes, to get the final read address */
sinfo->file_offset <<= 20; /* now in bytes, rather than 1MB units */
sinfo->file_offset += sinfo->block_offset;
}
static coroutine_fn int vhdx_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
BDRVVHDXState *s = bs->opaque;
int ret = 0;
VHDXSectorInfo sinfo;
uint64_t bytes_done = 0;
QEMUIOVector hd_qiov;
qemu_iovec_init(&hd_qiov, qiov->niov);
qemu_co_mutex_lock(&s->lock);
while (nb_sectors > 0) {
/* We are a differencing file, so we need to inspect the sector bitmap
* to see if we have the data or not */
if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
/* not supported yet */
ret = -ENOTSUP;
goto exit;
} else {
vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail);
/* check the payload block state */
switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) {
case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
case PAYLOAD_BLOCK_UNDEFINED: /* fall through */
case PAYLOAD_BLOCK_UNMAPPED: /* fall through */
case PAYLOAD_BLOCK_ZERO:
/* return zero */
qemu_iovec_memset(&hd_qiov, 0, 0, sinfo.bytes_avail);
break;
case PAYLOAD_BLOCK_FULL_PRESENT:
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_readv(bs->file,
sinfo.file_offset >> BDRV_SECTOR_BITS,
sinfo.sectors_avail, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto exit;
}
break;
case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
/* we don't yet support difference files, fall through
* to error */
default:
ret = -EIO;
goto exit;
break;
}
nb_sectors -= sinfo.sectors_avail;
sector_num += sinfo.sectors_avail;
bytes_done += sinfo.bytes_avail;
}
}
ret = 0;
exit:
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
return ret;
}
static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
return -ENOTSUP;
}
static void vhdx_close(BlockDriverState *bs)
{
BDRVVHDXState *s = bs->opaque;
qemu_vfree(s->headers[0]);
qemu_vfree(s->headers[1]);
qemu_vfree(s->bat);
qemu_vfree(s->parent_entries);
}
static BlockDriver bdrv_vhdx = {
.format_name = "vhdx",
.instance_size = sizeof(BDRVVHDXState),
.bdrv_probe = vhdx_probe,
.bdrv_open = vhdx_open,
.bdrv_close = vhdx_close,
.bdrv_reopen_prepare = vhdx_reopen_prepare,
.bdrv_co_readv = vhdx_co_readv,
.bdrv_co_writev = vhdx_co_writev,
};
static void bdrv_vhdx_init(void)
{
bdrv_register(&bdrv_vhdx);
}
block_init(bdrv_vhdx_init);
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