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d92aa8833c
xemu/block/vhdx.c
Jeff Cody d92aa8833c block: vhdx write support 
This adds support for writing to VHDX image files, using coroutines.
Writes into the BAT table goes through the VHDX log.  Currently, BAT
table writes occur when expanding a dynamic VHDX file, and allocating a
new BAT entry.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-11-07 13:58:59 +01:00

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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 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.
*
*/
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/crc32c.h"
#include "block/vhdx.h"
#include "migration/migration.h"
#include <uuid/uuid.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 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;
/* Calculates new checksum.
*
* Zero is substituted during crc calculation for the original crc field
* crc_offset: byte offset in buf of the buffer crc
* buf: buffer pointer
* size: size of buffer (must be > crc_offset+4)
*
* Note: The resulting checksum is in the CPU endianness, not necessarily
* in the file format endianness (LE). Any header export to disk should
* make sure that vhdx_header_le_export() is used to convert to the
* correct endianness
*/
uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
{
uint32_t crc;
assert(buf != NULL);
assert(size > (crc_offset + sizeof(crc)));
memset(buf + crc_offset, 0, sizeof(crc));
crc = crc32c(0xffffffff, buf, size);
memcpy(buf + crc_offset, &crc, sizeof(crc));
return crc;
}
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;
}
/*
* This generates a UUID that is compliant with the MS GUIDs used
* in the VHDX spec (and elsewhere).
*/
void vhdx_guid_generate(MSGUID *guid)
{
uuid_t uuid;
assert(guid != NULL);
uuid_generate(uuid);
memcpy(guid, uuid, sizeof(MSGUID));
}
/* Check for region overlaps inside the VHDX image */
static int vhdx_region_check(BDRVVHDXState *s, uint64_t start, uint64_t length)
{
int ret = 0;
uint64_t end;
VHDXRegionEntry *r;
end = start + length;
QLIST_FOREACH(r, &s->regions, entries) {
if (!((start >= r->end) || (end <= r->start))) {
ret = -EINVAL;
goto exit;
}
}
exit:
return ret;
}
/* Register a region for future checks */
static void vhdx_region_register(BDRVVHDXState *s,
uint64_t start, uint64_t length)
{
VHDXRegionEntry *r;
r = g_malloc0(sizeof(*r));
r->start = start;
r->end = start + length;
QLIST_INSERT_HEAD(&s->regions, r, entries);
}
/* Free all registered regions */
static void vhdx_region_unregister_all(BDRVVHDXState *s)
{
VHDXRegionEntry *r, *r_next;
QLIST_FOREACH_SAFE(r, &s->regions, entries, r_next) {
QLIST_REMOVE(r, entries);
g_free(r);
}
}
/*
* 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;
}
/* Update the VHDX headers
*
* This follows the VHDX spec procedures for header updates.
*
* - non-current header is updated with largest sequence number
*/
static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s,
bool generate_data_write_guid, MSGUID *log_guid)
{
int ret = 0;
int hdr_idx = 0;
uint64_t header_offset = VHDX_HEADER1_OFFSET;
VHDXHeader *active_header;
VHDXHeader *inactive_header;
VHDXHeader header_le;
uint8_t *buffer;
/* operate on the non-current header */
if (s->curr_header == 0) {
hdr_idx = 1;
header_offset = VHDX_HEADER2_OFFSET;
}
active_header = s->headers[s->curr_header];
inactive_header = s->headers[hdr_idx];
inactive_header->sequence_number = active_header->sequence_number + 1;
/* a new file guid must be generated before any file write, including
* headers */
inactive_header->file_write_guid = s->session_guid;
/* a new data guid only needs to be generated before any guest-visible
* writes (i.e. something observable via virtual disk read) */
if (generate_data_write_guid) {
vhdx_guid_generate(&inactive_header->data_write_guid);
}
/* update the log guid if present */
if (log_guid) {
inactive_header->log_guid = *log_guid;
}
/* the header checksum is not over just the packed size of VHDXHeader,
* but rather over the entire 'reserved' range for the header, which is
* 4KB (VHDX_HEADER_SIZE). */
buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE);
/* we can't assume the extra reserved bytes are 0 */
ret = bdrv_pread(bs->file, header_offset, buffer, VHDX_HEADER_SIZE);
if (ret < 0) {
goto exit;
}
/* overwrite the actual VHDXHeader portion */
memcpy(buffer, inactive_header, sizeof(VHDXHeader));
inactive_header->checksum =
vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
offsetof(VHDXHeader, checksum));
vhdx_header_le_export(inactive_header, &header_le);
ret = bdrv_pwrite_sync(bs->file, header_offset, &header_le,
sizeof(VHDXHeader));
if (ret < 0) {
goto exit;
}
s->curr_header = hdr_idx;
exit:
qemu_vfree(buffer);
return ret;
}
/*
* The VHDX spec calls for header updates to be performed twice, so that both
* the current and non-current header have valid info
*/
int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s,
bool generate_data_write_guid, MSGUID *log_guid)
{
int ret;
ret = vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
if (ret < 0) {
return ret;
}
ret = vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
return ret;
}
/* 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 & header2 are freed in vhdx_close() */
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;
}
}
vhdx_region_register(s, s->headers[s->curr_header]->log_offset,
s->headers[s->curr_header]->log_length);
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);
/* check for region overlap between these entries, and any
* other memory regions in the file */
ret = vhdx_region_check(s, rt_entry.file_offset, rt_entry.length);
if (ret < 0) {
goto fail;
}
vhdx_region_register(s, rt_entry.file_offset, rt_entry.length);
/* 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;
}
}
if (!bat_rt_found || !metadata_rt_found) {
ret = -EINVAL;
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;
}
static void vhdx_close(BlockDriverState *bs)
{
BDRVVHDXState *s = bs->opaque;
qemu_vfree(s->headers[0]);
s->headers[0] = NULL;
qemu_vfree(s->headers[1]);
s->headers[1] = NULL;
qemu_vfree(s->bat);
s->bat = NULL;
qemu_vfree(s->parent_entries);
s->parent_entries = NULL;
migrate_del_blocker(s->migration_blocker);
error_free(s->migration_blocker);
qemu_vfree(s->log.hdr);
s->log.hdr = NULL;
vhdx_region_unregister_all(s);
}
static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVVHDXState *s = bs->opaque;
int ret = 0;
uint32_t i;
uint64_t signature;
uint32_t data_blocks_cnt, bitmap_blocks_cnt;
bool log_flushed = false;
s->bat = NULL;
s->first_visible_write = true;
qemu_co_mutex_init(&s->lock);
QLIST_INIT(&s->regions);
/* 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;
}
/* This is used for any header updates, for the file_write_guid.
* The spec dictates that a new value should be used for the first
* header update */
vhdx_guid_generate(&s->session_guid);
ret = vhdx_parse_header(bs, s);
if (ret < 0) {
goto fail;
}
ret = vhdx_parse_log(bs, s, &log_flushed);
if (ret < 0) {
goto fail;
}
ret = vhdx_open_region_tables(bs, s);
if (ret < 0) {
goto fail;
}
ret = vhdx_parse_metadata(bs, s);
if (ret < 0) {
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 is freed in vhdx_close() */
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;
}
uint64_t payblocks = s->chunk_ratio;
/* endian convert, and verify populated BAT field file offsets against
* region table and log entries */
for (i = 0; i < s->bat_entries; i++) {
le64_to_cpus(&s->bat[i]);
if (payblocks--) {
/* payload bat entries */
if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) ==
PAYLOAD_BLOCK_FULLY_PRESENT) {
ret = vhdx_region_check(s, s->bat[i] & VHDX_BAT_FILE_OFF_MASK,
s->block_size);
if (ret < 0) {
goto fail;
}
}
} else {
payblocks = s->chunk_ratio;
/* Once differencing files are supported, verify sector bitmap
* blocks here */
}
}
if (flags & BDRV_O_RDWR) {
ret = vhdx_update_headers(bs, s, false, NULL);
if (ret < 0) {
goto fail;
}
}
/* TODO: differencing files */
/* Disable migration when VHDX images are used */
error_set(&s->migration_blocker,
QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
"vhdx", bs->device_name, "live migration");
migrate_add_blocker(s->migration_blocker);
return 0;
fail:
vhdx_close(bs);
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_FULLY_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;
}
/*
* Allocate a new payload block at the end of the file.
*
* Allocation will happen at 1MB alignment inside the file
*
* Returns the file offset start of the new payload block
*/
static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
uint64_t *new_offset)
{
*new_offset = bdrv_getlength(bs->file);
/* per the spec, the address for a block is in units of 1MB */
*new_offset = ROUND_UP(*new_offset, 1024 * 1024);
return bdrv_truncate(bs->file, *new_offset + s->block_size);
}
/*
* Update the BAT table entry with the new file offset, and the new entry
* state */
static void vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s,
VHDXSectorInfo *sinfo,
uint64_t *bat_entry_le,
uint64_t *bat_offset, int state)
{
/* The BAT entry is a uint64, with 44 bits for the file offset in units of
* 1MB, and 3 bits for the block state. */
s->bat[sinfo->bat_idx] = ((sinfo->file_offset>>20) <<
VHDX_BAT_FILE_OFF_BITS);
s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK;
*bat_entry_le = cpu_to_le64(s->bat[sinfo->bat_idx]);
*bat_offset = s->bat_offset + sinfo->bat_idx * sizeof(VHDXBatEntry);
}
/* Per the spec, on the first write of guest-visible data to the file the
* data write guid must be updated in the header */
int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s)
{
int ret = 0;
if (s->first_visible_write) {
s->first_visible_write = false;
ret = vhdx_update_headers(bs, s, true, NULL);
}
return ret;
}
static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
int ret = -ENOTSUP;
BDRVVHDXState *s = bs->opaque;
VHDXSectorInfo sinfo;
uint64_t bytes_done = 0;
uint64_t bat_entry = 0;
uint64_t bat_entry_offset = 0;
QEMUIOVector hd_qiov;
struct iovec iov1 = { 0 };
struct iovec iov2 = { 0 };
int sectors_to_write;
int bat_state;
uint64_t bat_prior_offset = 0;
bool bat_update = false;
qemu_iovec_init(&hd_qiov, qiov->niov);
qemu_co_mutex_lock(&s->lock);
ret = vhdx_user_visible_write(bs, s);
if (ret < 0) {
goto exit;
}
while (nb_sectors > 0) {
bool use_zero_buffers = false;
bat_update = false;
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);
sectors_to_write = sinfo.sectors_avail;
qemu_iovec_reset(&hd_qiov);
/* check the payload block state */
bat_state = s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK;
switch (bat_state) {
case PAYLOAD_BLOCK_ZERO:
/* in this case, we need to preserve zero writes for
* data that is not part of this write, so we must pad
* the rest of the buffer to zeroes */
/* if we are on a posix system with ftruncate() that extends
* a file, then it is zero-filled for us. On Win32, the raw
* layer uses SetFilePointer and SetFileEnd, which does not
* zero fill AFAIK */
/* Queue another write of zero buffers if the underlying file
* does not zero-fill on file extension */
if (bdrv_has_zero_init(bs->file) == 0) {
use_zero_buffers = true;
/* zero fill the front, if any */
if (sinfo.block_offset) {
iov1.iov_len = sinfo.block_offset;
iov1.iov_base = qemu_blockalign(bs, iov1.iov_len);
memset(iov1.iov_base, 0, iov1.iov_len);
qemu_iovec_concat_iov(&hd_qiov, &iov1, 1, 0,
sinfo.block_offset);
sectors_to_write += iov1.iov_len >> BDRV_SECTOR_BITS;
}
/* our actual data */
qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
sinfo.bytes_avail);
/* zero fill the back, if any */
if ((sinfo.bytes_avail - sinfo.block_offset) <
s->block_size) {
iov2.iov_len = s->block_size -
(sinfo.bytes_avail + sinfo.block_offset);
iov2.iov_base = qemu_blockalign(bs, iov2.iov_len);
memset(iov2.iov_base, 0, iov2.iov_len);
qemu_iovec_concat_iov(&hd_qiov, &iov2, 1, 0,
sinfo.block_offset);
sectors_to_write += iov2.iov_len >> BDRV_SECTOR_BITS;
}
}
/* fall through */
case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
case PAYLOAD_BLOCK_UNMAPPED: /* fall through */
case PAYLOAD_BLOCK_UNDEFINED: /* fall through */
bat_prior_offset = sinfo.file_offset;
ret = vhdx_allocate_block(bs, s, &sinfo.file_offset);
if (ret < 0) {
goto exit;
}
/* once we support differencing files, this may also be
* partially present */
/* update block state to the newly specified state */
vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
&bat_entry_offset,
PAYLOAD_BLOCK_FULLY_PRESENT);
bat_update = true;
/* since we just allocated a block, file_offset is the
* beginning of the payload block. It needs to be the
* write address, which includes the offset into the block */
if (!use_zero_buffers) {
sinfo.file_offset += sinfo.block_offset;
}
/* fall through */
case PAYLOAD_BLOCK_FULLY_PRESENT:
/* if the file offset address is in the header zone,
* there is a problem */
if (sinfo.file_offset < (1024 * 1024)) {
ret = -EFAULT;
goto error_bat_restore;
}
if (!use_zero_buffers) {
qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
sinfo.bytes_avail);
}
/* block exists, so we can just overwrite it */
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_writev(bs->file,
sinfo.file_offset >> BDRV_SECTOR_BITS,
sectors_to_write, &hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto error_bat_restore;
}
break;
case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
/* we don't yet support difference files, fall through
* to error */
default:
ret = -EIO;
goto exit;
break;
}
if (bat_update) {
/* this will update the BAT entry into the log journal, and
* then flush the log journal out to disk */
ret = vhdx_log_write_and_flush(bs, s, &bat_entry,
sizeof(VHDXBatEntry),
bat_entry_offset);
if (ret < 0) {
goto exit;
}
}
nb_sectors -= sinfo.sectors_avail;
sector_num += sinfo.sectors_avail;
bytes_done += sinfo.bytes_avail;
}
}
goto exit;
error_bat_restore:
if (bat_update) {
/* keep metadata in sync, and restore the bat entry state
* if error. */
sinfo.file_offset = bat_prior_offset;
vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
&bat_entry_offset, bat_state);
}
exit:
qemu_vfree(iov1.iov_base);
qemu_vfree(iov2.iov_base);
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
return ret;
}
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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