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xemu/block/vhdx.c
Jeff Cody 1e74a971cb block: vhdx - break out code operations to functions 
This is preperation for vhdx_create().  The ability to write headers,
and calculate the number of BAT entries will be needed within the
create() functions, so move this relevant code into helper functions.

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);
}
}
static void vhdx_set_shift_bits(BDRVVHDXState *s)
{
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);
}
/*
* 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;
}
/*
* Writes the header to the specified offset.
*
* This will optionally read in buffer data from disk (otherwise zero-fill),
* and then update the header checksum. Header is converted to proper
* endianness before being written to the specified file offset
*/
static int vhdx_write_header(BlockDriverState *bs_file, VHDXHeader *hdr,
uint64_t offset, bool read)
{
uint8_t *buffer = NULL;
int ret;
VHDXHeader header_le;
assert(bs_file != NULL);
assert(hdr != NULL);
/* 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_file, VHDX_HEADER_SIZE);
if (read) {
/* if true, we can't assume the extra reserved bytes are 0 */
ret = bdrv_pread(bs_file, offset, buffer, VHDX_HEADER_SIZE);
if (ret < 0) {
goto exit;
}
} else {
memset(buffer, 0, VHDX_HEADER_SIZE);
}
/* overwrite the actual VHDXHeader portion */
memcpy(buffer, hdr, sizeof(VHDXHeader));
hdr->checksum = vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
offsetof(VHDXHeader, checksum));
vhdx_header_le_export(hdr, &header_le);
ret = bdrv_pwrite_sync(bs_file, offset, &header_le, sizeof(VHDXHeader));
exit:
qemu_vfree(buffer);
return ret;
}
/* 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;
/* 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;
}
vhdx_write_header(bs->file, inactive_header, header_offset, true);
if (ret < 0) {
goto exit;
}
s->curr_header = hdr_idx;
exit:
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));
vhdx_region_header_le_import(&s->rt);
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);
vhdx_region_entry_le_import(&rt_entry);
/* 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);
vhdx_metadata_header_le_import(&s->metadata_hdr);
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);
vhdx_metadata_entry_le_import(&md_entry);
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;
}
vhdx_set_shift_bits(s);
ret = 0;
exit:
qemu_vfree(buffer);
return ret;
}
/*
* Calculate the number of BAT entries, including sector
* bitmap entries.
*/
static void vhdx_calc_bat_entries(BDRVVHDXState *s)
{
uint32_t data_blocks_cnt, bitmap_blocks_cnt;
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);
}
}
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;
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;
vhdx_calc_bat_entries(s);
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_MASK;
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 += 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;
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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