提交 4f18b782 编写于 作者: J Jeff Cody 提交者: Stefan Hajnoczi

block: vhdx - add header update capability.

This adds the ability to update the headers in a VHDX image, including
generating a new MS-compatible GUID.

As VHDX depends on uuid.h, VHDX is now a configurable build option.  If
VHDX support is enabled, that will also enable uuid as well.  The
default is to have VHDX enabled.

To enable/disable VHDX:  --enable-vhdx, --disable-vhdx
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
上级 6e9d290b
......@@ -2,7 +2,7 @@ block-obj-y += raw_bsd.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o v
block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o
block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
block-obj-y += qed-check.o
block-obj-y += vhdx.o
block-obj-$(CONFIG_VHDX) += vhdx.o
block-obj-y += parallels.o blkdebug.o blkverify.o
block-obj-y += snapshot.o qapi.o
block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
......
......@@ -22,6 +22,7 @@
#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. */
......@@ -157,12 +158,41 @@ typedef struct BDRVVHDXState {
VHDXBatEntry *bat;
uint64_t bat_offset;
MSGUID session_guid;
VHDXParentLocatorHeader parent_header;
VHDXParentLocatorEntry *parent_entries;
Error *migration_blocker;
} BDRVVHDXState;
/* 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)
{
......@@ -213,6 +243,19 @@ bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset)
}
/*
* 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));
}
/*
* Per the MS VHDX Specification, for every VHDX file:
* - The header section is fixed size - 1 MB
......@@ -251,6 +294,113 @@ static void vhdx_header_le_import(VHDXHeader *h)
le64_to_cpus(&h->log_offset);
}
/* All VHDX structures on disk are little endian */
static void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h)
{
assert(orig_h != NULL);
assert(new_h != NULL);
new_h->signature = cpu_to_le32(orig_h->signature);
new_h->checksum = cpu_to_le32(orig_h->checksum);
new_h->sequence_number = cpu_to_le64(orig_h->sequence_number);
new_h->file_write_guid = orig_h->file_write_guid;
new_h->data_write_guid = orig_h->data_write_guid;
new_h->log_guid = orig_h->log_guid;
cpu_to_leguids(&new_h->file_write_guid);
cpu_to_leguids(&new_h->data_write_guid);
cpu_to_leguids(&new_h->log_guid);
new_h->log_version = cpu_to_le16(orig_h->log_version);
new_h->version = cpu_to_le16(orig_h->version);
new_h->log_length = cpu_to_le32(orig_h->log_length);
new_h->log_offset = cpu_to_le64(orig_h->log_offset);
}
/* 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)
{
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);
}
/* 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
*/
static int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s,
bool generate_data_write_guid)
{
int ret;
ret = vhdx_update_header(bs, s, generate_data_write_guid);
if (ret < 0) {
return ret;
}
ret = vhdx_update_header(bs, s, generate_data_write_guid);
return ret;
}
/* opens the specified header block from the VHDX file header section */
static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s)
......@@ -742,6 +892,11 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
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) {
goto fail;
......@@ -804,8 +959,10 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
}
if (flags & BDRV_O_RDWR) {
ret = -ENOTSUP;
goto fail;
ret = vhdx_update_headers(bs, s, false);
if (ret < 0) {
goto fail;
}
}
/* TODO: differencing files, write */
......
......@@ -67,7 +67,7 @@ typedef struct VHDXFileIdentifier {
* Microsoft is not just 16 bytes though - it is a structure that is defined,
* so we need to follow it here so that endianness does not trip us up */
typedef struct MSGUID {
typedef struct QEMU_PACKED MSGUID {
uint32_t data1;
uint16_t data2;
uint16_t data3;
......@@ -309,17 +309,27 @@ typedef struct QEMU_PACKED VHDXParentLocatorEntry {
/* ----- END VHDX SPECIFICATION STRUCTURES ---- */
void vhdx_guid_generate(MSGUID *guid);
uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset);
uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
int crc_offset);
bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset);
static void leguid_to_cpus(MSGUID *guid)
static inline void leguid_to_cpus(MSGUID *guid)
{
le32_to_cpus(&guid->data1);
le16_to_cpus(&guid->data2);
le16_to_cpus(&guid->data3);
}
static inline void cpu_to_leguids(MSGUID *guid)
{
cpu_to_le32s(&guid->data1);
cpu_to_le16s(&guid->data2);
cpu_to_le16s(&guid->data3);
}
#endif
......@@ -247,6 +247,7 @@ gtk=""
gtkabi="2.0"
tpm="no"
libssh2=""
vhdx=""
# parse CC options first
for opt do
......@@ -972,6 +973,10 @@ for opt do
;;
--enable-libssh2) libssh2="yes"
;;
--enable-vhdx) vhdx="yes"
;;
--disable-vhdx) vhdx="no"
;;
*) echo "ERROR: unknown option $opt"; show_help="yes"
;;
esac
......@@ -1204,6 +1209,8 @@ echo " --gcov=GCOV use specified gcov [$gcov_tool]"
echo " --enable-tpm enable TPM support"
echo " --disable-libssh2 disable ssh block device support"
echo " --enable-libssh2 enable ssh block device support"
echo " --disable-vhdx disables support for the Microsoft VHDX image format"
echo " --enable-vhdx enable support for the Microsoft VHDX image format"
echo ""
echo "NOTE: The object files are built at the place where configure is launched"
exit 1
......@@ -2004,6 +2011,18 @@ EOF
fi
fi
if test "$vhdx" = "yes" ; then
if test "$uuid" = "no" ; then
error_exit "uuid required for VHDX support"
fi
elif test "$vhdx" != "no" ; then
if test "$uuid" = "yes" ; then
vhdx=yes
else
vhdx=no
fi
fi
##########################################
# xfsctl() probe, used for raw-posix
if test "$xfs" != "no" ; then
......@@ -3747,6 +3766,7 @@ echo "TPM support $tpm"
echo "libssh2 support $libssh2"
echo "TPM passthrough $tpm_passthrough"
echo "QOM debugging $qom_cast_debug"
echo "vhdx $vhdx"
if test "$sdl_too_old" = "yes"; then
echo "-> Your SDL version is too old - please upgrade to have SDL support"
......@@ -4141,6 +4161,10 @@ if test "$virtio_blk_data_plane" = "yes" ; then
echo 'CONFIG_VIRTIO_BLK_DATA_PLANE=$(CONFIG_VIRTIO)' >> $config_host_mak
fi
if test "$vhdx" = "yes" ; then
echo "CONFIG_VHDX=y" >> $config_host_mak
fi
# USB host support
if test "$libusb" = "yes"; then
echo "HOST_USB=libusb legacy" >> $config_host_mak
......
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