@@ -2,7 +2,7 @@ block-obj-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat
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-$(CONFIG_VHDX) += vhdx.o
block-obj-y += parallels.o blkdebug.o blkverify.o
block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
block-obj-$(CONFIG_POSIX) += raw-posix.o
@@ -21,6 +21,7 @@
#include "qemu/crc32c.h"
#include "block/vhdx.h"
+#include <uuid/uuid.h>
/* Several metadata and region table data entries are identified by
* guids in a MS-specific GUID format. */
@@ -156,11 +157,40 @@ typedef struct BDRVVHDXState {
vhdx_bat_entry *bat;
uint64_t bat_offset;
+ ms_guid session_guid;
+
+
vhdx_parent_locator_header parent_header;
vhdx_parent_locator_entry *parent_entries;
} 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
+ */
+static uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
+{
+ uint32_t crc;
+
+ assert(buf != NULL);
+ assert(size > (crc_offset+4));
+
+ 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)
{
@@ -212,6 +242,24 @@ 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).
+ *
+ * We can do this with uuid_generate if uuid.h is present,
+ * however not all systems have uuid and the generation is
+ * pretty straightforward for the DCE + random usage case
+ *
+ */
+static void vhdx_guid_generate(ms_guid *guid)
+{
+ uuid_t uuid;
+ assert(guid != NULL);
+
+ uuid_generate(uuid);
+ memcpy(guid, uuid, 16);
+}
+
+/*
* 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"
@@ -249,6 +297,107 @@ static void vhdx_header_le_import(vhdx_header *h)
le64_to_cpus(&h->log_offset);
}
+/* All VHDX structures on disk are little endian */
+static void vhdx_header_le_export(vhdx_header *orig_h, vhdx_header *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);
+
+ memcpy(&new_h->file_write_guid, &orig_h->file_write_guid, sizeof(ms_guid));
+ memcpy(&new_h->data_write_guid, &orig_h->data_write_guid, sizeof(ms_guid));
+ memcpy(&new_h->log_guid, &orig_h->log_guid, sizeof(ms_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 rw)
+{
+ int ret = 0;
+ int hdr_idx = 0;
+ uint64_t header_offset = VHDX_HEADER1_OFFSET;
+
+ vhdx_header *active_header;
+ vhdx_header *inactive_header;
+ vhdx_header 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 generate before any file write, including
+ * headers */
+ memcpy(&inactive_header->file_write_guid, &s->session_guid,
+ sizeof(ms_guid));
+
+ /* a new data guid only needs to be generate before any guest-visisble
+ * writes, so update it if the image is opened r/w. */
+ if (rw) {
+ vhdx_guid_generate(&inactive_header->data_write_guid);
+ }
+
+ /* the header checksum is not over just the packed size of vhdx_header,
+ * 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 fail;
+ }
+ /* overwrite the actual vhdx_header portion */
+ memcpy(buffer, inactive_header, sizeof(vhdx_header));
+ inactive_header->checksum = vhdx_update_checksum(buffer,
+ VHDX_HEADER_SIZE, 4);
+ vhdx_header_le_export(inactive_header, &header_le);
+ bdrv_pwrite_sync(bs->file, header_offset, &header_le, sizeof(vhdx_header));
+ s->curr_header = hdr_idx;
+
+fail:
+ 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 rw)
+{
+ int ret;
+
+ ret = vhdx_update_header(bs, s, rw);
+ if (ret < 0) {
+ return ret;
+ }
+ ret = vhdx_update_header(bs, s, rw);
+ return ret;
+}
/* opens the specified header block from the VHDX file header section */
static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s)
@@ -680,6 +829,11 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags)
qemu_co_mutex_init(&s->lock);
+ /* 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;
@@ -716,8 +870,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags)
}
if (flags & BDRV_O_RDWR) {
- ret = -ENOTSUP;
- goto fail;
+ vhdx_update_headers(bs, s, false);
}
/* TODO: differencing files, write */
@@ -242,6 +242,7 @@ gtk=""
gtkabi="2.0"
tpm="no"
libssh2=""
+vhdx="no"
# parse CC options first
for opt do
@@ -934,6 +935,11 @@ for opt do
;;
--enable-libssh2) libssh2="yes"
;;
+ --enable-vhdx) vhdx="yes" ;
+ uuid="yes"
+ ;;
+ --disable-vhdx) vhdx="no"
+ ;;
*) echo "ERROR: unknown option $opt"; show_help="yes"
;;
esac
@@ -1201,6 +1207,8 @@ echo " --gcov=GCOV use specified gcov [$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
@@ -3580,6 +3588,7 @@ echo "gcov enabled $gcov"
echo "TPM support $tpm"
echo "libssh2 support $libssh2"
echo "TPM passthrough $tpm_passthrough"
+echo "vhdx $vhdx"
if test "$sdl_too_old" = "yes"; then
echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -3968,6 +3977,10 @@ 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" >> $config_host_mak
+fi
+
# USB host support
case "$usb" in
linux)
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. To enable/disable VHDX: --enable-vhdx, --disable-vhdx Signed-off-by: Jeff Cody <jcody@redhat.com> --- block/Makefile.objs | 2 +- block/vhdx.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++++- configure | 13 +++++ 3 files changed, 169 insertions(+), 3 deletions(-)