virtio: move VirtQueueElement at the beginning of the structs

The next patch will make virtqueue_pop/vring_pop allocate memory for
the VirtQueueElement. In some cases (blk, scsi, gpu) the device wants
to extend VirtQueueElement with device-specific fields and, until now,
the place of the VirtQueueElement within the containing struct didn't
matter. When allocating the entire block in virtqueue_pop/vring_pop,
however, the containing struct must basically be a "subclass" of
VirtQueueElement, with the VirtQueueElement as the first field. Make
that the case for blk and scsi; gpu is already doing it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Paolo Bonzini 2016-01-31 11:28:57 +01:00 committed by Michael S. Tsirkin
parent 0734fb083c
commit 6aa46d8ff1
3 changed files with 8 additions and 10 deletions

View file

@ -45,8 +45,7 @@ VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq)
{
VirtIOSCSIReq *req;
VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
const size_t zero_skip = offsetof(VirtIOSCSIReq, elem)
+ sizeof(VirtQueueElement);
const size_t zero_skip = offsetof(VirtIOSCSIReq, vring);
req = g_malloc(sizeof(*req) + vs->cdb_size);
req->vq = vq;

View file

@ -60,9 +60,9 @@ typedef struct VirtIOBlock {
} VirtIOBlock;
typedef struct VirtIOBlockReq {
VirtQueueElement elem;
int64_t sector_num;
VirtIOBlock *dev;
VirtQueueElement elem;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr out;
QEMUIOVector qiov;

View file

@ -112,18 +112,17 @@ typedef struct VirtIOSCSI {
} VirtIOSCSI;
typedef struct VirtIOSCSIReq {
/* Note:
* - fields up to resp_iov are initialized by virtio_scsi_init_req;
* - fields starting at vring are zeroed by virtio_scsi_init_req.
* */
VirtQueueElement elem;
VirtIOSCSI *dev;
VirtQueue *vq;
QEMUSGList qsgl;
QEMUIOVector resp_iov;
/* Note:
* - fields before elem are initialized by virtio_scsi_init_req;
* - elem is uninitialized at the time of allocation.
* - fields after elem are zeroed by virtio_scsi_init_req.
* */
VirtQueueElement elem;
/* Set by dataplane code. */
VirtIOSCSIVring *vring;