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virtio-blk: always use dataplane path if ioeventfd is active

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Override start_ioeventfd and stop_ioeventfd to start/stop the
whole dataplane logic.  This has some positive side effects:

- no need anymore for virtio_add_queue_aio (i.e. a revert of
  commit 0ff841f6d1)

- no need anymore to switch from generic ioeventfd handlers to
  dataplane

It detects some errors better:

    $ qemu-system-x86_64 -object iothread,id=io \
          -drive id=null,file=null-aio://,if=none,format=raw \
          -device virtio-blk-pci,ioeventfd=off,iothread=io,drive=null
    qemu-system-x86_64: -device virtio-blk-pci,ioeventfd=off,iothread=io,drive=null:
    ioeventfd is required for iothread

while previously it would have started just fine.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
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>
This commit is contained in:
Paolo Bonzini 2016-10-21 22:48:09 +02:00 committed by Michael S. Tsirkin
parent 8e93cef14e
commit 9ffe337c08
3 changed files with 55 additions and 39 deletions
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73
hw/block/dataplane/virtio-blk.c
View File

@ -88,23 +88,28 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
*dataplane = NULL;
if (!conf->iothread) {
return;
}
if (conf->iothread) {
if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
error_setg(errp,
"device is incompatible with iothread "
"(transport does not support notifiers)");
return;
}
if (!virtio_device_ioeventfd_enabled(vdev)) {
error_setg(errp, "ioeventfd is required for iothread");
return;
}
/* If dataplane is (re-)enabled while the guest is running there could
* be block jobs that can conflict.
*/
if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
error_prepend(errp, "cannot start virtio-blk dataplane: ");
return;
}
}
/* Don't try if transport does not support notifiers. */
if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
error_setg(errp,
"device is incompatible with dataplane "
"(transport does not support notifiers)");
return;
}
/* If dataplane is (re-)enabled while the guest is running there could be
* block jobs that can conflict.
*/
if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
error_prepend(errp, "cannot start dataplane thread: ");
if (!virtio_device_ioeventfd_enabled(vdev)) {
return;
}
@ -112,9 +117,13 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
s->vdev = vdev;
s->conf = conf;
s->iothread = conf->iothread;
object_ref(OBJECT(s->iothread));
s->ctx = iothread_get_aio_context(s->iothread);
if (conf->iothread) {
s->iothread = conf->iothread;
object_ref(OBJECT(s->iothread));
s->ctx = iothread_get_aio_context(s->iothread);
} else {
s->ctx = qemu_get_aio_context();
}
s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
s->batch_notify_vqs = bitmap_new(conf->num_queues);
@ -124,14 +133,19 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
{
VirtIOBlock *vblk;
if (!s) {
return;
}
virtio_blk_data_plane_stop(s);
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
g_free(s->batch_notify_vqs);
qemu_bh_delete(s->bh);
object_unref(OBJECT(s->iothread));
if (s->iothread) {
object_unref(OBJECT(s->iothread));
}
g_free(s);
}
@ -147,17 +161,18 @@ static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
}
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
int virtio_blk_data_plane_start(VirtIODevice *vdev)
{
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
VirtIOBlock *vblk = VIRTIO_BLK(vdev);
VirtIOBlockDataPlane *s = vblk->dataplane;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vblk)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
unsigned i;
unsigned nvqs = s->conf->num_queues;
int r;
if (vblk->dataplane_started || s->starting) {
return;
return 0;
}
s->starting = true;
@ -204,20 +219,22 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
virtio_blk_data_plane_handle_output);
}
aio_context_release(s->ctx);
return;
return 0;
fail_guest_notifiers:
vblk->dataplane_disabled = true;
s->starting = false;
vblk->dataplane_started = true;
return -ENOSYS;
}
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
void virtio_blk_data_plane_stop(VirtIODevice *vdev)
{
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
VirtIOBlock *vblk = VIRTIO_BLK(vdev);
VirtIOBlockDataPlane *s = vblk->dataplane;
BusState *qbus = qdev_get_parent_bus(DEVICE(vblk));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
unsigned i;
unsigned nvqs = s->conf->num_queues;

6
hw/block/dataplane/virtio-blk.h
View File

@ -23,9 +23,9 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
VirtIOBlockDataPlane **dataplane,
Error **errp);
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s);
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq);
int virtio_blk_data_plane_start(VirtIODevice *vdev);
void virtio_blk_data_plane_stop(VirtIODevice *vdev);
#endif /* HW_DATAPLANE_VIRTIO_BLK_H */

15
hw/block/virtio-blk.c
View File

@ -611,7 +611,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
/* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
* dataplane here instead of waiting for .set_status().
*/
virtio_blk_data_plane_start(s->dataplane);
virtio_device_start_ioeventfd(vdev);
if (!s->dataplane_disabled) {
return;
}
@ -687,11 +687,9 @@ static void virtio_blk_reset(VirtIODevice *vdev)
virtio_blk_free_request(req);
}
if (s->dataplane) {
virtio_blk_data_plane_stop(s->dataplane);
}
aio_context_release(ctx);
assert(!s->dataplane_started);
blk_set_enable_write_cache(s->blk, s->original_wce);
}
@ -789,9 +787,8 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
if (s->dataplane && !(status & (VIRTIO_CONFIG_S_DRIVER |
VIRTIO_CONFIG_S_DRIVER_OK))) {
virtio_blk_data_plane_stop(s->dataplane);
if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
assert(!s->dataplane_started);
}
if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
@ -919,7 +916,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
for (i = 0; i < conf->num_queues; i++) {
virtio_add_queue_aio(vdev, 128, virtio_blk_handle_output);
virtio_add_queue(vdev, 128, virtio_blk_handle_output);
}
virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
if (err != NULL) {
@ -1002,6 +999,8 @@ static void virtio_blk_class_init(ObjectClass *klass, void *data)
vdc->reset = virtio_blk_reset;
vdc->save = virtio_blk_save_device;
vdc->load = virtio_blk_load_device;
vdc->start_ioeventfd = virtio_blk_data_plane_start;
vdc->stop_ioeventfd = virtio_blk_data_plane_stop;
}
static const TypeInfo virtio_blk_info = {