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virtio-blk: use aio handler for data plane

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In addition to handling IO in vcpu thread and in io thread, dataplane
introduces yet another mode: handling it by AioContext.

This reuses the same handler as previous modes, which triggers races as
these were not designed to be reentrant.  Use a separate handler just
for aio, and disable regular handlers when dataplane is active.

Signed-off-by: Michael S. Tsirkin <mst@redhat.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:
Michael S. Tsirkin 2016-04-06 12:16:26 +02:00
parent 344dc16fae
commit 8a2fad57eb
3 changed files with 32 additions and 10 deletions
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13
hw/block/dataplane/virtio-blk.c
View File

@ -184,6 +184,17 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
g_free(s);
}
static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOBlock *s = (VirtIOBlock *)vdev;
assert(s->dataplane);
assert(s->dataplane_started);
virtio_blk_handle_vq(s, vq);
}
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
{
@ -226,6 +237,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
/* Get this show started by hooking up our callbacks */
aio_context_acquire(s->ctx);
virtio_set_queue_aio(s->vq, virtio_blk_data_plane_handle_output);
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true);
aio_context_release(s->ctx);
return;
@ -262,6 +274,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
/* Stop notifications for new requests from guest */
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, false, false);
virtio_set_queue_aio(s->vq, NULL);
/* Drain and switch bs back to the QEMU main loop */
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());

27
hw/block/virtio-blk.c
View File

@ -578,20 +578,11 @@ void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
}
}
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq)
{
VirtIOBlock *s = VIRTIO_BLK(vdev);
VirtIOBlockReq *req;
MultiReqBuffer mrb = {};
/* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
* dataplane here instead of waiting for .set_status().
*/
if (s->dataplane && !s->dataplane_started) {
virtio_blk_data_plane_start(s->dataplane);
return;
}
blk_io_plug(s->blk);
while ((req = virtio_blk_get_request(s))) {
@ -605,6 +596,22 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
blk_io_unplug(s->blk);
}
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBlock *s = (VirtIOBlock *)vdev;
if (s->dataplane) {
/* 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);
if (!s->dataplane_disabled) {
return;
}
}
virtio_blk_handle_vq(s, vq);
}
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;

2
include/hw/virtio/virtio-blk.h
View File

@ -86,4 +86,6 @@ void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb);
void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb);
void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
#endif