Commit 8a2fad57 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio-blk: use aio handler for data plane 



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: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 344dc16f

hw/block/dataplane/virtio-blk.c

+13 −0
Original line number Diff line number Diff line
@@ -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());

hw/block/virtio-blk.c

+17 −10
Original line number Diff line number Diff line
@@ -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;

include/hw/virtio/virtio-blk.h

+2 −0
Original line number Diff line number Diff line
@@ -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