Commit 344dc16f authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio: add aio handler 



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

Currently, this reuses the same handler as previous modes,
which triggers races as these were not designed to be reentrant.
Add instead a separate handler just for aio; this will make
it possible to 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 43c696a2

hw/virtio/virtio.c

+32 −4
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ struct VirtQueue 


    uint16_t vector;

    void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);

    void (*handle_aio_output)(VirtIODevice *vdev, VirtQueue *vq);

    VirtIODevice *vdev;

    EventNotifier guest_notifier;

    EventNotifier host_notifier;
@@ -1088,6 +1089,16 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) 
    virtio_queue_update_rings(vdev, n);

}



static void virtio_queue_notify_aio_vq(VirtQueue *vq)

{

    if (vq->vring.desc && vq->handle_aio_output) {

        VirtIODevice *vdev = vq->vdev;



        trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);

        vq->handle_aio_output(vdev, vq);

    }

}



static void virtio_queue_notify_vq(VirtQueue *vq)

{

    if (vq->vring.desc && vq->handle_output) {
@@ -1143,10 +1154,19 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size, 
    vdev->vq[i].vring.num_default = queue_size;

    vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;

    vdev->vq[i].handle_output = handle_output;

    vdev->vq[i].handle_aio_output = NULL;



    return &vdev->vq[i];

}



void virtio_set_queue_aio(VirtQueue *vq,

                          void (*handle_output)(VirtIODevice *, VirtQueue *))

{

    assert(vq->handle_output);



    vq->handle_aio_output = handle_output;

}



void virtio_del_queue(VirtIODevice *vdev, int n)

{

    if (n < 0 || n >= VIRTIO_QUEUE_MAX) {
@@ -1780,11 +1800,11 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq) 
    return &vq->guest_notifier;

}



static void virtio_queue_host_notifier_read(EventNotifier *n)

static void virtio_queue_host_notifier_aio_read(EventNotifier *n)

{

    VirtQueue *vq = container_of(n, VirtQueue, host_notifier);

    if (event_notifier_test_and_clear(n)) {

        virtio_queue_notify_vq(vq);

        virtio_queue_notify_aio_vq(vq);

    }

}
@@ -1793,14 +1813,22 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, 
{

    if (assign && set_handler) {

        aio_set_event_notifier(ctx, &vq->host_notifier, true,

                               virtio_queue_host_notifier_read);

                               virtio_queue_host_notifier_aio_read);

    } else {

        aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL);

    }

    if (!assign) {

        /* Test and clear notifier before after disabling event,

         * in case poll callback didn't have time to run. */

        virtio_queue_host_notifier_read(&vq->host_notifier);

        virtio_queue_host_notifier_aio_read(&vq->host_notifier);

    }

}



static void virtio_queue_host_notifier_read(EventNotifier *n)

{

    VirtQueue *vq = container_of(n, VirtQueue, host_notifier);

    if (event_notifier_test_and_clear(n)) {

        virtio_queue_notify_vq(vq);

    }

}

include/hw/virtio/virtio.h

+3 −0
Original line number Diff line number Diff line
@@ -142,6 +142,9 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size, 
                            void (*handle_output)(VirtIODevice *,

                                                  VirtQueue *));



void virtio_set_queue_aio(VirtQueue *vq,

                          void (*handle_output)(VirtIODevice *, VirtQueue *));



void virtio_del_queue(VirtIODevice *vdev, int n);



void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_num);