Commit 0830c96d authored by Cornelia Huck's avatar Cornelia Huck Committed by Michael S. Tsirkin
Browse files

virtio: revert host notifiers to old semantics 



The host notifier rework tried both to unify host notifiers across
transports and plug a possible hole during host notifier
re-assignment. Unfortunately, this meant a change in semantics that
breaks vhost and iSCSI+dataplane.

As the minimal fix, keep the common host notifier code but revert
to the old semantics so that we have time to figure out the proper
fix.

Fixes: 6798e245 ("virtio-bus: common ioeventfd infrastructure")
Reported-by: default avatarPeter Lieven <pl@kamp.de>
Reported-by: default avatarJason Wang <jasowang@redhat.com>
Reported-by: default avatarMarc-André Lureau <marcandre.lureau@gmail.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Tested-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: default avatarJason Wang <jasowang@redhat.com>
Tested-by: default avatarJason Wang <jasowang@redhat.com>
Tested-by: default avatarPeter Lieven <pl@kamp.de>
parent 01c9742d

hw/virtio/virtio-bus.c

+10 −16
Original line number Diff line number Diff line
@@ -176,8 +176,8 @@ static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus, 
            return r;

        }

    } else {

        virtio_queue_set_host_notifier_fd_handler(vq, false, false);

        k->ioeventfd_assign(proxy, notifier, n, assign);

        virtio_queue_set_host_notifier_fd_handler(vq, false, false);

        event_notifier_cleanup(notifier);

    }

    return r;
@@ -251,31 +251,25 @@ int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign) 
{

    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);

    DeviceState *proxy = DEVICE(BUS(bus)->parent);

    VirtIODevice *vdev = virtio_bus_get_device(bus);

    VirtQueue *vq = virtio_get_queue(vdev, n);



    if (!k->ioeventfd_started) {

        return -ENOSYS;

    }

    k->ioeventfd_set_disabled(proxy, assign);

    if (assign) {

        /*

         * Stop using the generic ioeventfd, we are doing eventfd handling

         * ourselves below

         */

        k->ioeventfd_set_disabled(proxy, true);

    }

    /*

     * Just switch the handler, don't deassign the ioeventfd.

         *

         * FIXME: We should just switch the handler and not deassign the

         * ioeventfd.

         * Otherwise, there's a window where we don't have an

         * ioeventfd and we may end up with a notification where

         * we don't expect one.

         */

    virtio_queue_set_host_notifier_fd_handler(vq, assign, !assign);

    if (!assign) {

        /* Use generic ioeventfd handler again. */

        k->ioeventfd_set_disabled(proxy, false);

        virtio_bus_stop_ioeventfd(bus);

    }

    return 0;

    return set_host_notifier_internal(proxy, bus, n, assign, false);

}



static char *virtio_bus_get_dev_path(DeviceState *dev)