diff options
Diffstat (limited to 'hw/virtio/virtio.c')
| -rw-r--r-- | hw/virtio/virtio.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 7549094154..d229755eae 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -3556,6 +3556,17 @@ static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx) { + /* + * virtio_queue_aio_detach_host_notifier() can leave notifications disabled. + * Re-enable them. (And if detach has not been used before, notifications + * being enabled is still the default state while a notifier is attached; + * see virtio_queue_host_notifier_aio_poll_end(), which will always leave + * notifications enabled once the polling section is left.) + */ + if (!virtio_queue_get_notification(vq)) { + virtio_queue_set_notification(vq, 1); + } + aio_set_event_notifier(ctx, &vq->host_notifier, virtio_queue_host_notifier_read, virtio_queue_host_notifier_aio_poll, @@ -3563,6 +3574,13 @@ void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx) aio_set_event_notifier_poll(ctx, &vq->host_notifier, virtio_queue_host_notifier_aio_poll_begin, virtio_queue_host_notifier_aio_poll_end); + + /* + * We will have ignored notifications about new requests from the guest + * while no notifiers were attached, so "kick" the virt queue to process + * those requests now. + */ + event_notifier_set(&vq->host_notifier); } /* @@ -3573,14 +3591,38 @@ void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx) */ void virtio_queue_aio_attach_host_notifier_no_poll(VirtQueue *vq, AioContext *ctx) { + /* See virtio_queue_aio_attach_host_notifier() */ + if (!virtio_queue_get_notification(vq)) { + virtio_queue_set_notification(vq, 1); + } + aio_set_event_notifier(ctx, &vq->host_notifier, virtio_queue_host_notifier_read, NULL, NULL); + + /* + * See virtio_queue_aio_attach_host_notifier(). + * Note that this may be unnecessary for the type of virtqueues this + * function is used for. Still, it will not hurt to have a quick look into + * whether we can/should process any of the virtqueue elements. + */ + event_notifier_set(&vq->host_notifier); } void virtio_queue_aio_detach_host_notifier(VirtQueue *vq, AioContext *ctx) { aio_set_event_notifier(ctx, &vq->host_notifier, NULL, NULL, NULL); + + /* + * aio_set_event_notifier_poll() does not guarantee whether io_poll_end() + * will run after io_poll_begin(), so by removing the notifier, we do not + * know whether virtio_queue_host_notifier_aio_poll_end() has run after a + * previous virtio_queue_host_notifier_aio_poll_begin(), i.e. whether + * notifications are enabled or disabled. It does not really matter anyway; + * we just removed the notifier, so we do not care about notifications until + * we potentially re-attach it. The attach_host_notifier functions will + * ensure that notifications are enabled again when they are needed. + */ } void virtio_queue_host_notifier_read(EventNotifier *n) |