From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49850) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cihil-0003OJ-1K for qemu-devel@nongnu.org; Tue, 28 Feb 2017 08:21:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cihih-0004Js-1v for qemu-devel@nongnu.org; Tue, 28 Feb 2017 08:21:38 -0500 From: Paolo Bonzini Date: Tue, 28 Feb 2017 14:21:32 +0100 Message-Id: <20170228132132.20231-1-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH] virtio: always use handle_aio_output if registered List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: mst@redhat.com, kraxel@redhat.com, qemu-stable@nongnu.org Commit ad07cd6 ("virtio-scsi: always use dataplane path if ioeventfd is active", 2016-10-30) and 9ffe337 ("virtio-blk: always use dataplane path if ioeventfd is active", 2016-10-30) broke the virtio 1.0 indirect access registers. The indirect access registers bypass the ioeventfd, so that virtio-blk and virtio-scsi now repeatedly try to initialize dataplane instead of triggering the guest->host EventNotifier. Detect the situation by checking vq->handle_aio_output; if it is not NULL, trigger the EventNotifier, which is how the device expects to get notifications and in fact the only thread-safe manner to deliver them. Fixes: ad07cd6 Fixes: 9ffe337 Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini --- hw/virtio/virtio.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 23483c7..1206f6c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1458,7 +1458,18 @@ static void virtio_queue_notify_vq(VirtQueue *vq) void virtio_queue_notify(VirtIODevice *vdev, int n) { - virtio_queue_notify_vq(&vdev->vq[n]); + VirtQueue *vq = &vdev->vq[n]; + + if (unlikely(!vq->vring.desc || vdev->broken)) { + return; + } + + trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); + if (vq->handle_aio_output) { + event_notifier_set(&vq->host_notifier); + } else if (vq->handle_output) { + vq->handle_output(vdev, vq); + } } uint16_t virtio_queue_vector(VirtIODevice *vdev, int n) -- 2.9.3