From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bakGI-0002KY-FV for qemu-devel@nongnu.org; Fri, 19 Aug 2016 09:55:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bakGE-0002X6-HR for qemu-devel@nongnu.org; Fri, 19 Aug 2016 09:55:06 -0400 Received: from mail-he1eur01on0139.outbound.protection.outlook.com ([104.47.0.139]:41437 helo=EUR01-HE1-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bakGD-0002Wh-Sm for qemu-devel@nongnu.org; Fri, 19 Aug 2016 09:55:02 -0400 From: Roman Kagan Date: Fri, 19 Aug 2016 16:39:21 +0300 Message-ID: <1471613966-7267-3-git-send-email-rkagan@virtuozzo.com> In-Reply-To: <1471613966-7267-1-git-send-email-rkagan@virtuozzo.com> References: <1471613966-7267-1-git-send-email-rkagan@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain Subject: [Qemu-devel] [PATCH v2 2/6] virtio-balloon: make stats virtqueue length 1 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Denis V. Lunev" , Roman Kagan , "Michael S. Tsirkin" , Ladi Prosek , Stefan Hajnoczi The protocol for virtio-balloon stats virtqueue doesn't allow more than one element in the virtqueue. So, instead of trying to compensate for guest misbehavior if it sends new data before the slot has been released by the host, just define the stats virtqueue length to 1 initially and rely on the generic virtio code to handle overflows. Signed-off-by: Roman Kagan Cc: "Michael S. Tsirkin" Cc: Ladi Prosek Cc: Stefan Hajnoczi --- v1 > v2: - added assert in virtio_balloon_receive_stats hw/virtio/virtio-balloon.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 5af429a..fb8784e 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -262,12 +262,8 @@ static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) goto out; } - if (s->stats_vq_elem != NULL) { - /* This should never happen if the driver follows the spec. */ - virtqueue_push(vq, s->stats_vq_elem, 0); - virtio_notify(vdev, vq); - g_free(s->stats_vq_elem); - } + /* enforced by stats virtqueue depth being 1 */ + assert(!s->stats_vq_elem); s->stats_vq_elem = elem; @@ -443,7 +439,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); - s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); + s->svq = virtio_add_queue(vdev, 1, virtio_balloon_receive_stats); reset_stats(s); } -- 2.7.4