From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42977) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bZHPP-0005GE-M6 for qemu-devel@nongnu.org; Mon, 15 Aug 2016 08:54:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bZHPJ-0005d4-Io for qemu-devel@nongnu.org; Mon, 15 Aug 2016 08:54:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40646) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bZHPJ-0005cr-Cz for qemu-devel@nongnu.org; Mon, 15 Aug 2016 08:54:21 -0400 From: Stefan Hajnoczi Date: Mon, 15 Aug 2016 13:54:15 +0100 Message-Id: <1471265656-11227-2-git-send-email-stefanha@redhat.com> In-Reply-To: <1471265656-11227-1-git-send-email-stefanha@redhat.com> References: <1471265656-11227-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH 1/2] virtio: recalculate vq->inuse after migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" , Cornelia Huck , Fam Zheng , Stefan Hajnoczi The vq->inuse field is not migrated. Many devices don't hold VirtQueueElements across migration so it doesn't matter that vq->inuse starts at 0 on the destination QEMU. At least virtio-serial, virtio-blk, and virtio-balloon migrate while holding VirtQueueElements. For these devices we need to recalculate vq->inuse upon load so the value is correct. Signed-off-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Reviewed-by: Cornelia Huck --- hw/virtio/virtio.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 15ee3a7..6105c6e 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1648,6 +1648,21 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id) } vdev->vq[i].used_idx = vring_used_idx(&vdev->vq[i]); vdev->vq[i].shadow_avail_idx = vring_avail_idx(&vdev->vq[i]); + + /* + * Some devices migrate VirtQueueElements that have been popped + * from the avail ring but not yet returned to the used ring. + */ + vdev->vq[i].inuse = vdev->vq[i].last_avail_idx - + vdev->vq[i].used_idx; + if (vdev->vq[i].inuse > vdev->vq[i].vring.num) { + error_report("VQ %d size 0x%x < last_avail_idx 0x%x - " + "used_idx 0x%x", + i, vdev->vq[i].vring.num, + vdev->vq[i].last_avail_idx, + vdev->vq[i].used_idx); + return -1; + } } } -- 2.7.4