From 61e6b37854a5f32db4fcc0e96938f57ceede7112 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 12 Sep 2016 12:22:35 +0200 Subject: [PATCH 1/4] virtio: recalculate vq->inuse after migration RH-Author: Stefan Hajnoczi Message-id: <1473682956-31576-2-git-send-email-stefanha@redhat.com> Patchwork-id: 72284 O-Subject: [RHEV-7.3 qemu-kvm-rhev PATCH 1/2] virtio: recalculate vq->inuse after migration Bugzilla: 1372763 RH-Acked-by: Ladi Prosek RH-Acked-by: Michael S. Tsirkin RH-Acked-by: Paolo Bonzini 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. Cc: qemu-stable@nongnu.org Signed-off-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Reviewed-by: Cornelia Huck Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit bccdef6b1a204db0f41ffb6e24ce373e4d7890d4) Signed-off-by: Stefan Hajnoczi Signed-off-by: Miroslav Rezanina --- hw/virtio/virtio.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 300ce30..cf911f6 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1624,6 +1624,21 @@ 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; + } } } -- 1.8.3.1