From 258dc7c96bb4b7ca71d5bee811e73933310e168c Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 17 Oct 2010 20:23:48 +0200 Subject: [PATCH] virtio: sanity-check available index Checking available index upon load instead of only when vm is running makes is easier to debug failures. Signed-off-by: Michael S. Tsirkin --- hw/virtio.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/hw/virtio.c b/hw/virtio.c index c8a0fc6ff..a2a657e13 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -681,6 +681,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f) uint32_t features; uint32_t supported_features = vdev->binding->get_features(vdev->binding_opaque); + uint16_t num_heads; if (vdev->binding->load_config) { ret = vdev->binding->load_config(vdev->binding_opaque, f); @@ -713,6 +714,16 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f) if (vdev->vq[i].pa) { virtqueue_init(&vdev->vq[i]); } + num_heads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx; + /* Check it isn't doing very strange things with descriptor numbers. */ + if (num_heads > vdev->vq[i].vring.num) { + fprintf(stderr, "VQ %d size 0x%x Guest index 0x%x " + "inconsistent with Host index 0x%x: delta 0x%x\n", + i, vdev->vq[i].vring.num, + vring_avail_idx(&vdev->vq[i]), + vdev->vq[i].last_avail_idx, num_heads); + return -1; + } if (vdev->binding->load_queue) { ret = vdev->binding->load_queue(vdev->binding_opaque, i, f); if (ret)