On 15/12/2016 12:32, Halil Pasic wrote:
> static inline uint16_t vring_avail_idx(VirtQueue *vq)
> {
> hwaddr pa;
> pa = vq->vring.avail + offsetof(VRingAvail, idx);
> vq->shadow_avail_idx = virtio_lduw_phys(vq->vdev, pa);
>
> we should have an endiannes handling here before assigning shadow_avail_idx I
> guess
>
> return vq->shadow_avail_idx;
> }
Endianness is already handled:
static inline uint16_t virtio_lduw_phys(VirtIODevice *vdev, hwaddr pa)
{
if (virtio_access_is_big_endian(vdev)) {
return lduw_be_phys(&address_space_memory, pa);
}
return lduw_le_phys(&address_space_memory, pa);
}
> I will meditate a bit more on this and probably create a patch to fix it.
>
> What make me wonder is that according to the reports live migration usually
> works (ca 1% fails)...
What is the backtrace of the vring_avail_idx call? If your device is
virtio 1.0, and vdev->guest_features has not been initialized correctly,
you might incorrectly treat LE virtio 1.0 data as BE virtio 0.9 data:
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
/* Devices conforming to VIRTIO 1.0 or later are always LE. */
return false;
}
return true;
Thanks,
Paolo
