On Tue, 31 Jan 2017 16:56:13 +0100
Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx> wrote:
> On 01/30/2017 08:06 PM, Greg Kurz wrote:
> >> Currently, under certain circumstances vhost_init_is_le does just a part
> >> of the initialization job, and depends on vhost_reset_is_le being called
> >> too. For this reason vhost_vq_init_access used to call vhost_reset_is_le
> >> when vq->private_data is NULL. This is not only counter intuitive, but
> >> also real a problem because it breaks vhost_net. The bug was introduced to
> >> vhost_net with commit 2751c9882b94 ("vhost: cross-endian support for
> >> legacy devices"). The symptom is corruption of the vq's used.idx field
> >> (virtio) after VHOST_NET_SET_BACKEND was issued as a part of the vhost
> >> shutdown on a vq with pending descriptors.
> >>
> >> Let us make sure the outcome of vhost_init_is_le never depend on the state
> >> it is actually supposed to initialize, and fix virtio_net by removing the
> >> reset from vhost_vq_init_access.
> >>
> >> With the above, there is no reason for vhost_reset_is_le to do just half
> >> of the job. Let us make vhost_reset_is_le reinitialize is_le.
> >>
> >> Signed-off-by: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx>
> >> Reported-by: Michael A. Tebolt <miket@xxxxxxxxxx>
> >> Reported-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
> >> Fixes: commit 2751c9882b94 ("vhost: cross-endian support for legacy devices")
> >> ---
> > Reviewed-by: Greg Kurz <groug@xxxxxxxx>
> >
>
> Thanks!
>
> We have some tests on s390x (that is BE) running, but I won't be able to
> test the change with cross endian and legacy.
>
I'll try to find some time to run such tests on ppc.
Cheers.
--
Greg
> What do you think, should I/we RFT or are we fine without?
>
> Regards,
> Halil
>
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