Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore

On Wed, Sep 24, 2014 at 02:27:27AM +0100, Ben Hutchings wrote:

On Tue, 2014-09-23 at 13:32 +0300, Michael S. Tsirkin wrote:

quoted

On restore, virtio pci does the following:
+ set features
+ init vqs etc - device can be used at this point!
+ set ACKNOWLEDGE,DRIVER and DRIVER_OK status bits

This is in violation of the virtio spec, which
requires the following order:
- ACKNOWLEDGE
- DRIVER
- init vqs
- DRIVER_OK

Cc: stable@vger.kernel.org
Cc: Amit Shah <redacted>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

[...]

What concrete problem does this fix, such that it should be applied to
stable branches?

Ben.

It will break with hypervisors that assume spec compliant behaviour.
I would like this applied to stable branches so hypervisors don't
need to support broken behaviour forever.

-- 
MST