Re: [PATCH] virtio-ccw: commands on revision-less devices

[Cornelia Huck]

On Tue, 16 Feb 2021 06:40:41 -0500
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Tue, Feb 16, 2021 at 12:18:30PM +0100, Cornelia Huck wrote:
> > The virtio standard specifies that any non-transitional device must
> > reject commands prior to revision setting (which we do) and else
> > assume revision 0 (legacy) if the driver sends a non-revision-setting
> > command first. We neglected to do the latter.
> > 
> > Fortunately, nearly everything worked as intended anyway; the only
> > problem was not properly rejecting revision setting after some other
> > command had been issued. Easy to fix by setting revision to 0 if
> > we see a non-revision command on a legacy-capable revision-less
> > device.
> > 
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>  
> 
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Feel free to merge.
> 
> Curious how was this discovered.

Code reading :)

I have not seen any errors in the wild.