Re: [Qemu-devel] [PATCH RFC v6 13/20] virtio: allow to fail setting status

[Cornelia Huck]

On Wed, 7 Jan 2015 21:08:21 +0200
"Michael S. Tsirkin" <address@hidden> wrote:

> On Wed, Jan 07, 2015 at 05:13:32PM +0100, Cornelia Huck wrote:
> > On Tue, 30 Dec 2014 14:25:37 +0200
> > "Michael S. Tsirkin" <address@hidden> wrote:
> > 
> > > On Thu, Dec 11, 2014 at 02:25:15PM +0100, Cornelia Huck wrote:
> > > > virtio-1 allow setting of the FEATURES_OK status bit to fail if
> > > > the negotiated feature bits are inconsistent: let's fail
> > > > virtio_set_status() in that case and update virtio-ccw to post an
> > > > error to the guest.
> > > > 
> > > > Signed-off-by: Cornelia Huck <address@hidden>
> > > 
> > > Right but a separate validate_features call is awkward.
> > > How about we defer virtio_set_features until FEATURES_OK,
> > > and teach virtio_set_features that it can fail?
> > 
> > Hm. But we would need to keep virtio_set_features() where it is called
> > now for legacy devices, as they will never see FEATURES_OK, right?
> > So
> > we need to make this depending on revisions (or whatever the equivalent
> > is for pci/mmio), as we cannot check for VERSION_1. Not sure whether
> > this makes the code easier to follow.
> 
> So let's make this a separate callback then.
> virtio_legacy_set_features?

I'm not sure I like that. We'd need to touch every transport, right?