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

[Michael S. Tsirkin]

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?