Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Dec 09, 2021 at 02:29:25PM +0100, Halil Pasic wrote:
> On Wed, 8 Dec 2021 13:56:19 -0500
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Fri, Nov 12, 2021 at 03:57:44PM +0100, Halil Pasic wrote:
> > > This is an early RFC for a transport specific early detecton of
> > > modern virtio, which is most relevant for transitional devices on big
> > > endian platforms, when drivers access the config space before
> > > FEATURES_OK is set.
> > > 
> > > The most important part that is missing here is fixing all the problems
> > > that arise in the situation described in the previous paragraph, when
> > > the config is managed by a vhost device (and thus outside QEMU. This
> > > series tackles this problem only for virtio_net+vhost as an example. If
> > > this approach is deemed good, we need to do something very similar for
> > > every single affected device.
> > > 
> > > This series was only lightly tested. The vhost stuff is entirely
> > > untested, unfortunately I don't have a working setup where this
> > > handling would be needed (because the config space is handled in the
> > > device). DPDK is not supported on s390x so at the moment I can't test
> > > DPDK based setups.   
> > 
> > So this looks sane to me. Cornelia requested some name tweaks and we
> > need to add vhost-user things and more devices, but otherwise we are
> > good.
> 
> Thanks for your feedback! There were several points where I could
> not reach agreement with Cornelia. From your response I recon that:
> 
> 1) I should rename virtio_force_modern() to virtio_indicate_modern()
> (per maintainer request).
> 2) Keep the call to virtio_set_features()?
> 
> Is that right?
> 
> Regards,
> Halil

that's my take, yes.

-- 
MST