On Fri, 9 Sep 2016 13:44:35 +0200
Maxime Coquelin <maxime.coque...@redhat.com> wrote:
> On 09/09/2016 01:20 PM, Cornelia Huck wrote:
> > On Fri, 9 Sep 2016 14:04:55 +0300
> > Marcel Apfelbaum <mar...@redhat.com> wrote:
> >
> >> On 09/09/2016 01:40 PM, Cornelia Huck wrote:
> >>> On Fri, 9 Sep 2016 12:14:32 +0200
> >>> Maxime Coquelin <maxime.coque...@redhat.com> wrote:
> >>>
> >>>> This patch makes pci devices plugging more robust, by not confusing
> >>>> guest with modern interface when the backend doesn't support
> >>>> VIRTIO_F_VERSION_1.
> >>>>
> >>>> Cc: Marcel Apfelbaum <mar...@redhat.com>
> >>>> Cc: Michael S. Tsirkin <m...@redhat.com>
> >>>> Cc: qemu-sta...@nongnu.org
> >>>> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> >>>> ---
> >>>> hw/virtio/virtio-pci.c | 15 +++++++++++++++
> >>>> hw/virtio/virtio-pci.h | 5 +++++
> >>>> 2 files changed, 20 insertions(+)
> >>>
> >>> Note that 11380b361 ("virtio: handle non-virtio-1-capable backend for
> >>> ccw") fixes this issue for ccw via the introduction of a
> >>> ->post_plugged() callback. Unfortunately, we did not find a good way to
> >>> make it work for pci back then.
> >>
> >> It seems that for ccw is enough to rewind dev->rev_max,
> >> sadly for pci we need to rewind a lot of settings/resources.
> >
> > Yes, that what I meant with 'more flexibility for ccw'.
> Maybe we could replace post_plugged with a pre_plugged approach?
>
> In ->pre_plugged(), cww and pci would specify which features it can
> support using virtio_add_feature().
> Then we could call get_features() before ->device_plugged().
I think that would work for ccw (haven't looked at pci).
>
> Doing this, both ccw and pci would have the needed information without
> having to rewind any settings.
>
> Does that make sense?
>
> But for now, I think it would be better to merge something in the spirit
> of this series (taking into account to remarks).
> Indeed, I think we want this fixed in stable, but the above proposal
> would be too huge for stable.
A 'just check for VERSION_1' approach would probably be best for stable.
