Re: [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV

[Halil Pasic]

On Tue, 9 Jun 2020 18:05:59 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> Which devices are compatible in the end? It seems the only ones that
> are known to be working are virtio-ccw devices with IOMMU_PLATFORM on.
> virtio-pci devices and non-virtio ccw (vfio-ccw, 3270) seem to be out,
> as far as I understand it. What about non-ccw? PCI in general, vfio-ap?

I've already answered how virtio is special. Regarding PCI, it is
currently not supported in prot virt mode, and this is properly handled
by the ultravisor: facility bits fenced and operation exceptions
indicated if the guest were to try and do PCI instructions nevertheless.
That also means we don't have to worry about virtio-pci for the
moment. The status current of AP is analogous to that of PCI.

So AFAIU all we have to worry about at the moment is ccw and virtio-ccw.

Regards,
Halil