Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature

[Pierre Morel]

On 2020-06-19 14:02, Halil Pasic wrote:
> On Fri, 19 Jun 2020 11:20:51 +0200
> Cornelia Huck <cohuck@xxxxxxxxxx> wrote:
>
> > > > +	if (arch_needs_virtio_iommu_platform(dev) &&
> > > > +		!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> > > > +		dev_warn(&dev->dev,
> > > > +			 "virtio: device must provide VIRTIO_F_IOMMU_PLATFORM\n");
> > >
> > > I'm not sure, divulging the current Linux name of this feature bit is a
> > > good idea, but if everybody else is fine with this, I don't care that
> >
> > Not sure if that feature name will ever change, as it is exported in
> > headers. At most, we might want to add the new ACCESS_PLATFORM define
> > and keep the old one, but that would still mean some churn.
> >
> > > much. An alternative would be:
> > > "virtio: device falsely claims to have full access to the memory,
> > > aborting the device"
> >
> > "virtio: device does not work with limited memory access" ?
> >
> > But no issue with keeping the current message.
>
> I think I prefer Conny's version, but no strong feelings here.


The reason why the device is not accepted without IOMMU_PLATFORM is arch 
specific, I think it should be clearly stated.
If no strong oposition...

Thanks,
Pierre


--
Pierre Morel
IBM Lab Boeblingen