On Wed, 19 Aug 2020 10:50:18 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
> On 2020-08-18 19:19, Cornelia Huck wrote:
> > On Tue, 18 Aug 2020 16:58:30 +0200
> > Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
> >
> ...
> >> +config ARCH_HAS_RESTRICTED_MEMORY_ACCESS
> >> + bool
> >> + help
> >> + This option is selected by any architecture enforcing
> >> + VIRTIO_F_IOMMU_PLATFORM
> >
> > This option is only for a very specific case of "restricted memory
> > access", namely the kind that requires IOMMU_PLATFORM for virtio
> > devices. ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS? Or is this intended
> > to cover cases outside of virtio as well?
>
> AFAIK we did not identify other restrictions so adding VIRTIO in the
> name should be the best thing to do.
>
> If new restrictions appear they also may be orthogonal.
>
> I will change to ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS if no one
> complains.
>
> >
> >> +
> >> menuconfig VIRTIO_MENU
> >> bool "Virtio drivers"
> >> default y
> >> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> >> index a977e32a88f2..1471db7d6510 100644
> >> --- a/drivers/virtio/virtio.c
> >> +++ b/drivers/virtio/virtio.c
> >> @@ -176,6 +176,10 @@ int virtio_finalize_features(struct virtio_device *dev)
> >> if (ret)
> >> return ret;
> >>
> >> + ret = arch_has_restricted_memory_access(dev);
> >> + if (ret)
> >> + return ret;
> >
> > Hm, I'd rather have expected something like
> >
> > if (arch_has_restricted_memory_access(dev)) {
>
> may be also change the callback name to
> arch_has_restricted_virtio_memory_access() ?
Yes, why not.
>
> > // enforce VERSION_1 and IOMMU_PLATFORM
> > }
> >
> > Otherwise, you're duplicating the checks in the individual architecture
> > callbacks again.
>
> Yes, I agree and go back this way.
>
> >
> > [Not sure whether the device argument would be needed here; are there
> > architectures where we'd only require IOMMU_PLATFORM for a subset of
> > virtio devices?]
>
> I don't think so and since we do the checks locally, we do not need the
> device argument anymore.
Yes, that would also remove some layering entanglement.
