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

[Pierre Morel]

On 2020-06-17 13:22, Heiko Carstens wrote:
> On Wed, Jun 17, 2020 at 12:43:57PM +0200, Pierre Morel wrote:
> > An architecture protecting the guest memory against unauthorized host
> > access may want to enforce VIRTIO I/O device protection through the
> > use of VIRTIO_F_IOMMU_PLATFORM.
> >
> > Let's give a chance to the architecture to accept or not devices
> > without VIRTIO_F_IOMMU_PLATFORM.
> >
> > Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> > Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> > Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> > ---
> >   arch/s390/mm/init.c     |  6 ++++++
> >   drivers/virtio/virtio.c | 22 ++++++++++++++++++++++
> >   include/linux/virtio.h  |  2 ++
> >   3 files changed, 30 insertions(+)
> >
> > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> > index 6dc7c3b60ef6..215070c03226 100644
> > --- a/arch/s390/mm/init.c
> > +++ b/arch/s390/mm/init.c
> > @@ -45,6 +45,7 @@
> >   #include <asm/kasan.h>
> >   #include <asm/dma-mapping.h>
> >   #include <asm/uv.h>
> > +#include <linux/virtio.h>
> >
> >   pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
> >
> > @@ -161,6 +162,11 @@ bool force_dma_unencrypted(struct device *dev)
> >   	return is_prot_virt_guest();
> >   }
> >
> > +int arch_needs_virtio_iommu_platform(struct virtio_device *dev)
> > +{
> > +	return is_prot_virt_guest();
> > +}
> > +
> >   /* protected virtualization */
> >   static void pv_init(void)
>
> Can we please stop dumping random code to arch/s390/mm/init.c?
>
> All the protected virtualization functions should go into a separate
> file (e.g. mem_encrypt.c like on x86), some of which could also be in
> header files.
>
> Please consider this a comment for the future.. just go ahead with
> this patch as-is.

OK, thanks Heiko,
Pierre

--
Pierre Morel
IBM Lab Boeblingen