[v1,0/1] s390: virtio-ccw: PV needs VIRTIO I/O device protection

Message

Pierre Morel Aug. 6, 2020, 2:23 p.m. UTC

Hi all,

In another series I proposed to add an architecture specific
callback to fail feature negociation on architecture need.

In VIRTIO, we already have an entry to reject the features on the
transport basis.

Transport is not architecture so I send a separate series in which
we fail the feature negociation inside virtio_ccw_finalize_features,
the virtio_config_ops.finalize_features for S390 CCW transport,
when the device do not propose the VIRTIO_F_IOMMU_PLATFORM.

This solves the problem of crashing QEMU when this one is not using
a CCW device with iommu_platform=on in S390.

Regards,
Pierre

Regards,
Pierre

Pierre Morel (1):
  s390: virtio-ccw: PV needs VIRTIO I/O device protection

 drivers/s390/virtio/virtio_ccw.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

Comments

Pierre Morel Aug. 7, 2020, 2:25 p.m. UTC | #1

On 2020-08-06 17:47, Cornelia Huck wrote:
> On Thu,  6 Aug 2020 16:23:01 +0200
...
> This does work, and I'm tempted to queue this patch, but I'm wondering
> whether we need to give up on a cross-architecture solution already
> (especially keeping in mind that ccw is the only transport that is
> really architecture-specific).
> 
> I know that we've gone through a few rounds already, and I'm not sure
> whether we've been there already, but:
> 
> Could virtio_finalize_features() call an optional
> arch_has_restricted_memory_access() function and do the enforcing of
> IOMMU_PLATFORM? That would catch all transports, and things should work
> once an architecture opts in. That direction also shouldn't be a
> problem if virtio is a module.

Yes thanks, I rework it in this direction.