Re: [PATCH v6 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 14 Jul 2020 13:38:02 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> If protected virtualization is active on s390, the virtio queues are
> not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
> negotiated. Use the new arch_validate_virtio_features() interface to
> fail probe if that's not the case, preventing a host error on access
> attempt.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>  arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)

(...)

> +int arch_validate_virtio_features(struct virtio_device *dev)
> +{
> +	if (!is_prot_virt_guest())
> +		return 0;
> +
> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> +		dev_warn(&dev->dev,
> +			 "legacy virtio not supported with protected virtualizatio\n");

typo: s/virtualizatio/virtualization/

> +		return -ENODEV;
> +	}
> +
> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> +		dev_warn(&dev->dev,
> +			 "support for limited memory access required for protected virtualization\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
>  /* protected virtualization */
>  static void pv_init(void)
>  {