On Thu, 9 Jul 2020 10:39:19 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> ---
> arch/s390/mm/init.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index 6dc7c3b60ef6..b8e6f90117da 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_config.h>
>
> pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
>
> @@ -161,6 +162,32 @@ bool force_dma_unencrypted(struct device *dev)
> return is_prot_virt_guest();
> }
>
> +/*
> + * arch_validate_virtio_features
> + * @dev: the VIRTIO device being added
> + *
> + * Return an error if required features are missing on a guest running
> + * with protected virtualization.
> + */
> +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, "device must provide VIRTIO_F_VERSION_1\n");
I'd probably use "legacy virtio not supported with protected
virtualization".
> + return -ENODEV;
> + }
> +
> + if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> + dev_warn(&dev->dev,
> + "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
"support for limited memory access required for protected
virtualization"
?
Mentioning the feature flag is shorter in both cases, though.
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> /* protected virtualization */
> static void pv_init(void)
> {
Either way,
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
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