On Fri, 18 Mar 2022 14:27:33 -0300
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> +static int conv_iommu_prot(u32 map_flags)
> +{
> + int iommu_prot;
> +
> + /*
> + * We provide no manual cache coherency ioctls to userspace and most
> + * architectures make the CPU ops for cache flushing privileged.
> + * Therefore we require the underlying IOMMU to support CPU coherent
> + * operation.
> + */
> + iommu_prot = IOMMU_CACHE;
Where is this requirement enforced? AIUI we'd need to test
IOMMU_CAP_CACHE_COHERENCY somewhere since functions like
intel_iommu_map() simply drop the flag when not supported by HW.
This also seems like an issue relative to vfio compatibility that I
don't see mentioned in that patch. Thanks,
Alex
> + if (map_flags & IOMMU_IOAS_MAP_WRITEABLE)
> + iommu_prot |= IOMMU_WRITE;
> + if (map_flags & IOMMU_IOAS_MAP_READABLE)
> + iommu_prot |= IOMMU_READ;
> + return iommu_prot;
> +}
