Re: [PATCH] iommu: restrict scratch page quarantining to x86

["Roger Pau Monné" <roger.pau@citrix.com>]

On Thu, Jul 24, 2025 at 01:43:48PM -0400, Stewart Hildebrand wrote:
> All IOMMU_QUARANTINE_* options are exposed on Arm since 163c6b589879
> ("xen/arm: pci: introduce PCI_PASSTHROUGH Kconfig option"). However,
> only NONE and BASIC are implemented in any Arm iommu driver since
> 63919fc4d1ca ("xen/arm: smmuv3: Add PCI devices support for SMMUv3") and
> ca8f6ffeb6e3 ("xen/arm: smmuv2: Add PCI devices support for SMMUv2").
> SCRATCH_PAGE is not yet implemented in any Arm iommu driver. Restrict
> scratch page quarantining to x86 for now.
> 
> Reported-by: Jan Beulich <jbeulich@suse.com>
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com>
> ---
> Cc'ing Arm maintainers to request an Arm ack.
> ---
>  xen/drivers/passthrough/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/xen/drivers/passthrough/Kconfig b/xen/drivers/passthrough/Kconfig
> index 78edd805365e..11aece5f7bda 100644
> --- a/xen/drivers/passthrough/Kconfig
> +++ b/xen/drivers/passthrough/Kconfig
> @@ -90,4 +90,5 @@ choice
>  		bool "basic"
>  	config IOMMU_QUARANTINE_SCRATCH_PAGE
>  		bool "scratch page"
> +		depends on X86

Since this is tied to specific IOMMU implementations, could you please
tie it to AMD_IOMMU and INTEL_IOMMU instead of X86?

depends on AMD_IOMMU || INTEL_IOMMU

Should do it I think?

Thanks, Roger.