RE: [RFC PATCH v6 04/20] iommu/arm-smmu: add capability IOMMU_CAP_INTR_REMAP

[Varun Sethi]

> -----Original Message-----
> From: iommu-bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx [mailto:iommu-
> bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Antonios Motakis
> Sent: Thursday, June 05, 2014 10:33 PM
> To: alex.williamson@xxxxxxxxxx; kvmarm@xxxxxxxxxxxxxxxxxxxxx;
> iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: kvm@xxxxxxxxxxxxxxx; eric.auger@xxxxxxxxxx; open list;
> will.deacon@xxxxxxx; a.rigo@xxxxxxxxxxxxxxxxxxxxxx; Yoder Stuart-B08248;
> moderated list:ARM SMMU DRIVER; Antonios Motakis;
> tech@xxxxxxxxxxxxxxxxxxxxxx; christoffer.dall@xxxxxxxxxx
> Subject: [RFC PATCH v6 04/20] iommu/arm-smmu: add capability
> IOMMU_CAP_INTR_REMAP
> 
> With an ARM SMMU, interrupt remapping should always be safe from the
> SMMU's point of view, as it is properly handled by the GIC.
> 
> Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/arm-smmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
> 15ab2af..ff29402 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1544,7 +1544,7 @@ static int arm_smmu_domain_has_cap(struct
> iommu_domain *domain,
>  	if (smmu_domain->root_cfg.smmu->features &
> ARM_SMMU_FEAT_COHERENT_WALK)
>  		caps |= IOMMU_CAP_CACHE_COHERENCY;
> 
> -	caps |= IOMMU_CAP_NOEXEC;
> +	caps |= IOMMU_CAP_NOEXEC | IOMMU_CAP_INTR_REMAP;
> 
>  	return !!(cap & caps);
>  }
Why mention this as an IOMMU capability when IOMMU doesn't support it? Also, wouldn't this depend on the GIC IP version? What are we gaining by adding this IOMMU capability list?

-Varun
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