Re: [PATCH v2 6/8] xen/arm: Remove support for Stage-1 translation on SMMUv3.

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 26 Nov 2020, Rahul Singh wrote:
> Linux SMMUv3 driver supports both Stage-1 and Stage-2 translations.
> As of now only Stage-2 translation support has been tested.
> 
> Once Stage-1 translation support is tested this patch can be added.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>

[...]


> @@ -1871,19 +1476,9 @@ static int arm_smmu_domain_finalise(struct 
> iommu_domain *domain,
>       }
>  
>       /* Restrict the stage to what we can actually support */
> -     if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1))
> -             smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
> -     if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
> -             smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> +     smmu_domain->stage = ARM_SMMU_DOMAIN_S2;

It would be good to add an helpful error message if
ARM_SMMU_FEAT_TRANS_S2 is missing.


>       switch (smmu_domain->stage) {
> -     case ARM_SMMU_DOMAIN_S1:
> -             ias = (smmu->features & ARM_SMMU_FEAT_VAX) ? 52 : 48;
> -             ias = min_t(unsigned long, ias, VA_BITS);
> -             oas = smmu->ias;
> -             fmt = ARM_64_LPAE_S1;
> -             finalise_stage_fn = arm_smmu_domain_finalise_s1;
> -             break;
>       case ARM_SMMU_DOMAIN_NESTED:
>       case ARM_SMMU_DOMAIN_S2:
>               ias = smmu->ias;