[PATCH v3 3/4] iommu/arm-smmu-v3: Add support for dirty tracking in domain alloc

[Tian, Kevin]

> From: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> Sent: Tuesday, April 30, 2024 9:43 PM
> 
> @@ -2422,31 +2425,32 @@ static int arm_smmu_domain_finalise(struct
> arm_smmu_domain *smmu_domain,
>  	if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
>  		smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> 
> +	pgtbl_cfg = (struct io_pgtable_cfg) {
> +		.pgsize_bitmap	= smmu->pgsize_bitmap,
> +		.coherent_walk	= smmu->features &
> ARM_SMMU_FEAT_COHERENCY,
> +		.tlb		= &arm_smmu_flush_ops,
> +		.iommu_dev	= smmu->dev,
> +	};
> +
>  	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;
> +		unsigned long ias = (smmu->features &
> +				     ARM_SMMU_FEAT_VAX) ? 52 : 48;
> +		pgtbl_cfg.ias = min_t(unsigned long, ias, VA_BITS);
> +		pgtbl_cfg.oas = smmu->ias;
> +		if (enable_dirty)
> +			pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_ARM_HD;

why is dirty tracking considered as a quirk?

>  		fmt = ARM_64_LPAE_S1;
>  		break;
>  	case ARM_SMMU_DOMAIN_S2:
> -		ias = smmu->ias;
> -		oas = smmu->oas;
> +		pgtbl_cfg.ias = smmu->ias;
> +		pgtbl_cfg.oas = smmu->oas;
>  		fmt = ARM_64_LPAE_S2;
>  		break;

so dirty-tracking is not supported by s2? what about nesting?

if this is desired then attempting to set dirty_tracking on a s2 domain
should be rejected with an error.