[RFC PATCH v2 07/10] iommu/riscv: Add domain_alloc_paging_flags for second-stage domain

[Andrew Jones]

On Thu, May 07, 2026 at 07:37:03PM +0800, fangyu.yu at linux.alibaba.com wrote:
...
> +	case IOMMU_HWPT_ALLOC_NEST_PARENT:
> +	case IOMMU_HWPT_ALLOC_DIRTY_TRACKING:
> +	case IOMMU_HWPT_ALLOC_DIRTY_TRACKING | IOMMU_HWPT_ALLOC_NEST_PARENT:
> +		/*
> +		 * Second-stage (iohgatp) page table for KVM VFIO device
> +		 * pass-through and dirty tracking. The GPA space is 2 bits
> +		 * wider than the corresponding first-stage VA space (x4 root
> +		 * page table), so hw_max_vasz_lg2 values are 41/50/59.
> +		 */
> +		if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV57X4) {
> +			cfg.common.hw_max_vasz_lg2 = 59;
> +		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV48X4) {
> +			cfg.common.hw_max_vasz_lg2 = 50;
> +		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV39X4) {
> +			cfg.common.hw_max_vasz_lg2 = 41;
> +		} else {
> +			ret = -ENODEV;
> +			goto err_free;
> +		}
> +		domain->gscid = ida_alloc_range(&riscv_iommu_gscids, 1,
> +						RISCV_IOMMU_MAX_GSCID, GFP_KERNEL);
> +		if (domain->gscid < 0) {
> +			ret = -ENOMEM;
> +			goto err_free;
> +		}
> +		cfg.common.features |= BIT(PT_FEAT_RISCV_S2);

cfg.common.features currently has PT_FEAT_SIGN_EXTEND which isn't correct
for the second stage. So it needs to removed and then added back in for
the first stage. riscv_64_kunit_fmt_cfgs[] in the kunit test will then
need to also be updated.

Thanks,
drew