[RFC PATCH 01/11] iommupt: Add RISC-V Second-stage (iohgatp) page table support

[Jason Gunthorpe]

On Wed, Apr 29, 2026 at 09:06:50AM +0800, fangyu.yu at linux.alibaba.com wrote:
> >> @@ -263,6 +281,22 @@ riscvpt_iommu_fmt_init(struct pt_iommu_riscv_64 *iommu_table,
> >>  	case 57:
> >>  		pt_top_set_level(&table->common, 4);
> >>  		break;
> >> +	/*
> >> +	 * Second-stage (iohgatp): Sv39x4 / Sv48x4 / Sv57x4.
> >> +	 * The top level is the same as for the first-stage counterpart.
> >> +	 */
> >> +	case 41:
> >> +		pt_top_set_level(&table->common, 2);
> >> +		table->second_stage = true;
> >> +		break;
> >
> >Second stage needs to be an explicit PT_FEAT not implicitly deduced
> >based on the vasz.
> 
> Agreed. I will add an explicit PT_FEAT_RISCV_SECOND_STAGE flag and
> stop deriving second-stage semantics from vasz.

PT_FEAT_RISCV_S2 would match what I have for ARM

Jason