RE: [PATCH v3 06/17] iommufd: Only enforce IOMMU_RESV_SW_MSI when attaching user-managed HWPT

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Monday, July 24, 2023 7:04 PM
>  	}
> 
>  	rc = iopt_table_enforce_dev_resv_regions(&hwpt->ioas->iopt, idev-
> >dev,
> -						 &idev->igroup-
> >sw_msi_start);
> +						 &idev->igroup-
> >sw_msi_start,
> +						 !!hwpt->parent);
>  	if (rc)
>  		goto err_unlock;

I prefer to not setting parent ioas to hwpt in iommufd_hw_pagetable_alloc().

then here ioas can be retrieved from hwpt->parent and then it'd be pretty
clear that in nested case the sw_msi reservation happens in the parent
instead of pretending the stage-1 hwpt has an ioas too.