RE: [PATCH 4/6] iommufd/hw_pagetable: Support allocating nested parent domain

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Tuesday, September 19, 2023 5:25 PM
>
> @@ -83,6 +83,9 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx,
> struct iommufd_ioas *ioas,
> 
>  	lockdep_assert_held(&ioas->mutex);
> 
> +	if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !ops-
> >domain_alloc_user)
> +		return ERR_PTR(-EOPNOTSUPP);
> +

if (flags && !ops->domain_alloc_user)
	return ERR_PTR(-EOPNOTSUPP);

as long as flags is non-zero we'll need the new alloc_user ops.