RE: [PATCH v2 06/11] iommufd: IOMMU_HWPT_ALLOC allocation with user data

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Saturday, May 20, 2023 3:48 AM
> 
> 
> > >
> > > +     switch (pt_obj->type) {
> > > +     case IOMMUFD_OBJ_IOAS:
> > > +             ioas = container_of(pt_obj, struct iommufd_ioas, obj);
> > > +             break;
> >
> > this should fail if parent is specified.
> 
> I don't think that's necessaray: the parent is NULL by default
> and only specified (if IOMMUFD_OBJ_HW_PAGETABLE) by the exact
> pt_id/pt_obj here.

I didn't get. The uAPI describes that only hwpt not ioas can be specified
in the pt_id field as the parent.

If we don't check here it means the user can specify an ioas id as the
parent?