RE: [PATCH 04/12] iommufd: Pass parent hwpt and user_data to iommufd_hw_pagetable_alloc()

Tian, Kevin
2023-03-21T01:26:52Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Monday, March 20, 2023 8:47 PM
>
> On Fri, Mar 17, 2023 at 10:23:54AM +0000, Tian, Kevin wrote:
> > > From: Liu, Yi L <yi.l.liu@intel.com>
> > > Sent: Thursday, March 9, 2023 4:09 PM
> > >
> > > + /* It must be either NESTED or UNMANAGED, depending on
> > > parent_domain */
> > > + if ((parent_domain && hwpt->domain->type !=
> > > IOMMU_DOMAIN_NESTED) ||
> > > + (!parent_domain && hwpt->domain->type !=
> > > IOMMU_DOMAIN_UNMANAGED))
> > > + goto out_abort;
> > > +
> >
> > WARN_ON()
>
> Wouldn't that be userspace triggerable? It gets to pick the hwpt used.
>

The domain type is set by iommu driver instead of userspace. A sane
driver should pass above check, if it claims to support nested.