Commit 1062d810 authored by Yi Liu's avatar Yi Liu Committed by Jason Gunthorpe
Browse files

iommufd: Disallow allocating nested parent domain with fault ID 

Allocating a domain with a fault ID indicates that the domain is faultable.
However, there is a gap for the nested parent domain to support PRI. Some
hardware lacks the capability to distinguish whether PRI occurs at stage 1
or stage 2. This limitation may require software-based page table walking
to resolve. Since no in-tree IOMMU driver currently supports this
functionality, it is disallowed. For more details, refer to the related
discussion at [1].

[1] https://lore.kernel.org/linux-iommu/bd1655c6-8b2f-4cfa-adb1-badc00d01811@intel.com/

Link: https://patch.msgid.link/r/20250226104012.82079-1-yi.l.liu@intel.com


Suggested-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarYi Liu <yi.l.liu@intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 5e9f822c

drivers/iommu/iommufd/hw_pagetable.c

+3 −0
Original line number Diff line number Diff line
@@ -126,6 +126,9 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, 
	if ((flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING) &&

	    !device_iommu_capable(idev->dev, IOMMU_CAP_DIRTY_TRACKING))

		return ERR_PTR(-EOPNOTSUPP);

	if ((flags & IOMMU_HWPT_FAULT_ID_VALID) &&

	    (flags & IOMMU_HWPT_ALLOC_NEST_PARENT))

		return ERR_PTR(-EOPNOTSUPP);



	hwpt_paging = __iommufd_object_alloc(

		ictx, hwpt_paging, IOMMUFD_OBJ_HWPT_PAGING, common.obj);

tools/testing/selftests/iommu/iommufd.c

+4 −0
Original line number Diff line number Diff line
@@ -439,6 +439,10 @@ TEST_F(iommufd_ioas, alloc_hwpt_nested) 
				    &test_hwpt_id);

		test_err_hwpt_alloc(EINVAL, self->device_id, self->device_id, 0,

				    &test_hwpt_id);

		test_err_hwpt_alloc(EOPNOTSUPP, self->device_id, self->ioas_id,

				    IOMMU_HWPT_ALLOC_NEST_PARENT |

						IOMMU_HWPT_FAULT_ID_VALID,

				    &test_hwpt_id);



		test_cmd_hwpt_alloc(self->device_id, self->ioas_id,

				    IOMMU_HWPT_ALLOC_NEST_PARENT,