From: Yi Liu yi.l.liu@intel.com

[ Upstream commit 1062d81086156e42878d701b816d2f368b53a77c ]

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@int...

Link: https://patch.msgid.link/r/20250226104012.82079-1-yi.l.liu@intel.com Suggested-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Yi Liu yi.l.liu@intel.com Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/iommufd/hw_pagetable.c | 3 +++ tools/testing/selftests/iommu/iommufd.c | 4 ++++ 2 files changed, 7 insertions(+)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index d06bf6e6c19fd..2454627a8b61b 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -122,6 +122,9 @@ 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); diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c index 4927b9add5add..06f252733660a 100644 --- a/tools/testing/selftests/iommu/iommufd.c +++ b/tools/testing/selftests/iommu/iommufd.c @@ -289,6 +289,10 @@ 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,