Re: [PATCH v4 09/12] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Oct 31, 2024 at 02:21:11PM +0800, Zhangfei Gao wrote:

> > +static struct iommu_domain *
> > +arm_vsmmu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
> > +                             const struct iommu_user_data *user_data)
> > +{
> > +       struct arm_vsmmu *vsmmu = container_of(viommu, struct arm_vsmmu, core);
> > +       struct arm_smmu_nested_domain *nested_domain;
> > +       struct iommu_hwpt_arm_smmuv3 arg;
> > +       int ret;
> > +
> > +       if (flags)
> > +               return ERR_PTR(-EOPNOTSUPP);
> 
> This check fails when using user page fault, with flags =
> IOMMU_HWPT_FAULT_ID_VALID (4)
> Strange, the check is not exist in last version?
> 
> iommufd_viommu_alloc_hwpt_nested ->
> viommu->ops->alloc_domain_nested(viommu, flags, user_data) ->
> arm_vsmmu_alloc_domain_nested

It should permit IOMMU_HWPT_FAULT_ID_VALID, I'll add this hunk:

--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
@@ -178,12 +178,18 @@ arm_vsmmu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
                              const struct iommu_user_data *user_data)
 {
        struct arm_vsmmu *vsmmu = container_of(viommu, struct arm_vsmmu, core);
+       const u32 SUPPORTED_FLAGS = IOMMU_HWPT_FAULT_ID_VALID;
        struct arm_smmu_nested_domain *nested_domain;
        struct iommu_hwpt_arm_smmuv3 arg;
        bool enable_ats = false;
        int ret;
 
-       if (flags)
+       /*
+        * Faults delivered to the nested domain are faults that originated by
+        * the S1 in the domain. The core code will match all PASIDs when
+        * delivering the fault due to user_pasid_table
+        */
+       if (flags & ~SUPPORTED_FLAGS)
                return ERR_PTR(-EOPNOTSUPP);
 
        ret = iommu_copy_struct_from_user(&arg, user_data,

Thanks,
Jason