Re: [PATCH v5 05/13] iommufd: Allow hwpt_id to carry viommu_id for IOMMU_HWPT_INVALIDATE

On Fri, Oct 25, 2024 at 04:50:34PM -0700, Nicolin Chen wrote:

@@ -497,17 +497,35 @@ int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd) goto out; }

• hwpt = iommufd_get_hwpt_nested(ucmd, cmd->hwpt_id);
• if (IS_ERR(hwpt)) {

• rc = PTR_ERR(hwpt);
  

• pt_obj = iommufd_get_object(ucmd->ictx, cmd->hwpt_id, IOMMUFD_OBJ_ANY);
• if (IS_ERR(pt_obj)) {

• rc = PTR_ERR(pt_obj);
  

  goto out; }
• if (pt_obj->type == IOMMUFD_OBJ_HWPT_NESTED) {

• struct iommufd_hw_pagetable *hwpt =
  

• 	container_of(pt_obj, struct iommufd_hw_pagetable, obj);
  

• rc = hwpt->domain->ops->cache_invalidate_user(hwpt->domain,
  

• 					      &data_array);
  

• } else if (pt_obj->type == IOMMUFD_OBJ_VIOMMU) {

• struct iommufd_viommu *viommu =
  

• 	container_of(pt_obj, struct iommufd_viommu, obj);
  

• if (!viommu->ops || !viommu->ops->cache_invalidate) {
  

• 	rc = -EOPNOTSUPP;
  

• 	goto out_put_pt;
  

• }
  

• rc = viommu->ops->cache_invalidate(viommu, &data_array);
  

• } else {

• rc = -EINVAL;
  

• goto out_put_pt;
  

• }

Given the test in iommufd_viommu_alloc_hwpt_nested() is:

if (WARN_ON_ONCE(hwpt->domain->type != IOMMU_DOMAIN_NESTED || (!viommu->ops->cache_invalidate && !hwpt->domain->ops->cache_invalidate_user))) {

We will crash if the user passes a viommu allocated domain as IOMMUFD_OBJ_HWPT_NESTED since the above doesn't check it.

I suggest we put the required if (ops..) -EOPNOTSUPP above and remove the ops->cache_invalidate checks from both WARN_ONs.

Jason