iommufd: Share iommufd_hwpt_alloc with IOMMUFD_OBJ_HWPT_NESTED

Allow iommufd_hwpt_alloc() to have a common routine but jump to different
allocators corresponding to different user input pt_obj types, either an
IOMMUFD_OBJ_IOAS for a PAGING hwpt or an IOMMUFD_OBJ_HWPT_PAGING as the
parent for a NESTED hwpt.

Also, move the "flags" validation to the hwpt allocator (paging), so that
later the hwpt_nested allocator can do its own separate flags validation.

Link: https://lore.kernel.org/r/20231026043938.63898-6-yi.l.liu@intel.comSigned-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/iommufd/hw_pagetable.c

@@ -82,6 +82,8 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			  struct iommufd_device *idev, u32 flags,
 			  bool immediate_attach)
 {
+	const u32 valid_flags = IOMMU_HWPT_ALLOC_NEST_PARENT |
+				IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
 	const struct iommu_ops *ops = dev_iommu_ops(idev->dev);
 	struct iommufd_hwpt_paging *hwpt_paging;
 	struct iommufd_hw_pagetable *hwpt;
@@ -91,6 +93,8 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 
 	if (flags && !ops->domain_alloc_user)
 		return ERR_PTR(-EOPNOTSUPP);
+	if (flags & ~valid_flags)
+		return ERR_PTR(-EOPNOTSUPP);
 
 	hwpt_paging = __iommufd_object_alloc(
 		ictx, hwpt_paging, IOMMUFD_OBJ_HWPT_PAGING, common.obj);
@@ -167,35 +171,41 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 {
 	struct iommu_hwpt_alloc *cmd = ucmd->cmd;
-	struct iommufd_hwpt_paging *hwpt_paging;
 	struct iommufd_hw_pagetable *hwpt;
+	struct iommufd_ioas *ioas = NULL;
+	struct iommufd_object *pt_obj;
 	struct iommufd_device *idev;
-	struct iommufd_ioas *ioas;
 	int rc;
 
-	if ((cmd->flags & ~(IOMMU_HWPT_ALLOC_NEST_PARENT |
-			    IOMMU_HWPT_ALLOC_DIRTY_TRACKING)) ||
-	    cmd->__reserved)
+	if (cmd->__reserved)
 		return -EOPNOTSUPP;
 
 	idev = iommufd_get_device(ucmd, cmd->dev_id);
 	if (IS_ERR(idev))
 		return PTR_ERR(idev);
 
-	ioas = iommufd_get_ioas(ucmd->ictx, cmd->pt_id);
-	if (IS_ERR(ioas)) {
-		rc = PTR_ERR(ioas);
+	pt_obj = iommufd_get_object(ucmd->ictx, cmd->pt_id, IOMMUFD_OBJ_ANY);
+	if (IS_ERR(pt_obj)) {
+		rc = -EINVAL;
 		goto out_put_idev;
 	}
 
-	mutex_lock(&ioas->mutex);
-	hwpt_paging = iommufd_hwpt_paging_alloc(ucmd->ictx, ioas, idev,
-						cmd->flags, false);
-	if (IS_ERR(hwpt_paging)) {
-		rc = PTR_ERR(hwpt_paging);
-		goto out_unlock;
+	if (pt_obj->type == IOMMUFD_OBJ_IOAS) {
+		struct iommufd_hwpt_paging *hwpt_paging;
+
+		ioas = container_of(pt_obj, struct iommufd_ioas, obj);
+		mutex_lock(&ioas->mutex);
+		hwpt_paging = iommufd_hwpt_paging_alloc(ucmd->ictx, ioas, idev,
+							cmd->flags, false);
+		if (IS_ERR(hwpt_paging)) {
+			rc = PTR_ERR(hwpt_paging);
+			goto out_unlock;
+		}
+		hwpt = &hwpt_paging->common;
+	} else {
+		rc = -EINVAL;
+		goto out_put_pt;
 	}
-	hwpt = &hwpt_paging->common;
 
 	cmd->out_hwpt_id = hwpt->obj.id;
 	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
@@ -207,8 +217,10 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 out_hwpt:
 	iommufd_object_abort_and_destroy(ucmd->ictx, &hwpt->obj);
 out_unlock:
-	mutex_unlock(&ioas->mutex);
-	iommufd_put_object(&ioas->obj);
+	if (ioas)
+		mutex_unlock(&ioas->mutex);
+out_put_pt:
+	iommufd_put_object(pt_obj);
 out_put_idev:
 	iommufd_put_object(&idev->obj);
 	return rc;