iommufd: Add a nested HW pagetable object

IOMMU_HWPT_ALLOC already supports iommu_domain allocation for usersapce.
But it can only allocate a hw_pagetable that associates to a given IOAS,
i.e. only a kernel-managed hw_pagetable of IOMMUFD_OBJ_HWPT_PAGING type.

IOMMU drivers can now support user-managed hw_pagetables, for two-stage
translation use cases that require user data input from the user space.

Add a new IOMMUFD_OBJ_HWPT_NESTED type with its abort/destroy(). Pair it
with a new iommufd_hwpt_nested structure and its to_hwpt_nested() helper.
Update the to_hwpt_paging() helper, so a NESTED-type hw_pagetable can be
handled in the callers, for example iommufd_hw_pagetable_enforce_rr().

Screen the inputs including the parent PAGING-type hw_pagetable that has
a need of a new nest_parent flag in the iommufd_hwpt_paging structure.

Extend the IOMMU_HWPT_ALLOC ioctl to accept an IOMMU driver specific data
input which is tagged by the enum iommu_hwpt_data_type. Also, update the
@pt_id to accept hwpt_id too besides an ioas_id. Then, use them to allocate
a hw_pagetable of IOMMUFD_OBJ_HWPT_NESTED type using the
iommufd_hw_pagetable_alloc_nested() allocator.

Link: https://lore.kernel.org/r/20231026043938.63898-8-yi.l.liu@intel.com
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Co-developed-by: Yi Liu <yi.l.liu@intel.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>

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index cd8da289ed0b..a74cfefffbc6 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -124,6 +124,7 @@ enum iommufd_object_type {
 	IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE,
 	IOMMUFD_OBJ_DEVICE,
 	IOMMUFD_OBJ_HWPT_PAGING,
+	IOMMUFD_OBJ_HWPT_NESTED,
 	IOMMUFD_OBJ_IOAS,
 	IOMMUFD_OBJ_ACCESS,
 #ifdef CONFIG_IOMMUFD_TEST
@@ -255,10 +256,16 @@ struct iommufd_hwpt_paging {
 	bool auto_domain : 1;
 	bool enforce_cache_coherency : 1;
 	bool msi_cookie : 1;
+	bool nest_parent : 1;
 	/* Head at iommufd_ioas::hwpt_list */
 	struct list_head hwpt_item;
 };
 
+struct iommufd_hwpt_nested {
+	struct iommufd_hw_pagetable common;
+	struct iommufd_hwpt_paging *parent;
+};
+
 static inline bool hwpt_is_paging(struct iommufd_hw_pagetable *hwpt)
 {
 	return hwpt->obj.type == IOMMUFD_OBJ_HWPT_PAGING;
@@ -283,25 +290,32 @@ int iommufd_hwpt_get_dirty_bitmap(struct iommufd_ucmd *ucmd);
 struct iommufd_hwpt_paging *
 iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			  struct iommufd_device *idev, u32 flags,
-			  bool immediate_attach);
+			  bool immediate_attach,
+			  const struct iommu_user_data *user_data);
 int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 				struct iommufd_device *idev);
 struct iommufd_hw_pagetable *
 iommufd_hw_pagetable_detach(struct iommufd_device *idev);
 void iommufd_hwpt_paging_destroy(struct iommufd_object *obj);
 void iommufd_hwpt_paging_abort(struct iommufd_object *obj);
+void iommufd_hwpt_nested_destroy(struct iommufd_object *obj);
+void iommufd_hwpt_nested_abort(struct iommufd_object *obj);
 int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd);
 
 static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
 					    struct iommufd_hw_pagetable *hwpt)
 {
-	struct iommufd_hwpt_paging *hwpt_paging = to_hwpt_paging(hwpt);
+	if (hwpt->obj.type == IOMMUFD_OBJ_HWPT_PAGING) {
+		struct iommufd_hwpt_paging *hwpt_paging = to_hwpt_paging(hwpt);
 
-	lockdep_assert_not_held(&hwpt_paging->ioas->mutex);
-	if (hwpt_paging->auto_domain)
-		iommufd_object_deref_user(ictx, &hwpt->obj);
-	else
-		refcount_dec(&hwpt->obj.users);
+		lockdep_assert_not_held(&hwpt_paging->ioas->mutex);
+
+		if (hwpt_paging->auto_domain) {
+			iommufd_object_deref_user(ictx, &hwpt->obj);
+			return;
+		}
+	}
+	refcount_dec(&hwpt->obj.users);
 }
 
 struct iommufd_group {