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, 29 insertions, 2 deletions

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index c44eecf5d318..d816deac906f 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -362,19 +362,43 @@ enum iommufd_hwpt_alloc_flags {
 };
 
 /**
+ * enum iommu_hwpt_data_type - IOMMU HWPT Data Type
+ * @IOMMU_HWPT_DATA_NONE: no data
+ */
+enum iommu_hwpt_data_type {
+	IOMMU_HWPT_DATA_NONE,
+};
+
+/**
  * struct iommu_hwpt_alloc - ioctl(IOMMU_HWPT_ALLOC)
  * @size: sizeof(struct iommu_hwpt_alloc)
  * @flags: Combination of enum iommufd_hwpt_alloc_flags
  * @dev_id: The device to allocate this HWPT for
- * @pt_id: The IOAS to connect this HWPT to
+ * @pt_id: The IOAS or HWPT to connect this HWPT to
  * @out_hwpt_id: The ID of the new HWPT
  * @__reserved: Must be 0
+ * @data_type: One of enum iommu_hwpt_data_type
+ * @data_len: Length of the type specific data
+ * @data_uptr: User pointer to the type specific data
  *
  * Explicitly allocate a hardware page table object. This is the same object
  * type that is returned by iommufd_device_attach() and represents the
  * underlying iommu driver's iommu_domain kernel object.
  *
- * A HWPT will be created with the IOVA mappings from the given IOAS.
+ * A kernel-managed HWPT will be created with the mappings from the given
+ * IOAS via the @pt_id. The @data_type for this allocation must be set to
+ * IOMMU_HWPT_DATA_NONE. The HWPT can be allocated as a parent HWPT for a
+ * nesting configuration by passing IOMMU_HWPT_ALLOC_NEST_PARENT via @flags.
+ *
+ * A user-managed nested HWPT will be created from a given parent HWPT via
+ * @pt_id, in which the parent HWPT must be allocated previously via the
+ * same ioctl from a given IOAS (@pt_id). In this case, the @data_type
+ * must be set to a pre-defined type corresponding to an I/O page table
+ * type supported by the underlying IOMMU hardware.
+ *
+ * If the @data_type is set to IOMMU_HWPT_DATA_NONE, @data_len and
+ * @data_uptr should be zero. Otherwise, both @data_len and @data_uptr
+ * must be given.
  */
 struct iommu_hwpt_alloc {
 	__u32 size;
@@ -383,6 +407,9 @@ struct iommu_hwpt_alloc {
 	__u32 pt_id;
 	__u32 out_hwpt_id;
 	__u32 __reserved;
+	__u32 data_type;
+	__u32 data_len;
+	__aligned_u64 data_uptr;
 };
 #define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)