[PATCH v1 03/16] iommufd: Allow pt_id to carry viommu_id for IOMMU_HWPT_ALLOC

[Nicolin Chen <nicolinc@nvidia.com>]

Now a VIOMMU can wrap a shareable nested parent HWPT. So, it can act like
a nested parent HWPT to allocate a nested HWPT.

Support that in the IOMMU_HWPT_ALLOC ioctl handler, and update its kdoc.

Also, associate a viommu to an allocating nested HWPT.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/hw_pagetable.c    | 24 ++++++++++++++++++++++--
 drivers/iommu/iommufd/iommufd_private.h |  1 +
 include/uapi/linux/iommufd.h            | 12 ++++++------
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index c21bb59c4022..06adbcc304bc 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -57,6 +57,9 @@ void iommufd_hwpt_nested_destroy(struct iommufd_object *obj)
 		container_of(obj, struct iommufd_hwpt_nested, common.obj);
 
 	__iommufd_hwpt_destroy(&hwpt_nested->common);
+
+	if (hwpt_nested->viommu)
+		refcount_dec(&hwpt_nested->viommu->obj.users);
 	refcount_dec(&hwpt_nested->parent->common.obj.users);
 }
 
@@ -213,6 +216,7 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
  */
 static struct iommufd_hwpt_nested *
 iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
+			  struct iommufd_viommu *viommu,
 			  struct iommufd_hwpt_paging *parent,
 			  struct iommufd_device *idev, u32 flags,
 			  const struct iommu_user_data *user_data)
@@ -234,13 +238,16 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
 		return ERR_CAST(hwpt_nested);
 	hwpt = &hwpt_nested->common;
 
+	if (viommu)
+		refcount_inc(&viommu->obj.users);
+	hwpt_nested->viommu = viommu;
 	refcount_inc(&parent->common.obj.users);
 	hwpt_nested->parent = parent;
 
 	hwpt->domain = ops->domain_alloc_user(idev->dev,
 					      flags & ~IOMMU_HWPT_FAULT_ID_VALID,
 					      parent->common.domain,
-					      NULL, user_data);
+					      viommu, user_data);
 	if (IS_ERR(hwpt->domain)) {
 		rc = PTR_ERR(hwpt->domain);
 		hwpt->domain = NULL;
@@ -307,7 +314,7 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 		struct iommufd_hwpt_nested *hwpt_nested;
 
 		hwpt_nested = iommufd_hwpt_nested_alloc(
-			ucmd->ictx,
+			ucmd->ictx, NULL,
 			container_of(pt_obj, struct iommufd_hwpt_paging,
 				     common.obj),
 			idev, cmd->flags, &user_data);
@@ -316,6 +323,19 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 			goto out_unlock;
 		}
 		hwpt = &hwpt_nested->common;
+	} else if (pt_obj->type == IOMMUFD_OBJ_VIOMMU) {
+		struct iommufd_hwpt_nested *hwpt_nested;
+		struct iommufd_viommu *viommu;
+
+		viommu = container_of(pt_obj, struct iommufd_viommu, obj);
+		hwpt_nested = iommufd_hwpt_nested_alloc(
+			ucmd->ictx, viommu, viommu->hwpt, idev,
+			cmd->flags, &user_data);
+		if (IS_ERR(hwpt_nested)) {
+			rc = PTR_ERR(hwpt_nested);
+			goto out_unlock;
+		}
+		hwpt = &hwpt_nested->common;
 	} else {
 		rc = -EINVAL;
 		goto out_put_pt;
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 0e3755408911..443575fd3dd4 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -313,6 +313,7 @@ struct iommufd_hwpt_paging {
 struct iommufd_hwpt_nested {
 	struct iommufd_hw_pagetable common;
 	struct iommufd_hwpt_paging *parent;
+	struct iommufd_viommu *viommu;
 };
 
 static inline bool hwpt_is_paging(struct iommufd_hw_pagetable *hwpt)
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index ed6cdc2e0be1..0e384331a9c8 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -430,7 +430,7 @@ enum iommu_hwpt_data_type {
  * @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 or HWPT to connect this HWPT to
+ * @pt_id: The IOAS or HWPT or VIOMMU 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
@@ -449,11 +449,11 @@ enum iommu_hwpt_data_type {
  * 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.
+ * A user-managed nested HWPT will be created from a given VIOMMU (wrapping a
+ * parent HWPT) or a 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
-- 
2.43.0