[PATCH v3 05/17] iommufd/hw_pagetable: Do not populate user-managed hw_pagetables

[Yi Liu <yi.l.liu@xxxxxxxxx>]

From: Nicolin Chen <nicolinc@xxxxxxxxxx>

A user-managed hw_pagetable does not need to get populated, since it is
managed by a guest OS. Move the iopt_table_add_domain and list_add_tail
calls into a helper, where the hwpt pointer will be redirected to its
hwpt->parent if it's available.

Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/iommu/iommufd/hw_pagetable.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 28122a49b529..c7301cf0e85a 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -58,6 +58,24 @@ int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt)
 	return 0;
 }
 
+static int iommufd_hw_pagetable_link_ioas(struct iommufd_hw_pagetable *hwpt)
+{
+	int rc;
+
+	/*
+	 * Only a parent hwpt needs to be linked to the IOAS. And a hwpt->parent
+	 * must be linked to the IOAS already, when it's being allocated.
+	 */
+	if (hwpt->parent)
+		return 0;
+
+	rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain);
+	if (rc)
+		return rc;
+	list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
+	return 0;
+}
+
 /**
  * iommufd_hw_pagetable_alloc() - Get an iommu_domain for a device
  * @ictx: iommufd context
@@ -160,10 +178,9 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			goto out_abort;
 	}
 
-	rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain);
+	rc = iommufd_hw_pagetable_link_ioas(hwpt);
 	if (rc)
 		goto out_detach;
-	list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
 	return hwpt;
 
 out_detach:
-- 
2.34.1