[PATCH v3 09/17] iommufd: Add enforced_cache_coherency to iommufd_hw_pagetable_alloc()

[Jason Gunthorpe <jgg@nvidia.com>]

Logically the HWPT should have the coherency set properly for the device
that it is being created for when it is created.

This was happening implicitly if the immediate_attach was set because
iommufd_hw_pagetable_attach() does it as the first thing.

Do it unconditionally so !immediate_attach works properly.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommufd/device.c          | 20 +++++-------------
 drivers/iommu/iommufd/hw_pagetable.c    | 27 +++++++++++++++++++++++++
 drivers/iommu/iommufd/iommufd_private.h |  1 +
 3 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 8946de73660ece..ea01718f46ccb1 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -293,21 +293,11 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 	if (idev->igroup->hwpt != NULL && idev->igroup->hwpt != hwpt)
 		return -EINVAL;
 
-	/*
-	 * Try to upgrade the domain we have, it is an iommu driver bug to
-	 * report IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail
-	 * enforce_cache_coherency when there are no devices attached to the
-	 * domain.
-	 */
-	if (idev->enforce_cache_coherency && !hwpt->enforce_cache_coherency) {
-		if (hwpt->domain->ops->enforce_cache_coherency)
-			hwpt->enforce_cache_coherency =
-				hwpt->domain->ops->enforce_cache_coherency(
-					hwpt->domain);
-		if (!hwpt->enforce_cache_coherency) {
-			WARN_ON(list_empty(&idev->igroup->device_list));
-			return -EINVAL;
-		}
+	/* Try to upgrade the domain we have */
+	if (idev->enforce_cache_coherency) {
+		rc = iommufd_hw_pagetable_enforce_cc(hwpt);
+		if (rc)
+			return rc;
 	}
 
 	rc = iopt_table_enforce_dev_resv_regions(&hwpt->ioas->iopt, idev->dev,
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 566eba0cd9b917..2584f9038b29a2 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -25,6 +25,20 @@ void iommufd_hw_pagetable_destroy(struct iommufd_object *obj)
 	refcount_dec(&hwpt->ioas->obj.users);
 }
 
+int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt)
+{
+	if (hwpt->enforce_cache_coherency)
+		return 0;
+
+	if (hwpt->domain->ops->enforce_cache_coherency)
+		hwpt->enforce_cache_coherency =
+			hwpt->domain->ops->enforce_cache_coherency(
+				hwpt->domain);
+	if (!hwpt->enforce_cache_coherency)
+		return -EINVAL;
+	return 0;
+}
+
 /**
  * iommufd_hw_pagetable_alloc() - Get an iommu_domain for a device
  * @ictx: iommufd context
@@ -60,6 +74,19 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 		goto out_abort;
 	}
 
+	/*
+	 * Set the coherency mode before we do iopt_table_add_domain() as some
+	 * iommus have a per-PTE bit that controls it and need to decide before
+	 * doing any maps. It is an iommu driver bug to report
+	 * IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail enforce_cache_coherency on
+	 * a new domain.
+	 */
+	if (idev->enforce_cache_coherency) {
+		rc = iommufd_hw_pagetable_enforce_cc(hwpt);
+		if (WARN_ON(rc))
+			goto out_abort;
+	}
+
 	mutex_lock(&idev->igroup->lock);
 
 	/*
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 8bf053f4d4a9ce..471a3fdff1e0b6 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -254,6 +254,7 @@ struct iommufd_hw_pagetable {
 struct iommufd_hw_pagetable *
 iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			   struct iommufd_device *idev, bool immediate_attach);
+int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt);
 int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 				struct iommufd_device *idev);
 struct iommufd_hw_pagetable *
-- 
2.40.0