[PATCH 2/2] iommu: Undo pasid attachment only for the devices that have succeeded

[Yi Liu <yi.l.liu@intel.com>]

There is no error handling now in __iommu_set_group_pasid(), it relies on
its caller to loop all the devices to undo the pasid attachment. This is
not self-contained and has unnecessary remove_dev_pasid() calls on the
devices that have not changed in the __iommu_set_group_pasid() call. this
results in unnecessary warnings by the underlying iommu drivers. Like the
Intel iommu driver, it would warn when there is no pasid attachment to
destroy in the remove_dev_pasid() callback.

The ideal way is to handle the error within __iommu_set_group_pasid(). This
not only makes __iommu_set_group_pasid() self-contained, but also avoids
unnecessary warnings.

Fixes: 16603704559c7a68 ("iommu: Add attach/detach_dev_pasid iommu interfaces")
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/iommu/iommu.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 681e916d285b..2a12c9c9e045 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3317,15 +3317,25 @@ EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
 static int __iommu_set_group_pasid(struct iommu_domain *domain,
 				   struct iommu_group *group, ioasid_t pasid)
 {
-	struct group_device *device;
-	int ret = 0;
+	struct group_device *device, *last_gdev;
+	int ret;
 
 	for_each_group_device(group, device) {
 		ret = domain->ops->set_dev_pasid(domain, device->dev, pasid);
 		if (ret)
-			break;
+			goto err_revert;
 	}
 
+	return 0;
+
+err_revert:
+	last_gdev = device;
+	for_each_group_device(group, device) {
+		if (device == last_gdev)
+			break;
+		dev_iommu_ops(device->dev)->remove_dev_pasid(device->dev,
+							     pasid, domain);
+	}
 	return ret;
 }
 
@@ -3375,10 +3385,8 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
 	}
 
 	ret = __iommu_set_group_pasid(domain, group, pasid);
-	if (ret) {
-		__iommu_remove_group_pasid(group, pasid, domain);
+	if (ret)
 		xa_erase(&group->pasid_array, pasid);
-	}
 out_unlock:
 	mutex_unlock(&group->mutex);
 	return ret;
-- 
2.34.1