[RFC 3/3] vdpa/mlx5: take iommu_lock at dup_iotlb

["Eugenio Pérez" <eperezma@redhat.com>]

Both iommu changes and lookup are protected by mlx5_vdpa_net->reslock at
this moment, but:
* These iotlb changes / queries are not in the fast data path.
* reslock belongs to netdev, while dup_iotlb seems generic.
* It's located in a different file than the lock it needs to hold

Justifies the lock acquisition.

Fixes: 5262912ef3cf ("vdpa/mlx5: Add support for control VQ and MAC setting")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 drivers/vdpa/mlx5/core/mr.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/mlx5/core/mr.c b/drivers/vdpa/mlx5/core/mr.c
index 878ee94efa78..e9c8a7f8ee1d 100644
--- a/drivers/vdpa/mlx5/core/mr.c
+++ b/drivers/vdpa/mlx5/core/mr.c
@@ -454,13 +454,15 @@ static int dup_iotlb(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *src)
 {
 	struct vhost_iotlb_map *map;
 	u64 start = 0, last = ULLONG_MAX;
-	int err;
+	int err = 0;
+
+	spin_lock(&mvdev->cvq.iommu_lock);
 
 	vhost_iotlb_reset(mvdev->cvq.iotlb);
 
 	if (!src) {
 		err = vhost_iotlb_add_range(mvdev->cvq.iotlb, start, last, start, VHOST_ACCESS_RW);
-		return err;
+		goto out;
 	}
 
 	for (map = vhost_iotlb_itree_first(src, start, last); map;
@@ -468,9 +470,12 @@ static int dup_iotlb(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *src)
 		err = vhost_iotlb_add_range(mvdev->cvq.iotlb, map->start, map->last,
 					    map->addr, map->perm);
 		if (err)
-			return err;
+			goto out;
 	}
-	return 0;
+
+out:
+	spin_unlock(&mvdev->cvq.iommu_lock);
+	return err;
 }
 
 static void prune_iotlb(struct mlx5_vdpa_dev *mvdev)
-- 
2.31.1