vdpa/mlx5: Add mkey leak detection

Track allocated mrs in a list and show warning when leaks are detected
on device free or reset.
Reviewed-by: Gal Pressman <gal@nvidia.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Message-Id: <20231225151203.152687-9-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/mlx5/core/mlx5_vdpa.h

@@ -37,6 +37,7 @@ struct mlx5_vdpa_mr {
 	bool user_mr;
 
 	refcount_t refcount;
+	struct list_head mr_list;
 };
 
 struct mlx5_vdpa_resources {
@@ -95,6 +96,7 @@ struct mlx5_vdpa_dev {
 	u32 generation;
 
 	struct mlx5_vdpa_mr *mr[MLX5_VDPA_NUM_AS];
+	struct list_head mr_list_head;
 	/* serialize mr access */
 	struct mutex mr_mtx;
 	struct mlx5_control_vq cvq;

drivers/vdpa/mlx5/core/mr.c

@@ -508,6 +508,8 @@ static void _mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_
 
 	vhost_iotlb_free(mr->iotlb);
 
+	list_del(&mr->mr_list);
+
 	kfree(mr);
 }
 
@@ -560,12 +562,31 @@ void mlx5_vdpa_update_mr(struct mlx5_vdpa_dev *mvdev,
 	mutex_unlock(&mvdev->mr_mtx);
 }
 
+static void mlx5_vdpa_show_mr_leaks(struct mlx5_vdpa_dev *mvdev)
+{
+	struct mlx5_vdpa_mr *mr;
+
+	mutex_lock(&mvdev->mr_mtx);
+
+	list_for_each_entry(mr, &mvdev->mr_list_head, mr_list) {
+
+		mlx5_vdpa_warn(mvdev, "mkey still alive after resource delete: "
+				      "mr: %p, mkey: 0x%x, refcount: %u\n",
+				       mr, mr->mkey, refcount_read(&mr->refcount));
+	}
+
+	mutex_unlock(&mvdev->mr_mtx);
+
+}
+
 void mlx5_vdpa_destroy_mr_resources(struct mlx5_vdpa_dev *mvdev)
 {
 	for (int i = 0; i < MLX5_VDPA_NUM_AS; i++)
 		mlx5_vdpa_update_mr(mvdev, NULL, i);
 
 	prune_iotlb(mvdev->cvq.iotlb);
+
+	mlx5_vdpa_show_mr_leaks(mvdev);
 }
 
 static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev,
@@ -592,6 +613,8 @@ static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev,
 	if (err)
 		goto err_iotlb;
 
+	list_add_tail(&mr->mr_list, &mvdev->mr_list_head);
+
 	return 0;
 
 err_iotlb:

drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -3722,6 +3722,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
 	if (err)
 		goto err_mpfs;
 
+	INIT_LIST_HEAD(&mvdev->mr_list_head);
+
 	if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0)) {
 		err = mlx5_vdpa_create_dma_mr(mvdev);
 		if (err)