vdpa/mlx5: Use suspend/resume during VQP change

Resume a VQ if it is already created when the number of VQ pairs
increases. This is done in preparation for VQ pre-creation which is
coming in a later patch. It is necessary because calling setup_vq() on
an already created VQ will return early and will not enable the queue.

For symmetry, suspend a VQ instead of tearing it down when the number of
VQ pairs decreases. But only if the resume operation is supported.

Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Message-Id: <20240626-stage-vdpa-vq-precreate-v2-20-560c491078df@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index ce1f6a1..324604b 100644 (file)
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2130,14 +2130,22 @@ static int change_num_qps(struct mlx5_vdpa_dev *mvdev, int newqps)
                if (err)
                        return err;
 
-               for (i = ndev->cur_num_vqs - 1; i >= 2 * newqps; i--)
-                       teardown_vq(ndev, &ndev->vqs[i]);
+               for (i = ndev->cur_num_vqs - 1; i >= 2 * newqps; i--) {
+                       struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
+
+                       if (is_resumable(ndev))
+                               suspend_vq(ndev, mvq);
+                       else
+                               teardown_vq(ndev, mvq);
+               }
 
                ndev->cur_num_vqs = 2 * newqps;
        } else {
                ndev->cur_num_vqs = 2 * newqps;
                for (i = cur_qps * 2; i < 2 * newqps; i++) {
-                       err = setup_vq(ndev, &ndev->vqs[i], true);
+                       struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
+
+                       err = mvq->initialized ? resume_vq(ndev, mvq) : setup_vq(ndev, mvq, true);
                        if (err)
                                goto clean_added;
                }