[PATCH vhost v2 20/24] vdpa/mlx5: Use suspend/resume during VQP change

[Dragos Tatulea]

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 <cra...@nvidia.com>
Acked-by: Eugenio Pérez <epere...@redhat.com>
Signed-off-by: Dragos Tatulea <dtatu...@nvidia.com>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c 
b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index ce1f6a1f36cd..324604b16b91 100644
--- 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;
                }

-- 
2.45.1