Re: [PATCH vhost 19/23] vdpa/mlx5: Use suspend/resume during VQP change

Eugenio Perez Martin
2024-06-19T15:47:37Z

On Mon, Jun 17, 2024 at 5:09 PM Dragos Tatulea <dtatulea@nvidia.com> wrote:
>
> 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.
>
> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>

Acked-by: Eugenio Pérez <eperezma@redhat.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 0e1c1b7ff297..249b5afbe34a 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
>