Re: [PATCH vhost 12/23] vdpa/mlx5: Start off rqt_size with max VQPs

[Eugenio Perez Martin]

On Mon, Jun 17, 2024 at 5:09 PM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote:
>
> Currently rqt_size is initialized during device flag configuration.
> That's because it is the earliest moment when device knows if MQ
> (multi queue) is on or off.
>
> Shift this configuration earlier to device creation time. This implies
> that non-MQ devices will have a larger RQT size. But the configuration
> will still be correct.
>
> This is done in preparation for the pre-creation of hardware virtqueues
> at device add time. When that change will be added, RQT will be created
> at device creation time so it needs to be initialized to its max size.
>
> Signed-off-by: Dragos Tatulea <dtatulea@xxxxxxxxxx>
> Reviewed-by: Cosmin Ratiu <cratiu@xxxxxxxxxx>

Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 1181e0ac3671..0201c6fe61e1 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2731,10 +2731,6 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
>                 return err;
>
>         ndev->mvdev.actual_features = features & ndev->mvdev.mlx_features;
> -       if (ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_MQ))
> -               ndev->rqt_size = mlx5vdpa16_to_cpu(mvdev, ndev->config.max_virtqueue_pairs);
> -       else
> -               ndev->rqt_size = 1;
>
>         /* Interested in changes of vq features only. */
>         if (get_features(old_features) != get_features(mvdev->actual_features)) {
> @@ -3719,8 +3715,12 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>                 goto err_alloc;
>         }
>
> -       if (device_features & BIT_ULL(VIRTIO_NET_F_MQ))
> +       if (device_features & BIT_ULL(VIRTIO_NET_F_MQ)) {
>                 config->max_virtqueue_pairs = cpu_to_mlx5vdpa16(mvdev, max_vqs / 2);
> +               ndev->rqt_size = max_vqs / 2;
> +       } else {
> +               ndev->rqt_size = 1;
> +       }
>
>         ndev->mvdev.mlx_features = device_features;
>         mvdev->vdev.dma_dev = &mdev->pdev->dev;
>
> --
> 2.45.1
>