Re: [PATCH vhost 21/23] vdpa/mlx5: Re-create HW VQs under certain conditions

Eugenio Perez Martin
2024-06-19T16:05:01Z

On Mon, Jun 17, 2024 at 5:09 PM Dragos Tatulea <dtatulea@nvidia.com> wrote:
>
> There are a few conditions under which the hardware VQs need a full
> teardown and setup:
>
> - VQ size changed to something else than default value. Hardware VQ size
> modification is not supported.
>
> - User turns off certain device features: mergeable buffers, checksum
> virtio 1.0 compliance. In these cases, the TIR and RQT need to be
> re-created.
>
> Add a needs_teardown configuration variable and set it when detecting
> the above scenarios. On next DRIVER_OK, the resources will be torn down
> first.
>
> 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 | 15 +++++++++++++++
> drivers/vdpa/mlx5/net/mlx5_vnet.h | 1 +
> 2 files changed, 16 insertions(+)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index b2836fd3d1dd..d80d6b47da61 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2390,6 +2390,7 @@ static void mlx5_vdpa_set_vq_num(struct vdpa_device *vdev, u16 idx, u32 num)
> }
>
> mvq = &ndev->vqs[idx];
> + ndev->needs_teardown = num != mvq->num_ent;
> mvq->num_ent = num;
> }
>
> @@ -2800,6 +2801,7 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
> struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> u64 old_features = mvdev->actual_features;
> + u64 diff_features;
> int err;
>
> print_features(mvdev, features, true);
> @@ -2822,6 +2824,14 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
> }
> }
>
> + /* When below features diverge from initial device features, VQs need a full teardown. */
> +#define NEEDS_TEARDOWN_MASK (BIT_ULL(VIRTIO_NET_F_MRG_RXBUF) | \
> + BIT_ULL(VIRTIO_NET_F_CSUM) | \
> + BIT_ULL(VIRTIO_F_VERSION_1))
> +
> + diff_features = mvdev->mlx_features ^ mvdev->actual_features;
> + ndev->needs_teardown = !!(diff_features & NEEDS_TEARDOWN_MASK);
> +
> update_cvq_info(mvdev);
> return err;
> }
> @@ -3038,6 +3048,7 @@ static void teardown_vq_resources(struct mlx5_vdpa_net *ndev)
> destroy_rqt(ndev);
> teardown_virtqueues(ndev);
> ndev->setup = false;
> + ndev->needs_teardown = false;
> }
>
> static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
> @@ -3078,6 +3089,10 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> goto err_setup;
> }
> register_link_notifier(ndev);
> +
> + if (ndev->needs_teardown)
> + teardown_vq_resources(ndev);
> +
> if (ndev->setup) {
> err = resume_vqs(ndev);
> if (err) {
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.h b/drivers/vdpa/mlx5/net/mlx5_vnet.h
> index 2ada29767cc5..da7318f82d2a 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.h
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.h
> @@ -56,6 +56,7 @@ struct mlx5_vdpa_net {
> struct dentry *rx_dent;
> struct dentry *rx_table_dent;
> bool setup;
> + bool needs_teardown;
> u32 cur_num_vqs;
> u32 rqt_size;
> u16 default_queue_size;
>
> --
> 2.45.1
>