Re: [PATCH net-next 7/8] net/mlx5e: take into account device reconfiguration for xdp_features flag

[Tariq Toukan <ttoukan.linux@gmail.com>]

On 07/03/2023 16:54, Lorenzo Bianconi wrote:
> Take into account LRO and GRO configuration setting device xdp_features
> flag. Moreover consider channel rq_wq_type enabling rx scatter-gatter
> support in xdp_features flag.
> 
> Fixes: 66c0e13ad236 ("drivers: net: turn on XDP features")
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>   drivers/net/ethernet/mellanox/mlx5/core/en.h  |  1 +
>   .../ethernet/mellanox/mlx5/core/en_ethtool.c  | 10 ++++-
>   .../net/ethernet/mellanox/mlx5/core/en_main.c | 45 ++++++++++++++++---
>   .../net/ethernet/mellanox/mlx5/core/en_rep.c  |  3 ++
>   4 files changed, 51 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> index 88460b7796e5..4276c6eb6820 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> @@ -1243,6 +1243,7 @@ void mlx5e_build_nic_params(struct mlx5e_priv *priv, struct mlx5e_xsk *xsk, u16
>   void mlx5e_rx_dim_work(struct work_struct *work);
>   void mlx5e_tx_dim_work(struct work_struct *work);
>   
> +void mlx5e_set_xdp_feature(struct net_device *netdev);
>   netdev_features_t mlx5e_features_check(struct sk_buff *skb,
>   				       struct net_device *netdev,
>   				       netdev_features_t features);
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> index 7708acc9b2ab..79fd21ecb9cb 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> @@ -1985,6 +1985,7 @@ static int set_pflag_rx_striding_rq(struct net_device *netdev, bool enable)
>   	struct mlx5e_priv *priv = netdev_priv(netdev);
>   	struct mlx5_core_dev *mdev = priv->mdev;
>   	struct mlx5e_params new_params;
> +	int err;
>   
>   	if (enable) {
>   		/* Checking the regular RQ here; mlx5e_validate_xsk_param called
> @@ -2005,7 +2006,14 @@ static int set_pflag_rx_striding_rq(struct net_device *netdev, bool enable)
>   	MLX5E_SET_PFLAG(&new_params, MLX5E_PFLAG_RX_STRIDING_RQ, enable);
>   	mlx5e_set_rq_type(mdev, &new_params);
>   
> -	return mlx5e_safe_switch_params(priv, &new_params, NULL, NULL, true);
> +	err = mlx5e_safe_switch_params(priv, &new_params, NULL, NULL, true);
> +	if (err)
> +		return err;
> +
> +	/* update XDP supported features */
> +	mlx5e_set_xdp_feature(netdev);
> +
> +	return 0;
>   }
>   
>   static int set_pflag_rx_no_csum_complete(struct net_device *netdev, bool enable)
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index 76a9c5194a70..1b68dd2be2c5 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -4004,6 +4004,30 @@ static int mlx5e_handle_feature(struct net_device *netdev,
>   	return 0;
>   }
>   
> +void mlx5e_set_xdp_feature(struct net_device *netdev)
> +{
> +	struct mlx5e_priv *priv = netdev_priv(netdev);
> +	bool ndo_xmit = test_bit(MLX5E_STATE_XDP_ACTIVE, &priv->state);

Our driver doesn't require loading a dummy XDP program to have the 
redirect-in ability. It's always there.

I actually have a bug fix under internal review with Saeed that 
addresses this.

In addition, it cleans up the NETDEV_XDP_ACT_NDO_XMIT_SG as we do not 
support it yet. I have a series that's adding support and will submit it 
soon.

Any reason you're submitting these fixes to net-next rather than net?
Maybe it'd be better if we integrate the patches, here's my fix (still 
under review...):

Author: Tariq Toukan <tariqt@nvidia.com>
Date:   Thu Feb 23 08:58:04 2023 +0200

     net/mlx5e: Fix exposed xdp_features

     Always declare NETDEV_XDP_ACT_NDO_XMIT as the ndo_xdp_xmit callback
     is always functional per our design, and does not require loading
     a dummy xdp program.

     Although non-linear XDP buffer is supported for XDP_TX flow, do not
     declare NETDEV_XDP_ACT_NDO_XMIT_SG as it is yet supported for
     redirected-in frames.

     Fixes: 66c0e13ad236 ("drivers: net: turn on XDP features")
     Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 53feb0529943..9a5d3ce1fbcd 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -4741,13 +4741,6 @@ static int mlx5e_xdp_set(struct net_device 
*netdev, struct bpf_prog *prog)
         if (old_prog)
                 bpf_prog_put(old_prog);

-       if (reset) {
-               if (prog)
-                       xdp_features_set_redirect_target(netdev, true);
-               else
-                       xdp_features_clear_redirect_target(netdev);
-       }
-
         if (!test_bit(MLX5E_STATE_OPENED, &priv->state) || reset)
                 goto unlock;

@@ -5144,6 +5137,7 @@ static void mlx5e_build_nic_netdev(struct 
net_device *netdev)
         netdev->features         |= NETIF_F_HW_VLAN_STAG_FILTER;

         netdev->xdp_features = NETDEV_XDP_ACT_BASIC | 
NETDEV_XDP_ACT_REDIRECT |
+                              NETDEV_XDP_ACT_NDO_XMIT |
                                NETDEV_XDP_ACT_XSK_ZEROCOPY |
                                NETDEV_XDP_ACT_RX_SG;


> +	struct mlx5e_params *params = &priv->channels.params;
> +	xdp_features_t val;
> +
> +	if (params->packet_merge.type != MLX5E_PACKET_MERGE_NONE) {
> +		xdp_clear_features_flag(netdev);
> +		return;
> +	}
> +
> +	val = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
> +	      NETDEV_XDP_ACT_XSK_ZEROCOPY;
> +	if (ndo_xmit)
> +		val |= NETDEV_XDP_ACT_NDO_XMIT;
> +	if (params->rq_wq_type == MLX5_WQ_TYPE_CYCLIC) {
> +		val |= NETDEV_XDP_ACT_RX_SG;
> +		if (ndo_xmit)
> +			val |= NETDEV_XDP_ACT_NDO_XMIT_SG;

This NETDEV_XDP_ACT_NDO_XMIT_SG capability is not related to the RQ 
type. It's still not supported at this point.

BTW, I have a series completing all the missing capabilities (multibuf 
on Striding + multibuf redirect-in), should be submitted in this kernel.

> +	}
> +	xdp_set_features_flag(netdev, val);
> +}
> +
>   int mlx5e_set_features(struct net_device *netdev, netdev_features_t features)
>   {
>   	netdev_features_t oper_features = features;
> @@ -4030,6 +4054,9 @@ int mlx5e_set_features(struct net_device *netdev, netdev_features_t features)
>   		return -EINVAL;
>   	}
>   
> +	/* update XDP supported features */
> +	mlx5e_set_xdp_feature(netdev);
> +
>   	return 0;
>   }
>   
> @@ -4762,10 +4789,14 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
>   		bpf_prog_put(old_prog);
>   
>   	if (reset) {
> -		if (prog)
> -			xdp_features_set_redirect_target(netdev, true);
> -		else
> +		if (prog) {
> +			bool xmit_sg;
> +
> +			xmit_sg = new_params.rq_wq_type == MLX5_WQ_TYPE_CYCLIC;

Same, not related. Still not supported at this point.

> +			xdp_features_set_redirect_target(netdev, xmit_sg);
> +		} else {
>   			xdp_features_clear_redirect_target(netdev);
> +		}
>   	}
>   
>   	if (!test_bit(MLX5E_STATE_OPENED, &priv->state) || reset)
> @@ -5163,13 +5194,10 @@ static void mlx5e_build_nic_netdev(struct net_device *netdev)
>   	netdev->features         |= NETIF_F_HIGHDMA;
>   	netdev->features         |= NETIF_F_HW_VLAN_STAG_FILTER;
>   
> -	netdev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
> -			       NETDEV_XDP_ACT_XSK_ZEROCOPY |
> -			       NETDEV_XDP_ACT_RX_SG;
> -
>   	netdev->priv_flags       |= IFF_UNICAST_FLT;
>   
>   	netif_set_tso_max_size(netdev, GSO_MAX_SIZE);
> +	mlx5e_set_xdp_feature(netdev);
>   	mlx5e_set_netdev_dev_addr(netdev);
>   	mlx5e_macsec_build_netdev(priv);
>   	mlx5e_ipsec_build_netdev(priv);
> @@ -5241,6 +5269,9 @@ static int mlx5e_nic_init(struct mlx5_core_dev *mdev,
>   		mlx5_core_err(mdev, "TLS initialization failed, %d\n", err);
>   
>   	mlx5e_health_create_reporters(priv);
> +	/* update XDP supported features */
> +	mlx5e_set_xdp_feature(netdev);
> +
>   	return 0;
>   }
>   
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> index 9b9203443085..43fd12fb87b8 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> @@ -747,6 +747,9 @@ static void mlx5e_build_rep_params(struct net_device *netdev)
>   	/* RQ */
>   	mlx5e_build_rq_params(mdev, params);
>   
> +	/* update XDP supported features */
> +	mlx5e_set_xdp_feature(netdev);
> +
>   	/* CQ moderation params */
>   	params->rx_dim_enabled = MLX5_CAP_GEN(mdev, cq_moderation);
>   	mlx5e_set_rx_cq_mode_params(params, cq_period_mode);