net/mlx5e: Consider XSK in XDP MTU limit calculation

Use the existing mlx5e_get_linear_rq_headroom function to calculate the
headroom for mlx5e_xdp_max_mtu. This function takes the XSK headroom
into consideration, which will be used in the following patches.
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

drivers/net/ethernet/mellanox/mlx5/core/en/params.c

@@ -9,7 +9,7 @@ static inline bool mlx5e_rx_is_xdp(struct mlx5e_params *params,
 	return params->xdp_prog || xsk;
 }
 
-static inline u16 mlx5e_get_linear_rq_headroom(struct mlx5e_params *params,
+u16 mlx5e_get_linear_rq_headroom(struct mlx5e_params *params,
 				 struct mlx5e_xsk_param *xsk)
 {
 	u16 headroom = NET_IP_ALIGN;

drivers/net/ethernet/mellanox/mlx5/core/en/params.h

@@ -11,6 +11,8 @@ struct mlx5e_xsk_param {
 	u16 chunk_size;
 };
 
+u16 mlx5e_get_linear_rq_headroom(struct mlx5e_params *params,
+				 struct mlx5e_xsk_param *xsk);
 u32 mlx5e_rx_get_linear_frag_sz(struct mlx5e_params *params,
 				struct mlx5e_xsk_param *xsk);
 u8 mlx5e_mpwqe_log_pkts_per_wqe(struct mlx5e_params *params);

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c

@@ -32,10 +32,11 @@
 
 #include <linux/bpf_trace.h>
 #include "en/xdp.h"
+#include "en/params.h"
 
-int mlx5e_xdp_max_mtu(struct mlx5e_params *params)
+int mlx5e_xdp_max_mtu(struct mlx5e_params *params, struct mlx5e_xsk_param *xsk)
 {
-	int hr = NET_IP_ALIGN + XDP_PACKET_HEADROOM;
+	int hr = mlx5e_get_linear_rq_headroom(params, xsk);
 
 	/* Let S := SKB_DATA_ALIGN(sizeof(struct skb_shared_info)).
 	 * The condition checked in mlx5e_rx_is_linear_skb is:

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h

@@ -39,7 +39,8 @@
 	(sizeof(struct mlx5e_tx_wqe) / MLX5_SEND_WQE_DS)
 #define MLX5E_XDP_TX_DS_COUNT (MLX5E_XDP_TX_EMPTY_DS_COUNT + 1 /* SG DS */)
 
-int mlx5e_xdp_max_mtu(struct mlx5e_params *params);
+struct mlx5e_xsk_param;
+int mlx5e_xdp_max_mtu(struct mlx5e_params *params, struct mlx5e_xsk_param *xsk);
 bool mlx5e_xdp_handle(struct mlx5e_rq *rq, struct mlx5e_dma_info *di,
 		      void *va, u16 *rx_headroom, u32 *len);
 bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq);

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -3722,7 +3722,7 @@ int mlx5e_change_mtu(struct net_device *netdev, int new_mtu,
 	if (params->xdp_prog &&
 	    !mlx5e_rx_is_linear_skb(&new_channels.params)) {
 		netdev_err(netdev, "MTU(%d) > %d is not allowed while XDP enabled\n",
-			   new_mtu, mlx5e_xdp_max_mtu(params));
+			   new_mtu, mlx5e_xdp_max_mtu(params, NULL));
 		err = -EINVAL;
 		goto out;
 	}
@@ -4167,7 +4167,7 @@ static int mlx5e_xdp_allowed(struct mlx5e_priv *priv, struct bpf_prog *prog)
 	if (!mlx5e_rx_is_linear_skb(&new_channels.params)) {
 		netdev_warn(netdev, "XDP is not allowed with MTU(%d) > %d\n",
 			    new_channels.params.sw_mtu,
-			    mlx5e_xdp_max_mtu(&new_channels.params));
+			    mlx5e_xdp_max_mtu(&new_channels.params, NULL));
 		return -EINVAL;
 	}