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Commit b45f0674 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

mlx4: xdp: Allow raising MTU up to one page minus eth and vlan hdrs 



When XDP is active in mlx4, mlx4 is using one page/pkt.
At the same time (i.e. when XDP is active), it is currently
limiting MTU to be FRAG_SZ0 - ETH_HLEN - (2 * VLAN_HLEN)
which is 1514 in x86.  AFAICT, we can at least raise the MTU
limit up to PAGE_SIZE - ETH_HLEN - (2 * VLAN_HLEN) which this
patch is doing.  It will be useful in the next patch which
allows XDP program to extend the packet by adding new header(s).

Note: In the earlier XDP patches, there is already existing guard
to ensure the page/pkt scheme only applies when XDP is active
in mlx4.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 17bedab2

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

+20 −8
Original line number Diff line number Diff line
@@ -51,6 +51,8 @@ 
#include "mlx4_en.h"

#include "en_port.h"



#define MLX4_EN_MAX_XDP_MTU ((int)(PAGE_SIZE - ETH_HLEN - (2 * VLAN_HLEN)))



int mlx4_en_setup_tc(struct net_device *dev, u8 up)

{

	struct mlx4_en_priv *priv = netdev_priv(dev);
@@ -2249,6 +2251,19 @@ void mlx4_en_destroy_netdev(struct net_device *dev) 
	free_netdev(dev);

}



static bool mlx4_en_check_xdp_mtu(struct net_device *dev, int mtu)

{

	struct mlx4_en_priv *priv = netdev_priv(dev);



	if (mtu > MLX4_EN_MAX_XDP_MTU) {

		en_err(priv, "mtu:%d > max:%d when XDP prog is attached\n",

		       mtu, MLX4_EN_MAX_XDP_MTU);

		return false;

	}



	return true;

}



static int mlx4_en_change_mtu(struct net_device *dev, int new_mtu)

{

	struct mlx4_en_priv *priv = netdev_priv(dev);
@@ -2258,11 +2273,10 @@ static int mlx4_en_change_mtu(struct net_device *dev, int new_mtu) 
	en_dbg(DRV, priv, "Change MTU called - current:%d new:%d\n",

		 dev->mtu, new_mtu);



	if (priv->tx_ring_num[TX_XDP] && MLX4_EN_EFF_MTU(new_mtu) > FRAG_SZ0) {

		en_err(priv, "MTU size:%d requires frags but XDP running\n",

		       new_mtu);

		return -EOPNOTSUPP;

	}

	if (priv->tx_ring_num[TX_XDP] &&

	    !mlx4_en_check_xdp_mtu(dev, new_mtu))

		return -ENOTSUPP;



	dev->mtu = new_mtu;



	if (netif_running(dev)) {
@@ -2715,10 +2729,8 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog) 
		return 0;

	}



	if (priv->num_frags > 1) {

		en_err(priv, "Cannot set XDP if MTU requires multiple frags\n");

	if (!mlx4_en_check_xdp_mtu(dev, dev->mtu))

		return -EOPNOTSUPP;

	}



	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);

	if (!tmp)

drivers/net/ethernet/mellanox/mlx4/en_rx.c

+24 −22
Original line number Diff line number Diff line
@@ -1164,38 +1164,40 @@ static const int frag_sizes[] = { 


void mlx4_en_calc_rx_buf(struct net_device *dev)

{

	enum dma_data_direction dma_dir = PCI_DMA_FROMDEVICE;

	struct mlx4_en_priv *priv = netdev_priv(dev);

	int eff_mtu = MLX4_EN_EFF_MTU(dev->mtu);

	int order = MLX4_EN_ALLOC_PREFER_ORDER;

	u32 align = SMP_CACHE_BYTES;

	int buf_size = 0;

	int i = 0;



	/* bpf requires buffers to be set up as 1 packet per page.

	 * This only works when num_frags == 1.

	 */

	if (priv->tx_ring_num[TX_XDP]) {

		dma_dir = PCI_DMA_BIDIRECTIONAL;

		/* This will gain efficient xdp frame recycling at the expense

		 * of more costly truesize accounting

		priv->frag_info[0].order = 0;

		priv->frag_info[0].frag_size = eff_mtu;

		priv->frag_info[0].frag_prefix_size = 0;

		/* This will gain efficient xdp frame recycling at the

		 * expense of more costly truesize accounting

		 */

		align = PAGE_SIZE;

		order = 0;

	}

		priv->frag_info[0].frag_stride = PAGE_SIZE;

		priv->frag_info[0].dma_dir = PCI_DMA_BIDIRECTIONAL;

		i = 1;

	} else {

		int buf_size = 0;



		while (buf_size < eff_mtu) {

		priv->frag_info[i].order = order;

			priv->frag_info[i].order = MLX4_EN_ALLOC_PREFER_ORDER;

			priv->frag_info[i].frag_size =

				(eff_mtu > buf_size + frag_sizes[i]) ?

					frag_sizes[i] : eff_mtu - buf_size;

			priv->frag_info[i].frag_prefix_size = buf_size;

			priv->frag_info[i].frag_stride =

				ALIGN(priv->frag_info[i].frag_size, align);

		priv->frag_info[i].dma_dir = dma_dir;

				ALIGN(priv->frag_info[i].frag_size,

				      SMP_CACHE_BYTES);

			priv->frag_info[i].dma_dir = PCI_DMA_FROMDEVICE;

			buf_size += priv->frag_info[i].frag_size;

			i++;

		}

	}



	priv->num_frags = i;

	priv->rx_skb_size = eff_mtu;