Re: [RFC 3/4] net: mvneta: add basic XDP support

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Tue, Oct 01, 2019 at 11:24:43AM +0200, Lorenzo Bianconi wrote:
> Add basic XDP support to mvneta driver for devices that rely on software
> buffer management. Currently supported verdicts are:
> - XDP_DROP
> - XDP_PASS
> - XDP_REDIRECT
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 145 ++++++++++++++++++++++++--
>  1 file changed, 136 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index e842c744e4f3..f2d12556efa8 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
[...]
>  		.pool_size = size,
>  		.nid = cpu_to_node(0),
>  		.dev = pp->dev->dev.parent,
> -		.dma_dir = DMA_FROM_DEVICE,
> +		.dma_dir = xdp_prog ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE,
>  	};
> +	int err;
>  
>  	rxq->page_pool = page_pool_create(&pp_params);
>  	if (IS_ERR(rxq->page_pool)) {
> @@ -2851,7 +2920,22 @@ static int mvneta_create_page_pool(struct mvneta_port *pp,
>  		return PTR_ERR(rxq->page_pool);
>  	}
>  
> +	err = xdp_rxq_info_reg(&rxq->xdp_rxq, pp->dev, 0);
> +	if (err < 0)
> +		goto err_free_pp;
> +
> +	err = xdp_rxq_info_reg_mem_model(&rxq->xdp_rxq, MEM_TYPE_PAGE_POOL,
> +					 rxq->page_pool);
> +	if (err)
> +		goto err_unregister_pp;

I think this should be part of patch [1/4], adding page pol support. 
Jesper introduced the changes to track down inflight packets [1], so you need
those changes in place when implementing page_pool

> +
>  	return 0;
> +
> +err_unregister_pp:
> +	xdp_rxq_info_unreg(&rxq->xdp_rxq);
> +err_free_pp:
> +	page_pool_destroy(rxq->page_pool);
> +	return err;
>  }
>  
>  /* Handle rxq fill: allocates rxq skbs; called when initializing a port */
> @@ -3291,6 +3375,11 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
>  		mtu = ALIGN(MVNETA_RX_PKT_SIZE(mtu), 8);
>  	}
>  
> +	if (pp->xdp_prog && mtu > MVNETA_MAX_RX_BUF_SIZE) {
> +		netdev_info(dev, "Illegal MTU value %d for XDP mode\n", mtu);
> +		return -EINVAL;
> +	}
> +
>  	dev->mtu = mtu;
>  
>  	if (!netif_running(dev)) {
> @@ -3960,6 +4049,43 @@ static int mvneta_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>  	return phylink_mii_ioctl(pp->phylink, ifr, cmd);
>  }
>  
> +static int mvneta_xdp_setup(struct net_device *dev, struct bpf_prog *prog,
> +			    struct netlink_ext_ack *extack)
> +{
> +	struct mvneta_port *pp = netdev_priv(dev);
> +	struct bpf_prog *old_prog;
> +
> +	if (prog && dev->mtu > MVNETA_MAX_RX_BUF_SIZE) {
> +		NL_SET_ERR_MSG_MOD(extack, "Jumbo frames not supported on XDP");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	mvneta_stop(dev);
> +
> +	old_prog = xchg(&pp->xdp_prog, prog);
> +	if (old_prog)
> +		bpf_prog_put(old_prog);
> +
> +	mvneta_open(dev);
> +
> +	return 0;
> +}
> +
> +static int mvneta_xdp(struct net_device *dev, struct netdev_bpf *xdp)
> +{
> +	struct mvneta_port *pp = netdev_priv(dev);
> +
> +	switch (xdp->command) {
> +	case XDP_SETUP_PROG:
> +		return mvneta_xdp_setup(dev, xdp->prog, xdp->extack);
> +	case XDP_QUERY_PROG:
> +		xdp->prog_id = pp->xdp_prog ? pp->xdp_prog->aux->id : 0;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
>  /* Ethtool methods */
>  
>  /* Set link ksettings (phy address, speed) for ethtools */
> @@ -4356,6 +4482,7 @@ static const struct net_device_ops mvneta_netdev_ops = {
>  	.ndo_fix_features    = mvneta_fix_features,
>  	.ndo_get_stats64     = mvneta_get_stats64,
>  	.ndo_do_ioctl        = mvneta_ioctl,
> +	.ndo_bpf	     = mvneta_xdp,
>  };
>  
>  static const struct ethtool_ops mvneta_eth_tool_ops = {
> @@ -4646,7 +4773,7 @@ static int mvneta_probe(struct platform_device *pdev)
>  	SET_NETDEV_DEV(dev, &pdev->dev);
>  
>  	pp->id = global_port_id++;
> -	pp->rx_offset_correction = NET_SKB_PAD;
> +	pp->rx_offset_correction = MVNETA_SKB_HEADROOM;
>  
>  	/* Obtain access to BM resources if enabled and already initialized */
>  	bm_node = of_parse_phandle(dn, "buffer-manager", 0);
> -- 
> 2.21.0
> 

[1] https://lore.kernel.org/netdev/156086304827.27760.11339786046465638081.stgit@firesoul/


Regards
/Ilias