Re: [PATCH v3 1/1] net: fec: add initial XDP support

From: Paolo Abeni
Date: Thu Nov 03 2022 - 05:22:32 EST

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On Mon, 2022-10-31 at 13:53 -0500, Shenwei Wang wrote:
> This patch adds the initial XDP support to Freescale driver. It supports
> XDP_PASS, XDP_DROP and XDP_REDIRECT actions. Upcoming patches will add
> support for XDP_TX and Zero Copy features.
>
> As the patch is rather large, the part of codes to collect the
> statistics is separated and will prepare a dedicated patch for that
> part.
>
> I just tested with the application of xdpsock.
> -- Native here means running command of "xdpsock -i eth0"
> -- SKB-Mode means running command of "xdpsock -S -i eth0"
>
> The following are the testing result relating to XDP mode:
>
> root@imx8qxpc0mek:~/bpf# ./xdpsock -i eth0
> sock0@eth0:0 rxdrop xdp-drv
> pps pkts 1.00
> rx 371347 2717794
> tx 0 0
>
> root@imx8qxpc0mek:~/bpf# ./xdpsock -S -i eth0
> sock0@eth0:0 rxdrop xdp-skb
> pps pkts 1.00
> rx 202229 404528
> tx 0 0
>
> root@imx8qxpc0mek:~/bpf# ./xdp2 eth0
> proto 0: 496708 pkt/s
> proto 0: 505469 pkt/s
> proto 0: 505283 pkt/s
> proto 0: 505443 pkt/s
> proto 0: 505465 pkt/s
>
> root@imx8qxpc0mek:~/bpf# ./xdp2 -S eth0
> proto 0: 0 pkt/s
> proto 17: 118778 pkt/s
> proto 17: 118989 pkt/s
> proto 0: 1 pkt/s
> proto 17: 118987 pkt/s
> proto 0: 0 pkt/s
> proto 17: 118943 pkt/s
> proto 17: 118976 pkt/s
> proto 0: 1 pkt/s
> proto 17: 119006 pkt/s
> proto 0: 0 pkt/s
> proto 17: 119071 pkt/s
> proto 17: 119092 pkt/s
>
> Signed-off-by: Shenwei Wang <shenwei.wang@xxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> ---
> changes in V3:
> - remove the codes to update the RX ring size to avoid potential risk.
> - update the testing data based on the new implementation.
>
> changes in V2:
> - Get rid of the expensive fec_net_close/open function calls during
> XDP/Normal Mode switch.
> - Update the testing data on i.mx8qxp mek board.
> - fix the compile issue reported by kernel_test_robot
>
> drivers/net/ethernet/freescale/fec.h | 4 +-
> drivers/net/ethernet/freescale/fec_main.c | 224 +++++++++++++++++++++-
> 2 files changed, 226 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
> index 476e3863a310..61e847b18343 100644
> --- a/drivers/net/ethernet/freescale/fec.h
> +++ b/drivers/net/ethernet/freescale/fec.h
> @@ -348,7 +348,6 @@ struct bufdesc_ex {
> */
>
> #define FEC_ENET_XDP_HEADROOM (XDP_PACKET_HEADROOM)
> -
> #define FEC_ENET_RX_PAGES 256
> #define FEC_ENET_RX_FRSIZE (PAGE_SIZE - FEC_ENET_XDP_HEADROOM \
> - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
> @@ -663,6 +662,9 @@ struct fec_enet_private {
>
> struct imx_sc_ipc *ipc_handle;
>
> + /* XDP BPF Program */
> + struct bpf_prog *xdp_prog;
> +
> u64 ethtool_stats[];
> };
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index 6986b74fb8af..6b062a0663f4 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -89,6 +89,11 @@ static const u16 fec_enet_vlan_pri_to_queue[8] = {0, 0, 1, 1, 1, 2, 2, 2};
> #define FEC_ENET_OPD_V 0xFFF0
> #define FEC_MDIO_PM_TIMEOUT 100 /* ms */
>
> +#define FEC_ENET_XDP_PASS 0
> +#define FEC_ENET_XDP_CONSUMED BIT(0)
> +#define FEC_ENET_XDP_TX BIT(1)
> +#define FEC_ENET_XDP_REDIR BIT(2)
> +
> struct fec_devinfo {
> u32 quirks;
> };
> @@ -418,13 +423,14 @@ static int
> fec_enet_create_page_pool(struct fec_enet_private *fep,
> struct fec_enet_priv_rx_q *rxq, int size)
> {
> + struct bpf_prog *xdp_prog = READ_ONCE(fep->xdp_prog);
> struct page_pool_params pp_params = {
> .order = 0,
> .flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
> .pool_size = size,
> .nid = dev_to_node(&fep->pdev->dev),
> .dev = &fep->pdev->dev,
> - .dma_dir = DMA_FROM_DEVICE,
> + .dma_dir = xdp_prog ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE,
> .offset = FEC_ENET_XDP_HEADROOM,
> .max_len = FEC_ENET_RX_FRSIZE,
> };
> @@ -1499,6 +1505,59 @@ static void fec_enet_update_cbd(struct fec_enet_priv_rx_q *rxq,
> bdp->cbd_bufaddr = cpu_to_fec32(phys_addr);
> }
>
> +static u32
> +fec_enet_run_xdp(struct fec_enet_private *fep, struct bpf_prog *prog,
> + struct xdp_buff *xdp, struct fec_enet_priv_rx_q *rxq, int index)
> +{
> + unsigned int sync, len = xdp->data_end - xdp->data;
> + u32 ret = FEC_ENET_XDP_PASS;
> + struct page *page;
> + int err;
> + u32 act;
> +
> + act = bpf_prog_run_xdp(prog, xdp);
> +
> + /* Due xdp_adjust_tail: DMA sync for_device cover max len CPU touch */
> + sync = xdp->data_end - xdp->data_hard_start - FEC_ENET_XDP_HEADROOM;
> + sync = max(sync, len);
> +
> + switch (act) {
> + case XDP_PASS:
> + ret = FEC_ENET_XDP_PASS;
> + break;
> +
> + case XDP_REDIRECT:
> + err = xdp_do_redirect(fep->netdev, xdp, prog);
> + if (!err) {
> + ret = FEC_ENET_XDP_REDIR;
> + } else {
> + ret = FEC_ENET_XDP_CONSUMED;
> + page = virt_to_head_page(xdp->data);
> + page_pool_put_page(rxq->page_pool, page, sync, true);
> + }
> + break;
> +
> + default:
> + bpf_warn_invalid_xdp_action(fep->netdev, prog, act);
> + fallthrough;
> +
> + case XDP_TX:
> + bpf_warn_invalid_xdp_action(fep->netdev, prog, act);
> + fallthrough;
> +
> + case XDP_ABORTED:
> + fallthrough; /* handle aborts by dropping packet */
> +
> + case XDP_DROP:
> + ret = FEC_ENET_XDP_CONSUMED;
> + page = virt_to_head_page(xdp->data);
> + page_pool_put_page(rxq->page_pool, page, sync, true);
> + break;
> + }
> +
> + return ret;
> +}
> +
> /* During a receive, the bd_rx.cur points to the current incoming buffer.
> * When we update through the ring, if the next incoming buffer has
> * not been given to the system, we just set the empty indicator,
> @@ -1520,6 +1579,9 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
> u16 vlan_tag;
> int index = 0;
> bool need_swap = fep->quirks & FEC_QUIRK_SWAP_FRAME;
> + struct bpf_prog *xdp_prog = READ_ONCE(fep->xdp_prog);
> + u32 ret, xdp_result = FEC_ENET_XDP_PASS;
> + struct xdp_buff xdp;
> struct page *page;
>
> #ifdef CONFIG_M532x
> @@ -1531,6 +1593,7 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
> * These get messed up if we get called due to a busy condition.
> */
> bdp = rxq->bd.cur;
> + xdp_init_buff(&xdp, PAGE_SIZE, &rxq->xdp_rxq);
>
> while (!((status = fec16_to_cpu(bdp->cbd_sc)) & BD_ENET_RX_EMPTY)) {
>
> @@ -1580,6 +1643,17 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
> prefetch(page_address(page));
> fec_enet_update_cbd(rxq, bdp, index);
>
> + if (xdp_prog) {
> + xdp_buff_clear_frags_flag(&xdp);
> + xdp_prepare_buff(&xdp, page_address(page),
> + FEC_ENET_XDP_HEADROOM, pkt_len, false);
> +
> + ret = fec_enet_run_xdp(fep, xdp_prog, &xdp, rxq, index);
> + xdp_result |= ret;
> + if (ret != FEC_ENET_XDP_PASS)
> + goto rx_processing_done;
> + }
> +
> /* The packet length includes FCS, but we don't want to
> * include that when passing upstream as it messes up
> * bridging applications.
> @@ -1675,6 +1749,10 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
> writel(0, rxq->bd.reg_desc_active);
> }
> rxq->bd.cur = bdp;
> +
> + if (xdp_result & FEC_ENET_XDP_REDIR)
> + xdp_do_flush_map();
> +
> return pkt_received;
> }
>
> @@ -3476,6 +3554,148 @@ static u16 fec_enet_select_queue(struct net_device *ndev, struct sk_buff *skb,
> return fec_enet_vlan_pri_to_queue[vlan_tag >> 13];
> }
>
> +static int fec_enet_bpf(struct net_device *dev, struct netdev_bpf *bpf)
> +{
> + struct fec_enet_private *fep = netdev_priv(dev);
> + bool is_run = netif_running(dev);
> + struct bpf_prog *old_prog;
> +
> + switch (bpf->command) {
> + case XDP_SETUP_PROG:
> + if (is_run) {
> + napi_disable(&fep->napi);
> + netif_tx_disable(dev);
> + }
> +
> + old_prog = xchg(&fep->xdp_prog, bpf->prog);
> + fec_restart(dev);
> +
> + if (is_run) {
> + napi_enable(&fep->napi);
> + netif_tx_start_all_queues(dev);
> + }
> +
> + if (old_prog)
> + bpf_prog_put(old_prog);
> +
> + return 0;
> +
> + case XDP_SETUP_XSK_POOL:
> + return -EOPNOTSUPP;
> +
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int
> +fec_enet_xdp_get_tx_queue(struct fec_enet_private *fep, int cpu)
> +{
> + int index = cpu;
> +
> + if (unlikely(index < 0))
> + index = 0;
> +
> + while (index >= fep->num_tx_queues)
> + index -= fep->num_tx_queues;

Not a big deal, but I think kind of optimizations are not worthy and
potentially dangerous since late '90 ;)

You could consider switching to a simpler '%', but IMHO it's not
blocking.

Cheers,

Paolo

Next message: Vincent Guittot: "Re: [PATCH] sched/fair: Introduce priority load balance for CFS"
Previous message: Cristian Marussi: "Re: [PATCH v4 0/11] Introduce a unified API for SCMI Server testing"
In reply to: Jakub Kicinski: "Re: [PATCH v3 1/1] net: fec: add initial XDP support"
Next in thread: Shenwei Wang: "RE: [EXT] Re: [PATCH v3 1/1] net: fec: add initial XDP support"
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