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Message-ID: <20191014144838.7a6e931b@carbon>
Date: Mon, 14 Oct 2019 14:48:38 +0200
From: Jesper Dangaard Brouer <brouer@...hat.com>
To: Lorenzo Bianconi <lorenzo@...nel.org>
Cc: netdev@...r.kernel.org, lorenzo.bianconi@...hat.com,
davem@...emloft.net, thomas.petazzoni@...tlin.com,
ilias.apalodimas@...aro.org, matteo.croce@...hat.com,
mw@...ihalf.com, brouer@...hat.com
Subject: Re: [PATCH v3 net-next 5/8] net: mvneta: add basic XDP support
On Mon, 14 Oct 2019 12:49:52 +0200
Lorenzo Bianconi <lorenzo@...nel.org> 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
> - XDP_ABORTED
>
> - iptables drop:
> $iptables -t raw -I PREROUTING -p udp --dport 9 -j DROP
> $nstat -n && sleep 1 && nstat
> IpInReceives 151169 0.0
> IpExtInOctets 6953544 0.0
> IpExtInNoECTPkts 151165 0.0
>
> - XDP_DROP via xdp1
> $./samples/bpf/xdp1 3
> proto 0: 421419 pkt/s
> proto 0: 421444 pkt/s
> proto 0: 421393 pkt/s
> proto 0: 421440 pkt/s
> proto 0: 421184 pkt/s
>
> Tested-by: Matteo Croce <mcroce@...hat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> ---
> drivers/net/ethernet/marvell/mvneta.c | 147 ++++++++++++++++++++++++--
> 1 file changed, 138 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 1722dffe265d..b47a44cf9610 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -38,6 +38,7 @@
> #include <net/ipv6.h>
> #include <net/tso.h>
> #include <net/page_pool.h>
> +#include <linux/bpf_trace.h>
>
> /* Registers */
> #define MVNETA_RXQ_CONFIG_REG(q) (0x1400 + ((q) << 2))
> @@ -323,8 +324,10 @@
> ETH_HLEN + ETH_FCS_LEN, \
> cache_line_size())
>
> +#define MVNETA_SKB_HEADROOM (max(XDP_PACKET_HEADROOM, NET_SKB_PAD) + \
> + NET_IP_ALIGN)
> #define MVNETA_SKB_PAD (SKB_DATA_ALIGN(sizeof(struct skb_shared_info) + \
> - NET_SKB_PAD))
> + MVNETA_SKB_HEADROOM))
> #define MVNETA_SKB_SIZE(len) (SKB_DATA_ALIGN(len) + MVNETA_SKB_PAD)
> #define MVNETA_MAX_RX_BUF_SIZE (PAGE_SIZE - MVNETA_SKB_PAD)
>
> @@ -352,6 +355,11 @@ struct mvneta_statistic {
> #define T_REG_64 64
> #define T_SW 1
>
> +#define MVNETA_XDP_PASS BIT(0)
> +#define MVNETA_XDP_CONSUMED BIT(1)
I find it confusing that you call it "consumed" (MVNETA_XDP_CONSUMED),
because if I follow the code these are all drop-cases that are due to
errors.
Can we call it MVNETA_XDP_DROPPED?
I also checked, your XDP_TX patch[8/8], that all the return paths for
MVNETA_XDP_CONSUMED also leads to drop of the xdp_buff.
> +#define MVNETA_XDP_TX BIT(2)
> +#define MVNETA_XDP_REDIR BIT(3)
> +
> static const struct mvneta_statistic mvneta_statistics[] = {
> { 0x3000, T_REG_64, "good_octets_received", },
> { 0x3010, T_REG_32, "good_frames_received", },
> @@ -431,6 +439,8 @@ struct mvneta_port {
> u32 cause_rx_tx;
> struct napi_struct napi;
>
> + struct bpf_prog *xdp_prog;
> +
> /* Core clock */
> struct clk *clk;
> /* AXI clock */
> @@ -1950,11 +1960,51 @@ int mvneta_rx_refill_queue(struct mvneta_port *pp, struct mvneta_rx_queue *rxq)
> return i;
> }
>
> +static int
> +mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
> + struct bpf_prog *prog, struct xdp_buff *xdp)
> +{
> + u32 ret, act = bpf_prog_run_xdp(prog, xdp);
> +
> + switch (act) {
> + case XDP_PASS:
> + ret = MVNETA_XDP_PASS;
> + break;
> + case XDP_REDIRECT: {
> + int err;
> +
> + err = xdp_do_redirect(pp->dev, xdp, prog);
> + if (err) {
> + ret = MVNETA_XDP_CONSUMED;
> + xdp_return_buff(xdp);
Dropped in case of errors. As this is an error case, I don't mind that
you use the slower xdp_return_buff().
> + } else {
> + ret = MVNETA_XDP_REDIR;
> + }
> + break;
> + }
> + default:
> + bpf_warn_invalid_xdp_action(act);
> + /* fall through */
> + case XDP_ABORTED:
> + trace_xdp_exception(pp->dev, prog, act);
> + /* fall through */
> + case XDP_DROP:
> + page_pool_recycle_direct(rxq->page_pool,
> + virt_to_head_page(xdp->data));
> + ret = MVNETA_XDP_CONSUMED;
Also drop case.
> + break;
> + }
> +
> + return ret;
> +}
> +
> static int
> mvneta_swbm_rx_frame(struct mvneta_port *pp,
> struct mvneta_rx_desc *rx_desc,
> struct mvneta_rx_queue *rxq,
> - struct page *page)
> + struct xdp_buff *xdp,
> + struct bpf_prog *xdp_prog,
> + struct page *page, u32 *xdp_ret)
> {
> unsigned char *data = page_address(page);
> int data_len = -MVNETA_MH_SIZE, len;
> @@ -1974,7 +2024,26 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
> rx_desc->buf_phys_addr,
> len, dma_dir);
>
> - rxq->skb = build_skb(data, PAGE_SIZE);
> + xdp->data_hard_start = data;
> + xdp->data = data + MVNETA_SKB_HEADROOM + MVNETA_MH_SIZE;
> + xdp->data_end = xdp->data + data_len;
> + xdp_set_data_meta_invalid(xdp);
> +
> + if (xdp_prog) {
> + u32 ret;
> +
> + ret = mvneta_run_xdp(pp, rxq, xdp_prog, xdp);
> + if (ret != MVNETA_XDP_PASS) {
> + mvneta_update_stats(pp, 1,
> + xdp->data_end - xdp->data,
Good, you took into account that data_len cannot be used, as BPF/XDP program could have changed data pointer, thus affecting the length.
> + false);
> + rx_desc->buf_phys_addr = 0;
> + *xdp_ret |= ret;
> + return ret;
> + }
> + }
> +
> + rxq->skb = build_skb(xdp->data_hard_start, PAGE_SIZE);
> if (unlikely(!rxq->skb)) {
> netdev_err(dev,
> "Can't allocate skb on queue %d\n",
> @@ -1985,8 +2054,9 @@ mvneta_swbm_rx_frame(struct mvneta_port *pp,
> }
> page_pool_release_page(rxq->page_pool, page);
>
> - skb_reserve(rxq->skb, MVNETA_MH_SIZE + NET_SKB_PAD);
> - skb_put(rxq->skb, data_len);
> + skb_reserve(rxq->skb,
> + xdp->data - xdp->data_hard_start);
> + skb_put(rxq->skb, xdp->data_end - xdp->data);
> mvneta_rx_csum(pp, rx_desc->status, rxq->skb);
>
> rxq->left_size = rx_desc->data_size - len;
> @@ -2020,7 +2090,7 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
> /* refill descriptor with new buffer later */
> skb_add_rx_frag(rxq->skb,
> skb_shinfo(rxq->skb)->nr_frags,
> - page, NET_SKB_PAD, data_len,
> + page, MVNETA_SKB_HEADROOM, data_len,
> PAGE_SIZE);
> }
> page_pool_release_page(rxq->page_pool, page);
> @@ -2035,10 +2105,17 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
> {
> int rcvd_pkts = 0, rcvd_bytes = 0;
> int rx_pending, refill, done = 0;
> + struct bpf_prog *xdp_prog;
> + struct xdp_buff xdp_buf;
> + u32 xdp_ret = 0;
>
> /* Get number of received packets */
> rx_pending = mvneta_rxq_busy_desc_num_get(pp, rxq);
>
> + rcu_read_lock();
> + xdp_prog = READ_ONCE(pp->xdp_prog);
> + xdp_buf.rxq = &rxq->xdp_rxq;
Ok, thanks for following my review comments from last.
> /* Fairness NAPI loop */
> while (done < budget && done < rx_pending) {
> struct mvneta_rx_desc *rx_desc = mvneta_rxq_next_desc_get(rxq);
> @@ -2066,7 +2143,8 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
> continue;
> }
>
> - err = mvneta_swbm_rx_frame(pp, rx_desc, rxq, page);
> + err = mvneta_swbm_rx_frame(pp, rx_desc, rxq, &xdp_buf,
> + xdp_prog, page, &xdp_ret);
> if (err)
> continue;
> } else {
> @@ -2101,6 +2179,10 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
> /* clean uncomplete skb pointer in queue */
> rxq->skb = NULL;
> }
> + rcu_read_unlock();
> +
> + if (xdp_ret & MVNETA_XDP_REDIR)
> + xdp_do_flush_map();
>
> mvneta_update_stats(pp, rcvd_pkts, rcvd_bytes, false);
>
[...]
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
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