[PATCH net-next v3 6/6] net: stmmac: Add support for XDP_REDIRECT action

From: Ong Boon Leong
Date: Wed Mar 31 2021 - 11:39:01 EST


This patch adds the support of XDP_REDIRECT to another remote cpu for
further action. It also implements ndo_xdp_xmit ops, enabling the driver
to transmit packets forwarded to it by XDP program running on another
interface.

This patch has been tested using "xdp_redirect_cpu" for XDP_REDIRECT
+ drop testing. It also been tested with "xdp_redirect" sample app
which can be used to exercise ndo_xdp_xmit ops. The burst traffics are
generated using pktgen_sample03_burst_single_flow.sh in samples/pktgen
directory.

v3: Added 'nq->trans_start = jiffies' to avoid TX time-out as we are
sharing TX queue between slow path and XDP. Thanks to Jakub Kicinski
for point out.

Signed-off-by: Ong Boon Leong <boon.leong.ong@xxxxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/stmmac.h | 1 +
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 98 +++++++++++++++++--
2 files changed, 89 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index a93e22a6be59..c49debb62b05 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -39,6 +39,7 @@ struct stmmac_resources {
enum stmmac_txbuf_type {
STMMAC_TXBUF_T_SKB,
STMMAC_TXBUF_T_XDP_TX,
+ STMMAC_TXBUF_T_XDP_NDO,
};

struct stmmac_tx_info {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 35e9a738d663..370b3c084dda 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -72,6 +72,7 @@ MODULE_PARM_DESC(phyaddr, "Physical device address");
#define STMMAC_XDP_PASS 0
#define STMMAC_XDP_CONSUMED BIT(0)
#define STMMAC_XDP_TX BIT(1)
+#define STMMAC_XDP_REDIRECT BIT(2)

static int flow_ctrl = FLOW_AUTO;
module_param(flow_ctrl, int, 0644);
@@ -1458,7 +1459,8 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv, u32 queue, int i)
}

if (tx_q->xdpf[i] &&
- tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_TX) {
+ (tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_TX ||
+ tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_NDO)) {
xdp_return_frame(tx_q->xdpf[i]);
tx_q->xdpf[i] = NULL;
}
@@ -2220,7 +2222,8 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
struct dma_desc *p;
int status;

- if (tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_XDP_TX) {
+ if (tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_XDP_TX ||
+ tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_XDP_NDO) {
xdpf = tx_q->xdpf[entry];
skb = NULL;
} else if (tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_SKB) {
@@ -2292,6 +2295,12 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue)
tx_q->xdpf[entry] = NULL;
}

+ if (xdpf &&
+ tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_XDP_NDO) {
+ xdp_return_frame(xdpf);
+ tx_q->xdpf[entry] = NULL;
+ }
+
if (tx_q->tx_skbuff_dma[entry].buf_type == STMMAC_TXBUF_T_SKB) {
if (likely(skb)) {
pkts_compl++;
@@ -4246,10 +4255,9 @@ static unsigned int stmmac_rx_buf2_len(struct stmmac_priv *priv,
}

static int stmmac_xdp_xmit_xdpf(struct stmmac_priv *priv, int queue,
- struct xdp_frame *xdpf)
+ struct xdp_frame *xdpf, bool dma_map)
{
struct stmmac_tx_queue *tx_q = &priv->tx_queue[queue];
- struct page *page = virt_to_page(xdpf->data);
unsigned int entry = tx_q->cur_tx;
struct dma_desc *tx_desc;
dma_addr_t dma_addr;
@@ -4265,12 +4273,23 @@ static int stmmac_xdp_xmit_xdpf(struct stmmac_priv *priv, int queue,
else
tx_desc = tx_q->dma_tx + entry;

- dma_addr = page_pool_get_dma_addr(page) + sizeof(*xdpf) +
- xdpf->headroom;
- dma_sync_single_for_device(priv->device, dma_addr,
- xdpf->len, DMA_BIDIRECTIONAL);
+ if (dma_map) {
+ dma_addr = dma_map_single(priv->device, xdpf->data,
+ xdpf->len, DMA_TO_DEVICE);
+ if (dma_mapping_error(priv->device, dma_addr))
+ return STMMAC_XDP_CONSUMED;
+
+ tx_q->tx_skbuff_dma[entry].buf_type = STMMAC_TXBUF_T_XDP_NDO;
+ } else {
+ struct page *page = virt_to_page(xdpf->data);

- tx_q->tx_skbuff_dma[entry].buf_type = STMMAC_TXBUF_T_XDP_TX;
+ dma_addr = page_pool_get_dma_addr(page) + sizeof(*xdpf) +
+ xdpf->headroom;
+ dma_sync_single_for_device(priv->device, dma_addr,
+ xdpf->len, DMA_BIDIRECTIONAL);
+
+ tx_q->tx_skbuff_dma[entry].buf_type = STMMAC_TXBUF_T_XDP_TX;
+ }

tx_q->tx_skbuff_dma[entry].buf = dma_addr;
tx_q->tx_skbuff_dma[entry].map_as_page = false;
@@ -4339,7 +4358,7 @@ static int stmmac_xdp_xmit_back(struct stmmac_priv *priv,
__netif_tx_lock(nq, cpu);
/* Avoids TX time-out as we are sharing with slow path */
nq->trans_start = jiffies;
- res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf);
+ res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf, false);
if (res == STMMAC_XDP_TX) {
stmmac_flush_tx_descriptors(priv, queue);
stmmac_tx_timer_arm(priv, queue);
@@ -4372,6 +4391,12 @@ static struct sk_buff *stmmac_xdp_run_prog(struct stmmac_priv *priv,
case XDP_TX:
res = stmmac_xdp_xmit_back(priv, xdp);
break;
+ case XDP_REDIRECT:
+ if (xdp_do_redirect(priv->dev, xdp, prog) < 0)
+ res = STMMAC_XDP_CONSUMED;
+ else
+ res = STMMAC_XDP_REDIRECT;
+ break;
default:
bpf_warn_invalid_xdp_action(act);
fallthrough;
@@ -4407,6 +4432,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
unsigned int desc_size;
struct sk_buff *skb = NULL;
struct xdp_buff xdp;
+ int xdp_status = 0;
int buf_sz;

dma_dir = page_pool_get_dma_dir(rx_q->page_pool);
@@ -4576,6 +4602,12 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
skb = NULL;
count++;
continue;
+ } else if (xdp_res & STMMAC_XDP_REDIRECT) {
+ xdp_status |= xdp_res;
+ buf->page = NULL;
+ skb = NULL;
+ count++;
+ continue;
}
}
}
@@ -4658,6 +4690,9 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
rx_q->state.len = len;
}

+ if (xdp_status & STMMAC_XDP_REDIRECT)
+ xdp_do_flush();
+
stmmac_rx_refill(priv, queue);

priv->xstats.rx_pkt_n += count;
@@ -5584,6 +5619,48 @@ static int stmmac_bpf(struct net_device *dev, struct netdev_bpf *bpf)
}
}

+static int stmmac_xdp_xmit(struct net_device *dev, int num_frames,
+ struct xdp_frame **frames, u32 flags)
+{
+ struct stmmac_priv *priv = netdev_priv(dev);
+ int cpu = smp_processor_id();
+ struct netdev_queue *nq;
+ int i, nxmit = 0;
+ int queue;
+
+ if (unlikely(test_bit(STMMAC_DOWN, &priv->state)))
+ return -ENETDOWN;
+
+ if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
+ return -EINVAL;
+
+ queue = stmmac_xdp_get_tx_queue(priv, cpu);
+ nq = netdev_get_tx_queue(priv->dev, queue);
+
+ __netif_tx_lock(nq, cpu);
+ /* Avoids TX time-out as we are sharing with slow path */
+ nq->trans_start = jiffies;
+
+ for (i = 0; i < num_frames; i++) {
+ int res;
+
+ res = stmmac_xdp_xmit_xdpf(priv, queue, frames[i], true);
+ if (res == STMMAC_XDP_CONSUMED)
+ break;
+
+ nxmit++;
+ }
+
+ if (flags & XDP_XMIT_FLUSH) {
+ stmmac_flush_tx_descriptors(priv, queue);
+ stmmac_tx_timer_arm(priv, queue);
+ }
+
+ __netif_tx_unlock(nq);
+
+ return nxmit;
+}
+
static const struct net_device_ops stmmac_netdev_ops = {
.ndo_open = stmmac_open,
.ndo_start_xmit = stmmac_xmit,
@@ -5603,6 +5680,7 @@ static const struct net_device_ops stmmac_netdev_ops = {
.ndo_vlan_rx_add_vid = stmmac_vlan_rx_add_vid,
.ndo_vlan_rx_kill_vid = stmmac_vlan_rx_kill_vid,
.ndo_bpf = stmmac_bpf,
+ .ndo_xdp_xmit = stmmac_xdp_xmit,
};

static void stmmac_reset_subtask(struct stmmac_priv *priv)
--
2.25.1