Add basic AF_XDP support without zero-copy

Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
---
 drivers/net/ethernet/socionext/netsec.c | 211 ++++++++++++++++++++++++++++++--
 1 file changed, 202 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/socionext/netsec.c 
b/drivers/net/ethernet/socionext/netsec.c
index 666fee2..7464ca6 100644
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -9,6 +9,8 @@
 #include <linux/etherdevice.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/bpf.h>
+#include <linux/bpf_trace.h>
 
 #include <net/tcp.h>
 #include <net/ip6_checksum.h>
@@ -238,6 +240,11 @@
 
 #define NETSEC_F_NETSEC_VER_MAJOR_NUM(x)       ((x) & 0xffff0000)
 
+#define NETSEC_XDP_PASS          0
+#define NETSEC_XDP_CONSUMED      BIT(0)
+#define NETSEC_XDP_TX            BIT(1)
+#define NETSEC_XDP_REDIR         BIT(2)
+
 enum ring_id {
        NETSEC_RING_TX = 0,
        NETSEC_RING_RX
@@ -256,11 +263,13 @@ struct netsec_desc_ring {
        void *vaddr;
        u16 pkt_cnt;
        u16 head, tail;
+       struct xdp_rxq_info xdp_rxq;
 };
 
 struct netsec_priv {
        struct netsec_desc_ring desc_ring[NETSEC_RING_MAX];
        struct ethtool_coalesce et_coalesce;
+       struct bpf_prog *xdp_prog;
        spinlock_t reglock; /* protect reg access */
        struct napi_struct napi;
        phy_interface_t phy_interface;
@@ -297,6 +306,8 @@ struct netsec_rx_pkt_info {
 };
 
 static void netsec_rx_fill(struct netsec_priv *priv, u16 from, u16 num);
+static u32 netsec_run_xdp(struct netsec_desc *desc, struct netsec_priv *priv,
+                         struct bpf_prog *prog, u16 len);
 
 static void *netsec_alloc_rx_data(struct netsec_priv *priv,
                                  dma_addr_t *dma_addr, u16 *len);
@@ -613,13 +624,23 @@ static int netsec_clean_tx_dring(struct netsec_priv 
*priv, int budget)
 
                eop = (entry->attr >> NETSEC_TX_LAST) & 1;
 
-               dma_unmap_single(priv->dev, desc->dma_addr, desc->len,
-                                DMA_TO_DEVICE);
-               if (eop) {
-                       pkts++;
+               if (desc->skb) {
+                       dma_unmap_single(priv->dev, desc->dma_addr, desc->len,
+                                        DMA_TO_DEVICE);
+               }
+
+               if (!eop) {
+                       *desc = (struct netsec_desc){};
+                       continue;
+               }
+
+               if (!desc->skb) {
+                       skb_free_frag(desc->addr);
+               } else {
                        bytes += desc->skb->len;
                        dev_kfree_skb(desc->skb);
                }
+               pkts++;
                *desc = (struct netsec_desc){};
        }
        dring->pkt_cnt -= budget;
@@ -659,8 +680,11 @@ static void nsetsec_adv_desc(u16 *idx)
 static int netsec_process_rx(struct netsec_priv *priv, int budget)
 {
        struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
+       struct bpf_prog *xdp_prog = READ_ONCE(priv->xdp_prog);
        struct net_device *ndev = priv->ndev;
-       struct sk_buff *skb;
+       struct sk_buff *skb = NULL;
+       u32 xdp_flush = 0;
+       u32 xdp_result;
        int done = 0;
 
        while (done < budget) {
@@ -707,6 +731,26 @@ static int netsec_process_rx(struct netsec_priv *priv, int 
budget)
                if (unlikely(!buf_addr))
                        break;
 
+               if (xdp_prog) {
+                       xdp_result = netsec_run_xdp(desc, priv, xdp_prog,
+                                                   pkt_len);
+                       if (xdp_result != NETSEC_XDP_PASS) {
+                               xdp_flush |= xdp_result & NETSEC_XDP_REDIR;
+
+                               dma_unmap_single_attrs(priv->dev,
+                                                      desc->dma_addr,
+                                                      desc->len, DMA_TO_DEVICE,
+                                                      DMA_ATTR_SKIP_CPU_SYNC);
+
+                               desc->len = desc_len;
+                               desc->dma_addr = dma_handle;
+                               desc->addr = buf_addr;
+                               netsec_rx_fill(priv, idx, 1);
+                               nsetsec_adv_desc(&dring->tail);
+                       }
+                       continue;
+               }
+
                skb = build_skb(desc->addr, desc->len);
                if (unlikely(!skb)) {
                        dma_unmap_single(priv->dev, dma_handle, desc_len,
@@ -740,6 +784,9 @@ static int netsec_process_rx(struct netsec_priv *priv, int 
budget)
                nsetsec_adv_desc(&dring->tail);
        }
 
+       if (xdp_flush & NETSEC_XDP_REDIR)
+               xdp_do_flush_map();
+
        return done;
 }
 
@@ -892,6 +939,9 @@ static void netsec_uninit_pkt_dring(struct netsec_priv 
*priv, int id)
        if (!dring->vaddr || !dring->desc)
                return;
 
+       if (xdp_rxq_info_is_reg(&dring->xdp_rxq))
+               xdp_rxq_info_unreg(&dring->xdp_rxq);
+
        for (idx = 0; idx < DESC_NUM; idx++) {
                desc = &dring->desc[idx];
                if (!desc->addr)
@@ -994,7 +1044,7 @@ static int netsec_alloc_dring(struct netsec_priv *priv, 
enum ring_id id)
 static int netsec_setup_rx_dring(struct netsec_priv *priv)
 {
        struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
-       int i;
+       int i, err;
 
        for (i = 0; i < DESC_NUM; i++) {
                struct netsec_desc *desc = &dring->desc[i];
@@ -1003,20 +1053,29 @@ static int netsec_setup_rx_dring(struct netsec_priv 
*priv)
                u16 len;
 
                buf = netsec_alloc_rx_data(priv, &dma_handle, &len);
-               if (!buf) {
-                       netsec_uninit_pkt_dring(priv, NETSEC_RING_RX);
+               if (!buf)
                        goto err_out;
-               }
                desc->dma_addr = dma_handle;
                desc->addr = buf;
                desc->len = len;
        }
 
        netsec_rx_fill(priv, 0, DESC_NUM);
+       err = xdp_rxq_info_reg(&dring->xdp_rxq, priv->ndev, 0);
+       if (err)
+               goto err_out;
+
+       err = xdp_rxq_info_reg_mem_model(&dring->xdp_rxq, MEM_TYPE_PAGE_SHARED,
+                                        NULL);
+       if (err) {
+               xdp_rxq_info_unreg(&dring->xdp_rxq);
+               goto err_out;
+       }
 
        return 0;
 
 err_out:
+       netsec_uninit_pkt_dring(priv, NETSEC_RING_RX);
        return -ENOMEM;
 }
 
@@ -1353,6 +1412,9 @@ static int netsec_netdev_stop(struct net_device *ndev)
 
        napi_disable(&priv->napi);
 
+       if (priv->xdp_prog)
+               bpf_prog_put(priv->xdp_prog);
+
        netsec_write(priv, NETSEC_REG_INTEN_CLR, ~0);
        netsec_stop_gmac(priv);
 
@@ -1420,6 +1482,136 @@ static int netsec_netdev_ioctl(struct net_device *ndev, 
struct ifreq *ifr,
        return phy_mii_ioctl(ndev->phydev, ifr, cmd);
 }
 
+static u32 netsec_xmit_xdp(struct netsec_priv *priv, struct xdp_buff *xdp,
+                          struct netsec_desc *rx_desc)
+{
+       struct netsec_desc_ring *tx_ring = &priv->desc_ring[NETSEC_RING_TX];
+       struct netsec_tx_pkt_ctrl tx_ctrl = {};
+       struct netsec_desc tx_desc;
+       int filled;
+       u32 len;
+
+       len = xdp->data_end - xdp->data;
+
+       if (tx_ring->head >= tx_ring->tail)
+               filled = tx_ring->head - tx_ring->tail;
+       else
+               filled = tx_ring->head + DESC_NUM - tx_ring->tail;
+
+       if (DESC_NUM - filled <= 1)
+               return NETSEC_XDP_CONSUMED;
+
+       dma_sync_single_for_device(priv->dev, rx_desc->dma_addr, len,
+                                  DMA_TO_DEVICE);
+
+       tx_desc.dma_addr = rx_desc->dma_addr;
+       tx_desc.addr = xdp->data;
+       tx_desc.len = len;
+
+       netsec_set_tx_de(priv, tx_ring, &tx_ctrl, &tx_desc, NULL);
+       netsec_write(priv, NETSEC_REG_NRM_TX_PKTCNT, 1); /* submit another tx */
+
+       return NETSEC_XDP_TX;
+}
+
+static u32 netsec_run_xdp(struct netsec_desc *desc, struct netsec_priv *priv,
+                         struct bpf_prog *prog, u16 len)
+
+{
+       struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
+       struct xdp_buff xdp;
+       u32 ret = NETSEC_XDP_PASS;
+       int err;
+       u32 act;
+
+       xdp.data_hard_start = desc->addr;
+       xdp.data = desc->addr;
+       xdp_set_data_meta_invalid(&xdp);
+       xdp.data_end = xdp.data + len;
+       xdp.rxq = &dring->xdp_rxq;
+
+       rcu_read_lock();
+       act = bpf_prog_run_xdp(prog, &xdp);
+
+       switch (act) {
+       case XDP_PASS:
+               ret = NETSEC_XDP_PASS;
+               break;
+       case XDP_TX:
+               ret = netsec_xmit_xdp(priv, &xdp, desc);
+               break;
+       case XDP_REDIRECT:
+               err = xdp_do_redirect(priv->ndev, &xdp, prog);
+               if (!err) {
+                       ret = NETSEC_XDP_REDIR;
+               } else {
+                       ret = NETSEC_XDP_CONSUMED;
+                       xdp_return_buff(&xdp);
+               }
+               break;
+       default:
+               bpf_warn_invalid_xdp_action(act);
+               /* fall through */
+       case XDP_ABORTED:
+               trace_xdp_exception(priv->ndev, prog, act);
+               /* fall through -- handle aborts by dropping packet */
+       case XDP_DROP:
+               ret = NETSEC_XDP_CONSUMED;
+               break;
+       }
+
+       rcu_read_unlock();
+
+       return ret;
+}
+
+static int netsec_xdp_setup(struct netsec_priv *priv, struct bpf_prog *prog)
+{
+       struct net_device *dev = priv->ndev;
+       struct bpf_prog *old_prog;
+
+       /* For now just support only the usual MTU sized frames */
+       if (prog && dev->mtu > 1500) {
+               netdev_warn(dev, "Jumbo frames not yet supported with XDP\n");
+               return -EOPNOTSUPP;
+       }
+
+       if (netif_running(dev))
+               netsec_netdev_stop(dev);
+
+       /* Detach old prog, if any */
+       old_prog = xchg(&priv->xdp_prog, prog);
+       if (old_prog)
+               bpf_prog_put(old_prog);
+
+       if (priv->xdp_prog) {
+               /* Attach BPF program */
+               priv->xdp_prog = bpf_prog_add(priv->xdp_prog, 1);
+               if (IS_ERR(priv->xdp_prog))
+                       return PTR_ERR(priv->xdp_prog);
+       }
+
+       if (netif_running(dev))
+               netsec_netdev_open(dev);
+
+       return 0;
+}
+
+static int netsec_xdp(struct net_device *ndev, struct netdev_bpf *xdp)
+{
+       struct netsec_priv *priv = netdev_priv(ndev);
+
+       switch (xdp->command) {
+       case XDP_SETUP_PROG:
+               return netsec_xdp_setup(priv, xdp->prog);
+       case XDP_QUERY_PROG:
+               xdp->prog_id = priv->xdp_prog ? priv->xdp_prog->aux->id : 0;
+               return 0;
+       default:
+               return -EINVAL;
+       }
+}
+
 static const struct net_device_ops netsec_netdev_ops = {
        .ndo_init               = netsec_netdev_init,
        .ndo_uninit             = netsec_netdev_uninit,
@@ -1430,6 +1622,7 @@ static const struct net_device_ops netsec_netdev_ops = {
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_do_ioctl           = netsec_netdev_ioctl,
+       .ndo_bpf                = netsec_xdp,
 };
 
 static int netsec_of_probe(struct platform_device *pdev,
-- 
2.7.4

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