net: netsec: Add support for XDP frame size

This driver takes advantage of page_pool PP_FLAG_DMA_SYNC_DEV that
can help reduce the number of cache-lines that need to be flushed
when doing DMA sync for_device. Due to xdp_adjust_tail can grow the
area accessible to the by the CPU (can possibly write into), then max
sync length *after* bpf_prog_run_xdp() needs to be taken into account.

For XDP_TX action the driver is smart and does DMA-sync. When growing
tail this is still safe, because page_pool have DMA-mapped the entire
page size.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/bpf/158945336295.97035.15034759661036971024.stgit@firesoul

diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index a5a0fb60193abbc44523f09f3b328aec7a6a3953..e1f4be4b3d69debf90c12cf2bdf8c99016bea2a9 100644 (file)
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -884,23 +884,28 @@ static u32 netsec_run_xdp(struct netsec_priv *priv, struct bpf_prog *prog,
                          struct xdp_buff *xdp)
 {
        struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX];
-       unsigned int len = xdp->data_end - xdp->data;
+       unsigned int sync, len = xdp->data_end - xdp->data;
        u32 ret = NETSEC_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 - NETSEC_RXBUF_HEADROOM;
+       sync = max(sync, len);
+
        switch (act) {
        case XDP_PASS:
                ret = NETSEC_XDP_PASS;
                break;
        case XDP_TX:
                ret = netsec_xdp_xmit_back(priv, xdp);
-               if (ret != NETSEC_XDP_TX)
-                       page_pool_put_page(dring->page_pool,
-                                          virt_to_head_page(xdp->data), len,
-                                          true);
+               if (ret != NETSEC_XDP_TX) {
+                       page = virt_to_head_page(xdp->data);
+                       page_pool_put_page(dring->page_pool, page, sync, true);
+               }
                break;
        case XDP_REDIRECT:
                err = xdp_do_redirect(priv->ndev, xdp, prog);
@@ -908,9 +913,8 @@ static u32 netsec_run_xdp(struct netsec_priv *priv, struct bpf_prog *prog,
                        ret = NETSEC_XDP_REDIR;
                } else {
                        ret = NETSEC_XDP_CONSUMED;
-                       page_pool_put_page(dring->page_pool,
-                                          virt_to_head_page(xdp->data), len,
-                                          true);
+                       page = virt_to_head_page(xdp->data);
+                       page_pool_put_page(dring->page_pool, page, sync, true);
                }
                break;
        default:
@@ -921,8 +925,8 @@ static u32 netsec_run_xdp(struct netsec_priv *priv, struct bpf_prog *prog,
                /* fall through -- handle aborts by dropping packet */
        case XDP_DROP:
                ret = NETSEC_XDP_CONSUMED;
-               page_pool_put_page(dring->page_pool,
-                                  virt_to_head_page(xdp->data), len, true);
+               page = virt_to_head_page(xdp->data);
+               page_pool_put_page(dring->page_pool, page, sync, true);
                break;
        }
 
@@ -936,10 +940,14 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
        struct netsec_rx_pkt_info rx_info;
        enum dma_data_direction dma_dir;
        struct bpf_prog *xdp_prog;
+       struct xdp_buff xdp;
        u16 xdp_xmit = 0;
        u32 xdp_act = 0;
        int done = 0;
 
+       xdp.rxq = &dring->xdp_rxq;
+       xdp.frame_sz = PAGE_SIZE;
+
        rcu_read_lock();
        xdp_prog = READ_ONCE(priv->xdp_prog);
        dma_dir = page_pool_get_dma_dir(dring->page_pool);
@@ -953,7 +961,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
                struct sk_buff *skb = NULL;
                u16 pkt_len, desc_len;
                dma_addr_t dma_handle;
-               struct xdp_buff xdp;
                void *buf_addr;
 
                if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) {
@@ -1002,7 +1009,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
                xdp.data = desc->addr + NETSEC_RXBUF_HEADROOM;
                xdp_set_data_meta_invalid(&xdp);
                xdp.data_end = xdp.data + pkt_len;
-               xdp.rxq = &dring->xdp_rxq;
 
                if (xdp_prog) {
                        xdp_result = netsec_run_xdp(priv, xdp_prog, &xdp);