netdev - [PATCH net-next v2 05/33] net: netsec: Add support for XDP frame size

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Message-ID: <158824564680.2172139.16626813600636822835.stgit@firesoul>
Date:   Thu, 30 Apr 2020 13:20:46 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     sameehj@...zon.com
Cc:     Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org, zorik@...zon.com,
        akiyano@...zon.com, gtzalik@...zon.com,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        David Ahern <dsahern@...il.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        steffen.klassert@...unet.com
Subject: [PATCH net-next v2 05/33] net: netsec: Add support for XDP frame size

From: Ilias Apalodimas <ilias.apalodimas@...aro.org>

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@...aro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
Acked-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 drivers/net/ethernet/socionext/netsec.c |   30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index a5a0fb60193a..e1f4be4b3d69 100644
--- 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);