From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Date: Thu, 14 May 2020 12:49:23 +0200
Subject: net: netsec: Add support for XDP frame size

Git-commit: 495de55f70199bd7ea09079c484283e58bf75c82
Patch-mainline: v5.8-rc1
References: jsc#SLE-12251

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
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/net/ethernet/socionext/netsec.c |   31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -881,23 +881,28 @@ static u32 netsec_run_xdp(struct netsec_
 			  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);
@@ -905,9 +910,8 @@ static u32 netsec_run_xdp(struct netsec_
 			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:
@@ -918,9 +922,8 @@ static u32 netsec_run_xdp(struct netsec_
 		/* 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, len, true);
 		break;
 	}
 
@@ -934,10 +937,14 @@ static int netsec_process_rx(struct nets
 	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);
@@ -951,7 +958,6 @@ static int netsec_process_rx(struct nets
 		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)) {
@@ -1000,7 +1006,6 @@ static int netsec_process_rx(struct nets
 		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);