netdev - [PATCH net-next 4/6] tsnep: Prepare RX buffer for XDP support

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Date:   Sat,  3 Dec 2022 22:54:14 +0100
From:   Gerhard Engleder <gerhard@...leder-embedded.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
        pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com,
        Gerhard Engleder <gerhard@...leder-embedded.com>
Subject: [PATCH net-next 4/6] tsnep: Prepare RX buffer for XDP support

Reserve XDP_PACKET_HEADROOM in front of RX buffer if XDP is enabled.
Also set DMA direction properly in this case.

Signed-off-by: Gerhard Engleder <gerhard@...leder-embedded.com>
---
 drivers/net/ethernet/engleder/tsnep_main.c | 31 +++++++++++++++-------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index d9ba4a8deec5..d7dcac641180 100644
--- a/drivers/net/ethernet/engleder/tsnep_main.c
+++ b/drivers/net/ethernet/engleder/tsnep_main.c
@@ -26,9 +26,10 @@
 #include <linux/etherdevice.h>
 #include <linux/phy.h>
 #include <linux/iopoll.h>
+#include <linux/bpf.h>
 
 #define TSNEP_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
-#define TSNEP_HEADROOM ALIGN(TSNEP_SKB_PAD, 4)
+#define TSNEP_HEADROOM ALIGN(max(TSNEP_SKB_PAD, XDP_PACKET_HEADROOM), 4)
 #define TSNEP_MAX_RX_BUF_SIZE (PAGE_SIZE - TSNEP_HEADROOM - \
 			       SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 
@@ -808,6 +809,16 @@ static void tsnep_tx_close(struct tsnep_tx *tx)
 	tsnep_tx_ring_cleanup(tx);
 }
 
+static inline unsigned int tsnep_rx_offset(struct tsnep_rx *rx)
+{
+	struct tsnep_adapter *adapter = rx->adapter;
+
+	if (tsnep_xdp_is_enabled(adapter))
+		return XDP_PACKET_HEADROOM;
+
+	return TSNEP_SKB_PAD;
+}
+
 static void tsnep_rx_ring_cleanup(struct tsnep_rx *rx)
 {
 	struct device *dmadev = rx->adapter->dmadev;
@@ -869,9 +880,10 @@ static int tsnep_rx_ring_init(struct tsnep_rx *rx)
 	pp_params.pool_size = TSNEP_RING_SIZE;
 	pp_params.nid = dev_to_node(dmadev);
 	pp_params.dev = dmadev;
-	pp_params.dma_dir = DMA_FROM_DEVICE;
+	pp_params.dma_dir = tsnep_xdp_is_enabled(rx->adapter) ?
+			    DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
 	pp_params.max_len = TSNEP_MAX_RX_BUF_SIZE;
-	pp_params.offset = TSNEP_SKB_PAD;
+	pp_params.offset = tsnep_rx_offset(rx);
 	rx->page_pool = page_pool_create(&pp_params);
 	if (IS_ERR(rx->page_pool)) {
 		retval = PTR_ERR(rx->page_pool);
@@ -906,7 +918,7 @@ static void tsnep_rx_set_page(struct tsnep_rx *rx, struct tsnep_rx_entry *entry,
 	entry->page = page;
 	entry->len = TSNEP_MAX_RX_BUF_SIZE;
 	entry->dma = page_pool_get_dma_addr(entry->page);
-	entry->desc->rx = __cpu_to_le64(entry->dma + TSNEP_SKB_PAD);
+	entry->desc->rx = __cpu_to_le64(entry->dma + tsnep_rx_offset(rx));
 }
 
 static int tsnep_rx_alloc_buffer(struct tsnep_rx *rx, int index)
@@ -1010,14 +1022,14 @@ static struct sk_buff *tsnep_build_skb(struct tsnep_rx *rx, struct page *page,
 		return NULL;
 
 	/* update pointers within the skb to store the data */
-	skb_reserve(skb, TSNEP_SKB_PAD + TSNEP_RX_INLINE_METADATA_SIZE);
+	skb_reserve(skb, tsnep_rx_offset(rx) + TSNEP_RX_INLINE_METADATA_SIZE);
 	__skb_put(skb, length - TSNEP_RX_INLINE_METADATA_SIZE - ETH_FCS_LEN);
 
 	if (rx->adapter->hwtstamp_config.rx_filter == HWTSTAMP_FILTER_ALL) {
 		struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
 		struct tsnep_rx_inline *rx_inline =
 			(struct tsnep_rx_inline *)(page_address(page) +
-						   TSNEP_SKB_PAD);
+						   tsnep_rx_offset(rx));
 
 		skb_shinfo(skb)->tx_flags |=
 			SKBTX_HW_TSTAMP_NETDEV;
@@ -1077,11 +1089,12 @@ static int tsnep_rx_poll(struct tsnep_rx *rx, struct napi_struct *napi,
 		 */
 		dma_rmb();
 
-		prefetch(page_address(entry->page) + TSNEP_SKB_PAD);
+		prefetch(page_address(entry->page) + tsnep_rx_offset(rx));
 		length = __le32_to_cpu(entry->desc_wb->properties) &
 			 TSNEP_DESC_LENGTH_MASK;
-		dma_sync_single_range_for_cpu(dmadev, entry->dma, TSNEP_SKB_PAD,
-					      length, dma_dir);
+		dma_sync_single_range_for_cpu(dmadev, entry->dma,
+					      tsnep_rx_offset(rx), length,
+					      dma_dir);
 
 		rx->read = (rx->read + 1) % TSNEP_RING_SIZE;
 		desc_available++;
-- 
2.30.2