netdev - [PATCH net-next v4 07/10] tsnep: Prepare RX buffer for XDP support

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Date:   Mon,  9 Jan 2023 20:15:20 +0100
From:   Gerhard Engleder <gerhard@...leder-embedded.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
        pabeni@...hat.com, Gerhard Engleder <gerhard@...leder-embedded.com>
Subject: [PATCH net-next v4 07/10] tsnep: Prepare RX buffer for XDP support

Introduce tsnep_adapter::xdp_prog, which will later signal that XDP is
enabled.

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.h      |  3 +++
 drivers/net/ethernet/engleder/tsnep_main.c | 22 ++++++++++++++--------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/engleder/tsnep.h b/drivers/net/ethernet/engleder/tsnep.h
index 9cb267938794..855738d31d73 100644
--- a/drivers/net/ethernet/engleder/tsnep.h
+++ b/drivers/net/ethernet/engleder/tsnep.h
@@ -117,6 +117,7 @@ struct tsnep_rx {
 	struct tsnep_adapter *adapter;
 	void __iomem *addr;
 	int queue_index;
+	unsigned int offset;
 
 	void *page[TSNEP_RING_PAGE_COUNT];
 	dma_addr_t page_dma[TSNEP_RING_PAGE_COUNT];
@@ -183,6 +184,8 @@ struct tsnep_adapter {
 	int rxnfc_count;
 	int rxnfc_max;
 
+	struct bpf_prog *xdp_prog;
+
 	int num_tx_queues;
 	struct tsnep_tx tx[TSNEP_MAX_QUEUES];
 	int num_rx_queues;
diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index 1110530ec639..0c9669edb2dd 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)))
 
@@ -838,9 +839,10 @@ 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 = !!rx->adapter->xdp_prog ?
+			    DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
 	pp_params.max_len = TSNEP_MAX_RX_BUF_SIZE;
-	pp_params.offset = TSNEP_SKB_PAD;
+	pp_params.offset = rx->offset;
 	rx->page_pool = page_pool_create(&pp_params);
 	if (IS_ERR(rx->page_pool)) {
 		retval = PTR_ERR(rx->page_pool);
@@ -875,7 +877,7 @@ 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 + rx->offset);
 }
 
 static int tsnep_rx_alloc_buffer(struct tsnep_rx *rx, int index)
@@ -979,14 +981,14 @@ 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, rx->offset + TSNEP_RX_INLINE_METADATA_SIZE);
 	__skb_put(skb, length - 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);
+						   rx->offset);
 
 		skb_shinfo(skb)->tx_flags |=
 			SKBTX_HW_TSTAMP_NETDEV;
@@ -1046,10 +1048,10 @@ 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) + rx->offset);
 		length = __le32_to_cpu(entry->desc_wb->properties) &
 			 TSNEP_DESC_LENGTH_MASK;
-		dma_sync_single_range_for_cpu(dmadev, entry->dma, TSNEP_SKB_PAD,
+		dma_sync_single_range_for_cpu(dmadev, entry->dma, rx->offset,
 					      length, dma_dir);
 
 		/* RX metadata with timestamps is in front of actual data,
@@ -1111,6 +1113,10 @@ static int tsnep_rx_open(struct tsnep_adapter *adapter, void __iomem *addr,
 	rx->adapter = adapter;
 	rx->addr = addr;
 	rx->queue_index = queue_index;
+	if (!!adapter->xdp_prog)
+		rx->offset = XDP_PACKET_HEADROOM;
+	else
+		rx->offset = TSNEP_SKB_PAD;
 
 	retval = tsnep_rx_ring_init(rx);
 	if (retval)
-- 
2.30.2