libeth: xsk: add XSk XDP_TX sending helpers

Add Xsk counterparts for XDP_TX buffer sending and completion.
The same base structures and functions used from the libeth_xdp core,
with adjustments to that XSk Rx always operates on &xdp_buff_xsk for
both head and frags. And unlike regular Rx, here unlikely() are used
for frags, as the header split gives no benefits for XSk Rx, at
least for now.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

6 files changed, 51 insertions, 4 deletions

diff --git a/drivers/net/ethernet/intel/libeth/Kconfig b/drivers/net/ethernet/intel/libeth/Kconfig
index d8c4926574fb..2445b979c499 100644
--- a/drivers/net/ethernet/intel/libeth/Kconfig
+++ b/drivers/net/ethernet/intel/libeth/Kconfig
@@ -12,4 +12,4 @@ config LIBETH_XDP
 	tristate "Common XDP library (libeth_xdp)" if COMPILE_TEST
 	select LIBETH
 	help
-	  XDP helpers based on libeth hotpath management.
+	  XDP and XSk helpers based on libeth hotpath management.
diff --git a/drivers/net/ethernet/intel/libeth/Makefile b/drivers/net/ethernet/intel/libeth/Makefile
index 51669840ee06..350bc0b38bad 100644
--- a/drivers/net/ethernet/intel/libeth/Makefile
+++ b/drivers/net/ethernet/intel/libeth/Makefile
@@ -9,3 +9,4 @@ libeth-y			+= tx.o
 obj-$(CONFIG_LIBETH_XDP)	+= libeth_xdp.o
 
 libeth_xdp-y			+= xdp.o
+libeth_xdp-y			+= xsk.o
diff --git a/drivers/net/ethernet/intel/libeth/priv.h b/drivers/net/ethernet/intel/libeth/priv.h
index 1bd6e2d7a3e7..ebcb26f24401 100644
--- a/drivers/net/ethernet/intel/libeth/priv.h
+++ b/drivers/net/ethernet/intel/libeth/priv.h
@@ -8,12 +8,18 @@
 
 /* XDP */
 
+struct libeth_xdp_buff;
+struct libeth_xdp_tx_frame;
 struct skb_shared_info;
 struct xdp_frame_bulk;
 
+void libeth_xsk_tx_return_bulk(const struct libeth_xdp_tx_frame *bq,
+			       u32 count);
+
 struct libeth_xdp_ops {
 	void	(*bulk)(const struct skb_shared_info *sinfo,
 			struct xdp_frame_bulk *bq, bool frags);
+	void	(*xsk)(struct libeth_xdp_buff *xdp);
 };
 
 void libeth_attach_xdp(const struct libeth_xdp_ops *ops);
diff --git a/drivers/net/ethernet/intel/libeth/tx.c b/drivers/net/ethernet/intel/libeth/tx.c
index 227c841ab16a..e0167f43d2a8 100644
--- a/drivers/net/ethernet/intel/libeth/tx.c
+++ b/drivers/net/ethernet/intel/libeth/tx.c
@@ -10,6 +10,7 @@
 /* Tx buffer completion */
 
 DEFINE_STATIC_CALL_NULL(bulk, libeth_xdp_return_buff_bulk);
+DEFINE_STATIC_CALL_NULL(xsk, libeth_xsk_buff_free_slow);
 
 /**
  * libeth_tx_complete_any - perform Tx completion for one SQE of any type
@@ -23,7 +24,8 @@ DEFINE_STATIC_CALL_NULL(bulk, libeth_xdp_return_buff_bulk);
 void libeth_tx_complete_any(struct libeth_sqe *sqe, struct libeth_cq_pp *cp)
 {
 	if (sqe->type >= __LIBETH_SQE_XDP_START)
-		__libeth_xdp_complete_tx(sqe, cp, static_call(bulk));
+		__libeth_xdp_complete_tx(sqe, cp, static_call(bulk),
+					 static_call(xsk));
 	else
 		libeth_tx_complete(sqe, cp);
 }
@@ -34,5 +36,6 @@ EXPORT_SYMBOL_GPL(libeth_tx_complete_any);
 void libeth_attach_xdp(const struct libeth_xdp_ops *ops)
 {
 	static_call_update(bulk, ops ? ops->bulk : NULL);
+	static_call_update(xsk, ops ? ops->xsk : NULL);
 }
 EXPORT_SYMBOL_GPL(libeth_attach_xdp);
diff --git a/drivers/net/ethernet/intel/libeth/xdp.c b/drivers/net/ethernet/intel/libeth/xdp.c
index 4eb0f3c6cdab..bd334d314a1d 100644
--- a/drivers/net/ethernet/intel/libeth/xdp.c
+++ b/drivers/net/ethernet/intel/libeth/xdp.c
@@ -114,7 +114,7 @@ static void __cold libeth_trace_xdp_exception(const struct net_device *dev,
  * libeth_xdp_tx_exception - handle Tx exceptions of XDP frames
  * @bq: XDP Tx frame bulk
  * @sent: number of frames sent successfully (from this bulk)
- * @flags: internal libeth_xdp flags (.ndo_xdp_xmit etc.)
+ * @flags: internal libeth_xdp flags (XSk, .ndo_xdp_xmit etc.)
  *
  * Cold helper used by __libeth_xdp_tx_flush_bulk(), do not call directly.
  * Reports XDP Tx exceptions, frees the frames that won't be sent or adjust
@@ -136,7 +136,9 @@ void __cold libeth_xdp_tx_exception(struct libeth_xdp_tx_bulk *bq, u32 sent,
 		return;
 	}
 
-	if (!(flags & LIBETH_XDP_TX_NDO))
+	if (flags & LIBETH_XDP_TX_XSK)
+		libeth_xsk_tx_return_bulk(pos, left);
+	else if (!(flags & LIBETH_XDP_TX_NDO))
 		libeth_xdp_tx_return_bulk(pos, left);
 	else
 		libeth_xdp_xmit_return_bulk(pos, left, bq->dev);
@@ -413,6 +415,7 @@ EXPORT_SYMBOL_GPL(libeth_xdp_set_redirect);
 
 static const struct libeth_xdp_ops xdp_ops __initconst = {
 	.bulk	= libeth_xdp_return_buff_bulk,
+	.xsk	= libeth_xsk_buff_free_slow,
 };
 
 static int __init libeth_xdp_module_init(void)
diff --git a/drivers/net/ethernet/intel/libeth/xsk.c b/drivers/net/ethernet/intel/libeth/xsk.c
new file mode 100644
index 000000000000..fba6d7a025b0
--- /dev/null
+++ b/drivers/net/ethernet/intel/libeth/xsk.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2025 Intel Corporation */
+
+#define DEFAULT_SYMBOL_NAMESPACE	"LIBETH_XDP"
+
+#include <linux/export.h>
+
+#include <net/libeth/xsk.h>
+
+#include "priv.h"
+
+/* ``XDP_TX`` bulking */
+
+void __cold libeth_xsk_tx_return_bulk(const struct libeth_xdp_tx_frame *bq,
+				      u32 count)
+{
+	for (u32 i = 0; i < count; i++)
+		libeth_xsk_buff_free_slow(bq[i].xsk);
+}
+
+/* Rx polling path */
+
+/**
+ * libeth_xsk_buff_free_slow - free an XSk Rx buffer
+ * @xdp: buffer to free
+ *
+ * Slowpath version of xsk_buff_free() to be used on exceptions, cleanups etc.
+ * to avoid unwanted inlining.
+ */
+void libeth_xsk_buff_free_slow(struct libeth_xdp_buff *xdp)
+{
+	xsk_buff_free(&xdp->base);
+}
+EXPORT_SYMBOL_GPL(libeth_xsk_buff_free_slow);