[PATCH v4 1/4] net/ngbe: implement USO support

[Zaiyu Wang <zaiyuwang@trustnetic.com>]

USO (UDP Segmentation Offload), also known as UFO (UDP Fragmentation
Offload), is a hardware offload rarely seen in DPDK. Its implementation
is similar to TSO (TCP Segmentation Offload), so the driver enables
USO based on existing TSO support.

The driver has advertised RTE_ETH_TX_OFFLOAD_UDP_TSO in tx_offload_capa
since its initial integration, but the data path never implemented the
actual segmentation support. This commit fills that gap by enabling USO
in the transmit path, making the advertised capability fully functional.

Note:
USO segments UDP packets, requiring hardware to recalculate both IP
and UDP checksums due to length change. Thus, USO implicitly requires
IP and UDP checksum offloads, same as TSO.

Fixes: 9f3206140274 ("net/ngbe: support TSO")
Cc: stable@dpdk.org

Signed-off-by: Zaiyu Wang <zaiyuwang@trustnetic.com>
---
 doc/guides/rel_notes/release_26_07.rst |  7 +++++++
 drivers/net/ngbe/ngbe_rxtx.c           | 13 ++++++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/doc/guides/rel_notes/release_26_07.rst b/doc/guides/rel_notes/release_26_07.rst
index 4ca0a9ac77..c5a168fdc9 100644
--- a/doc/guides/rel_notes/release_26_07.rst
+++ b/doc/guides/rel_notes/release_26_07.rst
@@ -177,6 +177,13 @@ New Features
   Added AGENTS.md file for AI review
   and supporting scripts to review patches and documentation.
 
+* **Updated Wangxun ngbe driver.**
+
+  * Implemented UDP Segmentation Offload (USO) in the transmit path.
+    The ``RTE_ETH_TX_OFFLOAD_UDP_TSO`` capability was advertised since the
+    driver's initial integration but the data path was missing; it is now
+    functional.
+
 
 Removed Items
 -------------
diff --git a/drivers/net/ngbe/ngbe_rxtx.c b/drivers/net/ngbe/ngbe_rxtx.c
index 91e215694c..a1389de9c0 100644
--- a/drivers/net/ngbe/ngbe_rxtx.c
+++ b/drivers/net/ngbe/ngbe_rxtx.c
@@ -30,6 +30,7 @@ static const u64 NGBE_TX_OFFLOAD_MASK = (RTE_MBUF_F_TX_IP_CKSUM |
 		RTE_MBUF_F_TX_VLAN |
 		RTE_MBUF_F_TX_L4_MASK |
 		RTE_MBUF_F_TX_TCP_SEG |
+		RTE_MBUF_F_TX_UDP_SEG |
 		NGBE_TX_IEEE1588_TMST);
 
 #define NGBE_TX_OFFLOAD_NOTSUP_MASK \
@@ -317,7 +318,7 @@ ngbe_set_xmit_ctx(struct ngbe_tx_queue *txq,
 	type_tucmd_mlhl |= NGBE_TXD_PTID(tx_offload.ptid);
 
 	/* check if TCP segmentation required for this packet */
-	if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) {
+	if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) {
 		tx_offload_mask.l2_len |= ~0;
 		tx_offload_mask.l3_len |= ~0;
 		tx_offload_mask.l4_len |= ~0;
@@ -427,7 +428,7 @@ tx_desc_cksum_flags_to_olinfo(uint64_t ol_flags)
 		tmp |= NGBE_TXD_CC;
 		tmp |= NGBE_TXD_EIPCS;
 	}
-	if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) {
+	if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) {
 		tmp |= NGBE_TXD_CC;
 		/* implies IPv4 cksum */
 		if (ol_flags & RTE_MBUF_F_TX_IPV4)
@@ -447,7 +448,7 @@ tx_desc_ol_flags_to_cmdtype(uint64_t ol_flags)
 
 	if (ol_flags & RTE_MBUF_F_TX_VLAN)
 		cmdtype |= NGBE_TXD_VLE;
-	if (ol_flags & RTE_MBUF_F_TX_TCP_SEG)
+	if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG))
 		cmdtype |= NGBE_TXD_TSE;
 	return cmdtype;
 }
@@ -483,6 +484,8 @@ tx_desc_ol_flags_to_ptype(uint64_t oflags)
 
 	if (oflags & RTE_MBUF_F_TX_TCP_SEG)
 		ptype |= RTE_PTYPE_L4_TCP;
+	else if (oflags & RTE_MBUF_F_TX_UDP_SEG)
+		ptype |= RTE_PTYPE_L4_UDP;
 
 	return ptype;
 }
@@ -764,7 +767,7 @@ ngbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 
 		olinfo_status = 0;
 		if (tx_ol_req) {
-			if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) {
+			if (ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) {
 				/* when TSO is on, paylen in descriptor is the
 				 * not the packet len but the tcp payload len
 				 */
@@ -1991,7 +1994,7 @@ ngbe_get_tx_port_offloads(struct rte_eth_dev *dev)
 		RTE_ETH_TX_OFFLOAD_TCP_CKSUM   |
 		RTE_ETH_TX_OFFLOAD_SCTP_CKSUM  |
 		RTE_ETH_TX_OFFLOAD_TCP_TSO     |
-		RTE_ETH_TX_OFFLOAD_UDP_TSO	   |
+		RTE_ETH_TX_OFFLOAD_UDP_TSO     |
 		RTE_ETH_TX_OFFLOAD_MULTI_SEGS;
 
 	if (hw->is_pf)
-- 
2.21.0.windows.1