patch 'net/gve: copy data to QPL buffer when mbuf read does not' has been queued to stable release 25.11.3

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 25.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/04/26. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable/commit/461687d0d1540e312eadce4247c0c70a84d9dade

Thanks.

Kevin

---
>From 461687d0d1540e312eadce4247c0c70a84d9dade Mon Sep 17 00:00:00 2001
From: Joshua Washington <joshwash at google.com>
Date: Wed, 8 Jul 2026 21:07:31 -0700
Subject: [PATCH] net/gve: copy data to QPL buffer when mbuf read does not

[ upstream commit c75da01101658480d31fb2a96351b99418600c4f ]

The rte_pktmbuf_read method does not guarantee that data will be copied
from an mbuf. If the requested data is all contiguous, the method will
instead return a pointer to the memory location within the buffer that
should be read from, leaving the destination buffer empty.

This is problematic for TSO/multi-segment TX packets which only make use
of two mbufs. If all data in the second mbuf is contiguous, the data
will not be read to QPL memory.

Update the QPL copy logic to copy if the rte_pktmbuf_read does not.

Fixes: a46583cf43c8 ("net/gve: support Rx/Tx")

Signed-off-by: Joshua Washington <joshwash at google.com>
Reviewed-by: Jasper Tran O'Leary <jtranoleary at google.com>
---
 drivers/net/gve/gve_tx.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/net/gve/gve_tx.c b/drivers/net/gve/gve_tx.c
index 2d6a4272cc..ea9977ef5f 100644
--- a/drivers/net/gve/gve_tx.c
+++ b/drivers/net/gve/gve_tx.c
@@ -256,8 +256,8 @@ gve_tx_burst_qpl(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	uint16_t mask = txq->nb_tx_desc - 1;
 	uint16_t tx_id = txq->tx_tail & mask;
-	uint64_t ol_flags, addr, fifo_addr;
 	uint32_t tx_tail = txq->tx_tail;
 	struct rte_mbuf *tx_pkt, *first;
 	uint16_t sw_id = txq->sw_tail;
+	uint64_t ol_flags, fifo_addr;
 	uint16_t nb_used, i;
 	uint64_t bytes = 0;
@@ -274,4 +274,7 @@ gve_tx_burst_qpl(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 
 	for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
+		const void *mbuf_header_addr;
+		void *qpl_write_addr;
+
 		tx_pkt = *tx_pkts++;
 		ol_flags = tx_pkt->ol_flags;
@@ -307,5 +310,4 @@ gve_tx_burst_qpl(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 				goto end_of_tx;
 		}
-		addr = (uint64_t)(tx_pkt->buf_addr) + tx_pkt->data_off;
 		fifo_addr = gve_tx_alloc_from_fifo(txq, tx_id, hlen);
 
@@ -318,24 +320,30 @@ gve_tx_burst_qpl(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 			}
 		}
-		if (tx_pkt->nb_segs == 1 || ol_flags & RTE_MBUF_F_TX_TCP_SEG)
-			rte_memcpy((void *)(size_t)(fifo_addr + txq->fifo_base),
-				   (void *)(size_t)addr, hlen);
-		else
-			rte_pktmbuf_read(tx_pkt, 0, hlen,
-					 (void *)(size_t)(fifo_addr + txq->fifo_base));
+
+		qpl_write_addr = (void *)(size_t)(fifo_addr + txq->fifo_base);
+		mbuf_header_addr = rte_pktmbuf_read(tx_pkt, 0, hlen, qpl_write_addr);
+
+		/* Header data is linear in the mbuf head. Copy directly. */
+		if (mbuf_header_addr != qpl_write_addr)
+			rte_memcpy(qpl_write_addr, mbuf_header_addr, hlen);
+
 		gve_tx_fill_pkt_desc(txd, tx_pkt, nb_used, hlen, fifo_addr);
 
 		if (ol_flags & RTE_MBUF_F_TX_TCP_SEG) {
+			const void *mbuf_payload_addr;
+
 			tx_id = (tx_id + 1) & mask;
 			txd = &txr[tx_id];
-			addr = (uint64_t)(tx_pkt->buf_addr) + tx_pkt->data_off + hlen;
 			fifo_addr = gve_tx_alloc_from_fifo(txq, tx_id, tx_pkt->pkt_len - hlen);
-			if (tx_pkt->nb_segs == 1)
-				rte_memcpy((void *)(size_t)(fifo_addr + txq->fifo_base),
-					   (void *)(size_t)addr,
+			qpl_write_addr = (void *)(size_t)(txq->fifo_base + fifo_addr);
+			mbuf_payload_addr = rte_pktmbuf_read(tx_pkt, hlen, tx_pkt->pkt_len - hlen,
+							     qpl_write_addr);
+
+			/* Payload data is contiguous. Take the offset from the
+			 * read request and copy from there.
+			 */
+			if (mbuf_payload_addr != qpl_write_addr)
+				rte_memcpy(qpl_write_addr, mbuf_payload_addr,
 					   tx_pkt->pkt_len - hlen);
-			else
-				rte_pktmbuf_read(tx_pkt, hlen, tx_pkt->pkt_len - hlen,
-						 (void *)(size_t)(fifo_addr + txq->fifo_base));
 
 			gve_tx_fill_seg_desc(txd, ol_flags, tx_offload,
-- 
2.55.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2026-07-30 10:16:02.776024402 +0100
+++ 0044-net-gve-copy-data-to-QPL-buffer-when-mbuf-read-does-.patch	2026-07-30 10:16:01.483057424 +0100
@@ -1 +1 @@
-From c75da01101658480d31fb2a96351b99418600c4f Mon Sep 17 00:00:00 2001
+From 461687d0d1540e312eadce4247c0c70a84d9dade Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit c75da01101658480d31fb2a96351b99418600c4f ]
+
@@ -18 +19,0 @@
-Cc: stable at dpdk.org
@@ -27 +28 @@
-index 59c82b04ed..c0400b07bf 100644
+index 2d6a4272cc..ea9977ef5f 100644