netdev - [PATCH v1 iwl-next] igb: set skb hash type from RSS

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Message-ID: <20260119175922.199950-1-kohei@enjuk.jp>
Date: Mon, 19 Jan 2026 17:58:27 +0000
From: Kohei Enju <kohei@...uk.jp>
To: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
        Przemek Kitszel <przemyslaw.kitszel@...el.com>,
        Andrew Lunn <andrew+netdev@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, kohei.enju@...il.com,
        Takashi Kozu <takkozu@...zon.com>, Kohei Enju <kohei@...uk.jp>
Subject: [PATCH v1 iwl-next] igb: set skb hash type from RSS_TYPE

igb always marks the RX hash as L3 regardless of RSS_TYPE in the
advanced descriptor, which may indicate L4 (TCP/UDP) hash. This can
trigger unnecessary SW hash recalculation and breaks toeplitz selftests.

Use RSS_TYPE from pkt_info to set the correct PKT_HASH_TYPE_*

Tested by toeplitz.py with the igb RSS key get/set patches applied as
they are required for toeplitz.py (see Link below).
 # ethtool -N $DEV rx-flow-hash udp4 sdfn
 # ethtool -N $DEV rx-flow-hash udp6 sdfn
 # python toeplitz.py | grep -E "^# Totals"

Without patch:
 # Totals: pass:0 fail:12 xfail:0 xpass:0 skip:0 error:0

With patch:
 # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0

Link: https://lore.kernel.org/intel-wired-lan/20260119084511.95287-5-takkozu@amazon.com/
Signed-off-by: Kohei Enju <kohei@...uk.jp>
---
If a Fixes tag is needed, it would be Fixes: 42bdf083fe70 ("net: igb
calls skb_set_hash").

I'm not sure this qualifies as a fix, since the RX hash marking has been
wrong for a long time without reported issues. So I'm leaning toward
omitting Fixes.
---
 drivers/net/ethernet/intel/igb/e1000_82575.h | 21 ++++++++++++++++++++
 drivers/net/ethernet/intel/igb/igb_main.c    | 18 +++++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/e1000_82575.h b/drivers/net/ethernet/intel/igb/e1000_82575.h
index 63ec253ac788..a855bc10f5d4 100644
--- a/drivers/net/ethernet/intel/igb/e1000_82575.h
+++ b/drivers/net/ethernet/intel/igb/e1000_82575.h
@@ -87,6 +87,27 @@ union e1000_adv_rx_desc {
 	} wb;  /* writeback */
 };
 
+#define E1000_RSS_TYPE_NO_HASH		 0
+#define E1000_RSS_TYPE_HASH_TCP_IPV4	 1
+#define E1000_RSS_TYPE_HASH_IPV4	 2
+#define E1000_RSS_TYPE_HASH_TCP_IPV6	 3
+#define E1000_RSS_TYPE_HASH_IPV6_EX	 4
+#define E1000_RSS_TYPE_HASH_IPV6	 5
+#define E1000_RSS_TYPE_HASH_TCP_IPV6_EX	 6
+#define E1000_RSS_TYPE_HASH_UDP_IPV4	 7
+#define E1000_RSS_TYPE_HASH_UDP_IPV6	 8
+#define E1000_RSS_TYPE_HASH_UDP_IPV6_EX	 9
+
+#define E1000_RSS_TYPE_MASK		GENMASK(3, 0) /* 4-bits (3:0) = mask 0x0F */
+
+#define E1000_RSS_L4_TYPES_MASK	\
+	(BIT(E1000_RSS_TYPE_HASH_TCP_IPV4)	| \
+	 BIT(E1000_RSS_TYPE_HASH_TCP_IPV6)	| \
+	 BIT(E1000_RSS_TYPE_HASH_TCP_IPV6_EX)	| \
+	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV4)	| \
+	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV6)	| \
+	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV6_EX))
+
 #define E1000_RXDADV_HDRBUFLEN_MASK      0x7FE0
 #define E1000_RXDADV_HDRBUFLEN_SHIFT     5
 #define E1000_RXDADV_STAT_TS             0x10000 /* Pkt was time stamped */
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 8dab133296ca..ef0cbf532716 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -8824,10 +8824,20 @@ static inline void igb_rx_hash(struct igb_ring *ring,
 			       union e1000_adv_rx_desc *rx_desc,
 			       struct sk_buff *skb)
 {
-	if (ring->netdev->features & NETIF_F_RXHASH)
-		skb_set_hash(skb,
-			     le32_to_cpu(rx_desc->wb.lower.hi_dword.rss),
-			     PKT_HASH_TYPE_L3);
+	u16 rss_type;
+
+	if (!(ring->netdev->features & NETIF_F_RXHASH))
+		return;
+
+	rss_type = le16_to_cpu(rx_desc->wb.lower.lo_dword.pkt_info) &
+		   E1000_RSS_TYPE_MASK;
+
+	if (!rss_type)
+		return;
+
+	skb_set_hash(skb, le32_to_cpu(rx_desc->wb.lower.hi_dword.rss),
+		     (E1000_RSS_L4_TYPES_MASK & BIT(rss_type)) ?
+		     PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
 }
 
 /**
-- 
2.51.0