linux-kernel - [PATCH net] gve: set xdp redirect target only when it is available

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Message-ID: <20250214224417.1237818-1-joshwash@google.com>
Date: Fri, 14 Feb 2025 14:43:59 -0800
From: joshwash@...gle.com
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, kuba@...nel.org, stable@...nel.org, 
	Joshua Washington <joshwash@...gle.com>, stable@...r.kernel.org, 
	Praveen Kaligineedi <pkaligineedi@...gle.com>, Jeroen de Borst <jeroendb@...gle.com>, 
	Harshitha Ramamurthy <hramamurthy@...gle.com>, Andrew Lunn <andrew+netdev@...n.ch>, 
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Jesper Dangaard Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, 
	Willem de Bruijn <willemb@...gle.com>, Ziwei Xiao <ziweixiao@...gle.com>, 
	Shailend Chand <shailend@...gle.com>, open list <linux-kernel@...r.kernel.org>, 
	"open list:XDP (eXpress Data Path):Keyword:(?:b|_)xdp(?:b|_)" <bpf@...r.kernel.org>
Subject: [PATCH net] gve: set xdp redirect target only when it is available

From: Joshua Washington <joshwash@...gle.com>

Before this patch the NETDEV_XDP_ACT_NDO_XMIT XDP feature flag is set by
default as part of driver initialization, and is never cleared. However,
this flag differs from others in that it is used as an indicator for
whether the driver is ready to perform the ndo_xdp_xmit operation as
part of an XDP_REDIRECT. Kernel helpers
xdp_features_(set|clear)_redirect_target exist to convey this meaning.

This patch ensures that the netdev is only reported as a redirect target
when XDP queues exist to forward traffic.

Fixes: 39a7f4aa3e4a ("gve: Add XDP REDIRECT support for GQI-QPL format")
Cc: stable@...r.kernel.org
Reviewed-by: Praveen Kaligineedi <pkaligineedi@...gle.com>
Reviewed-by: Jeroen de Borst <jeroendb@...gle.com>
Signed-off-by: Joshua Washington <joshwash@...gle.com>
---
 drivers/net/ethernet/google/gve/gve.h      | 10 ++++++++++
 drivers/net/ethernet/google/gve/gve_main.c |  6 +++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 8167cc5fb0df..78d2a19593d1 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -1116,6 +1116,16 @@ static inline u32 gve_xdp_tx_start_queue_id(struct gve_priv *priv)
 	return gve_xdp_tx_queue_id(priv, 0);
 }
 
+static inline bool gve_supports_xdp_xmit(struct gve_priv *priv)
+{
+	switch (priv->queue_format) {
+	case GVE_GQI_QPL_FORMAT:
+		return true;
+	default:
+		return false;
+	}
+}
+
 /* gqi napi handler defined in gve_main.c */
 int gve_napi_poll(struct napi_struct *napi, int budget);
 
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 533e659b15b3..92237fb0b60c 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -1903,6 +1903,8 @@ static void gve_turndown(struct gve_priv *priv)
 	/* Stop tx queues */
 	netif_tx_disable(priv->dev);
 
+	xdp_features_clear_redirect_target(priv->dev);
+
 	gve_clear_napi_enabled(priv);
 	gve_clear_report_stats(priv);
 
@@ -1972,6 +1974,9 @@ static void gve_turnup(struct gve_priv *priv)
 		napi_schedule(&block->napi);
 	}
 
+	if (priv->num_xdp_queues && gve_supports_xdp_xmit(priv))
+		xdp_features_set_redirect_target(priv->dev, false);
+
 	gve_set_napi_enabled(priv);
 }
 
@@ -2246,7 +2251,6 @@ static void gve_set_netdev_xdp_features(struct gve_priv *priv)
 	if (priv->queue_format == GVE_GQI_QPL_FORMAT) {
 		xdp_features = NETDEV_XDP_ACT_BASIC;
 		xdp_features |= NETDEV_XDP_ACT_REDIRECT;
-		xdp_features |= NETDEV_XDP_ACT_NDO_XMIT;
 		xdp_features |= NETDEV_XDP_ACT_XSK_ZEROCOPY;
 	} else {
 		xdp_features = 0;
-- 
2.48.1.601.g30ceb7b040-goog