From d7db7775ea2e31502d46427f5efd385afc4ff1eb Mon Sep 17 00:00:00 2001 From: Ignat Korchagin Date: Wed, 13 Mar 2024 19:37:58 +0100 Subject: [PATCH 1/2] net: veth: do not manipulate GRO when using XDP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP") tried to fix the fact that GRO was not possible without XDP, because veth did not use NAPI without XDP. However, it also introduced the behaviour that GRO is always enabled, when XDP is enabled. While it might be desired for most cases, it is confusing for the user at best as the GRO flag suddenly changes, when an XDP program is attached. It also introduces some complexities in state management as was partially addressed in commit fe9f801355f0 ("net: veth: clear GRO when clearing XDP even when down"). But the biggest problem is that it is not possible to disable GRO at all, when an XDP program is attached, which might be needed for some use cases. Fix this by not touching the GRO flag on XDP enable/disable as the code already supports switching to NAPI if either GRO or XDP is requested. Link: https://lore.kernel.org/lkml/20240311124015.38106-1-ignat@cloudflare.com/ Fixes: d3256efd8e8b ("veth: allow enabling NAPI even without XDP") Fixes: fe9f801355f0 ("net: veth: clear GRO when clearing XDP even when down") Signed-off-by: Ignat Korchagin Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- drivers/net/veth.c | 18 ------------------ 1 file changed, 18 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 13d902462d8e..bcdfbf61eb66 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -1464,8 +1464,6 @@ static netdev_features_t veth_fix_features(struct net_device *dev, if (peer_priv->_xdp_prog) features &= ~NETIF_F_GSO_SOFTWARE; } - if (priv->_xdp_prog) - features |= NETIF_F_GRO; return features; } @@ -1569,14 +1567,6 @@ static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog, } if (!old_prog) { - if (!veth_gro_requested(dev)) { - /* user-space did not require GRO, but adding - * XDP is supposed to get GRO working - */ - dev->features |= NETIF_F_GRO; - netdev_features_change(dev); - } - peer->hw_features &= ~NETIF_F_GSO_SOFTWARE; peer->max_mtu = max_mtu; } @@ -1592,14 +1582,6 @@ static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog, if (dev->flags & IFF_UP) veth_disable_xdp(dev); - /* if user-space did not require GRO, since adding XDP - * enabled it, clear it now - */ - if (!veth_gro_requested(dev)) { - dev->features &= ~NETIF_F_GRO; - netdev_features_change(dev); - } - if (peer) { peer->hw_features |= NETIF_F_GSO_SOFTWARE; peer->max_mtu = ETH_MAX_MTU; From ba5a6476e3866c97e2c85f64b0c7dfb8fbdda18a Mon Sep 17 00:00:00 2001 From: Ignat Korchagin Date: Wed, 13 Mar 2024 19:37:59 +0100 Subject: [PATCH 2/2] selftests: net: veth: test the ability to independently manipulate GRO and XDP We should be able to independently flip either XDP or GRO states and toggling one should not affect the other. Adjust other tests as well that had implicit expectation that GRO would be automatically enabled. Signed-off-by: Ignat Korchagin Signed-off-by: David S. Miller --- tools/testing/selftests/net/udpgro_fwd.sh | 4 ++++ tools/testing/selftests/net/veth.sh | 24 ++++++++++++++++++++--- 2 files changed, 25 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/net/udpgro_fwd.sh b/tools/testing/selftests/net/udpgro_fwd.sh index 9cd5e885e91f..380cb15e942e 100755 --- a/tools/testing/selftests/net/udpgro_fwd.sh +++ b/tools/testing/selftests/net/udpgro_fwd.sh @@ -217,6 +217,7 @@ for family in 4 6; do cleanup create_ns + ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on ip netns exec $NS_DST ethtool -K veth$DST rx-gro-list on run_test "GRO frag list" $BM_NET$DST 1 0 cleanup @@ -227,6 +228,7 @@ for family in 4 6; do # use NAT to circumvent GRO FWD check create_ns ip -n $NS_DST addr add dev veth$DST $BM_NET$DST_NAT/$SUFFIX + ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on ip netns exec $NS_DST $IPT -t nat -I PREROUTING -d $BM_NET$DST_NAT \ -j DNAT --to-destination $BM_NET$DST @@ -240,6 +242,7 @@ for family in 4 6; do cleanup create_vxlan_pair + ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on ip netns exec $NS_DST ethtool -K veth$DST rx-gro-list on run_test "GRO frag list over UDP tunnel" $OL_NET$DST 1 1 cleanup @@ -247,6 +250,7 @@ for family in 4 6; do # use NAT to circumvent GRO FWD check create_vxlan_pair ip -n $NS_DST addr add dev $VXDEV$DST $OL_NET$DST_NAT/$SUFFIX + ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on ip netns exec $NS_DST $IPT -t nat -I PREROUTING -d $OL_NET$DST_NAT \ -j DNAT --to-destination $OL_NET$DST diff --git a/tools/testing/selftests/net/veth.sh b/tools/testing/selftests/net/veth.sh index 5ae85def0739..3a394b43e274 100755 --- a/tools/testing/selftests/net/veth.sh +++ b/tools/testing/selftests/net/veth.sh @@ -249,9 +249,9 @@ cleanup create_ns ip -n $NS_DST link set dev veth$DST up ip -n $NS_DST link set dev veth$DST xdp object ${BPF_FILE} section xdp -chk_gro_flag "gro vs xdp while down - gro flag on" $DST on +chk_gro_flag "gro vs xdp while down - gro flag off" $DST off ip -n $NS_DST link set dev veth$DST down -chk_gro_flag " - after down" $DST on +chk_gro_flag " - after down" $DST off ip -n $NS_DST link set dev veth$DST xdp off chk_gro_flag " - after xdp off" $DST off ip -n $NS_DST link set dev veth$DST up @@ -260,6 +260,21 @@ ip -n $NS_SRC link set dev veth$SRC xdp object ${BPF_FILE} section xdp chk_gro_flag " - after peer xdp" $DST off cleanup +create_ns +ip -n $NS_DST link set dev veth$DST up +ip -n $NS_DST link set dev veth$DST xdp object ${BPF_FILE} section xdp +ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on +chk_gro_flag "gro vs xdp while down - gro flag on" $DST on +ip -n $NS_DST link set dev veth$DST down +chk_gro_flag " - after down" $DST on +ip -n $NS_DST link set dev veth$DST xdp off +chk_gro_flag " - after xdp off" $DST on +ip -n $NS_DST link set dev veth$DST up +chk_gro_flag " - after up" $DST on +ip -n $NS_SRC link set dev veth$SRC xdp object ${BPF_FILE} section xdp +chk_gro_flag " - after peer xdp" $DST on +cleanup + create_ns chk_channels "default channels" $DST 1 1 @@ -327,11 +342,14 @@ if [ $CPUS -gt 2 ]; then fi ip -n $NS_DST link set dev veth$DST xdp object ${BPF_FILE} section xdp 2>/dev/null -chk_gro_flag "with xdp attached - gro flag" $DST on +chk_gro_flag "with xdp attached - gro flag" $DST off chk_gro_flag " - peer gro flag" $SRC off chk_tso_flag " - tso flag" $SRC off chk_tso_flag " - peer tso flag" $DST on ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on +chk_gro " - no aggregation" 10 +ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on +chk_gro_flag " - gro flag with GRO on" $DST on chk_gro " - aggregation" 1