From 35d2f80b07bbe03fb358afb0bdeff7437a7d67ff Mon Sep 17 00:00:00 2001 From: Vlad Yasevich Date: Tue, 23 May 2017 13:38:41 -0400 Subject: [PATCH 1/3] vlan: Fix tcp checksum offloads in Q-in-Q vlans It appears that TCP checksum offloading has been broken for Q-in-Q vlans. The behavior was execerbated by the series commit afb0bc972b52 ("Merge branch 'stacked_vlan_tso'") that that enabled accleleration features on stacked vlans. However, event without that series, it is possible to trigger this issue. It just requires a lot more specialized configuration. The root cause is the interaction between how netdev_intersect_features() works, the features actually set on the vlan devices and HW having the ability to run checksum with longer headers. The issue starts when netdev_interesect_features() replaces NETIF_F_HW_CSUM with a combination of NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM, if the HW advertises IP|IPV6 specific checksums. This happens for tagged and multi-tagged packets. However, HW that enables IP|IPV6 checksum offloading doesn't gurantee that packets with arbitrarily long headers can be checksummed. This patch disables IP|IPV6 checksums on the packet for multi-tagged packets. CC: Toshiaki Makita CC: Michal Kubecek Signed-off-by: Vladislav Yasevich Acked-by: Toshiaki Makita Signed-off-by: David S. Miller --- include/linux/if_vlan.h | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index 8d5fcd6284ce0..283dc2f5364d7 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -614,14 +614,16 @@ static inline bool skb_vlan_tagged_multi(const struct sk_buff *skb) static inline netdev_features_t vlan_features_check(const struct sk_buff *skb, netdev_features_t features) { - if (skb_vlan_tagged_multi(skb)) - features = netdev_intersect_features(features, - NETIF_F_SG | - NETIF_F_HIGHDMA | - NETIF_F_FRAGLIST | - NETIF_F_HW_CSUM | - NETIF_F_HW_VLAN_CTAG_TX | - NETIF_F_HW_VLAN_STAG_TX); + if (skb_vlan_tagged_multi(skb)) { + /* In the case of multi-tagged packets, use a direct mask + * instead of using netdev_interesect_features(), to make + * sure that only devices supporting NETIF_F_HW_CSUM will + * have checksum offloading support. + */ + features &= NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_HW_CSUM | + NETIF_F_FRAGLIST | NETIF_F_HW_VLAN_CTAG_TX | + NETIF_F_HW_VLAN_STAG_TX; + } return features; } From cc6e9de62a7f84c9293a2ea41bc412b55bb46e85 Mon Sep 17 00:00:00 2001 From: Vlad Yasevich Date: Tue, 23 May 2017 13:38:42 -0400 Subject: [PATCH 2/3] be2net: Fix offload features for Q-in-Q packets At least some of the be2net cards do not seem to be capabled of performing checksum offload computions on Q-in-Q packets. In these case, the recevied checksum on the remote is invalid and TCP syn packets are dropped. This patch adds a call to check disbled acceleration features on Q-in-Q tagged traffic. CC: Sathya Perla CC: Ajit Khaparde CC: Sriharsha Basavapatna CC: Somnath Kotur Signed-off-by: Vladislav Yasevich Signed-off-by: David S. Miller --- drivers/net/ethernet/emulex/benet/be_main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c index f3a09ab559004..4eee18ce9be46 100644 --- a/drivers/net/ethernet/emulex/benet/be_main.c +++ b/drivers/net/ethernet/emulex/benet/be_main.c @@ -5078,9 +5078,11 @@ static netdev_features_t be_features_check(struct sk_buff *skb, struct be_adapter *adapter = netdev_priv(dev); u8 l4_hdr = 0; - /* The code below restricts offload features for some tunneled packets. + /* The code below restricts offload features for some tunneled and + * Q-in-Q packets. * Offload features for normal (non tunnel) packets are unchanged. */ + features = vlan_features_check(skb, features); if (!skb->encapsulation || !(adapter->flags & BE_FLAGS_VXLAN_OFFLOADS)) return features; From 2836b4f224d4fd7d1a2b23c3eecaf0f0ae199a74 Mon Sep 17 00:00:00 2001 From: Vlad Yasevich Date: Tue, 23 May 2017 13:38:43 -0400 Subject: [PATCH 3/3] virtio-net: enable TSO/checksum offloads for Q-in-Q vlans Since virtio does not provide it's own ndo_features_check handler, TSO, and now checksum offload, are disabled for stacked vlans. Re-enable the support and let the host take care of it. This restores/improves Guest-to-Guest performance over Q-in-Q vlans. Acked-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: Vladislav Yasevich Signed-off-by: David S. Miller --- drivers/net/virtio_net.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 9320d96a1632b..3e9246cc49c37 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1989,6 +1989,7 @@ static const struct net_device_ops virtnet_netdev = { .ndo_poll_controller = virtnet_netpoll, #endif .ndo_xdp = virtnet_xdp, + .ndo_features_check = passthru_features_check, }; static void virtnet_config_changed_work(struct work_struct *work)