[PATCH 5.4 64/85] virtio-net: dont disable guest csum when disable LRO

From: Greg Kroah-Hartman
Date: Mon Oct 12 2020 - 09:45:04 EST


From: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>

[ Upstream commit 1a03b8a35a957f9f38ecb8a97443b7380bbf6a8b ]

Open vSwitch and Linux bridge will disable LRO of the interface
when this interface added to them. Now when disable the LRO, the
virtio-net csum is disable too. That drops the forwarding performance.

Fixes: a02e8964eaf9 ("virtio-net: ethtool configurable LRO")
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
Acked-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/virtio_net.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 030d30603c295..99e1a7bc06886 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -63,6 +63,11 @@ static const unsigned long guest_offloads[] = {
VIRTIO_NET_F_GUEST_CSUM
};

+#define GUEST_OFFLOAD_LRO_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
+ (1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
+ (1ULL << VIRTIO_NET_F_GUEST_ECN) | \
+ (1ULL << VIRTIO_NET_F_GUEST_UFO))
+
struct virtnet_stat_desc {
char desc[ETH_GSTRING_LEN];
size_t offset;
@@ -2572,7 +2577,8 @@ static int virtnet_set_features(struct net_device *dev,
if (features & NETIF_F_LRO)
offloads = vi->guest_offloads_capable;
else
- offloads = 0;
+ offloads = vi->guest_offloads_capable &
+ ~GUEST_OFFLOAD_LRO_MASK;

err = virtnet_set_guest_offloads(vi, offloads);
if (err)
--
2.25.1