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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Willem de Bruijn <willemb@google.com>,
        Tonghao Zhang <xiangxia.m.yue@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.8 077/124] virtio-net: dont disable guest csum when disable LRO
Date:   Mon, 12 Oct 2020 15:31:21 +0200
Message-Id: <20201012133150.586204035@linuxfoundation.org>
In-Reply-To: <20201012133146.834528783@linuxfoundation.org>
References: <20201012133146.834528783@linuxfoundation.org>
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From: Tonghao Zhang <xiangxia.m.yue@gmail.com>

[ 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@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 ba38765dc4905..c34927b1d806e 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;
@@ -2547,7 +2552,8 @@ 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