[PATCH AUTOSEL 4.14 31/35] virtio-net: disable guest csum during XDP set

Sasha Levin
2018-11-29T06:03:16Z

From: Jason Wang <jasowang@redhat.com>

[ Upstream commit e59ff2c49ae16e1d179de679aca81405829aee6c ]

We don't disable VIRTIO_NET_F_GUEST_CSUM if XDP was set. This means we
can receive partial csumed packets with metadata kept in the
vnet_hdr. This may have several side effects:

- It could be overridden by header adjustment, thus is might be not
correct after XDP processing.
- There's no way to pass such metadata information through
XDP_REDIRECT to another driver.
- XDP does not support checksum offload right now.

So simply disable guest csum if possible in this the case of XDP.

Fixes: 3f93522ffab2d ("virtio-net: switch off offloads on demand if possible on XDP set")
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pavel Popa <pashinho1990@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.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, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f528e9ac3413..2ffa7b290591 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -61,7 +61,8 @@ static const unsigned long guest_offloads[] = {
VIRTIO_NET_F_GUEST_TSO4,
VIRTIO_NET_F_GUEST_TSO6,
VIRTIO_NET_F_GUEST_ECN,
- VIRTIO_NET_F_GUEST_UFO
+ VIRTIO_NET_F_GUEST_UFO,
+ VIRTIO_NET_F_GUEST_CSUM
};

struct virtnet_stats {
@@ -1939,9 +1940,6 @@ static int virtnet_clear_guest_offloads(struct virtnet_info *vi)
if (!vi->guest_offloads)
return 0;

- if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
- offloads = 1ULL << VIRTIO_NET_F_GUEST_CSUM;
-
return virtnet_set_guest_offloads(vi, offloads);
}

@@ -1951,8 +1949,6 @@ static int virtnet_restore_guest_offloads(struct virtnet_info *vi)

if (!vi->guest_offloads)
return 0;
- if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
- offloads |= 1ULL << VIRTIO_NET_F_GUEST_CSUM;

return virtnet_set_guest_offloads(vi, offloads);
}
--
2.17.1