netdev - Re: [PATCH 1/2] virtio-net: don't disable guest csum when disable LRO

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Message-ID: <CAMDZJNX2yUv9rL4v++SnL34bcKRiX2zJ2Qnjni4U_SDtjeOLWQ@mail.gmail.com>
Date:   Mon, 28 Sep 2020 17:21:18 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        virtualization@...ts.linux-foundation.org,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/2] virtio-net: don't disable guest csum when disable LRO

On Mon, Sep 28, 2020 at 4:35 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> On Mon, Sep 28, 2020 at 5:41 AM <xiangxia.m.yue@...il.com> wrote:
> >
> > From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> >
> > 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: e59ff2c49ae1 ("virtio-net: disable guest csum during XDP set")
>
> Patch looks fine to me, but wrong commit here?
Yes, I will change the tag.
> That commit disables csum on purpose when enabling xdp with ndp_bpf.
>
> This patch refines disabling LRO with ndo_set_features.
>
> The relevant commit is a02e8964eaf9 ("virtio-net: ethtool configurable LRO").
>
> If this is a fix, it should target [PATCH net] separately from the
> second patch in the patchset, which is a new feature and targets
> [PATCH net-next]. They can arguably target net-next together, but then
> it should not have a fixes tag.
Thanks, I will send first patch for net, and next one to net-next.
>
> > Cc: Michael S. Tsirkin <mst@...hat.com>
> > Cc: Jason Wang <jasowang@...hat.com>
> > Cc: Willem de Bruijn <willemb@...gle.com>
> > Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> > ---
> >  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 7145c83c6c8c..21b71148c532 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;
> > @@ -2531,7 +2536,8 @@ 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)
> > --
> > 2.23.0
> >



-- 
Best regards, Tonghao