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

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Date:   Tue, 29 Sep 2020 09:40:22 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        virtualization@...ts.linux-foundation.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH 1/2] virtio-net: don't disable guest csum when disable LRO

On Tue, Sep 29, 2020 at 3:21 AM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Mon, Sep 28, 2020 at 11:39:14AM +0800, 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")
>
> I am a bit confused by this tag. Did this change bring about
> disabling checksum when LRO is disabled? I am not sure
> I follow how ...
Hi Michael
It's not right fix tag.
The commit a02e8964eaf9 ("virtio-net: ethtool configurable LRO"),
disable the csum, when we disable the LRO

> > 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