netdev - Re: [PATCH net-next v2] virtio-net: ethtool configurable RXCSUM

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Message-ID: <CAMDZJNWX=3ikS5f0H+xD-dByW2=JHXjvk1=R=CkDLt0TW-orTg@mail.gmail.com>
Date:   Fri, 9 Oct 2020 09:16:14 +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 net-next v2] virtio-net: ethtool configurable RXCSUM

On Wed, Sep 30, 2020 at 6:05 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> On Wed, Sep 30, 2020 at 4:05 AM <xiangxia.m.yue@...il.com> wrote:
> >
> > From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> >
> > Allow user configuring RXCSUM separately with ethtool -K,
> > reusing the existing virtnet_set_guest_offloads helper
> > that configures RXCSUM for XDP. This is conditional on
> > VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.
> >
> > If Rx checksum is disabled, LRO should also be disabled.
> >
> > Cc: Michael S. Tsirkin <mst@...hat.com>
> > Cc: Jason Wang <jasowang@...hat.com>
> > Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
>
> The first patch was merged into net.
>
> Please wait until that is merged into net-next, as this depends on the
> other patch.
>
> > ---
> > v2:
> > * LRO depends the rx csum
> > * remove the unnecessary check
> > ---
> >  drivers/net/virtio_net.c | 49 ++++++++++++++++++++++++++++++----------
> >  1 file changed, 37 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 21b71148c532..5407a0106771 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -68,6 +68,8 @@ static const unsigned long guest_offloads[] = {
> >                                 (1ULL << VIRTIO_NET_F_GUEST_ECN)  | \
> >                                 (1ULL << VIRTIO_NET_F_GUEST_UFO))
> >
> > +#define GUEST_OFFLOAD_CSUM_MASK (1ULL << VIRTIO_NET_F_GUEST_CSUM)
> > +
> >  struct virtnet_stat_desc {
> >         char desc[ETH_GSTRING_LEN];
> >         size_t offset;
> > @@ -2522,29 +2524,49 @@ static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
> >         return 0;
> >  }
> >
> > +static netdev_features_t virtnet_fix_features(struct net_device *netdev,
> > +                                             netdev_features_t features)
> > +{
> > +       /* If Rx checksum is disabled, LRO should also be disabled.
> > +        * That is life. :)
>
> Please remove this second line.
OK
> > +        */
> > +       if (!(features & NETIF_F_RXCSUM))
> > +               features &= ~NETIF_F_LRO;
> > +
> > +       return features;
> > +}
> > +
> >  static int virtnet_set_features(struct net_device *dev,
> >                                 netdev_features_t features)
> >  {
> >         struct virtnet_info *vi = netdev_priv(dev);
> > -       u64 offloads;
> > +       u64 offloads = vi->guest_offloads &
> > +                      vi->guest_offloads_capable;
>
> When can vi->guest_offloads have bits set outside the mask of
> vi->guest_offloads_capable?
In this case, we can use only vi->guest_offloads. and
guest_offloads_capable will not be used any more.
so should we remove guest_offloads_capable ?


-- 
Best regards, Tonghao