Re: [virtio-dev] Re: [PATCH v9] virtio-net: support inner header hash

[Jason Wang <jasowang@redhat.com>]

On Thu, Mar 2, 2023 at 4:41âPM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Mar 02, 2023 at 04:15:39PM +0800, Jason Wang wrote:
> > On Thu, Mar 2, 2023 at 4:10âPM Michael S. Tsirkin <mst@redhat.com> wrote:
> > >
> > > On Thu, Mar 02, 2023 at 03:57:10PM +0800, Jason Wang wrote:
> > > > Kernel had already used the eBPF program for hashing, classifying
> > > > various types of eBPF program other than XDP/socket filter
> > > > (pass/drop).
> > > >
> > > > Thanks
> > >
> > > where is it used for hashing?
> >
> > I can see it is used by team/lb:
> >
> > static unsigned int lb_get_skb_hash(struct lb_priv *lb_priv,
> >                                     struct sk_buff *skb)
> > {
> >         struct bpf_prog *fp;
> >         uint32_t lhash;
> >         unsigned char *c;
> >
> >         fp = rcu_dereference_bh(lb_priv->fp);
> >         if (unlikely(!fp))
> >                 return 0;
> >         lhash = bpf_prog_run(fp, skb);
> >         c = (char *) &lhash;
> >         return c[0] ^ c[1] ^ c[2] ^ c[3];
> > }
> >
> > But the point is that the return value is determined by the prog type
> > (or the context).
> >
> > Thanks
>
> OK so assuming we do this, how will users program this exactly?

For DPDK users, it could be integrated with the PMD.
For kernel ueres, it probably requires a virtio specific netlink or char device.

> Given this is not standard, which tools will be used to attach such
> a program to the device?

vDPA tool?

Thanks

>
>
> > >
> > > --
> > > MST
> > >
> > >
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>