virtio_net: Support the RX hash XDP hint

[PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Liang Chen 1 year, 11 months ago

For the XDP_PASS scenario of the XDP path, the skb constructed with
xdp_buff does not include the virtio header. Adding the virtio header
information back when creating the skb.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
---
 drivers/net/virtio_net.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b56828804e5f..2de46eb4c661 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 	if (unlikely(!skb))
 		goto err;
 
+	/* Store the original virtio header for subsequent use by the driver. */
+	memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);
+
 	if (metasize)
 		skb_metadata_set(skb, metasize);
 
@@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
 		head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
 		if (unlikely(!head_skb))
 			break;
+		/* Store the original virtio header for subsequent use by the driver. */
+		memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
+
 		return head_skb;
 
 	case XDP_TX:
-- 
2.40.1

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Heng Qi 1 year, 11 months ago


在 2024/1/24 下午4:57, Liang Chen 写道:
> For the XDP_PASS scenario of the XDP path, the skb constructed with
> xdp_buff does not include the virtio header. Adding the virtio header
> information back when creating the skb.
>
> Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> ---
>   drivers/net/virtio_net.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index b56828804e5f..2de46eb4c661 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
>   	if (unlikely(!skb))
>   		goto err;
>   
> +	/* Store the original virtio header for subsequent use by the driver. */
> +	memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);

If xdp push or xdp pull modifies xdp_buff, will the original header 
still apply to the modified data?

Thanks,
Heng

> +
>   	if (metasize)
>   		skb_metadata_set(skb, metasize);
>   
> @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
>   		head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
>   		if (unlikely(!head_skb))
>   			break;
> +		/* Store the original virtio header for subsequent use by the driver. */
> +		memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> +
>   		return head_skb;
>   
>   	case XDP_TX:

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Liang Chen 1 year, 11 months ago

On Wed, Jan 24, 2024 at 7:04 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
>
>
>
> 在 2024/1/24 下午4:57, Liang Chen 写道:
> > For the XDP_PASS scenario of the XDP path, the skb constructed with
> > xdp_buff does not include the virtio header. Adding the virtio header
> > information back when creating the skb.
> >
> > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> > ---
> >   drivers/net/virtio_net.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index b56828804e5f..2de46eb4c661 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
> >       if (unlikely(!skb))
> >               goto err;
> >
> > +     /* Store the original virtio header for subsequent use by the driver. */
> > +     memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);
>
> If xdp push or xdp pull modifies xdp_buff, will the original header
> still apply to the modified data?
>

No, it would be an issue then. Anyway, this patch will be dropped in v3. Thanks.

> Thanks,
> Heng
>
> > +
> >       if (metasize)
> >               skb_metadata_set(skb, metasize);
> >
> > @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> >               head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
> >               if (unlikely(!head_skb))
> >                       break;
> > +             /* Store the original virtio header for subsequent use by the driver. */
> > +             memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> > +
> >               return head_skb;
> >
> >       case XDP_TX:
>

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Xuan Zhuo 1 year, 11 months ago

On Wed, 24 Jan 2024 16:57:20 +0800, Liang Chen <liangchen.linux@gmail.com> wrote:
> For the XDP_PASS scenario of the XDP path, the skb constructed with
> xdp_buff does not include the virtio header. Adding the virtio header
> information back when creating the skb.
>
> Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> ---
>  drivers/net/virtio_net.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index b56828804e5f..2de46eb4c661 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
>  	if (unlikely(!skb))
>  		goto err;
>
> +	/* Store the original virtio header for subsequent use by the driver. */
> +	memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);

About this, a spec is waiting for voting.

This may change the logic of the csum offset and so on.

Please not do this.

Thanks.


> +
>  	if (metasize)
>  		skb_metadata_set(skb, metasize);
>
> @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
>  		head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
>  		if (unlikely(!head_skb))
>  			break;
> +		/* Store the original virtio header for subsequent use by the driver. */
> +		memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> +
>  		return head_skb;
>
>  	case XDP_TX:
> --
> 2.40.1
>

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Liang Chen 1 year, 11 months ago

On Wed, Jan 24, 2024 at 5:16 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Wed, 24 Jan 2024 16:57:20 +0800, Liang Chen <liangchen.linux@gmail.com> wrote:
> > For the XDP_PASS scenario of the XDP path, the skb constructed with
> > xdp_buff does not include the virtio header. Adding the virtio header
> > information back when creating the skb.
> >
> > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> > ---
> >  drivers/net/virtio_net.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index b56828804e5f..2de46eb4c661 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
> >       if (unlikely(!skb))
> >               goto err;
> >
> > +     /* Store the original virtio header for subsequent use by the driver. */
> > +     memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);
>
> About this, a spec is waiting for voting.
>
> This may change the logic of the csum offset and so on.
>
> Please not do this.
>

Sure. This will be dropped in v3. Thanks.

> Thanks.
>
>
> > +
> >       if (metasize)
> >               skb_metadata_set(skb, metasize);
> >
> > @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> >               head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
> >               if (unlikely(!head_skb))
> >                       break;
> > +             /* Store the original virtio header for subsequent use by the driver. */
> > +             memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> > +
> >               return head_skb;
> >
> >       case XDP_TX:
> > --
> > 2.40.1
> >

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Jason Wang 1 year, 11 months ago

On Wed, Jan 24, 2024 at 5:16 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Wed, 24 Jan 2024 16:57:20 +0800, Liang Chen <liangchen.linux@gmail.com> wrote:
> > For the XDP_PASS scenario of the XDP path, the skb constructed with
> > xdp_buff does not include the virtio header. Adding the virtio header
> > information back when creating the skb.
> >
> > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> > ---
> >  drivers/net/virtio_net.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index b56828804e5f..2de46eb4c661 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
> >       if (unlikely(!skb))
> >               goto err;
> >
> > +     /* Store the original virtio header for subsequent use by the driver. */
> > +     memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);
>
> About this, a spec is waiting for voting.
>

A pointer?

> This may change the logic of the csum offset and so on.

 Btw, doesn't it need a new feature bit?

Thanks

>
> Please not do this.
>
> Thanks.
>
>
> > +
> >       if (metasize)
> >               skb_metadata_set(skb, metasize);
> >
> > @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> >               head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
> >               if (unlikely(!head_skb))
> >                       break;
> > +             /* Store the original virtio header for subsequent use by the driver. */
> > +             memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> > +
> >               return head_skb;
> >
> >       case XDP_TX:
> > --
> > 2.40.1
> >
>

Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

Posted by Xuan Zhuo 1 year, 11 months ago

On Thu, 25 Jan 2024 11:48:18 +0800, Jason Wang <jasowang@redhat.com> wrote:
> On Wed, Jan 24, 2024 at 5:16 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
> >
> > On Wed, 24 Jan 2024 16:57:20 +0800, Liang Chen <liangchen.linux@gmail.com> wrote:
> > > For the XDP_PASS scenario of the XDP path, the skb constructed with
> > > xdp_buff does not include the virtio header. Adding the virtio header
> > > information back when creating the skb.
> > >
> > > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> > > ---
> > >  drivers/net/virtio_net.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index b56828804e5f..2de46eb4c661 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
> > >       if (unlikely(!skb))
> > >               goto err;
> > >
> > > +     /* Store the original virtio header for subsequent use by the driver. */
> > > +     memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);
> >
> > About this, a spec is waiting for voting.
> >
>
> A pointer?

Sorry.

http://lore.kernel.org/all/1704263702-50528-1-git-send-email-hengqi@linux.alibaba.com


>
> > This may change the logic of the csum offset and so on.
>
>  Btw, doesn't it need a new feature bit?

Yes.

But this patch set should not include this.
We may do the similar thing, but the commit log will
include more info about the spec.

Thanks.


>
> Thanks
>
> >
> > Please not do this.
> >
> > Thanks.
> >
> >
> > > +
> > >       if (metasize)
> > >               skb_metadata_set(skb, metasize);
> > >
> > > @@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
> > >               head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz);
> > >               if (unlikely(!head_skb))
> > >                       break;
> > > +             /* Store the original virtio header for subsequent use by the driver. */
> > > +             memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, vi->hdr_len);
> > > +
> > >               return head_skb;
> > >
> > >       case XDP_TX:
> > > --
> > > 2.40.1
> > >
> >
>