From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3015C35249 for ; Wed, 5 Feb 2020 04:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A89D221582 for ; Wed, 5 Feb 2020 04:11:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="i2c9SGzP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727873AbgBEELC (ORCPT ); Tue, 4 Feb 2020 23:11:02 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:43677 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727836AbgBEELC (ORCPT ); Tue, 4 Feb 2020 23:11:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580875859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mZTJknh5sK2MHEpZvb12IRTeffrqu13C1stnHofSxGc=; b=i2c9SGzPwJjBraJ0xuFwFHw0Hf5RbezHTExtE72hHC3dGdvowqdokuHTEX/adsHtP+tumn QpE4CH4rHOFxJ+ZPkn8R+SqgRNRWq9KQp2XSC35+0g8XgU0YaaEfmVKAjD5e15XOIaSOGQ u2jWAet/us/cgJXxR54Y4+7WlUSVjC8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-197-cUk5z23YN_Se3RSdtgiohw-1; Tue, 04 Feb 2020 23:10:55 -0500 X-MC-Unique: cUk5z23YN_Se3RSdtgiohw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D114D1081FA1; Wed, 5 Feb 2020 04:10:52 +0000 (UTC) Received: from [10.72.13.188] (ovpn-13-188.pek2.redhat.com [10.72.13.188]) by smtp.corp.redhat.com (Postfix) with ESMTP id F17277792B; Wed, 5 Feb 2020 04:10:44 +0000 (UTC) Subject: Re: [PATCH bpf-next v4] virtio_net: add XDP meta data support To: Yuya Kusakabe Cc: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, hawk@kernel.org, john.fastabend@gmail.com, kafai@fb.com, mst@redhat.com, songliubraving@fb.com, yhs@fb.com, kuba@kernel.org, andriin@fb.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org References: <8da1b560-3128-b885-b453-13de5c7431fb@redhat.com> <20200204071655.94474-1-yuya.kusakabe@gmail.com> From: Jason Wang Message-ID: <9a0a1469-c8a7-8223-a4d5-dad656a142fc@redhat.com> Date: Wed, 5 Feb 2020 12:10:43 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200204071655.94474-1-yuya.kusakabe@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 2020/2/4 =E4=B8=8B=E5=8D=883:16, Yuya Kusakabe wrote: > Implement support for transferring XDP meta data into skb for > virtio_net driver; before calling into the program, xdp.data_meta point= s > to xdp.data and copy vnet header to the front of xdp.data_hard_start > to avoid overwriting it, where on program return with pass verdict, > we call into skb_metadata_set(). > > Fixes: de8f3a83b0a0 ("bpf: add meta pointer for direct access") > Signed-off-by: Yuya Kusakabe > --- > drivers/net/virtio_net.c | 47 ++++++++++++++++++++++++++++-----------= - > 1 file changed, 33 insertions(+), 14 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 2fe7a3188282..5fdd6ea0e3f1 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -371,7 +371,7 @@ static struct sk_buff *page_to_skb(struct virtnet_i= nfo *vi, > struct receive_queue *rq, > struct page *page, unsigned int offset, > unsigned int len, unsigned int truesize, > - bool hdr_valid) > + bool hdr_valid, unsigned int metasize) > { > struct sk_buff *skb; > struct virtio_net_hdr_mrg_rxbuf *hdr; > @@ -393,7 +393,7 @@ static struct sk_buff *page_to_skb(struct virtnet_i= nfo *vi, > else > hdr_padded_len =3D sizeof(struct padded_vnet_hdr); > =20 > - if (hdr_valid) > + if (hdr_valid && !metasize) hdr_valid means no XDP, so I think we can remove the check for metasize=20 here and add a comment instead? > memcpy(hdr, p, hdr_len); > =20 > len -=3D hdr_len; > @@ -405,6 +405,11 @@ static struct sk_buff *page_to_skb(struct virtnet_= info *vi, > copy =3D skb_tailroom(skb); > skb_put_data(skb, p, copy); > =20 > + if (metasize) { > + __skb_pull(skb, metasize); > + skb_metadata_set(skb, metasize); > + } > + > len -=3D copy; > offset +=3D copy; > =20 > @@ -644,6 +649,7 @@ static struct sk_buff *receive_small(struct net_dev= ice *dev, > unsigned int delta =3D 0; > struct page *xdp_page; > int err; > + unsigned int metasize =3D 0; > =20 > len -=3D vi->hdr_len; > stats->bytes +=3D len; > @@ -683,10 +689,15 @@ static struct sk_buff *receive_small(struct net_d= evice *dev, > =20 > xdp.data_hard_start =3D buf + VIRTNET_RX_PAD + vi->hdr_len; > xdp.data =3D xdp.data_hard_start + xdp_headroom; > - xdp_set_data_meta_invalid(&xdp); > xdp.data_end =3D xdp.data + len; > + xdp.data_meta =3D xdp.data; > xdp.rxq =3D &rq->xdp_rxq; > orig_data =3D xdp.data; > + /* Copy the vnet header to the front of data_hard_start to avoid > + * overwriting it by XDP meta data. > + */ > + memcpy(xdp.data_hard_start - vi->hdr_len, > + xdp.data - vi->hdr_len, vi->hdr_len); I think we don't need this. And it looks to me there's a bug in the=20 current code. Commit 436c9453a1ac0 ("virtio-net: keep vnet header zeroed after=20 processing XDP") leave the a corner case for receive_small() which still=20 use: =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!delta) { =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 buf +=3D header_offset; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len); =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } /* keep zeroed vnet hdr sin= ce packet was changed by bpf */ Which seems wrong, we need check xdp_prog instead of delta. With this fixed, there's no need to care about the vnet header here=20 since we don't know whether or not packet is modified by XDP. > act =3D bpf_prog_run_xdp(xdp_prog, &xdp); > stats->xdp_packets++; > =20 > @@ -695,9 +706,11 @@ static struct sk_buff *receive_small(struct net_de= vice *dev, > /* Recalculate length in case bpf program changed it */ > delta =3D orig_data - xdp.data; > len =3D xdp.data_end - xdp.data; > + metasize =3D xdp.data - xdp.data_meta; > break; > case XDP_TX: > stats->xdp_tx++; > + xdp.data_meta =3D xdp.data; I think we should remove the xdp_set_data_meta_invalid() at least? And=20 move this initialization just after xdp.data is initialized. Testing receive_small() requires to disable mrg_rxbuf, guest_tso4,=20 guest_tso6 and guest_ufo from qemu command line. > xdpf =3D convert_to_xdp_frame(&xdp); > if (unlikely(!xdpf)) > goto err_xdp; > @@ -736,10 +749,12 @@ static struct sk_buff *receive_small(struct net_d= evice *dev, > skb_reserve(skb, headroom - delta); > skb_put(skb, len); > if (!delta) { Need to check xdp_prog (need another patch). > - buf +=3D header_offset; > - memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len); > + memcpy(skb_vnet_hdr(skb), buf + VIRTNET_RX_PAD, vi->hdr_len); > } /* keep zeroed vnet hdr since packet was changed by bpf */ > =20 > + if (metasize) > + skb_metadata_set(skb, metasize); > + > err: > return skb; > =20 > @@ -760,8 +775,8 @@ static struct sk_buff *receive_big(struct net_devic= e *dev, > struct virtnet_rq_stats *stats) > { > struct page *page =3D buf; > - struct sk_buff *skb =3D page_to_skb(vi, rq, page, 0, len, > - PAGE_SIZE, true); > + struct sk_buff *skb =3D > + page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, true, 0); > =20 > stats->bytes +=3D len - vi->hdr_len; > if (unlikely(!skb)) > @@ -793,6 +808,7 @@ static struct sk_buff *receive_mergeable(struct net= _device *dev, > unsigned int truesize; > unsigned int headroom =3D mergeable_ctx_to_headroom(ctx); > int err; > + unsigned int metasize =3D 0; > =20 > head_skb =3D NULL; > stats->bytes +=3D len - vi->hdr_len; > @@ -839,8 +855,8 @@ static struct sk_buff *receive_mergeable(struct net= _device *dev, > data =3D page_address(xdp_page) + offset; > xdp.data_hard_start =3D data - VIRTIO_XDP_HEADROOM + vi->hdr_len; > xdp.data =3D data + vi->hdr_len; > - xdp_set_data_meta_invalid(&xdp); > xdp.data_end =3D xdp.data + (len - vi->hdr_len); > + xdp.data_meta =3D xdp.data; > xdp.rxq =3D &rq->xdp_rxq; > =20 > act =3D bpf_prog_run_xdp(xdp_prog, &xdp); > @@ -852,8 +868,9 @@ static struct sk_buff *receive_mergeable(struct net= _device *dev, > * adjustments. Note other cases do not build an > * skb and avoid using offset > */ > - offset =3D xdp.data - > - page_address(xdp_page) - vi->hdr_len; > + metasize =3D xdp.data - xdp.data_meta; > + offset =3D xdp.data - page_address(xdp_page) - > + vi->hdr_len - metasize; > =20 > /* recalculate len if xdp.data or xdp.data_end were > * adjusted > @@ -863,14 +880,15 @@ static struct sk_buff *receive_mergeable(struct n= et_device *dev, > if (unlikely(xdp_page !=3D page)) { > rcu_read_unlock(); > put_page(page); > - head_skb =3D page_to_skb(vi, rq, xdp_page, > - offset, len, > - PAGE_SIZE, false); > + head_skb =3D page_to_skb(vi, rq, xdp_page, offset, > + len, PAGE_SIZE, false, > + metasize); > return head_skb; > } > break; > case XDP_TX: > stats->xdp_tx++; > + xdp.data_meta =3D xdp.data; Any reason for doing this? Thanks > xdpf =3D convert_to_xdp_frame(&xdp); > if (unlikely(!xdpf)) > goto err_xdp; > @@ -921,7 +939,8 @@ static struct sk_buff *receive_mergeable(struct net= _device *dev, > goto err_skb; > } > =20 > - head_skb =3D page_to_skb(vi, rq, page, offset, len, truesize, !xdp_pr= og); > + head_skb =3D page_to_skb(vi, rq, page, offset, len, truesize, !xdp_pr= og, > + metasize); > curr_skb =3D head_skb; > =20 > if (unlikely(!curr_skb))