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=-8.3 required=3.0 tests=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 C2B15C606CF for ; Tue, 9 Jul 2019 03:04:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D22F21537 for ; Tue, 9 Jul 2019 03:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727132AbfGIDEv (ORCPT ); Mon, 8 Jul 2019 23:04:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33764 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725886AbfGIDEv (ORCPT ); Mon, 8 Jul 2019 23:04:51 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D0ABF30C1321; Tue, 9 Jul 2019 03:04:49 +0000 (UTC) Received: from [10.72.12.197] (ovpn-12-197.pek2.redhat.com [10.72.12.197]) by smtp.corp.redhat.com (Postfix) with ESMTP id 21B6C5D9E5; Tue, 9 Jul 2019 03:04:41 +0000 (UTC) Subject: Re: [PATCH bpf-next v3] virtio_net: add XDP meta data support To: Daniel Borkmann , Yuya Kusakabe Cc: ast@kernel.org, davem@davemloft.net, hawk@kernel.org, jakub.kicinski@netronome.com, john.fastabend@gmail.com, kafai@fb.com, mst@redhat.com, netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com References: <32dc2f4e-4f19-4fa5-1d24-17a025a08297@gmail.com> <20190702081646.23230-1-yuya.kusakabe@gmail.com> <52e3fc0d-bdd7-83ee-58e6-488e2b91cc83@gmail.com> From: Jason Wang Message-ID: Date: Tue, 9 Jul 2019 11:04:40 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Tue, 09 Jul 2019 03:04:50 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/7/9 上午6:38, Daniel Borkmann wrote: > On 07/02/2019 04:11 PM, Yuya Kusakabe wrote: >> On 7/2/19 5:33 PM, Jason Wang wrote: >>> On 2019/7/2 下午4:16, Yuya Kusakabe wrote: >>>> This adds XDP meta data support to both receive_small() and >>>> receive_mergeable(). >>>> >>>> Fixes: de8f3a83b0a0 ("bpf: add meta pointer for direct access") >>>> Signed-off-by: Yuya Kusakabe >>>> --- >>>> v3: >>>>   - fix preserve the vnet header in receive_small(). >>>> v2: >>>>   - keep copy untouched in page_to_skb(). >>>>   - preserve the vnet header in receive_small(). >>>>   - fix indentation. >>>> --- >>>>   drivers/net/virtio_net.c | 45 +++++++++++++++++++++++++++------------- >>>>   1 file changed, 31 insertions(+), 14 deletions(-) >>>> >>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>> index 4f3de0ac8b0b..03a1ae6fe267 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_info *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_info *vi, >>>>       else >>>>           hdr_padded_len = sizeof(struct padded_vnet_hdr); >>>>   -    if (hdr_valid) >>>> +    if (hdr_valid && !metasize) >>>>           memcpy(hdr, p, hdr_len); >>>>         len -= hdr_len; >>>> @@ -405,6 +405,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, >>>>           copy = skb_tailroom(skb); >>>>       skb_put_data(skb, p, copy); >>>>   +    if (metasize) { >>>> +        __skb_pull(skb, metasize); >>>> +        skb_metadata_set(skb, metasize); >>>> +    } >>>> + >>>>       len -= copy; >>>>       offset += copy; >>>>   @@ -644,6 +649,7 @@ static struct sk_buff *receive_small(struct net_device *dev, >>>>       unsigned int delta = 0; >>>>       struct page *xdp_page; >>>>       int err; >>>> +    unsigned int metasize = 0; >>>>         len -= vi->hdr_len; >>>>       stats->bytes += len; >>>> @@ -683,10 +689,13 @@ static struct sk_buff *receive_small(struct net_device *dev, >>>>             xdp.data_hard_start = buf + VIRTNET_RX_PAD + vi->hdr_len; >>>>           xdp.data = xdp.data_hard_start + xdp_headroom; >>>> -        xdp_set_data_meta_invalid(&xdp); >>>>           xdp.data_end = xdp.data + len; >>>> +        xdp.data_meta = xdp.data; >>>>           xdp.rxq = &rq->xdp_rxq; >>>>           orig_data = xdp.data; >>>> +        /* Copy the vnet header to the front of data_hard_start to avoid >>>> +         * overwriting by XDP meta data */ >>>> +        memcpy(xdp.data_hard_start - vi->hdr_len, xdp.data - vi->hdr_len, vi->hdr_len); > I'm not fully sure if I'm following this one correctly, probably just missing > something. Isn't the vnet header based on how we set up xdp.data_hard_start > earlier already in front of it? Wouldn't we copy invalid data from xdp.data - > vi->hdr_len into the vnet header at that point (given there can be up to 256 > bytes of headroom between the two)? If it's relative to xdp.data and headroom > is >0, then BPF prog could otherwise mangle this; something doesn't add up to > me here. Could you clarify? Thx Vnet headr sits just in front of xdp.data not xdp.data_hard_start. So it could be overwrote by metadata, that's why we need a copy here. Thanks > >>> What happens if we have a large metadata that occupies all headroom here? >>> >>> Thanks >> Do you mean a large "XDP" metadata? If a large metadata is a large "XDP" metadata, I think we can not use a metadata that occupies all headroom. The size of metadata limited by bpf_xdp_adjust_meta() as below. >> bpf_xdp_adjust_meta() in net/core/filter.c: >> if (unlikely((metalen & (sizeof(__u32) - 1)) || >> (metalen > 32))) >> return -EACCES; >> >> Thanks. >> >>> >>>>           act = bpf_prog_run_xdp(xdp_prog, &xdp); >>>>           stats->xdp_packets++; >>>>   @@ -695,9 +704,11 @@ static struct sk_buff *receive_small(struct net_device *dev, >>>>               /* Recalculate length in case bpf program changed it */ >>>>               delta = orig_data - xdp.data; >>>>               len = xdp.data_end - xdp.data; >>>> +            metasize = xdp.data - xdp.data_meta; >>>>               break; >>>>           case XDP_TX: >>>>               stats->xdp_tx++; >>>> +            xdp.data_meta = xdp.data; >>>>               xdpf = convert_to_xdp_frame(&xdp); >>>>               if (unlikely(!xdpf)) >>>>                   goto err_xdp; >>>> @@ -736,10 +747,12 @@ static struct sk_buff *receive_small(struct net_device *dev, >>>>       skb_reserve(skb, headroom - delta); >>>>       skb_put(skb, len); >>>>       if (!delta) { >>>> -        buf += 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 */ >>>>   +    if (metasize) >>>> +        skb_metadata_set(skb, metasize); >>>> + >>>>   err: >>>>       return skb; >>>>   @@ -760,8 +773,8 @@ static struct sk_buff *receive_big(struct net_device *dev, >>>>                      struct virtnet_rq_stats *stats) >>>>   { >>>>       struct page *page = buf; >>>> -    struct sk_buff *skb = page_to_skb(vi, rq, page, 0, len, >>>> -                      PAGE_SIZE, true); >>>> +    struct sk_buff *skb = >>>> +        page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, true, 0); >>>>         stats->bytes += len - vi->hdr_len; >>>>       if (unlikely(!skb)) >>>> @@ -793,6 +806,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>>>       unsigned int truesize; >>>>       unsigned int headroom = mergeable_ctx_to_headroom(ctx); >>>>       int err; >>>> +    unsigned int metasize = 0; >>>>         head_skb = NULL; >>>>       stats->bytes += len - vi->hdr_len; >>>> @@ -839,8 +853,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>>>           data = page_address(xdp_page) + offset; >>>>           xdp.data_hard_start = data - VIRTIO_XDP_HEADROOM + vi->hdr_len; >>>>           xdp.data = data + vi->hdr_len; >>>> -        xdp_set_data_meta_invalid(&xdp); >>>>           xdp.data_end = xdp.data + (len - vi->hdr_len); >>>> +        xdp.data_meta = xdp.data; >>>>           xdp.rxq = &rq->xdp_rxq; >>>>             act = bpf_prog_run_xdp(xdp_prog, &xdp); >>>> @@ -852,8 +866,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>>>                * adjustments. Note other cases do not build an >>>>                * skb and avoid using offset >>>>                */ >>>> -            offset = xdp.data - >>>> -                    page_address(xdp_page) - vi->hdr_len; >>>> +            metasize = xdp.data - xdp.data_meta; >>>> +            offset = xdp.data - page_address(xdp_page) - >>>> +                 vi->hdr_len - metasize; >>>>                 /* recalculate len if xdp.data or xdp.data_end were >>>>                * adjusted >>>> @@ -863,14 +878,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>>>               if (unlikely(xdp_page != page)) { >>>>                   rcu_read_unlock(); >>>>                   put_page(page); >>>> -                head_skb = page_to_skb(vi, rq, xdp_page, >>>> -                               offset, len, >>>> -                               PAGE_SIZE, false); >>>> +                head_skb = 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 = xdp.data; >>>>               xdpf = convert_to_xdp_frame(&xdp); >>>>               if (unlikely(!xdpf)) >>>>                   goto err_xdp; >>>> @@ -921,7 +937,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>>>           goto err_skb; >>>>       } >>>>   -    head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog); >>>> +    head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog, >>>> +                   metasize); >>>>       curr_skb = head_skb; >>>>         if (unlikely(!curr_skb))