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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 EAA5DC433B4 for ; Mon, 12 Apr 2021 08:46:55 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 91C4961243 for ; Mon, 12 Apr 2021 08:46:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 91C4961243 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 5EC7A83843; Mon, 12 Apr 2021 08:46:55 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1uVNx633EzGS; Mon, 12 Apr 2021 08:46:54 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTP id E1E058375B; Mon, 12 Apr 2021 08:46:53 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 99ECFC000C; Mon, 12 Apr 2021 08:46:53 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 62B57C000A for ; Mon, 12 Apr 2021 08:46:51 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 3B18B4037D for ; Mon, 12 Apr 2021 08:46:51 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp4.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=linuxfoundation.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id XD8QYtBvf3xa for ; Mon, 12 Apr 2021 08:46:49 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp4.osuosl.org (Postfix) with ESMTPS id DCF2140354 for ; Mon, 12 Apr 2021 08:46:49 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 1716C61247; Mon, 12 Apr 2021 08:46:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1618217209; bh=trgiaBG4kEh8rt00jC3X9zIWjcQ2Ue7UylSCEk2Qjkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LCS9HHt9hGdaA5G3mvAWUYwLKjCXSGKuZra4FCJFT3++uPN0sTHU1nOzwn83izMIs CL3cBGc3ow9oY7Pt2Q/D3LRQXnnHpuP4y+oMaR1pxL8Hhv536GdMnPfYgs7E0T0dgE 0sbJX6VrKkfjMy3GyUkgh5sMiFKPRYTg/loMcoy0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Subject: [PATCH 5.4 042/111] virtio_net: Do not pull payload in skb->head Date: Mon, 12 Apr 2021 10:40:20 +0200 Message-Id: <20210412084005.653952525@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210412084004.200986670@linuxfoundation.org> References: <20210412084004.200986670@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Cc: Sasha Levin , Xuan Zhuo , "Michael S. Tsirkin" , Greg Kroah-Hartman , stable@vger.kernel.org, virtualization@lists.linux-foundation.org, Eric Dumazet , "David S. Miller" X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" From: Eric Dumazet [ Upstream commit 0f6925b3e8da0dbbb52447ca8a8b42b371aac7db ] Xuan Zhuo reported that commit 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs") brought a ~10% performance drop. The reason for the performance drop was that GRO was forced to chain sk_buff (using skb_shinfo(skb)->frag_list), which uses more memory but also cause packet consumers to go over a lot of overhead handling all the tiny skbs. It turns out that virtio_net page_to_skb() has a wrong strategy : It allocates skbs with GOOD_COPY_LEN (128) bytes in skb->head, then copies 128 bytes from the page, before feeding the packet to GRO stack. This was suboptimal before commit 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs") because GRO was using 2 frags per MSS, meaning we were not packing MSS with 100% efficiency. Fix is to pull only the ethernet header in page_to_skb() Then, we change virtio_net_hdr_to_skb() to pull the missing headers, instead of assuming they were already pulled by callers. This fixes the performance regression, but could also allow virtio_net to accept packets with more than 128bytes of headers. Many thanks to Xuan Zhuo for his report, and his tests/help. Fixes: 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs") Reported-by: Xuan Zhuo Link: https://www.spinics.net/lists/netdev/msg731397.html Co-Developed-by: Xuan Zhuo Signed-off-by: Xuan Zhuo Signed-off-by: Eric Dumazet Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: virtualization@lists.linux-foundation.org Acked-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/virtio_net.c | 10 +++++++--- include/linux/virtio_net.h | 14 +++++++++----- 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index b67460864b3c..d8ee001d8e8e 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -406,9 +406,13 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, offset += hdr_padded_len; p += hdr_padded_len; - copy = len; - if (copy > skb_tailroom(skb)) - copy = skb_tailroom(skb); + /* Copy all frame if it fits skb->head, otherwise + * we let virtio_net_hdr_to_skb() and GRO pull headers as needed. + */ + if (len <= skb_tailroom(skb)) + copy = len; + else + copy = ETH_HLEN + metasize; skb_put_data(skb, p, copy); if (metasize) { diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index 98775d7fa696..b465f8f3e554 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -65,14 +65,18 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, skb_reset_mac_header(skb); if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) { - u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start); - u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset); + u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start); + u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset); + u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16)); + + if (!pskb_may_pull(skb, needed)) + return -EINVAL; if (!skb_partial_csum_set(skb, start, off)) return -EINVAL; p_off = skb_transport_offset(skb) + thlen; - if (p_off > skb_headlen(skb)) + if (!pskb_may_pull(skb, p_off)) return -EINVAL; } else { /* gso packets without NEEDS_CSUM do not set transport_offset. @@ -102,14 +106,14 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, } p_off = keys.control.thoff + thlen; - if (p_off > skb_headlen(skb) || + if (!pskb_may_pull(skb, p_off) || keys.basic.ip_proto != ip_proto) return -EINVAL; skb_set_transport_header(skb, keys.control.thoff); } else if (gso_type) { p_off = thlen; - if (p_off > skb_headlen(skb)) + if (!pskb_may_pull(skb, p_off)) return -EINVAL; } } -- 2.30.2 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization