From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C9E75366DA0 for ; Wed, 19 Nov 2025 15:27:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763566078; cv=none; b=YO8Nv1uJEiaCRphrafpxokiF7/qwFWvW/7oddQlUPhMkxCfsqty4iL49iQmB66ZGupsX6tdDmUttlYSEtTLaWLN5YV7bFevCeVbk4ngALIaXcG0CudZ7UapoS2GwFOeTq6cZ69jBPGcnzbVHLHbHOTm9iGG1kCjwsvMW64iNajk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763566078; c=relaxed/simple; bh=2AHtk/lQXbNZZpPx6nfAIJ2au2S7m30j106Z1+vqVM4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=obTaSzGm1cs3/pRq/YQHHZro6Ofa6v6NHHDNr5O+GOVxQEoiemmXiJ0qqAYs6gu/mtFLJiy/G7DHk09as/wiwlPnCM6Fj+DcbZupd+krzv+5KAb48FjZX24QYvsYbYemyLbB7pPtfmJ0JQJ7+Y8AXn89764yYDLKfTkBfoNjnlY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=O8P9DelU; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O8P9DelU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763566075; 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: in-reply-to:in-reply-to:references:references; bh=eHlhvFLfyKP0IuFGERbeyuWea/xjnUWPpjGJ0qsZJv4=; b=O8P9DelUEUVe/ZPwFA15GwCudvZFaDp/QdfgXlUnHgdISFx20DRpG4iEyLU5bIeyaosLVT J9hFsMnyGPPV+hrs9n3VXSOD0+aPkHBj/yB5NHUrpKBDAlpgvv3M0pCiPKOtWSrGhaQ0Q5 Fyt2imVQpDUTepLYky1I0f8V3UdvYM8= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-663-UEIJCBvLNWuC4fpThhnD7w-1; Wed, 19 Nov 2025 10:27:52 -0500 X-MC-Unique: UEIJCBvLNWuC4fpThhnD7w-1 X-Mimecast-MFC-AGG-ID: UEIJCBvLNWuC4fpThhnD7w_1763566071 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-47775585257so52495045e9.1 for ; Wed, 19 Nov 2025 07:27:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763566071; x=1764170871; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=eHlhvFLfyKP0IuFGERbeyuWea/xjnUWPpjGJ0qsZJv4=; b=jFU2/UUWN9M2wrPQP2NuaivaqOySwEhZDQOWgNzbV1t8QndRMyyvaz071aQ0qiYpJ3 m7v0jSE3fg7VXjyOgfGcjukbO1V9poRBlWcefJiGnEDucWnyIIw5CxTkFEpoA/uQJ412 44UgCrIvvsdudNpugCDYscXcvYAWx5UThsU24tyAENDh/CJvIom1lPvNHpH7FTZyFHed LHtByp9gtMMC2Ex/9+havbmnDxgUy5PY2ibFiZPWQ6o1NQAC6HWAe14rFKKeypJriPwK j75UW+HgJWlGhLuqb5A/tIfrkKJXWia2sL5aVn/h4XPV0BQzsQMrN4q244B1Kf3l+2Z5 fymQ== X-Forwarded-Encrypted: i=1; AJvYcCWMIkV346JbhB0OGUxp3X+CA3BvU2jgm/x0871kCAy+oKv6RLrh1F7Q0ubrylQ35XzGcRGa6MElqCNdv2FiHA==@lists.linux.dev X-Gm-Message-State: AOJu0YxpPszL2hb/k6z0oBIBRXV+HWefdTX+K/aobO2KOmL9D9/qVY3e Xm5BoU5CAouVU+fr55uhpVAYDbnX5YaoY8I93ohHgZIKVuNDvGNXGwunPeTJqp/qePkEFthRMoQ Ioo9x8LAUaiJkiUy9xbT8KvXeVnGHflvRiSPPVBk5CDBiD8fRfpPcDwVKNHfS2RO0PIBa X-Gm-Gg: ASbGnctWoYCY14CapN4WQryltkpeyUAnHx07Jn+1fKZ+NfeB5JkZElrooTv8njh6jND hbFobOGC70Tn7+l7msyANHTLhNENY79Oj4kmMAjhHOpg1+k/1TEoS2qXq24/leqSN3gwG4aJmO3 oomZn9tMAC7s8FgKF+S0vgyblAWiUdEeHP1ITRk/9f0Y2d/oaOP0/wlwBnSefeUof/qR6JO91cw /6XkaIl5dFu5MriSa2q/ssAHCQlscpahm2SILQhdBJmcjFb9pRzNNn7H8BO4Lo0vNaY49OiBKMG 8r7JVTuhK4bb6Rf0oe3MfgNOQkTyA9l3+QSjDR8zJRu7SYXtFFEhRMKApEFliUSPMXowz/Cqkeb bUH/sHwf9FGc99HkXjrcpYzypsbqaUA== X-Received: by 2002:a05:600c:4995:b0:477:9671:3a42 with SMTP id 5b1f17b1804b1-47796713b41mr111156685e9.35.1763566070984; Wed, 19 Nov 2025 07:27:50 -0800 (PST) X-Google-Smtp-Source: AGHT+IGCuJHBRec3mpLMUz50uZ6t1pbpsWtDxU16tpLG7QVSudm09TacV9uCNP3CKm0YHndmXcfHlg== X-Received: by 2002:a05:600c:4995:b0:477:9671:3a42 with SMTP id 5b1f17b1804b1-47796713b41mr111156385e9.35.1763566070324; Wed, 19 Nov 2025 07:27:50 -0800 (PST) Received: from redhat.com (IGLD-80-230-39-63.inter.net.il. [80.230.39.63]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477afb54774sm26915625e9.3.2025.11.19.07.27.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Nov 2025 07:27:49 -0800 (PST) Date: Wed, 19 Nov 2025 10:27:46 -0500 From: "Michael S. Tsirkin" To: Xuan Zhuo Cc: netdev@vger.kernel.org, Willem de Bruijn , Jason Wang , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Eugenio =?iso-8859-1?Q?P=E9rez?= , Jiri Pirko , Alvaro Karsz , virtualization@lists.linux.dev Subject: Re: [PATCH net v6 1/2] virtio-net: correct hdr_len handling for VIRTIO_NET_F_GUEST_HDRLEN Message-ID: <20251119102708-mutt-send-email-mst@kernel.org> References: <20251119055522.617-1-xuanzhuo@linux.alibaba.com> <20251119055522.617-2-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20251119055522.617-2-xuanzhuo@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: y7iz8K-KK0GODR3pjXBMhflLAfM2Lort7sA3IrxDS98_1763566071 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Nov 19, 2025 at 01:55:21PM +0800, Xuan Zhuo wrote: > The commit be50da3e9d4a ("net: virtio_net: implement exact header length > guest feature") introduces support for the VIRTIO_NET_F_GUEST_HDRLEN > feature in virtio-net. > > This feature requires virtio-net to set hdr_len to the actual header > length of the packet when transmitting, the number of > bytes from the start of the packet to the beginning of the > transport-layer payload. > > However, in practice, hdr_len was being set using skb_headlen(skb), > which is clearly incorrect. This commit fixes that issue. > > Fixes: be50da3e9d4a ("net: virtio_net: implement exact header length guest feature") > Signed-off-by: Xuan Zhuo > --- > drivers/net/tun_vnet.h | 2 +- > drivers/net/virtio_net.c | 8 ++++-- > include/linux/virtio_net.h | 58 ++++++++++++++++++++++++++++++-------- > 3 files changed, 54 insertions(+), 14 deletions(-) > > diff --git a/drivers/net/tun_vnet.h b/drivers/net/tun_vnet.h > index 81662328b2c7..b06aa6f2aade 100644 > --- a/drivers/net/tun_vnet.h > +++ b/drivers/net/tun_vnet.h > @@ -244,7 +244,7 @@ tun_vnet_hdr_tnl_from_skb(unsigned int flags, > > if (virtio_net_hdr_tnl_from_skb(skb, tnl_hdr, has_tnl_offload, > tun_vnet_is_little_endian(flags), > - vlan_hlen)) { > + false, vlan_hlen)) { > struct virtio_net_hdr_v1 *hdr = &tnl_hdr->hash_hdr.hdr; > struct skb_shared_info *sinfo = skb_shinfo(skb); > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 0369dda5ed60..a62acfaf631b 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3317,9 +3317,12 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb, bool orphan) > const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest; > struct virtnet_info *vi = sq->vq->vdev->priv; > struct virtio_net_hdr_v1_hash_tunnel *hdr; > - int num_sg; > unsigned hdr_len = vi->hdr_len; > + bool guest_hdrlen; > bool can_push; > + int num_sg; > + > + guest_hdrlen = virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_HDRLEN); > > pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest); > > @@ -3339,7 +3342,8 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb, bool orphan) > hdr = &skb_vnet_common_hdr(skb)->tnl_hdr; > > if (virtio_net_hdr_tnl_from_skb(skb, hdr, vi->tx_tnl, > - virtio_is_little_endian(vi->vdev), 0)) > + virtio_is_little_endian(vi->vdev), > + guest_hdrlen, 0)) > return -EPROTO; > > if (vi->mergeable_rx_bufs) > diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h > index b673c31569f3..ee960ec9a35e 100644 > --- a/include/linux/virtio_net.h > +++ b/include/linux/virtio_net.h > @@ -207,20 +207,40 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, > return __virtio_net_hdr_to_skb(skb, hdr, little_endian, hdr->gso_type); > } > > -static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb, > - struct virtio_net_hdr *hdr, > - bool little_endian, > - bool has_data_valid, > - int vlan_hlen) > +static inline void virtio_net_set_hdrlen(const struct sk_buff *skb, > + struct virtio_net_hdr *hdr, > + bool little_endian, > + bool guest_hdrlen) > +{ > + u16 hdr_len; > + > + if (guest_hdrlen) { > + hdr_len = skb_transport_offset(skb); > + > + if (hdr->gso_type == VIRTIO_NET_HDR_GSO_UDP_L4) > + hdr_len += sizeof(struct udphdr); > + else > + hdr_len += tcp_hdrlen(skb); > + } else { > + /* This is a hint as to how much should be linear. */ > + hdr_len = skb_headlen(skb); > + } > + > + hdr->hdr_len = __cpu_to_virtio16(little_endian, hdr_len); > +} So this adds code that is broken for tunnels, then the follow up patch fixes it up. I don't feel it's worth it, just squash the two patches together please. > + > +static inline int __virtio_net_hdr_from_skb(const struct sk_buff *skb, > + struct virtio_net_hdr *hdr, > + bool little_endian, > + bool has_data_valid, > + bool guest_hdrlen, > + int vlan_hlen) > { > memset(hdr, 0, sizeof(*hdr)); /* no info leak */ > > if (skb_is_gso(skb)) { > struct skb_shared_info *sinfo = skb_shinfo(skb); > > - /* This is a hint as to how much should be linear. */ > - hdr->hdr_len = __cpu_to_virtio16(little_endian, > - skb_headlen(skb)); > hdr->gso_size = __cpu_to_virtio16(little_endian, > sinfo->gso_size); > if (sinfo->gso_type & SKB_GSO_TCPV4) > @@ -231,6 +251,10 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb, > hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4; > else > return -EINVAL; > + > + virtio_net_set_hdrlen(skb, hdr, little_endian, > + guest_hdrlen); > + > if (sinfo->gso_type & SKB_GSO_TCP_ECN) > hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN; > } else > @@ -250,6 +274,16 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb, > return 0; > } > > +static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb, > + struct virtio_net_hdr *hdr, > + bool little_endian, > + bool has_data_valid, > + int vlan_hlen) > +{ > + return __virtio_net_hdr_from_skb(skb, hdr, little_endian, > + has_data_valid, false, vlan_hlen); > +} > + > static inline unsigned int virtio_l3min(bool is_ipv6) > { > return is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr); > @@ -384,6 +418,7 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb, > struct virtio_net_hdr_v1_hash_tunnel *vhdr, > bool tnl_hdr_negotiated, > bool little_endian, > + bool guest_hdrlen, > int vlan_hlen) > { > struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)vhdr; > @@ -394,8 +429,8 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb, > tnl_gso_type = skb_shinfo(skb)->gso_type & (SKB_GSO_UDP_TUNNEL | > SKB_GSO_UDP_TUNNEL_CSUM); > if (!tnl_gso_type) > - return virtio_net_hdr_from_skb(skb, hdr, little_endian, false, > - vlan_hlen); > + return __virtio_net_hdr_from_skb(skb, hdr, little_endian, false, > + guest_hdrlen, vlan_hlen); > > /* Tunnel support not negotiated but skb ask for it. */ > if (!tnl_hdr_negotiated) > @@ -408,7 +443,8 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb, > > /* Let the basic parsing deal with plain GSO features. */ > skb_shinfo(skb)->gso_type &= ~tnl_gso_type; > - ret = virtio_net_hdr_from_skb(skb, hdr, true, false, vlan_hlen); > + ret = __virtio_net_hdr_from_skb(skb, hdr, true, false, > + guest_hdrlen, vlan_hlen); > skb_shinfo(skb)->gso_type |= tnl_gso_type; > if (ret) > return ret; > -- > 2.32.0.3.g01195cf9f