From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.221.182 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792527583; b=TW8995o3JEWBR2rAW+vsaf8MdysKnpDa1j51rOLWMpqvbYthxpgKVLNmrY2TrtZt7n+f Nsi5dD+8oM3lf/JeGH6sBPW1KeKP/hNA55ivcw50IURNj1LxncXzBRUiefPxzbayhJSKO xWmsWH/Byb4Xktp1UtbtiRdB6DCtJE5mjD5H+NIQyEMNb4Epw/8GKZKbToZGmg32a51fj V7ZmtPHQNsLXgDAPIQrdzYEqXqfIegU3Z6HzGuB6OT6HWhTtE0FlJ7uGELf8LCtyHeQf6 9Hn4eyq8RQiw0ZyZTJJCEiW3QOiFnIZe6hGqVqmqCdz7RqA15sXZS0l8vRtbhP/K7nA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792527583; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=mSISClxN0AquiYKdkApngEQlUAzth9oYRTtKq3bxFPE=; b=P5IOaz8xesTLvB3dssDZkHgNhtFZlp0t177AESjAdFkjWIGvilRZuiAg0xOJsuk9+8li UfLkogXZ5RqLCyh6Alqb2deixFN+2PqcDyqVf6kKBSvnwGhzYmtiDacqRFJd7in7yvR3O J3lKlFQbcRGYGtB6vMruLNpJ7sz4Kk1lAfAkTBbE21Zl1maOpzLv3dwF/N3hfMeE9RqlP iSsuVacugsBdh4w6ti9jpSgqCfnAwMb/P4pSE6MevOL3aPtQL6GCFuwPCoHJr5FSuYUoe AQszucbElvc8iqE50zbZpmlIq4wUfMcyChf7KbOaFlKpm3JWATCV0gPv6C7RpPyj6hg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=FfAkulI9; arc=none smtp.remote-ip=209.85.221.182 Received: from mail-vk1-f182.google.com (mail-vk1-f182.google.com [209.85.221.182]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DCB7606A31D for ; Tue, 20 Oct 2026 20:19:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 0DCB7606A31D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=FfAkulI9 Received: by mail-vk1-f182.google.com with SMTP id 71dfb90a1353d-5eaaa9b1591so2066642e0c.3 for ; Tue, 20 Oct 2026 13:19:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792527582; x=1793132382; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:subject :references:in-reply-to:message-id:cc:to:from:date:from:to:cc :subject:date:message-id:reply-to:content-type; bh=mSISClxN0AquiYKdkApngEQlUAzth9oYRTtKq3bxFPE=; b=FfAkulI9Bq9jgjuKbpc2WTxKrxx5qvuqmeib+YNWdNmtOnNCEb53aPjdhTqp8g/ypU bEATnZMrnnX9VXxhghW6c1iQjancMVRR+cbDqpZzhgisRRXw96qCnXr0cQ93InHBqn1h mWqkn9vB2+FbuU1J0vWLw7Zi73HtehU9Zby1eUbidAb4TXc0m7Z3uHgn+10K89TW9UEp Wq30omMyfxPtRXYMrM49K1jZOAKe3fzLxSzOBzsiNUYVU2+9D8BKlfDqnDSugiaInGSs 7zVgoLliVBJOTQpvFoJ4HqYoLiPthGxdngPMJjLEkpApX1g0WITKKvPie6TgX2XxhPJA ckfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792527582; x=1793132382; h=content-transfer-encoding:content-type:mime-version:subject :references:in-reply-to:message-id:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=mSISClxN0AquiYKdkApngEQlUAzth9oYRTtKq3bxFPE=; b=trKpBSgB7PKKmorif1LwWJXg2uDNtmp9t00SrzymwlvyS6lgRQEpRi6SdJPcVtaVQ1 AL6y2xdxzhVkLfrV8GNTop06m/PO+mL+B2VGqlZurXLB2U9gWaj8UzPmO0aFGLlrMafL q/UxZ17nN/vQ2Vfb3Ix0kn4bzTOMjBZHo2R6vBj9xEoS+11+sj/65+x7gojyHJz2OZk4 Qxd2oc8Q9s2lTIlneUR7kFjpjEdJyHGoycTllKAYhlYAM+rVjIj4dU78Ku5tVhlkaERk f4PwVICj8X2f7M5YwcP4d+k/bCiTVw9LPcfrsiFIN7QTpjlc0QWZuKygQ1KBur5i9Goc BRVQ== X-Forwarded-Encrypted: i=1; AKwUvBw78D4IxQrIcjDoQYz6nAG/IUvFM0qn/aB4UVjjSDBNmv09R9OcrZJVvemiFJKjshXTs7gs9Xcx63k=@vger.kernel.org X-Gm-Message-State: AFq9FYJWbh62xy/zgEi3wvn9Wc0puK2Ip96TCcjOMHTMnhl3QZ08aFyi IW/7ro/iaiLmboVNfoXL1kGbtQ40foDT2QyOv415cDq8DFPHdilqqidL X-Gm-Gg: AYBFou0J9+3FTqHVfXUxbciie3uzOwM2JzhvYCUTm41FQcI0M+50Khk48HBBK/mLKlY gxifRjzyptma2eALdaBgBWIqauT3juqFPHAD1qJzf1/dOtSqB2W/i7QXImdApLyiBe15JDkc8Yf OxbdXDFjJVrqzUWlv7HHROVhZXmDB9/XAPHeTlOXWK6u80ufxXPv23cSkYkRt8njFQ4mpBvc5Hs 8GY7ojP149arsLz1cOtq8jeocum1mmy+327Iy3qjrKNvxXa8lCNb4iiCoYjqGelyiHT4dBmDO1+ R7Gwc/VEqWvzdJGre3PaSVVbIhg17HwjbqsdtaYzVej7VJdBorG23k3I44KzH3RaloltFFobOWA VFuwt3Ee75GX+Dq925PkC/BuxI8ZTAE3xvkMoJfOq+Giy8gldiZKj4tH3wjc9bEHTF57EUZjZKy eSgEnhpT2fYLfUofnPTpOVrgCF7pjFzm/ILXwbAiw1XyWKW9tz8RZ8Yf5K1tP5yDVWsvSbXZCij JjA66Q8OoXjmWfa6d/QYXxYVZULJ9ZPErIZHidT9YrJAE3ZImpTSwpZVWfhVNLsUgIoWk+Z+Ms9 1IiTCZebk27l95vMJ4S4l1Glgjt8tzNUOhgFBA== X-Received: by 2002:ac5:c00e:0:20b0:5ea:389c:520b with SMTP id 71dfb90a1353d-5eaaa3a4e95mr3071748e0c.8.1792527581939; Tue, 20 Oct 2026 13:19:41 -0700 (PDT) Received: from gmail.com (111.46.245.35.bc.googleusercontent.com. [35.245.46.111]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5eae983efe8sm587906e0c.17.2026.10.20.13.19.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 13:19:41 -0700 (PDT) Date: Tue, 20 Oct 2026 16:19:41 -0400 From: Willem de Bruijn To: "Michael S. Tsirkin" , Willem de Bruijn Cc: linux-kernel@vger.kernel.org, Chris Arges , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Phil Sutter , Jason Wang , =?UTF-8?B?RXVnZW5pbyBQw6lyZXo=?= , Xuan Zhuo , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, virtualization@lists.linux.dev, Max Krasnyansky , Rusty Russell , Jonathan Corbet , Shuah Khan , Randy Dunlap , Simon Horman , linux-doc@vger.kernel.org Message-ID: In-Reply-To: <20261020155917-mutt-send-email-mst@kernel.org> References: <6f23c55c6eba3e3ec6b2c7e3a80728a326ed58af.1792411304.git.mst@redhat.com> <20261020155917-mutt-send-email-mst@kernel.org> Subject: Re: [PATCH net v3 6/8] net: add a sysctl to opt out of virtio net hdr checksum validation X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Michael S. Tsirkin wrote: > On Tue, Oct 20, 2026 at 03:54:23PM -0400, Willem de Bruijn wrote: > > Michael S. Tsirkin wrote: > > > The ingress validation as implemented by the previous > > > patch is stricter than what it replaced: GSO > > > packets whose checksum metadata matches no transport header are > > > dropped, and non-GSO ones get their checksum completed in place. > > > Such packets used to pass with the metadata unvalidated, > > > and with no overhead. > > > > > > I judge that this should not affect any deployments, but there is still > > > some risk that it does. In case a deployment depends on them anyway, > > > provide a per-netns switch to get the old behavior back: > > > > > > echo 0 > /proc/sys/net/core/virtio_net_hdr_csum_check > > > > > > The default is validating. > > > > > > Assisted-by: LLM > > > Signed-off-by: Michael S. Tsirkin > > > --- > > > Documentation/admin-guide/sysctl/net.rst | 19 ++++++++ > > > include/linux/virtio_net.h | 23 +++++++++ > > > include/net/netns/core.h | 1 + > > > net/core/dev.c | 6 +++ > > > net/core/net_namespace.c | 1 + > > > net/core/sysctl_net_core.c | 60 ++++++++++++++++++++++++ > > > 6 files changed, 110 insertions(+) > > > > > > diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst > > > index e586e17fc7a5..b1a1c4714b22 100644 > > > --- a/Documentation/admin-guide/sysctl/net.rst > > > +++ b/Documentation/admin-guide/sysctl/net.rst > > > @@ -246,6 +246,25 @@ processes are dropped unless socket option SOF_TIMESTAMPING_OPT_TSONLY is set. > > > Default: 1 (on) > > > > > > > > > +virtio_net_hdr_csum_check > > > +------------------------- > > > > virtio_net_hdr_validate? In case we do have to add more validation > > later. > > If you insist. My worry would be what if that validation is again > user-visible somehow and we need to distinguish users who want > to disable that future thing and users who want to disable > just this current thing. > > Hard to predict the future. But I will go with your intuition. Thanks, but definitely feel free to ignore my suggestions. My intuition would be to define as 0: off 1: everything one 2+: sadly needed fudge values because we keep having to tighten, but some crazy workloads need to opt-out to avoid breakage.