From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 ECB4D3570BE for ; Wed, 11 Feb 2026 09:37:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770802628; cv=none; b=Df1kZDTa0efp2/YPjoQwICBxdcCQQbQCYBzzHr1SwzyNZy8W2ijcKPEcEennMv2H+N7vetEparWT2RUXXj778pMBulyn7saRJhK5B9YdIp1dA/fE0g4W9M5gqHByBtYgnisYukAewqtQc8RcilwWJM94LoNq1f/X90yt8z6S18M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770802628; c=relaxed/simple; bh=bspBO2FdrrAqZFdWd9MvqX8zHS/3AYlNK2RPVUvzVDg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BRD8Z1lW079li3HzlnIt1cv/bJCw5J0gJbg4jlk1+2tZvNiPHLDoVMD8uP7B1tg4pJGeInPg9nyKJXZ2wBmpSLSR4NA82rtlt/kjeHhTZtazdjbcloyQ4FnKhVKIY4tQ27GlhweHff/FqLfyLdsLR/1isYOzd2rubmO5CRbGyGg= 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=ZQzf1Sop; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=Hujw+aPI; arc=none smtp.client-ip=170.10.133.124 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="ZQzf1Sop"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="Hujw+aPI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770802626; 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=gBmAJXaSxyay4y/Pt9nQaFQQMgJqtE9oD0z31uD46SE=; b=ZQzf1Sop9rgPR/Z6mzwAuXvHKs3m9pnoIu4W7jkE0enKwhc80RgAQ+4Ru/xhouLef4gq/D f3ff9KJitC9vb8BXZbLXcvFmFwOC0gLnB3MbqsHVpQOpOWIoT11rCFe1SASYESDH6Q17iL p6PlqjsLBiDgFDl0qH26JGIT/l867MU= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-496-w7W3-aSROfi7z7fnWgzreA-1; Wed, 11 Feb 2026 04:37:04 -0500 X-MC-Unique: w7W3-aSROfi7z7fnWgzreA-1 X-Mimecast-MFC-AGG-ID: w7W3-aSROfi7z7fnWgzreA_1770802624 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-435aadfaf4eso3598727f8f.2 for ; Wed, 11 Feb 2026 01:37:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1770802623; x=1771407423; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=gBmAJXaSxyay4y/Pt9nQaFQQMgJqtE9oD0z31uD46SE=; b=Hujw+aPIpneY16LXyrLRJn6ckLs49FR4uZXNjjJirLrh/eawPpG7ZZkM8wXKM/GV0k tm+Bc0jVBF4eisTPesny3PuN1wGdrm04ohFeAXdRMOhQ1XxH/xfuiZWEma1DWeH858cd PtmOFQqxCek3P5x5MIqxLt+lBgrYPWeoTittKBEIEupse+YRM2qa7eBFV4C3PhaHzjOv kRgRxLiaumdA8JXlUFg1z+QZ746P1OI5K1xJOETOgcnpxZLrCStUvnWkgImvi0MbDfbG r4JqmJHxWdG6dtv5KBLI85yIrwmg4cgqLAnKtniHZctQWwt9qFoIPshrmMcxTy1/sif9 BJ6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770802623; x=1771407423; 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=gBmAJXaSxyay4y/Pt9nQaFQQMgJqtE9oD0z31uD46SE=; b=NnDNM3DErjtFrJf6vrpdMWxC+ac0mqhUrgeRGmjba2rh+i3+06vvTV+TAt/8+CcZZO 5vakCeL5tlDIpToGYspMEAwq3bLhsV34Nsnvn7jwJ7Zv93vpHOEbrg9p3UqembtlM7Nk D0qCiReDWpgmmJgMhlPhc7d33qZkc1r2krJ5tRSwfZfj9JVwAuD21/ZZF/AR1JPA3e8I jNBKcHwyhbPdM911g705fCfLrLmH0J5LI3WsM+xJWolIxC/5HQC45Ghli7kX4U/o+byN NlZStjwgDSNtIq3L1la9gBVmqpFl7BWNQ3kdQeNSQE0Q7T+OEtvOEGhUPewgnPTwrsXe Jl+Q== X-Forwarded-Encrypted: i=1; AJvYcCX33Uj8l6EOxFer+EKQFg5lGtKXsrOXaYes9c24UAT/V3R/Gvc1pwK2v6A5QbwtCbQP0awQb0k=@vger.kernel.org X-Gm-Message-State: AOJu0YxDXDxdyVR4mUDHakMrjpef8JZZ0VFM4Isemrx1LX0tCWvdk4Sx eh7IaFy2prNDddR2rX1ewMryePfRfrXneaanWZchmHyqrGUAzQIe6AuCTuqnKxMYCKksZqURs6p F/se/UnmgG2O85rvEs1MkQA7m59PJURFMfpo0dDF8wUyb+njIvXPEV48hL6NiQNBiEg== X-Gm-Gg: AZuq6aKJLwYjXlBZDIGw6uro8mVMsfTiYsbYagdzP5BKD5xpwRqvGLIzy6zWJGtW6fR gNJEMSG+qNpbV69xqZvWF/kiCXxCbQmmN6SmCB27chTQWV16rVu0mE+0lIifZki2L0j2A+K1OH0 fuBZc5dbCtBvjE8Hs81opglUWIYS85+oInGAapRdJ1roIH5DLqqWS7ua5F0lW07TU3tBlY4Oba/ ue7Cgy9gkyvCZqk+/EQH/KGOR8EzAHkDIcXgUlkVd41VOOQqrifBTH0ua/kwsNG+SZZf9WHL9n6 RiMRqU9Fep/hCxDLqsBbr259xemTpBw2D0kyL4FzOX/I9VtLHCC41BuJMWoggj2NP3SA32XsYm6 a5IvH1tswKIickx/ulS6L1sdP5hjJVxouddfLoxEYnQRuNQ== X-Received: by 2002:a05:600c:a43:b0:480:52fe:58f5 with SMTP id 5b1f17b1804b1-4835d54f897mr20485065e9.31.1770802623390; Wed, 11 Feb 2026 01:37:03 -0800 (PST) X-Received: by 2002:a05:600c:a43:b0:480:52fe:58f5 with SMTP id 5b1f17b1804b1-4835d54f897mr20484195e9.31.1770802622456; Wed, 11 Feb 2026 01:37:02 -0800 (PST) Received: from redhat.com (IGLD-80-230-34-155.inter.net.il. [80.230.34.155]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4834d835f6bsm102408485e9.14.2026.02.11.01.37.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 01:37:01 -0800 (PST) Date: Wed, 11 Feb 2026 04:36:59 -0500 From: "Michael S. Tsirkin" To: Srujana Challa Cc: Jakub Kicinski , "netdev@vger.kernel.org" , "virtualization@lists.linux.dev" , "pabeni@redhat.com" , "jasowang@redhat.com" , "xuanzhuo@linux.alibaba.com" , "eperezma@redhat.com" , "davem@davemloft.net" , "edumazet@google.com" , Nithin Kumar Dabilpuram , Shiva Shankar Kommula Subject: Re: [EXTERNAL] Re: [PATCH v2 net-next] virtio_net: Improve RSS key size validation and use NETDEV_RSS_KEY_LEN Message-ID: <20260211043542-mutt-send-email-mst@kernel.org> References: <20260206120154.2548079-1-schalla@marvell.com> <20260206191308.7fdbfef4@kernel.org> <20260207045416-mutt-send-email-mst@kernel.org> <20260211030643-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Feb 11, 2026 at 09:33:26AM +0000, Srujana Challa wrote: > > On Wed, Feb 11, 2026 at 07:44:54AM +0000, Srujana Challa wrote: > > > > On Fri, Feb 06, 2026 at 07:13:08PM -0800, Jakub Kicinski wrote: > > > > > On Fri, 6 Feb 2026 17:31:54 +0530 Srujana Challa wrote: > > > > > > Replace hardcoded RSS max key size limit with NETDEV_RSS_KEY_LEN > > > > > > to align with kernel's standard RSS key length. Add validation > > > > > > for RSS key size against spec minimum (40 bytes) and driver > > > > > > maximum. When validation fails, gracefully disable RSS features > > > > > > and continue initialization rather than failing completely. > > > > > > > > > > Hm, FWIW clang says: > > > > > > > > > > drivers/net/virtio_net.c:6841:31: warning: result of comparison of > > > > > constant > > > > 256 with expression of type 'u8' (aka 'unsigned char') is always > > > > false [- Wtautological-constant-out-of-range-compare] > > > > > 6841 | } else if (vi->rss_key_size > > > VIRTIO_NET_RSS_MAX_KEY_SIZE) > > > > { > > > > > | ~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > > > > > > > Which is kinda annoying because the value was increased in net-next. > > > > > If Machael wants this backported then we need to keep the check > > > > > and follow up in net-next? We could try to cast the u32 away but > > > > > that feels dirty.. > > > > > > > > > > > > I'd say yes. the warning is harmless. > > > > so > > > > patch 1 - this code > > > > patch 2 - replace with BUILD_BUG_ON > > > > > > > > but i ask then whether this code was actually tested against net-next. > > > Yes, tested against net-next (before NETDEV_RSS_KEY_LEN was changed to > > 256). > > > BUILD_BUG_ON would always fail as-is on net-next since rss_key_size is u8. > > > > BUILD_BUG_ON(type_max(vi->rss_key_size) >= > > VIRTIO_NET_RSS_MAX_KEY_SIZE) > > > > why would it fail? > I was assuming BUILD_BUG_ON was intended to catch the type mismatch > (when VIRTIO_NET_RSS_MAX_KEY_SIZE exceeds what u8 can hold). I understand > now - thanks for clarifying! maybe we should just #define VIRTIO_NET_RSS_MAX_KEY_SIZE type_max(vi->rss_key_size) + 1 > > > > > > > Can we cast the comparison to u32 instead? > > > Thanks! > > > > > > > > > > > -- > > > > MST > > > > > > > forcing compiler to generate code where we do not need any really seems silly. > > > > -- > > MST >