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 46C702FF17A for ; Wed, 8 Apr 2026 14:49:05 +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=1775659746; cv=none; b=F8yM10HpQPQapgzy4H20itEO1Exm4EnUJeO/KQctspwH2dj/pAU4ZCJ+GqI259vujSqj2lkNqOjpUks72/26siRm4mFUZDEyA6yeqeuBh80TVyJs5XGiNpneFI0GnNcJEYmPmC0/8vytzsqElmGwToqhzzAxKNqSX0mImtOWWy0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775659746; c=relaxed/simple; bh=/kC9ML9lt49S+EL48uyk3OO+7Avvh6NtEYfLVQo7YbY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oolx3Ef+TNZrfJ2CadpF+M6iMTkXTm9FuCPCy4cpCzmsZk1Xwz/xTcUF1TxthuQ3ZxiFt2cYZGr7sgqD1qMPT1mEUWZEWwLpjGZokVnkbyEmKnrzVeqRt9NK+fZGUJ7xpcNvL+7l2dSFRxGRyG8TU2xmPxEGU4gEoGgdjC5YgbE= 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=Nue8w/FA; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=N8KbAo6y; 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="Nue8w/FA"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="N8KbAo6y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775659744; 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=YJ8auDO3S7o6AakY7fJm8XHjf2a2nhy+U/65Q7pQXUc=; b=Nue8w/FAtsx9Oh2gxWvVzHOLVOFAS4iPG3o1eJQcID5dMYX5oeqedDbd3Jv822Yk/hk6uS Bn0yyBYEFHjy4LxI9U6J+hWex0SWrV/+S8aHuYQYpAvgy/UAiaegSEW0nDJxXIVDY8BBcN UkmgCjlTQzVM8Ng8FfrroNwfH9P8f4U= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-85-Et2LYCmXM9qctSvNNogGaw-1; Wed, 08 Apr 2026 10:49:02 -0400 X-MC-Unique: Et2LYCmXM9qctSvNNogGaw-1 X-Mimecast-MFC-AGG-ID: Et2LYCmXM9qctSvNNogGaw_1775659741 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-488cc31ea57so1595235e9.3 for ; Wed, 08 Apr 2026 07:49:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1775659741; x=1776264541; 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=YJ8auDO3S7o6AakY7fJm8XHjf2a2nhy+U/65Q7pQXUc=; b=N8KbAo6yP5f1JFRj8A4vCQVRoBqW0QHEx2KdeRfK2N/mBen7xekZgMzWrs+zRseu0V Jkb9bWC+l6dQ8y4pNNRvrB0ZeZx8c7SCM1/dq59yjWltdoYnE/VT0scAsGWP2I2E+N8k wgfnygi/3VZbvEJiCjEuUc6Hk4wrCx6aKaq5KmClNlyRub/ial/L+lekrYUaechyVHyj HPk8mv9YSwiDUEzZWUTXNZ1NiLV5DaRQAilcjS5tKRkpfZulAIaISRt/96yTh/866znz EY2L0bdFTetnXvHwHHIPpsAER5DPFWSHedLmTWD1lgV6SDgu635irh5M58GEJ9HWp865 Z86A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775659741; x=1776264541; 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=YJ8auDO3S7o6AakY7fJm8XHjf2a2nhy+U/65Q7pQXUc=; b=E0SWXSACzqpeFunNkDwARTcw/SwKmQYsjRtNDQI0k+MLIr022LmGwomK9qK2QdGmKc 6PkxfBJVwW3emPbB2Pkdvd+DBpYcHqivylYrwkzH38U/CvhsWYjy+WkQRH9HEZZY3KHl 6HpIbTjkQKyk5XIVMmZfiP2Ws41WlcD+jkG+tW7zw0eQp7wf8YlNgdFQLIx/ZOq0eOqO mqTZJulCCpReW2ORjWaq6qZpJy6yP4VTAPKTbmgG6yK5vIXg/fzSY1Hqx3bng+pUrUA/ Q2XEf2DOzlIJ/v5pvOh5flKtPMi1Z8lA0PzyQ3YYSm8JGFhx+AvJA/bLXmtnrmchjpnw viWw== X-Forwarded-Encrypted: i=1; AJvYcCUdYBYmFSjJ+2YcOjwlnsM7Ey3Fm5ZncAU+F+bZ9jMQCRbdbDuWF+ixfA4gQpCkSB9PuJfTE3E=@vger.kernel.org X-Gm-Message-State: AOJu0YyxGnGwbqWCEXv2a7KrDaDRVNSi5aUdakOePVKHeq/xjZC68x8a 5mMU+IBAZYEu4fZC2Iyg8bqE9CxInBTMuYvNUHfaXEQpJTpqa1HTKNMKojWKnu84pA8RV5P+kT1 DFMwP82pDvpSc1Fx89GmRWM9nH+jg/Ej+0FtN4vIhSeTZa8buvX0gm/wwcA== X-Gm-Gg: AeBDievsuPW/jI5TfpBptwcQlQq3EKTrLaDHG79cpnupfAPbbtctDKKFN8jQ7OyosUM ic3TbIJ06FQvEdfAEYr9hhHCOrDDdUd45pQltzqVh1oyqnLQFoHi809U9rX67w8lgpK1Fn1/qo+ BS795tM9DO1GhiSoB29Xuv66hlRscupF5j+IFK+L2QP36evt9LVKZnR/iZOVk5+kwBu2Sb9xCnU Ydu7moWE7uYaBg+PEXJiHVEA0Y2HDbBJ11EV5u/x4FwaF9gg4HretaVLRMC8nMuKksoJTe9hu1G CRbQtURhKfCic5l3EjAimK16X9ozQ/dw11brxXmErZ5xDNeuZTCrjNw4tPxzb00PLSeQZmMYt+y UcMNV21Cv+LPpvcb0UL5SJsIBIDuIrlrSDYA6wE2WX/k= X-Received: by 2002:a05:600c:c165:b0:485:7f02:afd5 with SMTP id 5b1f17b1804b1-488ccfc056dmr103135e9.13.1775659741269; Wed, 08 Apr 2026 07:49:01 -0700 (PDT) X-Received: by 2002:a05:600c:c165:b0:485:7f02:afd5 with SMTP id 5b1f17b1804b1-488ccfc056dmr102665e9.13.1775659740710; Wed, 08 Apr 2026 07:49:00 -0700 (PDT) Received: from redhat.com (IGLD-80-230-25-21.inter.net.il. [80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4887e80a616sm1199968945e9.2.2026.04.08.07.48.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 07:49:00 -0700 (PDT) Date: Wed, 8 Apr 2026 10:48:57 -0400 From: "Michael S. Tsirkin" To: Srujana Challa Cc: Sasha Levin , "stable@vger.kernel.org" , Jakub Kicinski Subject: Re: [EXTERNAL] [PATCH 6.12.y] virtio_net: clamp rss_max_key_size to NETDEV_RSS_KEY_LEN Message-ID: <20260408104825-mutt-send-email-mst@kernel.org> References: <2026040855-hatless-marbled-c4ed@gregkh> <20260408131906.1087303-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@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, Apr 08, 2026 at 01:49:48PM +0000, Srujana Challa wrote: > > From: Srujana Challa > > > > [ Upstream commit b4e5f04c58a29c499faa85d12952ca9a4faf1cb9 ] > > > > rss_max_key_size in the virtio spec is the maximum key size supported by the > > device, not a mandatory size the driver must use. Also the value 40 is a spec > > minimum, not a spec maximum. > > > > The current code rejects RSS and can fail probe when the device reports a > > larger rss_max_key_size than the driver buffer limit. Instead, clamp the > > effective key length to min(device rss_max_key_size, NETDEV_RSS_KEY_LEN) > > and keep RSS enabled. > > > > This keeps probe working on devices that advertise larger maximum key sizes > > while respecting the netdev RSS key buffer size limit. > > > > Fixes: 3f7d9c1964fc ("virtio_net: Add hash_key_length check") > > Cc: stable@vger.kernel.org > > Signed-off-by: Srujana Challa > > Acked-by: Michael S. Tsirkin > > Link: https://urldefense.proofpoint.com/v2/url?u=https- > > 3A__patch.msgid.link_20260326142344.1171317-2D1-2Dschalla- > > 40marvell.com&d=DwIDAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=Fj4OoD5hcKFp > > ANhTWdwQzjT1Jpf7veC5263T47JVpnc&m=0XuKVXgk9_1LUIZHeqL0znGhAh > > x5KvAOLvrCl-orVeQSt__4o6Djr-79rwCl6KNp&s=cfQpAcZTTE7nTYku- > > MVkfip0xUJoBBw4ikqm9iEdgcc&e= > > Signed-off-by: Jakub Kicinski [ changed clamp target from > > NETDEV_RSS_KEY_LEN to VIRTIO_NET_RSS_MAX_KEY_SIZE ] > > Signed-off-by: Sasha Levin > > --- > > drivers/net/virtio_net.c | 16 ++++++++-------- > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index > > 5c83983f0eb3f..5a31ccdae2e22 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -6502,6 +6502,7 @@ static int virtnet_probe(struct virtio_device *vdev) > > struct virtnet_info *vi; > > u16 max_queue_pairs; > > int mtu = 0; > > + u16 key_sz; > > > > /* Find if host supports multiqueue/rss virtio_net device */ > > max_queue_pairs = 1; > > @@ -6624,14 +6625,13 @@ static int virtnet_probe(struct virtio_device > > *vdev) > > goto free; > > > > if (vi->has_rss || vi->has_rss_hash_report) { > > - vi->rss_key_size = > > - virtio_cread8(vdev, offsetof(struct virtio_net_config, > > rss_max_key_size)); > > - if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) { > > - dev_err(&vdev->dev, "rss_max_key_size=%u exceeds > > the limit %u.\n", > > - vi->rss_key_size, > > VIRTIO_NET_RSS_MAX_KEY_SIZE); > > - err = -EINVAL; > > - goto free; > > - } > > + key_sz = virtio_cread8(vdev, offsetof(struct virtio_net_config, > > +rss_max_key_size)); > > + > > + vi->rss_key_size = min_t(u16, key_sz, > > VIRTIO_NET_RSS_MAX_KEY_SIZE); > > + if (key_sz > vi->rss_key_size) > > + dev_warn(&vdev->dev, > > + "rss_max_key_size=%u exceeds driver limit > > %u, clamping\n", > > + key_sz, vi->rss_key_size); > > > > vi->rss_hash_types_supported = > > virtio_cread32(vdev, offsetof(struct virtio_net_config, > > supported_hash_types)); > > -- > > 2.53.0 > > We used `NETDEV_RSS_KEY_LEN` intentionally for clamping. > `rss_max_key_size` is the maximum supported by the device, > while `40` is a spec minimum, not a maximum. > Clamping to `VIRTIO_NET_RSS_MAX_KEY_SIZE` would unnecessarily > limit valid devices(for example devices advertising 48/52 bytes) and > could reintroduce the original issue. > > Could you please share the reason for changing the clamp target > from `NETDEV_RSS_KEY_LEN` to `VIRTIO_NET_RSS_MAX_KEY_SIZE`? > > Thanks! Srujana, do you want to do the stable backport yourself? -- MST