From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) (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 A229120334; Wed, 27 Mar 2024 02:28:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711506491; cv=none; b=puEfXgFJ5CrourBhZzOvQq96B4WYE4RNKtO6kFa8C01TWKreLItMv82DtudK6Ks7PZhP7M8xm6DY4NtjLLXFmNPzryFkz0iDkpMGFAUZ5w6Lg1kzbvZt9mHcawD9XDFxIGCBWUE2XNAA0Vu8QQbkD++i8ZCGHpC/xkWyfELgXKk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711506491; c=relaxed/simple; bh=suO/hxHkYIiR7aN5fNMxxIMiIKDf7s7yifppD3JVj0k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UGJDyie/1XsRB9X7ERTb0oh8kx6aTRyov8ZGu6qI0r7vUuNKW30FhT2UZBJVbaZOu95Mgodp3NC+juyjpSLRlF7++11X4pckBi3XqOiExVK+nfjomDdXQVreAywmd53x7dp3n5HomTbCKgLyfEJ5w7K0dRmnn6zbCiU7dnxgF0E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=Q+w9NU5B; arc=none smtp.client-ip=115.124.30.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="Q+w9NU5B" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1711506481; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=/zfwjKKsw5HeZkRsJXEcqJbxo+5sK1+snEjBOm3OoIY=; b=Q+w9NU5B9Krkmfa+4MMlen2FiZBR713PSX35fsyzFuwIKo2HqxHWA5BAQbbu9P6W4MxsHifoknxTn+YvUCRRSrQIqG+z3tvtgHaU26PYKkfpRqDQVmSpCtNMrsoHk8c+V+p1oZRwVFRaL8fDKoiq4LWXvgnGT4kuDegQPanhGWs= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=hengqi@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0W3Mvu.x_1711506478; Received: from 30.221.148.214(mailfrom:hengqi@linux.alibaba.com fp:SMTPD_---0W3Mvu.x_1711506478) by smtp.aliyun-inc.com; Wed, 27 Mar 2024 10:27:59 +0800 Message-ID: Date: Wed, 27 Mar 2024 10:27:58 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v2 2/2] virtio_net: Do not send RSS key if it is not supported To: Breno Leitao , xuanzhuo@linux.alibaba.com, "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Melnychenko Cc: rbc@meta.com, riel@surriel.com, stable@vger.kernel.org, qemu-devel@nongnu.org, "open list:VIRTIO CORE AND NET DRIVERS" , "open list:NETWORKING DRIVERS" , open list References: <20240326151911.2155689-1-leitao@debian.org> <20240326151911.2155689-2-leitao@debian.org> From: Heng Qi In-Reply-To: <20240326151911.2155689-2-leitao@debian.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/3/26 下午11:19, Breno Leitao 写道: > There is a bug when setting the RSS options in virtio_net that can break > the whole machine, getting the kernel into an infinite loop. > > Running the following command in any QEMU virtual machine with virtionet > will reproduce this problem: > > # ethtool -X eth0 hfunc toeplitz > > This is how the problem happens: > > 1) ethtool_set_rxfh() calls virtnet_set_rxfh() > > 2) virtnet_set_rxfh() calls virtnet_commit_rss_command() > > 3) virtnet_commit_rss_command() populates 4 entries for the rss > scatter-gather > > 4) Since the command above does not have a key, then the last > scatter-gatter entry will be zeroed, since rss_key_size == 0. > sg_buf_size = vi->rss_key_size; > > 5) This buffer is passed to qemu, but qemu is not happy with a buffer > with zero length, and do the following in virtqueue_map_desc() (QEMU > function): > > if (!sz) { > virtio_error(vdev, "virtio: zero sized buffers are not allowed"); > > 6) virtio_error() (also QEMU function) set the device as broken > > vdev->broken = true; > > 7) Qemu bails out, and do not repond this crazy kernel. > > 8) The kernel is waiting for the response to come back (function > virtnet_send_command()) > > 9) The kernel is waiting doing the following : > > while (!virtqueue_get_buf(vi->cvq, &tmp) && > !virtqueue_is_broken(vi->cvq)) > cpu_relax(); > > 10) None of the following functions above is true, thus, the kernel > loops here forever. Keeping in mind that virtqueue_is_broken() does > not look at the qemu `vdev->broken`, so, it never realizes that the > vitio is broken at QEMU side. > > Fix it by not sending RSS commands if the feature is not available in > the device. > > Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.") > Cc: stable@vger.kernel.org > Cc: qemu-devel@nongnu.org > Signed-off-by: Breno Leitao > --- > drivers/net/virtio_net.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index c640fdf28fc5..e6b0eaf08ac2 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3809,6 +3809,9 @@ static int virtnet_set_rxfh(struct net_device *dev, > struct virtnet_info *vi = netdev_priv(dev); > int i; > > + if (!vi->has_rss && !vi->has_rss_hash_report) > + return -EOPNOTSUPP; > + Why not make the second patch as the first, this seems to work better. Or squash them into one patch. Apart from these and Xuan's comments. For series:         Reviewed-by: Heng Qi Regards, Heng > if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE && > rxfh->hfunc != ETH_RSS_HASH_TOP) > return -EOPNOTSUPP;