From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (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 1D9222EB08; Sun, 31 Mar 2024 13:23:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711891389; cv=none; b=LPxdNPTQYubClB+XrBga/fM3q6b52sArWKdtMvUMFTuO3Tej33gYNZiFiv4pnAPcmdwPBP2hWK7cBgt3+48fRjN3K+neN9F9zziSj7LdkEs9bmmBevxCnTwoq5Mm35gxgltZGga6VgLzqkVQXdQi8YASKsCaN9S+SYOG6Tc69no= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711891389; c=relaxed/simple; bh=0JdnalII33ICqSebxleFo2xxjuuYod6bhO/Ywq4s8/0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NoqUlETmyZI73zoxV6OcludGi++MNrPXCy3rOOm5RDyI93jqu2eeAsi5vw7e+/yy7SxC/RSgvkcRQLwDh8NBTBMe5ERbg8cDzWdICLXXYX2pZJyxyhc4gJgx/BfUmjK3u5M1OEzpHIKpf1MmpkN6LChuLD1AdlAnX7CefSDV0KQ= 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=fn2rK449; arc=none smtp.client-ip=115.124.30.132 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="fn2rK449" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1711891378; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=DNVFJe7fzXJ46hFedS/yET7Jx+L9l6utZ/e9Xt9A6X8=; b=fn2rK449UwxAktwc06z/gHLkd7nxrhpX7uWiykXzVdT27RatS3BoIPlE5eLtg6xVpZ4vhBovaNpCHm5sBSnjugXpmKstOdcgg8XnbUlUPScpMFRS5/wRJtR0TMJgr9R1dn/nzhr7qwc8K5EOPw/egpB6h/ifdb36uJXH57tgDSM= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=hengqi@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0W3bgCBV_1711891376; Received: from 30.121.31.164(mailfrom:hengqi@linux.alibaba.com fp:SMTPD_---0W3bgCBV_1711891376) by smtp.aliyun-inc.com; Sun, 31 Mar 2024 21:22:57 +0800 Message-ID: <8b6f03a9-1afb-42ef-82aa-7eaf7517133c@linux.alibaba.com> Date: Sun, 31 Mar 2024 21:22:55 +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 v3] virtio_net: Do not send RSS key if it is not supported To: Breno Leitao 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 , Xuan Zhuo , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Melnychenko References: <20240329171641.366520-1-leitao@debian.org> From: Heng Qi In-Reply-To: <20240329171641.366520-1-leitao@debian.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/3/30 上午1:16, 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 > --- > Changelog: > > V2: > * Moved from creating a valid packet, by rejecting the request > completely > V3: > * Got some good feedback from and Xuan Zhuo and Heng Qi, and reworked > the rejection path. > > --- > drivers/net/virtio_net.c | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index c22d1118a133..c4a21ec51adf 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3807,6 +3807,7 @@ static int virtnet_set_rxfh(struct net_device *dev, > struct netlink_ext_ack *extack) > { > struct virtnet_info *vi = netdev_priv(dev); > + bool update = false; > int i; > > if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE && > @@ -3814,13 +3815,24 @@ static int virtnet_set_rxfh(struct net_device *dev, > return -EOPNOTSUPP; > > if (rxfh->indir) { > + if (!vi->has_rss) > + return -EOPNOTSUPP; > + > for (i = 0; i < vi->rss_indir_table_size; ++i) > vi->ctrl->rss.indirection_table[i] = rxfh->indir[i]; > + update = true; > } > - if (rxfh->key) > + > + if (rxfh->key) { > + if (!vi->has_rss && !vi->has_rss_hash_report) > + return -EOPNOTSUPP; > + > memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size); > + update = true; > + } > > - virtnet_commit_rss_command(vi); > + if (update) > + virtnet_commit_rss_command(vi); > > return 0; > } > @@ -4729,13 +4741,15 @@ static int virtnet_probe(struct virtio_device *vdev) > if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) > vi->has_rss_hash_report = true; > > - if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) > + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) { > vi->has_rss = true; > > - if (vi->has_rss || vi->has_rss_hash_report) { > vi->rss_indir_table_size = > virtio_cread16(vdev, offsetof(struct virtio_net_config, > rss_max_indirection_table_length)); > + } > + > + 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)); > Reviewed-by: Heng Qi Thanks.