From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) (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 9CC5612B83; Sun, 7 Apr 2024 08:13:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.110 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712477583; cv=none; b=qK7/3/k864epQzLWcnoAb+tsS5upNcjbbGJy9Smkn04M1jNKIr6LK8Vm5AeyEuSfcWRyK+njtO4Un2xnbibHmuDyajTbUUDebg+l4GUaeGEjGeKV6U6HiFQTYW+/O0XElpI2psYkdsuctrZ+4huhWq3pRMM8Pr7FWLKwOxx+sug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712477583; c=relaxed/simple; bh=fgvBYr5qb0CRValf4l8NVrLApElBgdEGuMbFLvYJTZM=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To; b=i+M5vGC7KcqNLvPI7R4n+AZtJ+mjlQf7Xwm1sofemCeE8twtLlxX+Hom1H2D8VMjhR7VIQipB6FdEoAnKtFbKyeDw3exTgBfZCACSTx7uZSw01nx14LXDMXbkWZgU2DPH9itvjhMqNc0pmBh0X89o0g70P5DQzcA9bQjfzNQ+q8= 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=FQfjlvnL; arc=none smtp.client-ip=115.124.30.110 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="FQfjlvnL" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1712477578; h=Message-ID:Subject:Date:From:To; bh=Jyrgw+fdsx70sA5rZNTdVtftvjSvV7dvUm0DDwjdLJw=; b=FQfjlvnLyb9rS6Jf0JpTxFfCIl9PAdi0OpCW8/hNhAl/XzkjpfV6eHFjrsmntHnqkorBfrBj6N7Z9hfvFFId451b9EAJr0yGenfuy9yMUkrBC4MqAAq1j9aFe5jR/KFOsnZBR/mC3bFx6FwOusWePbCkflxkqcHaJZXEAPZF0vM= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R731e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0W4.rUrS_1712477576; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W4.rUrS_1712477576) by smtp.aliyun-inc.com; Sun, 07 Apr 2024 16:12:57 +0800 Message-ID: <1712477565.823871-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH net v4] virtio_net: Do not send RSS key if it is not supported Date: Sun, 7 Apr 2024 16:12:45 +0800 From: Xuan Zhuo To: Breno Leitao Cc: rbc@meta.com, riel@surriel.com, stable@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux.dev (open list:VIRTIO CORE AND NET DRIVERS), netdev@vger.kernel.org (open list:NETWORKING DRIVERS), linux-kernel@vger.kernel.org (open list), hengqi@linux.alibaba.com, "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Melnychenko References: <20240403154313.1331319-1-leitao@debian.org> In-Reply-To: <20240403154313.1331319-1-leitao@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Wed, 3 Apr 2024 08:43:12 -0700, Breno Leitao wrote: > 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 > Reviewed-by: Heng Qi Reviewed-by: Xuan Zhuo > --- > 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. > V4: > * Added a comment in an "if" clause, as suggested by Michael S. Tsirkin. > > --- > drivers/net/virtio_net.c | 26 ++++++++++++++++++++++---- > 1 file changed, 22 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index c22d1118a133..115c3c5414f2 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 +3815,28 @@ 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 either _F_HASH_REPORT or _F_RSS are negotiated, the > + * device provides hash calculation capabilities, that is, > + * hash_key is configured. > + */ > + 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 +4745,15 @@ 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)); > > -- > 2.43.0 >