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 E840F10FA; Fri, 22 Mar 2024 02:02:50 +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=1711072974; cv=none; b=O6XRMgPvL9kIcHCKRq+hcCKntsMF7IT8zTdwpL2etp0OoAFbjBBa/sC04eLiOLyxjpjnZBkoOPlQE4IVlBl2fJgFzR1FAs4LCCQQrwBgH+1I2a7JMyV8Ae7WVErS/0AJv33Zuh2USYxlCgqmHyKU8dFI7L7JsQJCLo02l8PhgAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711072974; c=relaxed/simple; bh=2194g1paJ8iOlnAMy9lsEIbmtlsUjcd9QLT2ghW2vt0=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To; b=Llu6YRMu7MqpUyEiDP295XQ1JboRzHnnp4cfjApPpklKwsyXYVc6C1jDKFE2yo6LtVTFmsg60BvcVarQ9AOJMMGd9lkUjjdV7wfbyZLGIMjk13Ce3c1cRRHWIqlBGcVSWpPnMMzKRH2IC2aLVHN+c2t3YQxrYuAGlB+OW3+cIC8= 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=gQwzMsof; 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="gQwzMsof" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1711072963; h=Message-ID:Subject:Date:From:To; bh=u+tMN1LwSbe9n5PNdUk4hVRTCTGRyukBQQgHRB/HjG0=; b=gQwzMsofuI6CHMGWSTO531VoxSI5eOv5f331uYnnSS5YZbC8kLpar/xGRyliLgo/gIFs/RCQKtPF3R2SV+QKiSGi+udv4so3BxsAhMf3zKzI1o8CRFjVJsqMed5XqdLa0v6DlSC4cxWbpxYCa3OM1aLU4AK50HGJT62dxB/d58A= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045168;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=15;SR=0;TI=SMTPD_---0W3077TT_1711072960; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W3077TT_1711072960) by smtp.aliyun-inc.com; Fri, 22 Mar 2024 10:02:41 +0800 Message-ID: <1711072822.882584-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH] virtio_net: Do not send RSS key if it is not supported Date: Fri, 22 Mar 2024 10:00:22 +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), "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Melnychenko References: <20240321165431.3517868-1-leitao@debian.org> In-Reply-To: <20240321165431.3517868-1-leitao@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Thu, 21 Mar 2024 09:54:30 -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; 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)); vi->rss_key_size = virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size)); vi->rss_hash_types_supported = virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types)); vi->rss_hash_types_supported &= ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX | VIRTIO_NET_RSS_HASH_TYPE_TCP_EX | VIRTIO_NET_RSS_HASH_TYPE_UDP_EX); dev->hw_features |= NETIF_F_RXHASH; } vi->rss_key_size is initiated here, I wonder if there is something wrong? Thanks. > > 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 the key scatter-gatter key if it is not set. > > Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.") > Signed-off-by: Breno Leitao > Cc: stable@vger.kernel.org > Cc: qemu-devel@nongnu.org > --- > drivers/net/virtio_net.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index d7ce4a1011ea..5a7700b103f8 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3041,11 +3041,16 @@ static int virtnet_set_ringparam(struct net_device *dev, > static bool virtnet_commit_rss_command(struct virtnet_info *vi) > { > struct net_device *dev = vi->dev; > + int has_key = vi->rss_key_size; > struct scatterlist sgs[4]; > unsigned int sg_buf_size; > + int nents = 3; > + > + if (has_key) > + nents += 1; > > /* prepare sgs */ > - sg_init_table(sgs, 4); > + sg_init_table(sgs, nents); > > sg_buf_size = offsetof(struct virtio_net_ctrl_rss, indirection_table); > sg_set_buf(&sgs[0], &vi->ctrl->rss, sg_buf_size); > @@ -3057,8 +3062,13 @@ static bool virtnet_commit_rss_command(struct virtnet_info *vi) > - offsetof(struct virtio_net_ctrl_rss, max_tx_vq); > sg_set_buf(&sgs[2], &vi->ctrl->rss.max_tx_vq, sg_buf_size); > > - sg_buf_size = vi->rss_key_size; > - sg_set_buf(&sgs[3], vi->ctrl->rss.key, sg_buf_size); > + if (has_key) { > + /* Only populate if key is available, otherwise > + * populating a buffer with zero size breaks virtio > + */ > + sg_buf_size = vi->rss_key_size; > + sg_set_buf(&sgs[3], vi->ctrl->rss.key, sg_buf_size); > + } > > if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ, > vi->has_rss ? VIRTIO_NET_CTRL_MQ_RSS_CONFIG > -- > 2.43.0 >