From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8CEDC43381 for ; Wed, 20 Mar 2019 21:44:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DA4C218B0 for ; Wed, 20 Mar 2019 21:44:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="NplieGsS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727479AbfCTVoJ (ORCPT ); Wed, 20 Mar 2019 17:44:09 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:56150 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727381AbfCTVoJ (ORCPT ); Wed, 20 Mar 2019 17:44:09 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2KLhsYB059343; Wed, 20 Mar 2019 21:43:54 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=ReBYmU3CRsyiKzS3vc3bGH0P6JvXYMqh3/9KmPV87Ls=; b=NplieGsSLbexMH/rVuBCmYUm69HYZL5aFmw0ISkOQ00gJlCz0MQBmKbGYixGI7Lha1K+ KHwdc7ikzp08PUasBPTOYJwtls/jpkaXORbEm8uAP6/8Z9uUuHS4IjIxHRAU4NWpk18H IzSvsnJAWD0zt1psCFCedsCrcGG3HHx2EMzwXZ/pu8kUwhIUCyVLwdv7yW2mUto1GeQV Xkx2aTic16VB5W3BdWiDrlK5nOGhqifJsNrE4FYY3Qpse3M/gm+kvJz8YH7ox4pUWYRm S6sIxlET3A9Z8T1jhNOP57f7EaXl01NVYkE7tNcgQWgxX7n7MJh8TnxkmELzSQA7Jswa 8g== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2r8pnewm10-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Mar 2019 21:43:53 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x2KLhoiu030676 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Mar 2019 21:43:50 GMT Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x2KLhlwY012747; Wed, 20 Mar 2019 21:43:48 GMT Received: from [192.168.14.112] (/79.178.225.133) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 20 Mar 2019 14:43:47 -0700 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.1 \(3445.4.7\)) Subject: Re: [summary] virtio network device failover writeup From: Liran Alon In-Reply-To: <20190320100747-mutt-send-email-mst@kernel.org> Date: Wed, 20 Mar 2019 23:43:41 +0200 Cc: Stephen Hemminger , Si-Wei Liu , Sridhar Samudrala , Alexander Duyck , Jakub Kicinski , Jiri Pirko , David Miller , Netdev , virtualization@lists.linux-foundation.org, boris.ostrovsky@oracle.com, vijay.balakrishna@oracle.com, jfreimann@redhat.com, ogerlitz@mellanox.com, vuhuong@mellanox.com Content-Transfer-Encoding: quoted-printable Message-Id: <36772E22-7A8F-4C42-A731-398E3204B418@oracle.com> References: <20190317095052-mutt-send-email-mst@kernel.org> <54E7C3AF-C3C5-4AF2-86C9-AA50389F855F@oracle.com> <20190319084647.727f8dcf@shemminger-XPS-13-9360> <20190319171638-mutt-send-email-mst@kernel.org> <79F5D7C0-BBAA-4F78-9039-27A444970002@oracle.com> <20190320061632-mutt-send-email-mst@kernel.org> <20190320100747-mutt-send-email-mst@kernel.org> To: "Michael S. Tsirkin" X-Mailer: Apple Mail (2.3445.4.7) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9201 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903200156 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > On 20 Mar 2019, at 16:09, Michael S. Tsirkin wrote: >=20 > On Wed, Mar 20, 2019 at 02:23:36PM +0200, Liran Alon wrote: >>=20 >>=20 >>> On 20 Mar 2019, at 12:25, Michael S. Tsirkin wrote: >>>=20 >>> On Wed, Mar 20, 2019 at 01:25:58AM +0200, Liran Alon wrote: >>>>=20 >>>>=20 >>>>> On 19 Mar 2019, at 23:19, Michael S. Tsirkin = wrote: >>>>>=20 >>>>> On Tue, Mar 19, 2019 at 08:46:47AM -0700, Stephen Hemminger wrote: >>>>>> On Tue, 19 Mar 2019 14:38:06 +0200 >>>>>> Liran Alon wrote: >>>>>>=20 >>>>>>> b.3) cloud-init: If configured to perform network-configuration, = it attempts to configure all available netdevs. It should avoid however = doing so on net-failover slaves. >>>>>>> (Microsoft has handled this by adding a mechanism in cloud-init = to blacklist a netdev from being configured in case it is owned by a = specific PCI driver. Specifically, they blacklist Mellanox VF driver. = However, this technique doesn=E2=80=99t work for the net-failover = mechanism because both the net-failover netdev and the virtio-net netdev = are owned by the virtio-net PCI driver). >>>>>>=20 >>>>>> Cloud-init should really just ignore all devices that have a = master device. >>>>>> That would have been more general, and safer for other use cases. >>>>>=20 >>>>> Given lots of userspace doesn't do this, I wonder whether it would = be >>>>> safer to just somehow pretend to userspace that the slave links = are >>>>> down? And add a special attribute for the actual link state. >>>>=20 >>>> I think this may be problematic as it would also break legit use = case >>>> of userspace attempt to set various config on VF slave. >>>> In general, lying to userspace usually leads to problems. >>>=20 >>> I hear you on this. So how about instead of lying, >>> we basically just fail some accesses to slaves >>> unless a flag is set e.g. in ethtool. >>>=20 >>> Some userspace will need to change to set it but in a minor way. >>> Arguably/hopefully failure to set config would generally be a safer >>> failure. >>=20 >> Once userspace will set this new flag by ethtool, all operations done = by other userspace components will still work. >=20 > Sorry about being unclear, the idea would be to require the flag on = each ethtool operation. Oh. I have indeed misunderstood your previous email then. :) Thanks for clarifying. >=20 >> E.g. Running dhclient without parameters, after this flag was set, = will still attempt to perform DHCP on it and will now succeed. >=20 > I think sending/receiving should probably just fail unconditionally. You mean that you wish that somehow kernel will prevent Tx on = net-failover slave netdev unless skb is marked with some flag to indicate it has been sent via the = net-failover master? This indeed resolves the group of userspace issues around performing = DHCP on net-failover slaves directly (By dracut/initramfs, dhclient and = etc.). However, I see a couple of down-sides to it: 1) It doesn=E2=80=99t resolve all userspace issues listed in this email = thread. For example, cloud-init will still attempt to perform network = config on net-failover slaves. It also doesn=E2=80=99t help with regard to Ubuntu=E2=80=99s netplan = issue that creates udev rules that match only by MAC. 2) It brings non-intuitive customer experience. For example, a customer = may attempt to analyse connectivity issue by checking the connectivity on a net-failover slave (e.g. the VF) but will see no connectivity when = in-fact checking the connectivity on the net-failover master netdev = shows correct connectivity. The set of changes I vision to fix our issues are: 1) Hide net-failover slaves in a different netns created and managed by = the kernel. But that user can enter to it and manage the netdevs there = if wishes to do so explicitly. (E.g. Configure the net-failover VF slave in some special way). 2) Match the virtio-net and the VF based on a PV attribute instead of = MAC. (Similar to as done in NetVSC). E.g. Provide a virtio-net interface = to get PCI slot where the matching VF will be hot-plugged by hypervisor. 3) Have an explicit virtio-net control message to command hypervisor to = switch data-path from virtio-net to VF and vice-versa. Instead of = relying on intercepting the PCI master enable-bit as an indicator on when VF is about to be set up. (Similar to as done in = NetVSC). Is there any clear issue we see regarding the above suggestion? -Liran >=20 >> Therefore, this proposal just effectively delays when the = net-failover slave can be operated on by userspace. >> But what we actually want is to never allow a net-failover slave to = be operated by userspace unless it is explicitly stated >> by userspace that it wishes to perform a set of actions on the = net-failover slave. >>=20 >> Something that was achieved if, for example, the net-failover slaves = were in a different netns than default netns. >> This also aligns with expected customer experience that most = customers just want to see a 1:1 mapping between a vNIC and a visible = netdev. >> But of course maybe there are other ideas that can achieve similar = behaviour. >>=20 >> -Liran >>=20 >>>=20 >>> Which things to fail? Probably sending/receiving packets? Getting = MAC? >>> More? >>>=20 >>>> If we reach >>>> to a scenario where we try to avoid userspace issues generically = and >>>> not on a userspace component basis, I believe the right path should = be >>>> to hide the net-failover slaves such that explicit action is = required >>>> to actually manipulate them (As described in blog-post). E.g. >>>> Automatically move net-failover slaves by kernel to a different = netns. >>>>=20 >>>> -Liran >>>>=20 >>>>>=20 >>>>> --=20 >>>>> MST