From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH net-next v5 3/4] virtio_net: Extend virtio to use VF datapath when available Date: Wed, 11 Apr 2018 17:45:07 +0300 Message-ID: <20180411174157-mutt-send-email-mst@kernel.org> References: <16b2e531-7bfa-7f25-2702-f3f8069663ee@intel.com> <20180410105504.GA2028@nanopsycho> <2ccfad76-589d-9dca-7e4b-9bafee41f844@intel.com> <20180410152205.GF2028@nanopsycho> <20180410154304.GG2028@nanopsycho> <82f741a2-2512-39de-84c6-874f126c27ea@intel.com> <20180411060327.GH2028@nanopsycho> <5d56e572-24f1-745d-49ae-c2dada5db03c@intel.com> <20180411080332.GL2028@nanopsycho> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: "Samudrala, Sridhar" , stephen@networkplumber.org, davem@davemloft.net, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, jesse.brandeburg@intel.com, alexander.h.duyck@intel.com, kubakici@wp.pl, jasowang@redhat.com, loseweigh@gmail.com To: Jiri Pirko Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46324 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753679AbeDKOpJ (ORCPT ); Wed, 11 Apr 2018 10:45:09 -0400 Content-Disposition: inline In-Reply-To: <20180411080332.GL2028@nanopsycho> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Apr 11, 2018 at 10:03:32AM +0200, Jiri Pirko wrote: > Wed, Apr 11, 2018 at 08:24:43AM CEST, sridhar.samudrala@intel.com wrote: > >On 4/10/2018 11:03 PM, Jiri Pirko wrote: > >> Tue, Apr 10, 2018 at 05:59:02PM CEST, sridhar.samudrala@intel.com wrote: > >> > On 4/10/2018 8:43 AM, Jiri Pirko wrote: > >> > > Tue, Apr 10, 2018 at 05:27:48PM CEST, sridhar.samudrala@intel.com wrote: > >> > > > On 4/10/2018 8:22 AM, Jiri Pirko wrote: > >> > > > > Tue, Apr 10, 2018 at 05:13:40PM CEST, sridhar.samudrala@intel.com wrote: > >> > > > > > On 4/10/2018 3:55 AM, Jiri Pirko wrote: > >> > > > > > > Mon, Apr 09, 2018 at 08:47:06PM CEST, sridhar.samudrala@intel.com wrote: > >> > > > > > > > On 4/9/2018 1:07 AM, Jiri Pirko wrote: > >> > > > > > > > > Sat, Apr 07, 2018 at 12:59:14AM CEST, sridhar.samudrala@intel.com wrote: > >> > > > > > > > > > On 4/6/2018 5:48 AM, Jiri Pirko wrote: > >> > > > > > > > > > > Thu, Apr 05, 2018 at 11:08:22PM CEST, sridhar.samudrala@intel.com wrote: > >> > > > > > > > > [...] > >> > > > > > > > > > >> > > > > > > > > > > > +static int virtnet_bypass_join_child(struct net_device *bypass_netdev, > >> > > > > > > > > > > > + struct net_device *child_netdev) > >> > > > > > > > > > > > +{ > >> > > > > > > > > > > > + struct virtnet_bypass_info *vbi; > >> > > > > > > > > > > > + bool backup; > >> > > > > > > > > > > > + > >> > > > > > > > > > > > + vbi = netdev_priv(bypass_netdev); > >> > > > > > > > > > > > + backup = (child_netdev->dev.parent == bypass_netdev->dev.parent); > >> > > > > > > > > > > > + if (backup ? rtnl_dereference(vbi->backup_netdev) : > >> > > > > > > > > > > > + rtnl_dereference(vbi->active_netdev)) { > >> > > > > > > > > > > > + netdev_info(bypass_netdev, > >> > > > > > > > > > > > + "%s attempting to join bypass dev when %s already present\n", > >> > > > > > > > > > > > + child_netdev->name, backup ? "backup" : "active"); > >> > > > > > > > > > > Bypass module should check if there is already some other netdev > >> > > > > > > > > > > enslaved and refuse right there. > >> > > > > > > > > > This will work for virtio-net with 3 netdev model, but this check has to be done by netvsc > >> > > > > > > > > > as its bypass_netdev is same as the backup_netdev. > >> > > > > > > > > > Will add a flag while registering with the bypass module to indicate if the driver is doing > >> > > > > > > > > > a 2 netdev or 3 netdev model and based on that flag this check can be done in bypass module > >> > > > > > > > > > for 3 netdev scenario. > >> > > > > > > > > Just let me undestand it clearly. What I expect the difference would be > >> > > > > > > > > between 2netdev and3 netdev model is this: > >> > > > > > > > > 2netdev: > >> > > > > > > > > bypass_master > >> > > > > > > > > / > >> > > > > > > > > / > >> > > > > > > > > VF_slave > >> > > > > > > > > > >> > > > > > > > > 3netdev: > >> > > > > > > > > bypass_master > >> > > > > > > > > / \ > >> > > > > > > > > / \ > >> > > > > > > > > VF_slave backup_slave > >> > > > > > > > > > >> > > > > > > > > Is that correct? If not, how does it look like? > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > Looks correct. > >> > > > > > > > VF_slave and backup_slave are the original netdevs and are present in both the models. > >> > > > > > > > In the 3 netdev model, bypass_master netdev is created and VF_slave and backup_slave are > >> > > > > > > > marked as the 2 slaves of this new netdev. > >> > > > > > > You say it looks correct and in another sentence you provide completely > >> > > > > > > different description. Could you please look again? > >> > > > > > > > >> > > > > > To be exact, 2 netdev model with netvsc looks like this. > >> > > > > > > >> > > > > > netvsc_netdev > >> > > > > > / > >> > > > > > / > >> > > > > > VF_slave > >> > > > > > > >> > > > > > With virtio_net, 3 netdev model > >> > > > > > > >> > > > > > bypass_netdev > >> > > > > > / \ > >> > > > > > / \ > >> > > > > > VF_slave virtio_net netdev > >> > > > > Could you also mark the original netdev which is there now? is it > >> > > > > bypass_netdev or virtio_net_netdev ? > >> > > > bypass_netdev > >> > > > / \ > >> > > > / \ > >> > > > VF_slave virtio_net netdev (original) > >> > > That does not make sense. > >> > > 1) You diverge from the behaviour of the netvsc, where the original > >> > > netdev is a master of the VF > >> > > 2) If the original netdev is a slave, you cannot have any IP address > >> > > configured on it (well you could, but the rx_handler would eat every > >> > > incoming packet). So you will break the user bacause he would have to > >> > > move the configuration to the new master device. > >> > > This only makes sense that the original netdev becomes the master for both > >> > > netvsc and virtio_net. > >> > Forgot to mention that bypass_netdev takes over the name of the original > >> > netdev and > >> > virtio_net netdev will get the backup name. > >> What do you mean by "name"? > > > >bypass_netdev also is associated with the same pci device as the original virtio_net > >netdev via SET_NETDEV_DEV().  Also, we added ndo_get_phys_port_name() to virtio_net > >that will return _bkup when BACKUP feature is enabled. > > Okay. > > > > >So for ex: if virtio_net inteface was getting 'ens12' as the name assigned by udev > >without BACKUP feature,  when BACKUP feature is enabled,  the  bypass_netdev will be > >named 'ens12' and the original virtio_net will get named as ens12n_bkup. > > Got it. > > I don't like the bypass_master to look differently in netvsc and > virtio_net :/ The best would be to convert netvsc to 3 netdev model and > treat them the same. The more I think about it, the more the 2 netdev > model feels wrong. If you believe that, then this patchset is a step in the right direction. With something like this patchset applied, converting netvsc to a 3 device model will presumably be just a flag flip away. Afterwards we'll be able to drop dead code handling the bypass_master flag. > > > > > > >> > >> > So the userspace network configuration doesn't need to change. > >> > > >> > > >