From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:35587 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751823AbeDKGDa (ORCPT ); Wed, 11 Apr 2018 02:03:30 -0400 Received: by mail-wm0-f66.google.com with SMTP id r82so1522895wme.0 for ; Tue, 10 Apr 2018 23:03:29 -0700 (PDT) Date: Wed, 11 Apr 2018 08:03:27 +0200 From: Jiri Pirko To: "Samudrala, Sridhar" Cc: mst@redhat.com, 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 Subject: Re: [RFC PATCH net-next v5 3/4] virtio_net: Extend virtio to use VF datapath when available Message-ID: <20180411060327.GH2028@nanopsycho> References: <20180406124814.GA24525@nanopsycho> <20180409080751.GE19345@nanopsycho> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <82f741a2-2512-39de-84c6-874f126c27ea@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: 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"? >So the userspace network configuration doesn't need to change. > >