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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_HK_NAME_DR,USER_AGENT_MUTT 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 DDEE4C04AB6 for ; Fri, 31 May 2019 08:24:58 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A5ADA265B7 for ; Fri, 31 May 2019 08:24:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5ADA265B7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:38500 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hWcqP-0008H3-VW for qemu-devel@archiver.kernel.org; Fri, 31 May 2019 04:24:57 -0400 Received: from eggs.gnu.org ([209.51.188.92]:56563) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hWcpZ-0007tk-P7 for qemu-devel@nongnu.org; Fri, 31 May 2019 04:24:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hWcpY-0005g8-08 for qemu-devel@nongnu.org; Fri, 31 May 2019 04:24:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57800) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hWcpX-0005Ys-MG for qemu-devel@nongnu.org; Fri, 31 May 2019 04:24:03 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0E7D251145 for ; Fri, 31 May 2019 08:23:59 +0000 (UTC) Received: from work-vm (ovpn-117-254.ams2.redhat.com [10.36.117.254]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F0A935C231; Fri, 31 May 2019 08:23:46 +0000 (UTC) Date: Fri, 31 May 2019 09:23:44 +0100 From: "Dr. David Alan Gilbert" To: "Michael S. Tsirkin" Message-ID: <20190531082343.GA3169@work-vm> References: <20190517125820.2885-1-jfreimann@redhat.com> <20190517125820.2885-4-jfreimann@redhat.com> <20190521094504.GB2915@work-vm> <20190530145645.tjwkgi4hae5yblsi@jenstp.localdomain> <20190530134631-mutt-send-email-mst@kernel.org> <20190530180022.GB2864@work-vm> <20190530140419-mutt-send-email-mst@kernel.org> <20190530190822.GL2823@work-vm> <20190530152104-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190530152104-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 31 May 2019 08:23:59 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pkrempa@redhat.com, berrange@redhat.com, ehabkost@redhat.com, aadam@redhat.com, qemu-devel@nongnu.org, laine@redhat.com, Jens Freimann , ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Michael S. Tsirkin (mst@redhat.com) wrote: > On Thu, May 30, 2019 at 08:08:23PM +0100, Dr. David Alan Gilbert wrote: > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > On Thu, May 30, 2019 at 07:00:23PM +0100, Dr. David Alan Gilbert wrote: > > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > > On Thu, May 30, 2019 at 04:56:45PM +0200, Jens Freimann wrote: > > > > > > Hi David, > > > > > > > > > > > > sorry for the delayed reply. > > > > > > > > > > > > On Tue, May 28, 2019 at 11:04:15AM -0400, Michael S. Tsirkin wrote: > > > > > > > On Tue, May 21, 2019 at 10:45:05AM +0100, Dr. David Alan Gilbert wrote: > > > > > > > > * Jens Freimann (jfreimann@redhat.com) wrote: > > > > > > > > > +static void virtio_net_primary_plug_timer(void *opaque); > > > > > > > > > + > > > > > > > > > static void virtio_net_set_link_status(NetClientState *nc) > > > > > > > > > { > > > > > > > > > VirtIONet *n = qemu_get_nic_opaque(nc); > > > > > > > > > @@ -786,6 +796,14 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features) > > > > > > > > > } else { > > > > > > > > > memset(n->vlans, 0xff, MAX_VLAN >> 3); > > > > > > > > > } > > > > > > > > > + > > > > > > > > > + if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) { > > > > > > > > > + atomic_set(&n->primary_should_be_hidden, false); > > > > > > > > > + if (n->primary_device_timer) > > > > > > > > > + timer_mod(n->primary_device_timer, > > > > > > > > > + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + > > > > > > > > > + 4000); > > > > > > > > > + } > > > > > > > > > > > > > > > > What's this magic timer constant and why? > > > > > > > > > > > > To be honest it's a leftover from previous versions (before I took > > > > > > over) of the patches and I'm not sure why the timer is there. > > > > > > I removed it and so far see no reason to keep it. > > > > > > > > > > > > > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd, > > > > > > > > > @@ -2626,6 +2644,87 @@ void virtio_net_set_netclient_name(VirtIONet *n, const char *name, > > > > > > > > > n->netclient_type = g_strdup(type); > > > > > > > > > } > > > > > > > > > > > > > > > > > > +static void virtio_net_primary_plug_timer(void *opaque) > > > > > > > > > +{ > > > > > > > > > + VirtIONet *n = opaque; > > > > > > > > > + Error *err = NULL; > > > > > > > > > + > > > > > > > > > + if (n->primary_device_dict) > > > > > > > > > + n->primary_device_opts = qemu_opts_from_qdict(qemu_find_opts("device"), > > > > > > > > > + n->primary_device_dict, &err); > > > > > > > > > + if (n->primary_device_opts) { > > > > > > > > > + n->primary_dev = qdev_device_add(n->primary_device_opts, &err); > > > > > > > > > + error_setg(&err, "virtio_net: couldn't plug in primary device"); > > > > > > > > > + return; > > > > > > > > > + } > > > > > > > > > + if (!n->primary_device_dict && err) { > > > > > > > > > + if (n->primary_device_timer) { > > > > > > > > > + timer_mod(n->primary_device_timer, > > > > > > > > > + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + > > > > > > > > > + 100); > > > > > > > > > > > > > > > > same here. > > > > > > > > > > > > see above > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + } > > > > > > > > > + } > > > > > > > > > +} > > > > > > > > > + > > > > > > > > > +static void virtio_net_handle_migration_primary(VirtIONet *n, > > > > > > > > > + MigrationState *s) > > > > > > > > > +{ > > > > > > > > > + Error *err = NULL; > > > > > > > > > + bool should_be_hidden = atomic_read(&n->primary_should_be_hidden); > > > > > > > > > + > > > > > > > > > + n->primary_dev = qdev_find_recursive(sysbus_get_default(), > > > > > > > > > + n->primary_device_id); > > > > > > > > > + if (!n->primary_dev) { > > > > > > > > > + error_setg(&err, "virtio_net: couldn't find primary device"); > > > > > > > > > > > > > > > > There's something broken with the error handling in this function - the > > > > > > > > 'err' never goes anywhere - I don't think it ever gets printed or > > > > > > > > reported or stops the migration. > > > > > > > > > > > > yes, I'll fix it. > > > > > > > > > > > > > > > + } > > > > > > > > > + if (migration_in_setup(s) && !should_be_hidden && n->primary_dev) { > > > > > > > > > + qdev_unplug(n->primary_dev, &err); > > > > > > > > > > > > > > > > Not knowing unplug well; can you just explain - is that device hard > > > > > > > > unplugged and it's gone by the time this function returns or is it still > > > > > > > > hanging around for some indeterminate time? > > > > > > > > > > > > Qemu will trigger an unplug request via pcie attention button in which case > > > > > > there could be a delay by the guest operating system. We could give it some > > > > > > amount of time and if nothing happens try surpise removal or handle the > > > > > > error otherwise. > > > > > > > > > > > > > > > > > > regards, > > > > > > Jens > > > > > > > > > > That's a subject for another day. Let's get the basic thing > > > > > working. > > > > > > > > Well no, we need to know this thing isn't going to hang in the migration > > > > setup phase, or if it does how we recover. > > > > > > > > > This thing is *supposed* to be stuck in migration startup phase > > > if guest is malicious. > > > > > > If migration does not progress management needs > > > a way to detect this and cancel. > > > > > > Some more documentation about how this is supposed to happen > > > would be helpful. > > > > I want to see that first; because I want to convinced it's just a > > documentation problem and that we actually really have a method of > > recovering. > > > > > > This patch series is very > > > > odd precisely because it's trying to do the unplug itself in the > > > > migration phase rather than let the management layer do it - so unless > > > > it's nailed down how to make sure that's really really bullet proof > > > > then we've got to go back and ask the question about whether we should > > > > really fix it so it can be done by the management layer. > > > > > > > > Dave > > > > > > management already said they can't because files get closed and > > > resources freed on unplug and so they might not be able to re-add device > > > on migration failure. We do it in migration because that is > > > where failures can happen and we can recover. > > > > I find this explanation confusing - I can kind of see where it's coming > > from, but we've got a pretty clear separation between a NIC and the > > netdev that backs it; those files and resources should be associated > > with the netdev and not the NIC. So does hot-removing the NIC really > > clean up the netdev? (I guess maybe this is a different in vfio > > which is the problem) > > > > Dave > > what we are removing is the VFIO device. > Nothing to do with nic or netdev. OK, but at the same time why can't we hold open the VFIOs devices resources in a comparable way - i.e. don't really let qemu let go of it even when the guest has unplugged it? Dave > > > > > -- > > > > > MST > > > > -- > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK