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 6A262C28CC0 for ; Thu, 30 May 2019 19:17:24 +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 2E6DA23ABA for ; Thu, 30 May 2019 19:17:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2E6DA23ABA 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]:58135 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hWQYF-0004i2-Fd for qemu-devel@archiver.kernel.org; Thu, 30 May 2019 15:17:23 -0400 Received: from eggs.gnu.org ([209.51.188.92]:59032) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hWQPk-0006xV-6c for qemu-devel@nongnu.org; Thu, 30 May 2019 15:08:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hWQPi-0007gw-Ry for qemu-devel@nongnu.org; Thu, 30 May 2019 15:08:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41148) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hWQPi-0007gP-J0 for qemu-devel@nongnu.org; Thu, 30 May 2019 15:08:34 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E3E34882FD for ; Thu, 30 May 2019 19:08:33 +0000 (UTC) Received: from work-vm (ovpn-117-91.ams2.redhat.com [10.36.117.91]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A980E7E31C; Thu, 30 May 2019 19:08:25 +0000 (UTC) Date: Thu, 30 May 2019 20:08:23 +0100 From: "Dr. David Alan Gilbert" To: "Michael S. Tsirkin" Message-ID: <20190530190822.GL2823@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20190530140419-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 30 May 2019 19:08:33 +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 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, > > > >=20 > > > > sorry for the delayed reply. > > > >=20 > > > > 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 =3D qemu_get_nic_opaque(nc); > > > > > > > @@ -786,6 +796,14 @@ static void virtio_net_set_features(Virt= IODevice *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); > > > > > > > + } > > > > > >=20 > > > > > > What's this magic timer constant and why? > > > >=20 > > > > 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. > > > >=20 > > > > > >=20 > > > > > > > } > > > > > > > > > > > > > > static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t c= md, > > > > > > > @@ -2626,6 +2644,87 @@ void virtio_net_set_netclient_name(Vir= tIONet *n, const char *name, > > > > > > > n->netclient_type =3D g_strdup(type); > > > > > > > } > > > > > > > > > > > > > > +static void virtio_net_primary_plug_timer(void *opaque) > > > > > > > +{ > > > > > > > + VirtIONet *n =3D opaque; > > > > > > > + Error *err =3D NULL; > > > > > > > + > > > > > > > + if (n->primary_device_dict) > > > > > > > + n->primary_device_opts =3D qemu_opts_from_qdict(qemu= _find_opts("device"), > > > > > > > + n->primary_device_dict, &err); > > > > > > > + if (n->primary_device_opts) { > > > > > > > + n->primary_dev =3D qdev_device_add(n->primary_device= _opts, &err); > > > > > > > + error_setg(&err, "virtio_net: couldn't plug in prima= ry 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); > > > > > >=20 > > > > > > same here. > > > >=20 > > > > see above > > > >=20 > > > > > >=20 > > > > > >=20 > > > > > > > + } > > > > > > > + } > > > > > > > +} > > > > > > > + > > > > > > > +static void virtio_net_handle_migration_primary(VirtIONet *n, > > > > > > > + MigrationSta= te *s) > > > > > > > +{ > > > > > > > + Error *err =3D NULL; > > > > > > > + bool should_be_hidden =3D atomic_read(&n->primary_should= _be_hidden); > > > > > > > + > > > > > > > + n->primary_dev =3D qdev_find_recursive(sysbus_get_defaul= t(), > > > > > > > + n->primary_device_id); > > > > > > > + if (!n->primary_dev) { > > > > > > > + error_setg(&err, "virtio_net: couldn't find primary = device"); > > > > > >=20 > > > > > > There's something broken with the error handling in this functi= on - the > > > > > > 'err' never goes anywhere - I don't think it ever gets printed = or > > > > > > reported or stops the migration. > > > >=20 > > > > yes, I'll fix it. > > > >=20 > > > > > > > + } > > > > > > > + if (migration_in_setup(s) && !should_be_hidden && n->pri= mary_dev) { > > > > > > > + qdev_unplug(n->primary_dev, &err); > > > > > >=20 > > > > > > 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? > > > >=20 > > > > Qemu will trigger an unplug request via pcie attention button in wh= ich 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. > > > >=20 > > > >=20 > > > > regards, > > > > Jens > > >=20 > > > That's a subject for another day. Let's get the basic thing > > > working. > >=20 > > 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. >=20 >=20 > This thing is *supposed* to be stuck in migration startup phase > if guest is malicious. >=20 > If migration does not progress management needs > a way to detect this and cancel. >=20 > 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. > >=20 > > Dave >=20 > 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 =66rom, 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 > > > --=20 > > > MST > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK