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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 73B8DC282DD for ; Thu, 23 May 2019 15:39:29 +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 491D72133D for ; Thu, 23 May 2019 15:39:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 491D72133D 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]:39045 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hTpoW-0005FK-Ib for qemu-devel@archiver.kernel.org; Thu, 23 May 2019 11:39:28 -0400 Received: from eggs.gnu.org ([209.51.188.92]:49560) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hTpnQ-0004Z4-US for qemu-devel@nongnu.org; Thu, 23 May 2019 11:38:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hTpnP-0000li-Uw for qemu-devel@nongnu.org; Thu, 23 May 2019 11:38:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53780) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hTpnP-0000kW-PN for qemu-devel@nongnu.org; Thu, 23 May 2019 11:38:19 -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 0D6A330024AD for ; Thu, 23 May 2019 15:38:11 +0000 (UTC) Received: from work-vm (ovpn-117-235.ams2.redhat.com [10.36.117.235]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 095605C69A; Thu, 23 May 2019 15:38:00 +0000 (UTC) Date: Thu, 23 May 2019 16:37:58 +0100 From: "Dr. David Alan Gilbert" To: Jens Freimann Message-ID: <20190523153756.GB2995@work-vm> References: <20190517125820.2885-1-jfreimann@redhat.com> <20190517125820.2885-2-jfreimann@redhat.com> <20190521093336.GA2915@work-vm> <20190523080109.kwvr6ufmxufenshy@jenstp.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190523080109.kwvr6ufmxufenshy@jenstp.localdomain> 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 [10.5.110.40]); Thu, 23 May 2019 15:38:16 +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 1/4] migration: allow unplug during migration for failover devices 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, mst@redhat.com, aadam@redhat.com, qemu-devel@nongnu.org, laine@redhat.com, ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Jens Freimann (jfreimann@redhat.com) wrote: > On Tue, May 21, 2019 at 10:33:36AM +0100, Dr. David Alan Gilbert wrote: > > * Jens Freimann (jfreimann@redhat.com) wrote: > > > In "b06424de62 migration: Disable hotplug/unplug during migration" we > > > added a check to disable unplug for all devices until we have figured > > > out what works. For failover primary devices qdev_unplug() is called > > > from the migration handler, i.e. during migration. > > > > > > This patch adds a flag to DeviceState which is set to false for all > > > devices and makes an exception for vfio-pci devices that are also > > > primary devices in a failover pair. > > > > > > Signed-off-by: Jens Freimann > > > > So I think this is safe in your case, because you trigger the unplug > > right at the start of migration during setup and plug after failure; > > however it's not generally safe - I can't unplug a device while the > > migration is actually in progress. > > I tried to limit it to only allow it in failover case. You're saying > it's missing something and not strict enough? I could allow it only > during migration setup. I guess we'll need a similar exception for > failover in libvirt. I might be wrong, but I think with your patch I could hot unplug your device part way through migration; where as I think you only care about it doing it at a very specific point during setup. (I still would prefer the hotplug to be done outside qemu, but still that's separate). Dave > regards, > Jens -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK