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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 26531C433B4 for ; Tue, 20 Apr 2021 11:55:20 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 68FE861155 for ; Tue, 20 Apr 2021 11:55:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68FE861155 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 ([::1]:39646 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lYoyM-0004Sj-CN for qemu-devel@archiver.kernel.org; Tue, 20 Apr 2021 07:55:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45514) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lYovU-0001yz-9s for qemu-devel@nongnu.org; Tue, 20 Apr 2021 07:52:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:22390) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lYovI-00069W-W6 for qemu-devel@nongnu.org; Tue, 20 Apr 2021 07:52:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618919520; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1YZdRHHvUrkdxaFyYFPpN3Cl1TaQwQwRUEBvwzLo14E=; b=ZJaBje14/rD02rQLbKqPhKSNehFqmG5btqhkMVIMmZZ8J7bPRrmWE6+GM+t+/aXU+vD/Wx I5TW7IACXrzXxBmFif/MUhYA7u3SfEJPBuR1FUPwTTtGFryIwYbMREkDbGjWuAUqqJoQNM rXyRveocSyid3O8Lq2sC9HhAyra2Qs8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-477-Y6P3qk4LOCmDUyrG4h2k0g-1; Tue, 20 Apr 2021 07:51:59 -0400 X-MC-Unique: Y6P3qk4LOCmDUyrG4h2k0g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1050F8030B5 for ; Tue, 20 Apr 2021 11:51:58 +0000 (UTC) Received: from work-vm (ovpn-112-16.ams2.redhat.com [10.36.112.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E3D960CED; Tue, 20 Apr 2021 11:51:46 +0000 (UTC) Date: Tue, 20 Apr 2021 12:51:43 +0100 From: "Dr. David Alan Gilbert" To: Eduardo Habkost Subject: Re: [PATCH RFC] migration: warn about non-migratable configurations unless '--no-migration' was specified Message-ID: References: <20210415154402.28424-1-vkuznets@redhat.com> <874kg68z07.fsf@vitty.brq.redhat.com> <20210416162801.zluqlbvyipoanedw@habkost.net> <20210419193228.q5e6vdnqwygh22bq@habkost.net> MIME-Version: 1.0 In-Reply-To: <20210419193228.q5e6vdnqwygh22bq@habkost.net> User-Agent: Mutt/2.0.6 (2021-03-06) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Juan Quintela , qemu-devel@nongnu.org, Markus Armbruster , Paolo Bonzini , Vitaly Kuznetsov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Eduardo Habkost (ehabkost@redhat.com) wrote: > On Mon, Apr 19, 2021 at 07:47:34PM +0100, Dr. David Alan Gilbert wrote: > > * Daniel P. Berrangé (berrange@redhat.com) wrote: > > > On Mon, Apr 19, 2021 at 06:15:56PM +0100, Daniel P. Berrangé wrote: > > > > On Mon, Apr 19, 2021 at 06:11:47PM +0100, Dr. David Alan Gilbert wrote: > > > > > * Eduardo Habkost (ehabkost@redhat.com) wrote: > > > > > > I would make live migration policy an enum, just to make sure > > > > > > we are explicit about the requirements: > > > > > > > > > > > > - UNKNOWN: this is the current state in QEMU 6.0, where we don't > > > > > > really know what the user expects. > > > > > > This can be the default on existing versioned machine types, > > > > > > just for compatibility. > > > > > > I suggest making this print warnings for every migration > > > > > > blocker (like this patch does). > > > > > > I suggest deprecating this behavior as soon as we can. > > > > > > > > > > > > - PREFERRED: try to make the VM migratable when possible, but > > > > > > don't print a warning or error out if migration is blocked. > > > > > > This seems to be the behavior expected by libvirt today. > > > > > > > > > > > > - NOT_NEEDED: live migration is not needed, and QEMU is free to > > > > > > enable features that block live migration or change guest ABI. > > > > > > We can probably make this the default on machine types that > > > > > > never supported live migration. > > > > > > > > > > I suggest you could do this by adding: > > > > > -warn-none-migratable > > > > > -no-warn-none-migratable > > > > > > > > > > and then argue about defaults another time. > > > > > > > > If we're going to add new args, lets at least future proof our > > > > approach with an extensible option that we can wire into QMP > > > > too later > > > > > > > > -migratable none|preferred|required > > > > > > > > and letting us add extra key/value pairs to tune it if desired. > > > > > > Having said that, we potentially don't need a dedicated arg if we > > > just make 'migratable=none|preferred|required' be a property of > > > the machine type and hook everything off that > > > > I think my only difficulty with that is that I don't find any of those > > 3 words 'obvious'. > > Any suggestions of replacements for those 3 words? > > Would the descriptions below be enough to clarify their meaning > in documentation? I prefer things that are fairly obvious without needing to look at the documentation until you want the detail. > - NONE: live migration is not needed, and device or machine code > is allowed to enable features that block live migration or > change guest ABI. > (Not implemented yet) > > - PREFERRED: machine and device code should try to make the VM > migratable when possible, but won't emit a warning or error out > if migration is blocked. > (Current default behavior) > > - REQUIRED: live migration support is required, and adding a > migration blocker will be an error. > (Implemented today by --only-migratable) How about -migratable blocked Live migration is not allowed; an outbound migration will fail -migratable allowed Live migration is allowed, but some devices/options may block it if they're unable to migrate [current default] -migratable warn Live migration is allowed, but if some device/option is unable to migrate, migration will be blocked and a warning printed -migratable required Live migration is allowed, attempting to add a device or enable an option that can't migrate will fail. [--only-migratable] Dave > -- > Eduardo -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK