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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 34E47EB64D7 for ; Fri, 23 Jun 2023 07:19:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qCb3Q-0006M3-By; Fri, 23 Jun 2023 03:18:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qCb3M-0006IP-HO for qemu-devel@nongnu.org; Fri, 23 Jun 2023 03:17:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qCb3K-0002EI-B3 for qemu-devel@nongnu.org; Fri, 23 Jun 2023 03:17:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687504672; h=from:from:reply-to: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=LX4+9+XNZyrM/1cmeaYfPrZ3BNVhcPuEFH0Afgcb+X8=; b=CURP6ymcZ5m6vpSOuS+X4WAhZMzpsB9iZ9NJTyfIdwFxDqD+9YpU4WPikcM+8TD4M4OsGj pHDEVUR5vQrb2mJ3jUBZ+sjN30o9LqebqIzP3BmP8R1NFZHTZZKqX+SbDyDMHAI5L1Jyl7 JJIvUvmlnM0hAV6bM3nw0RQU1auCyH8= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-564-rBJvZg6LMVOMN1xkfYVayQ-1; Fri, 23 Jun 2023 03:17:51 -0400 X-MC-Unique: rBJvZg6LMVOMN1xkfYVayQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C0D831C060CA; Fri, 23 Jun 2023 07:17:50 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.44]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B47E72166B25; Fri, 23 Jun 2023 07:17:48 +0000 (UTC) Date: Fri, 23 Jun 2023 08:17:46 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Xu Cc: Juan Quintela , Paolo Bonzini , qemu-devel@nongnu.org, Markus Armbruster , Leonardo Bras , qemu-block@nongnu.org, Stefan Hajnoczi , Eric Blake , Fam Zheng , Thomas Huth , libvir-list@redhat.com Subject: Re: [RFC 4/6] migration: Deprecate -incoming Message-ID: References: <20230612193344.3796-1-quintela@redhat.com> <20230612193344.3796-5-quintela@redhat.com> <875y7sflqb.fsf@secure.mitica> <87wmzv7ubn.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Jun 22, 2023 at 03:20:01PM -0400, Peter Xu wrote: > On Thu, Jun 22, 2023 at 05:33:29PM +0100, Daniel P. Berrangé wrote: > > On Thu, Jun 22, 2023 at 11:54:43AM -0400, Peter Xu wrote: > > > I can try to move the todo even higher. Trying to list the initial goals > > > here: > > > > > > - One extra phase of handshake between src/dst (maybe the time to boost > > > QEMU_VM_FILE_VERSION) before anything else happens. > > > > > > - Dest shouldn't need to apply any cap/param, it should get all from src. > > > Dest still need to be setup with an URI and that should be all it needs. > > > > > > - Src shouldn't need to worry on the binary version of dst anymore as long > > > as dest qemu supports handshake, because src can fetch it from dest. > > > > I'm not sure that works in general. Even if we have a handshake and > > bi-directional comms for live migration, we still haave the save/restore > > to file codepath to deal with. The dst QEMU doesn't exist at the time > > the save process is done, so we can't add logic to VMSate handling that > > assumes knowledge of the dst version at time of serialization. > > My current thought was still based on a new cap or anything the user would > need to specify first on both sides (but hopefully the last cap to set on > dest). > > E.g. if with a new handshake cap we shouldn't set it on a exec: or file: > protocol migration, and it should just fail on qmp_migrate() telling that > the URI is not supported if the cap is set. Return path is definitely > required here. exec can support bi-directional migration - we have both stdin + stdout for the command. For exec it is mostly a documentation problem - you can't merely use 'cat' for example, but if you used 'socat' that could be made to work bi-directionally. > > I don't think its possible for QEMU to validate that it has a fully > > bi-directional channel, without adding timeouts to its detection which I > > think we should strive to avoid. > > > > I don't think we actually need self-bootstrapping anyway. > > > > I think the mgmt app can just indicate the new v2 bi-directional > > protocol when issuing the 'migrate' and 'migrate-incoming' > > commands. This becomes trivial when Het's refactoring of the > > migrate address QAPI is accepted: > > > > https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg04851.html > > > > eg: > > > > { "execute": "migrate", > > "arguments": { > > "channels": [ { "channeltype": "main", > > "addr": { "transport": "socket", "type": "inet", > > "host": "10.12.34.9", > > "port": "1050" } } ] } } > > > > note the 'channeltype' parameter here. If we declare the 'main' > > refers to the existing migration protocol, then we merely need > > to define a new 'channeltype' to use as an indicator for the > > v2 migration handshake protocol. > > Using a new channeltype would also work at least on src qemu, but I'm not > sure on how dest qemu would know that it needs a handshake in that case, > because it knows nothing until the connection is established. In Het's series the 'migrate_incoming' command similarly has a chaneltype parameter. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|