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 59494CCD1BE for ; Thu, 23 Oct 2025 14:05:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vBvw1-0000va-9w; Thu, 23 Oct 2025 10:04:57 -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 1vBvvy-0000v1-LX for qemu-devel@nongnu.org; Thu, 23 Oct 2025 10:04:54 -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 1vBvvu-00065l-Nz for qemu-devel@nongnu.org; Thu, 23 Oct 2025 10:04:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761228288; 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: in-reply-to:in-reply-to:references:references; bh=P77pi1wKutGKL4BNucJ0kfBnD5+r5bOHi46pn6dbPvw=; b=VwOuxwvK7VJRbw6X7jPbN0pJLCd8i5B6SJGhtBFGOa3urQbueCj3SRKEb/OxGFYcJ1SjUV kyQsKOP5nbqguoNvKdylQx3LI7GI4ZJGNn213G0R8ZUiSciHZ184EmKsTjckdlQ6wsZA1p 1YjPmUtaSyt1/6cEPQ8Pl4cNYNWpxis= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-214-IfeQZtJpP2uw4yEX_otCUA-1; Thu, 23 Oct 2025 10:04:44 -0400 X-MC-Unique: IfeQZtJpP2uw4yEX_otCUA-1 X-Mimecast-MFC-AGG-ID: IfeQZtJpP2uw4yEX_otCUA_1761228283 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7A6B0180A997; Thu, 23 Oct 2025 14:04:43 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.19]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 219CD1800597; Thu, 23 Oct 2025 14:04:43 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3D51D21E6A27; Thu, 23 Oct 2025 16:04:40 +0200 (CEST) From: Markus Armbruster To: Peter Xu Cc: Markus Armbruster , qemu-devel@nongnu.org, Fabiano Rosas , Juraj Marcin Subject: Re: [PATCH] migration/qmp: Update "resume" flag doc in "migrate" command In-Reply-To: (Peter Xu's message of "Thu, 23 Oct 2025 09:55:22 -0400") References: <20251022190425.2730441-1-peterx@redhat.com> <87cy6eb25c.fsf@pond.sub.org> Date: Thu, 23 Oct 2025 16:04:40 +0200 Message-ID: <87sef94suf.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Thu, Oct 23, 2025 at 07:47:11AM +0200, Markus Armbruster wrote: >> Peter Xu writes: >> >> > It wasn't obvious how the resume flag should be used when staring at the >> > QAPI doc. Enrich it to be crystal clear. >> > >> > Reported-by: Markus Armbruster >> > Signed-off-by: Peter Xu >> > --- >> > qapi/migration.json | 5 ++++- >> > 1 file changed, 4 insertions(+), 1 deletion(-) >> > >> > diff --git a/qapi/migration.json b/qapi/migration.json >> > index be0f3fcc12..48856078db 100644 >> > --- a/qapi/migration.json >> > +++ b/qapi/migration.json >> > @@ -1732,7 +1732,10 @@ >> > # @detach: this argument exists only for compatibility reasons and is >> > # ignored by QEMU >> > # >> > -# @resume: resume one paused migration, default "off". (since 3.0) >> > +# @resume: when set, resume one paused postcopy migration, using the new >> >> Scratch "one" unless there can be more than one. > > Sure. > >> >> > +# URI/channels specified to replace the old/broken channels. The user >> > +# should make sure the migration is in "postcopy-paused" state before >> > +# the resume request. Default "off". (since 3.0) >> > # >> > # Features: >> > # >> >> What happens when migration is not in state "postcopy-paused"? > > The QMP command "migrate" with resume=true set will be rejected, > corresponds to: > > migrate_prepare(): > if (s->state != MIGRATION_STATUS_POSTCOPY_PAUSED) { > error_setg(errp, "Cannot resume if there is no " > "paused migration"); > return false; > } Makes sense, thanks! I'd suggest something like 'Resume fails unless migration is in "postcopy-paused" state. (default: false, since 3.0)' >> Remind me, how can migration get into and out of this state? > > It can happen if any interruption happened during a postcopy migration. So > it needs to be postcopy-active state first, then something wrong happened > e.g. the network is down. Then the channel will break on both sides of > QEMU, and both QEMUs will jump into postcopy-paused. > > To get out of the state, one needs to explicitly recover the migration, the > core steps are: > > - (optional) Run migrate_recover on dest QEMU to re-establish the ports, > if the old listening ports are not available anymore. > > - Run migrate on src QEMU with resume=true flag here to resume the > postcopy migration. > > If the recover succeeded, it'll switch from postcopy-paused finally back to > postcopy-active. > > Thanks, Got it, thanks!