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 08DC9EB64DA for ; Wed, 5 Jul 2023 11:22:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qH0aI-0007Zk-1e; Wed, 05 Jul 2023 07:22:10 -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 1qH0aG-0007Z5-74 for qemu-devel@nongnu.org; Wed, 05 Jul 2023 07:22:08 -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 1qH0aE-0006JH-BW for qemu-devel@nongnu.org; Wed, 05 Jul 2023 07:22:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1688556123; 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=fj0ULByj4TyR4SsyJV5QOhKKNDHJv7ywDzU7PNxBtV4=; b=NmR0sIEyJz3kUD/xU0w2Aa9kf9/9+BJzvscsSfRZ3cBpze+OA2B3JIIMizaRqxcuQ1U7Mn bgJNPo6YEZJuNsSmXs1J1fhhvs7CEtct0wl6LrgKmjp7SXawWZjrhWY4MwCJaSCq4MzjVk fzkbpk7sTbMlk2O5f9JOnb/0grF61M8= 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-166-fSudfr_INIW7rZ5D25l5GA-1; Wed, 05 Jul 2023 07:21:59 -0400 X-MC-Unique: fSudfr_INIW7rZ5D25l5GA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 66B7B3806713; Wed, 5 Jul 2023 11:21:59 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.65]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4319F200B402; Wed, 5 Jul 2023 11:21:59 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3411A21E6A1F; Wed, 5 Jul 2023 13:21:58 +0200 (CEST) From: Markus Armbruster To: Het Gala Cc: qemu-devel@nongnu.org, prerna.saxena@nutanix.com, quintela@redhat.com, dgilbert@redhat.com, pbonzini@redhat.com, berrange@redhat.com, eblake@redhat.com, manish.mishra@nutanix.com, aravind.retnakaran@nutanix.com Subject: Re: [PATCH v6 1/9] migration: introduced 'MigrateAddress' in QAPI for migration wire protocol. References: <20230606101557.202060-1-het.gala@nutanix.com> <20230606101557.202060-2-het.gala@nutanix.com> Date: Wed, 05 Jul 2023 13:21:58 +0200 In-Reply-To: <20230606101557.202060-2-het.gala@nutanix.com> (Het Gala's message of "Tue, 6 Jun 2023 10:15:49 +0000") Message-ID: <87cz16iox5.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 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_H4=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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Het Gala writes: > This patch introduces well defined MigrateAddress struct and its related > child objects. > > The existing argument of 'migrate' and 'migrate-incoming' QAPI - 'uri' > is of string type. The current migration flow follows double encoding > scheme for fetching migration parameters such as 'uri' and this is > not an ideal design. > > Motive for intoducing struct level design is to prevent double encoding > of QAPI arguments, as Qemu should be able to directly use the QAPI > arguments without any level of encoding. > > Suggested-by: Aravind Retnakaran > Signed-off-by: Het Gala > Reviewed-by: Juan Quintela > Reviewed-by: Daniel P. Berrang=C3=A9 > --- > qapi/migration.json | 45 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/qapi/migration.json b/qapi/migration.json > index 179af0c4d8..e61d25eba2 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -1407,6 +1407,51 @@ > ## > { 'command': 'migrate-continue', 'data': {'state': 'MigrationStatus'} } >=20=20 > +## > +# @MigrationAddressType: > +# > +# The migration stream transport mechanisms. > +# > +# @socket: Migrate via socket. > +# > +# @exec: Direct the migration stream to another process. > +# > +# @rdma: Migrate via RDMA. > +# > +# Since 8.1 > +## > +{ 'enum': 'MigrationAddressType', > + 'data': ['socket', 'exec', 'rdma'] } > + > +## > +# @MigrationExecCommand: > +# > +# @args: list of commands for migraton stream execution to a file. Typo: migration > +# > +# Notes: > +# > +# 1. @args[0] needs to be the path to the new program. @args can't be a "list of commands", as we're spawning just one process. So what is it? Digging through the code with the entire series applied... Member @args is used in two places: 1. qemu_start_incoming_migration() passes it to exec_start_incoming_migration(), which translates it into an array and passes it to qio_channel_command_new_spawn(). 2. qmp_migrate() passes it to exec_start_outgoing_migration(), which does the same. qio_channel_command_new_spawn() passes it to g_spawn_async_with_pipes(). A close read of the latter's documentation leads me to: * args[0] is the excutable's file name. As usual, a relative name is relative to the QEMU process's current working directory. * args[1..] are the arguments. Unlike POSIX interfaces like execv() and posix_spawn(), this doesn't separate the executable's file name and 0-th argument. In short, the head of @args is the executable's filename, and the remainder are the arguments. The fact that the the executable's filename is passed as 0-th argument to the child process is detail. Perhaps this could do: ## # @MigrationExecCommand: # # @args: command and arguments to execute. If we want more detail, perhaps: # @args: command (list head) and arguments (list tail) to execute. Not sure we need it. Thoughts? > +# > +# Since 8.1 > +## > +{ 'struct': 'MigrationExecCommand', > + 'data': {'args': [ 'str' ] } } > + > +## > +# @MigrationAddress: > +# > +# Migration endpoint configuration. > +# > +# Since 8.1 > +## > +{ 'union': 'MigrationAddress', > + 'base': { 'transport' : 'MigrationAddressType'}, > + 'discriminator': 'transport', > + 'data': { > + 'socket': 'SocketAddress', > + 'exec': 'MigrationExecCommand', > + 'rdma': 'InetSocketAddress' } } > + > ## > # @migrate: > #