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 4FA22C433EF for ; Tue, 14 Jun 2022 11:35:02 +0000 (UTC) Received: from localhost ([::1]:37532 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o14p2-0003rH-UW for qemu-devel@archiver.kernel.org; Tue, 14 Jun 2022 07:35:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54058) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o14n4-0002oR-HJ for qemu-devel@nongnu.org; Tue, 14 Jun 2022 07:32:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29017) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o14n0-0005bI-IO for qemu-devel@nongnu.org; Tue, 14 Jun 2022 07:32:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655206373; 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:in-reply-to:in-reply-to: references:references; bh=H7jPL/mXBcc3gbp6/LTyKu7jZDBOok28vKuXHBsHV+o=; b=BtT9NJ70M2nxfxhReEAW7o1p3xFrENB+Rbohav/smejCiQf52CPHvFPKJ4z6uce32h7odu d/OpvyvUTYtfckYpvCZOvbkDIJz3epfkAFgSZaH5qpS/KPbSIBOpSSz1mfu/td9exC5tIF abo2OeVBFje6cCBX+78fVOXw07Rp9xs= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-348-eAuhee18Mu-MD1rTvktLBg-1; Tue, 14 Jun 2022 07:32:47 -0400 X-MC-Unique: eAuhee18Mu-MD1rTvktLBg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0D2F913183C3; Tue, 14 Jun 2022 11:32:38 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5E1764010E32; Tue, 14 Jun 2022 11:32:28 +0000 (UTC) Date: Tue, 14 Jun 2022 12:32:22 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Andrey Ryabinin Cc: qemu-devel@nongnu.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Paolo Bonzini , Juan Quintela , "Dr. David Alan Gilbert" , Jason Wang , Stefan Hajnoczi , yc-core@yandex-team.ru Subject: Re: [PATCH 0/2] Make local migration with TAP network device possible Message-ID: References: <20220614111843.24960-1-arbn@yandex-team.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220614111843.24960-1-arbn@yandex-team.com> User-Agent: Mutt/2.2.1 (2022-02-19) X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 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: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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" On Tue, Jun 14, 2022 at 02:18:41PM +0300, Andrey Ryabinin wrote: > Hi > > These couple patches aims to make possible local migration (within one host) > on the same TAP device used by source and destination QEMU > > The scenario looks like this > 1. Create TAP devices and pass file descriptors to source QEMU > 2. Launch destination QEMU (-incoming defer) and pass same descriptors to it. > 3. Start migration > > > Regarding the first patch: It makes possible to receive file descriptor in non-blocking > state. But I probably didn't cover all FD users which might need to set blocking state after > the patch. So I'm hopping for the hints where else, besides fd_start_incoming_migration() > I need to put qemu_socket_set_block() calls. You'll need to check all callers of qio_channel_readv_full qio_channel_readv_full_all qio_channel_readv_full_all_eof and identify which pass a non-NULL parameter for 'fds'. If the caller does NOT have a qemu_setnonblock call on the FD it gets back, then you have to assume it is expecting it in blocking mode and so need to add qemu_setblock 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 :|