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 4DEBCEB64DD for ; Thu, 17 Aug 2023 11:26:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qWb7p-00074f-RS; Thu, 17 Aug 2023 07:25:13 -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 1qWb7l-00074D-Sk for qemu-devel@nongnu.org; Thu, 17 Aug 2023 07:25:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qWb7j-00027y-0b for qemu-devel@nongnu.org; Thu, 17 Aug 2023 07:25:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692271505; 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=ssO9zux6n7AwbvA4uizFhmJCBLwENvpQ2cwPr/thqrE=; b=apYLS/m0dNNVpyT3mY2bK2Au0rH2nB+Wy4NfbUYHGyKAJST3QAyXfclut5LP+8mH/eeyOh T92JFx9zIYis9Fy1HAt3ikcjBIT/8FVcWaM6PUnTWDSrxein6oP5DjVCMCWjNqGfrxrwwT oEeAI8QCtHjKym0ahRFPXeZClWO4MBc= 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-259--IFEMcfWO0qEjvCUWl8SQw-1; Thu, 17 Aug 2023 07:25:01 -0400 X-MC-Unique: -IFEMcfWO0qEjvCUWl8SQw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7CC06101A528; Thu, 17 Aug 2023 11:25:01 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.120]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A7B240C207A; Thu, 17 Aug 2023 11:25:00 +0000 (UTC) Date: Thu, 17 Aug 2023 12:24:58 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Denis V. Lunev" Cc: Efim Shevrin , qemu-devel@nongnu.org, kkostiuk@redhat.com, michael.roth@amd.com, pbonzini@redhat.com, den@openvz.org Subject: Re: [PATCH] qga: Start qemu-ga service after NetworkManager start Message-ID: References: <20230816200446.1408797-1-efim.shevrin@virtuozzo.com> <59a42366-58e2-7147-1bd4-e85b446b0477@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <59a42366-58e2-7147-1bd4-e85b446b0477@virtuozzo.com> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.129.124; 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=-0.021, 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 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, Aug 17, 2023 at 12:47:48PM +0200, Denis V. Lunev wrote: > On 8/17/23 12:26, Daniel P. Berrangé wrote: > > On Thu, Aug 17, 2023 at 04:04:46AM +0800, Efim Shevrin via wrote: > > > From: Fima Shevrin > > > > > > When the guest OS starts, qemu-ga sends an event to the host. > > > This event allows services on the host to start configuring > > > the already running guest OS. When configuring network settings, > > > it is possible that an external service will receive a signal > > > from qemu-ga about the start of guest OS, while NetworkManager > > > may not be running yet. Therefore, network setting may not > > > be available. With the current patch, we eliminate the described > > > race condition between qemu-ga and NetworkManager for guest OS > > > network setting cases. > > A host mgmt app should not be assuming that networking is > > running at all, and if it is, the guest might not even be > > on the same subnet as the host. Conceivably someone could > > even be using QGA to inject files to configure networking. > > > > Overall, IMHO, it is wrong to correlate host notification > > that QGA is running, with any assumption about state of > > the guest networking. > > > > IOW, I don't think we should make an attempt to serialize > > startup of QGA after guest networking. The QGA should be > > run as soon as its data transport (virtio-serial/vsock) > > is available, which is the current state. > > > > If a host consumer of QGA wants to do something with > > guest networking, they should check for guest network > > state with the 'guest-network-get-interfaces' command. > > This is very tight question at my opinion. > > Frankly speaking my original intention here would be > to put QGA at the very end of the startup sequence > in order to avoid complications. In the other case > any host side software, which would like to control > the guest behavior will be in trouble. > > For example, yet another common application is a > guest backup, here I would say application based > backup. In a normal case this is done through >    /etc/qemu-ga/fsfreeze-hook It will already be started after local-fs.target, since it does not have DefaultDependencies=no set. This should be sufficient for fsfreeze use cases IIUC. > I would say that agent should start very last, in the > other case *ANY* software working through the agent > must take efforts to avoid such transient state, which > is complicated. 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 :|