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 X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3ABECA9ECF for ; Fri, 1 Nov 2019 17:10:09 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 742A3218AC for ; Fri, 1 Nov 2019 17:10:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="c9aFcNfr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 742A3218AC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41578 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iQaR6-0002pL-JS for qemu-devel@archiver.kernel.org; Fri, 01 Nov 2019 13:10:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40517) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iQaQI-0002Mx-Cz for qemu-devel@nongnu.org; Fri, 01 Nov 2019 13:09:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iQaQF-0002YJ-75 for qemu-devel@nongnu.org; Fri, 01 Nov 2019 13:09:16 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:44912 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iQaQE-0002Wf-Ul for qemu-devel@nongnu.org; Fri, 01 Nov 2019 13:09:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572628153; 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=owFfsAFfbx6xHmd5kz54mM3ND889MjNomTPtv5+jNbo=; b=c9aFcNfrw/LxeL4jOrLkHhwjHgbffxGvHQ2FNnSwzPpHjkryqhazA7JVBmj57NhTlZ4GCh tku3NZcRPPy7Zbk7rRMOEHhbXcUTsHnSOX1Dr7U2y2IcNq4Q3u2jW2mXqPhCmyeGOXzbDp BRl5ugPevQvzbKrrK+saUI5LROtLcH0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-314-9H84DV5NNGSPGEc7tGhhtg-1; Fri, 01 Nov 2019 13:09:08 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EA108107ACC0; Fri, 1 Nov 2019 17:09:07 +0000 (UTC) Received: from redhat.com (ovpn-112-25.ams2.redhat.com [10.36.112.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A479019C58; Fri, 1 Nov 2019 17:09:06 +0000 (UTC) Date: Fri, 1 Nov 2019 18:09:03 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Christian Ehrhardt Subject: Re: Best practices to handle shared objects through qemu upgrades? Message-ID: <20191101170903.GA13325@redhat.com> References: <20191101093403.GE11296@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: 9H84DV5NNGSPGEc7tGhhtg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Paolo Bonzini , qemu-devel Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Nov 01, 2019 at 10:55:29AM +0100, Christian Ehrhardt wrote: > On Fri, Nov 1, 2019 at 10:34 AM Daniel P. Berrang=C3=A9 wrote: > > > > On Fri, Nov 01, 2019 at 08:14:08AM +0100, Christian Ehrhardt wrote: > > > Hi everyone, > > > we've got a bug report recently - on handling qemu .so's through > > > upgrades - that got me wondering how to best handle it. > > > After checking with Paolo yesterday that there is no obvious solution > > > that I missed we agreed this should be brought up on the list for > > > wider discussion. > > > Maybe there already is a good best practise out there, or if it > > > doesn't exist we might want to agree upon one going forward. > > > Let me outline the case and the ideas brought up so far. > > > > > > Case > > > - You have qemu representing a Guest > > > - Due to other constraints e.g. PT you can't live migrate (which woul= d > > > be preferred) > > > - You haven't used a specific shared object yet - lets say RBD storag= e > > > driver as example > > > - Qemu gets an update, packaging replaces the .so files on disk > > > - The Qemu process and the .so files on disk now have a mismatch in $= buildid > > > - If you hotplug an RBD device it will fail to load the (now new) .so > > > > What happens when it fails to load ? Does the user get a graceful > > error message or does QEMU abort ? I'd hope the former. > > >=20 > It is fortunately a graceful error message, here an example: >=20 > $ virsh attach-device lateload curldisk.xml > Reported issue happens on attach: > root@b:~# virsh attach-device lateload cdrom-curl.xml > error: Failed to attach device from cdrom-curl.xml > error: internal error: unable to execute QEMU command 'device_add': > Property 'virtio-blk-device.drive' can't find value > 'drive-virtio-disk2' Ok, that's graceful, but horrifically useless as an error message :-) I'd like to think there would be a way to do better. It looks like the 'drive-add' (or whatever we run to add the backend) is failing, and then we blindly run device_add anyway. This means either there's some error message printed that we are missing, or QEMU is not reporting it back to the monitor. Either way, I think this can be improved so that libvirt can directly report the message you found hidden in the log: >=20 > In the qemu output log we can see: > Failed to initialize module: /usr/lib/x86_64-linux-gnu/qemu/block-curl.so > Note: only modules from the same build can be loaded. Regards, Daniel --=20 |: 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= :|