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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 908F9C3A59C for ; Fri, 16 Aug 2019 16:57:28 +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 5444A2077C for ; Fri, 16 Aug 2019 16:57:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5444A2077C 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]:58620 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyfXb-000880-Ev for qemu-devel@archiver.kernel.org; Fri, 16 Aug 2019 12:57:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47399) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyfWt-0007UJ-AS for qemu-devel@nongnu.org; Fri, 16 Aug 2019 12:56:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hyfWr-0007cW-Sm for qemu-devel@nongnu.org; Fri, 16 Aug 2019 12:56:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39928) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hyfWr-0007bm-Jn for qemu-devel@nongnu.org; Fri, 16 Aug 2019 12:56:41 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0DB81796E0; Fri, 16 Aug 2019 16:56:40 +0000 (UTC) Received: from localhost (ovpn-116-32.gru2.redhat.com [10.97.116.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2C4C384278; Fri, 16 Aug 2019 16:56:36 +0000 (UTC) Date: Fri, 16 Aug 2019 13:56:35 -0300 From: Eduardo Habkost To: Igor Mammedov Message-ID: <20190816165635.GC3908@habkost.net> References: <20190815183803.13346-1-ehabkost@redhat.com> <20190815183803.13346-4-ehabkost@redhat.com> <20190816152011.0c673027@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190816152011.0c673027@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 16 Aug 2019 16:56:40 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 3/3] pc: Don't make CPU properties mandatory unless necessary 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: , Cc: Peter Krempa , Like Xu , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Aug 16, 2019 at 03:20:11PM +0200, Igor Mammedov wrote: > On Thu, 15 Aug 2019 15:38:03 -0300 > Eduardo Habkost wrote: > > > We have this issue reported when using libvirt to hotplug CPUs: > > https://bugzilla.redhat.com/show_bug.cgi?id=1741451 > > > > Basically, libvirt is not copying die-id from > > query-hotpluggable-cpus, but die-id is now mandatory. > > this should have been gated on compat property and affect > only new machine types. > Maybe we should do just that instead of fixup so libvirt > would finally make proper handling of query-hotpluggable-cpus. > > > > We could blame libvirt and say it is not following the documented > > interface, because we have this buried in the QAPI schema > > documentation: > > I wouldn't say buried, if I understand it right QAPI schema > should be the authoritative source of interface description. > > If I recall it's not the first time, there was similar issue > for exactly the same reason (libvirt not passing through > all properties from query-hotpluggable-cpus). > > And we had to fix it up on QEMU side (numa_cpu_pre_plug), > but it seems 2 years later libvirt is still broken the same way :( > > Should we really do fixups or finaly fix it on libvirt side? Is it truly a bug in libvirt? Making QEMU behave differently when getting exactly the same input sounds like a bad idea, even if we documented that at the QAPI documentation. My suggestion is to instead drop the comment below from the QAPI documentation. New properties shouldn't become mandatory. > > > > Note: currently there are 5 properties that could be present > > > but management should be prepared to pass through other > > > properties with device_add command to allow for future > > > interface extension. This also requires the filed names to be kept in > > > sync with the properties passed to -device/device_add. > > > > But I don't think this would be reasonable from us. We can just > > make QEMU more flexible and let CPU properties to be omitted when > > there's no ambiguity. This will allow us to keep compatibility > > with existing libvirt versions. > > I don't really like making rule from exceptions so I'd suggest doing > it only for die_id if we have to do fix it up (with fat comment > like in numa_cpu_pre_plug). > The rest are working fine as is. I will insist we make it consistent for all properties, but I don't want this discussion to hold the bug fix. So I'll do this: I will submit a new patch that makes only die-id optional, and CC qemu-stable. After that, i will submit this patch again, and we can discuss whether we should make all properties optional. -- Eduardo