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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 30D57C07E95 for ; Mon, 19 Jul 2021 16:47:49 +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 BCAAA61006 for ; Mon, 19 Jul 2021 16:47:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BCAAA61006 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]:44380 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m5WQl-00012E-SU for qemu-devel@archiver.kernel.org; Mon, 19 Jul 2021 12:47:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35884) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5WPV-0008Tv-6j for qemu-devel@nongnu.org; Mon, 19 Jul 2021 12:46:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:28464) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5WPR-0001WW-Ge for qemu-devel@nongnu.org; Mon, 19 Jul 2021 12:46:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626713184; 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=SGjEHHGPGK+T8qu3HSJVSSd/mlfWqFWBjri8o4U6Dto=; b=FmEutEqqEvsBNYqvBJC9rA1wCLlHzgzixcQiUp7PzzLfL6A+DCocZhGiVQD8YEvuQTtami oKtT8+2Gbq+zcLkxTqFP8qZ7sx5wF9W7zgQo/GNqPzlvxdJfoDP9uH9KCVG1vdSOw63JdH YtWL7PraLfShLsD2KaQDrifw4nlsFQQ= 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-466-PeEk5sxVPzKm7quO4eSDog-1; Mon, 19 Jul 2021 12:46:23 -0400 X-MC-Unique: PeEk5sxVPzKm7quO4eSDog-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E2FFF107B263; Mon, 19 Jul 2021 16:46:21 +0000 (UTC) Received: from redhat.com (ovpn-112-193.ams2.redhat.com [10.36.112.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5C9165D9F0; Mon, 19 Jul 2021 16:46:10 +0000 (UTC) Date: Mon, 19 Jul 2021 17:46:06 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Yanan Wang Subject: Re: [PATCH for-6.2 v2 01/11] machine: Disallow specifying topology parameters as zero Message-ID: References: <20210719032043.25416-1-wangyanan55@huawei.com> <20210719032043.25416-2-wangyanan55@huawei.com> MIME-Version: 1.0 In-Reply-To: <20210719032043.25416-2-wangyanan55@huawei.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline 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: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.469, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Peter Maydell , Andrew Jones , Eduardo Habkost , "Michael S . Tsirkin" , wanghaibin.wang@huawei.com, Richard Henderson , qemu-devel@nongnu.org, Greg Kurz , Halil Pasic , yuzenghui@huawei.com, Igor Mammedov , Thomas Huth , Paolo Bonzini , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jul 19, 2021 at 11:20:33AM +0800, Yanan Wang wrote: > In the SMP configuration, we should either specify a topology > parameter with a reasonable value (equal to or greater than 1) > or just leave it omitted and QEMU will calculate its value. > > Configurations which explicitly specify the topology parameters > as zero like "sockets=0" are meaningless, so disallow them. > > Suggested-by: Andrew Jones > Signed-off-by: Yanan Wang > --- > hw/core/machine.c | 31 +++++++++++++++++++++++-------- > hw/i386/pc.c | 29 +++++++++++++++++++++-------- > qapi/machine.json | 4 ++-- > 3 files changed, 46 insertions(+), 18 deletions(-) > > diff --git a/hw/core/machine.c b/hw/core/machine.c > index 775add0795..d73daa10f4 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp) > { > unsigned cpus = config->has_cpus ? config->cpus : 0; > unsigned sockets = config->has_sockets ? config->sockets : 0; > + unsigned dies = config->has_dies ? config->dies : 1; It looks odd to set dies=1 by default at initially, when everything else is set to 0. I realize you're just copying existing pc_smp_parse code in this respect, but I feel like could benefit from a separate initialization with a comment to explain why we're hardcoding it to 1.... > unsigned cores = config->has_cores ? config->cores : 0; > unsigned threads = config->has_threads ? config->threads : 0; > + unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0; > + > + if ((config->has_cpus && config->cpus == 0) || > + (config->has_sockets && config->sockets == 0) || > + (config->has_dies && config->dies == 0) || > + (config->has_cores && config->cores == 0) || > + (config->has_threads && config->threads == 0) || > + (config->has_maxcpus && config->maxcpus == 0)) { > + error_setg(errp, "parameters must be equal to or greater than one" > + "if provided"); > + return; > + } > > - if (config->has_dies && config->dies != 0 && config->dies != 1) { > + if (dies > 1) { > error_setg(errp, "dies not supported by this machine's CPU topology"); > + return; > } .... eg how about here adding /* Never try to assign multiple dies when defaulting omitted topology */ if (dies == 0) { dies = 1; } > diff --git a/qapi/machine.json b/qapi/machine.json > index c3210ee1fb..c11b2e6f73 100644 > --- a/qapi/machine.json > +++ b/qapi/machine.json > @@ -1288,8 +1288,8 @@ > ## > # @SMPConfiguration: > # > -# Schema for CPU topology configuration. "0" or a missing value lets > -# QEMU figure out a suitable value based on the ones that are provided. > +# Schema for CPU topology configuration. A missing value lets QEMU > +# figure out a suitable value based on the ones that are provided. Hmm, so we had actually documented that '0' had the same semantics as omitting a parameter. This was done in: commit 1e63fe685804dfadddd643bf3860b1a59702d4bf Author: Paolo Bonzini Date: Thu Jun 17 17:53:06 2021 +0200 machine: pass QAPI struct to mc->smp_parse which hasn't been released yet. This was possible, but never documented, with the traditiaonl -smp impl before it was qapi-ified. I think that historical behaviour was simply a side effect of the QemuOpts impl rather than an intentional design, hence not documented. At the very least I think need to get rid of this bit of docs about "0" before this release, otherwise we'll have stronger need to consider a real deprecation process. 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 :|