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=-13.6 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,URIBL_BLOCKED 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 A508EC4338F for ; Fri, 23 Jul 2021 07:07:40 +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 05FC160EAF for ; Fri, 23 Jul 2021 07:07:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 05FC160EAF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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bh=vF+Ctgl+UTk027RymWUjLQCG9r0lLXEP2VZlk9E3wUA=; b=GONJEyp9vxz5ryvnIn5F4OyRxRyCw4OrNunuWPLOa1xx1pbjWVK3P1jYNYzaNQzJm59xeR GVoAwt9TOwenSmydi1mWYyLpGsv8GROS7EEXwG1KT0POBs0sH+qrD03ZVZnoZO00cDEEm8 NV2f+ewqlxbbQ6roNvtsJe9YrrQbdb0= 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-456-la8NieF2N82LquavFBqoQA-1; Fri, 23 Jul 2021 03:06:40 -0400 X-MC-Unique: la8NieF2N82LquavFBqoQA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B3E8510086C4; Fri, 23 Jul 2021 07:06:38 +0000 (UTC) Received: from localhost (unknown [10.39.192.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D46B760862; Fri, 23 Jul 2021 07:06:37 +0000 (UTC) From: Cornelia Huck To: Yanan Wang , qemu-devel@nongnu.org Subject: Re: [PATCH for-6.1 v3 1/1] machine: Disallow specifying topology parameters as zero In-Reply-To: <20210723020002.18456-2-wangyanan55@huawei.com> Organization: Red Hat GmbH References: <20210723020002.18456-1-wangyanan55@huawei.com> <20210723020002.18456-2-wangyanan55@huawei.com> User-Agent: Notmuch/0.32.1 (https://notmuchmail.org) Date: Fri, 23 Jul 2021 09:06:36 +0200 Message-ID: <8735s57blv.fsf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=170.10.133.124; envelope-from=cohuck@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=-1.472, 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: , Cc: Peter Maydell , Andrew Jones , =?utf-8?Q?Danie?= =?utf-8?Q?l_P_=2E_Berrang=C3=A9?= , Eduardo Habkost , Pierre Morel , Pankaj Gupta , wanghaibin.wang@huawei.com, Markus Armbruster , Yanan Wang , Cleber Rosa , yuzenghui@huawei.com, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jul 23 2021, 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. > > However, the commit 1e63fe685804d > (machine: pass QAPI struct to mc->smp_parse) has documented that > '0' has the same semantics as omitting a parameter in the qapi > comment for SMPConfiguration. So this patch fixes the doc and > also adds the corresponding sanity check in the smp parsers. > > Reviewed-by: Andrew Jones > Reviewed-by: Daniel P. Berrange > Tested-by: Daniel P. Berrange > Suggested-by: Andrew Jones > Signed-off-by: Yanan Wang > --- > hw/core/machine.c | 15 +++++++++++++++ > qapi/machine.json | 6 +++--- > qemu-options.hx | 12 +++++++----- > 3 files changed, 25 insertions(+), 8 deletions(-) > > diff --git a/hw/core/machine.c b/hw/core/machine.c > index 775add0795..d95e8b6903 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -829,6 +829,21 @@ static void machine_set_smp(Object *obj, Visitor *v, const char *name, > return; > } > > + /* > + * The topology parameters must be specified equal to or great than one s/great/greater/ > + * or just omitted, explicit configuration like "cpus=0" is not allowed. > + */ > + 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, "CPU topology parameters must be equal to " > + "or greater than one if provided"); > + goto out_free; > + } > + > mc->smp_parse(ms, config, errp); > if (errp) { > goto out_free; > diff --git a/qapi/machine.json b/qapi/machine.json > index c3210ee1fb..9272cb3cf8 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. > # > # @cpus: number of virtual CPUs in the virtual machine > # > @@ -1297,7 +1297,7 @@ > # > # @dies: number of dies per socket in the CPU topology > # > -# @cores: number of cores per thread in the CPU topology > +# @cores: number of cores per die in the CPU topology > # > # @threads: number of threads per core in the CPU topology > # > diff --git a/qemu-options.hx b/qemu-options.hx > index 99ed5ec5f1..b0168f8c48 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -223,11 +223,13 @@ SRST > of computing the CPU maximum count. > > Either the initial CPU count, or at least one of the topology parameters > - must be specified. Values for any omitted parameters will be computed > - from those which are given. Historically preference was given to the > - coarsest topology parameters when computing missing values (ie sockets > - preferred over cores, which were preferred over threads), however, this > - behaviour is considered liable to change. > + must be specified. The specified parameters must be equal to or great s/great/greater/ > + than one, explicit configuration like "cpus=0" is not allowed. Values > + for any omitted parameters will be computed from those which are given. > + Historically preference was given to the coarsest topology parameters > + when computing missing values (ie sockets preferred over cores, which > + were preferred over threads), however, this behaviour is considered > + liable to change. > ERST > > DEF("numa", HAS_ARG, QEMU_OPTION_numa, Reviewed-by: Cornelia Huck