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bh=x2kdi5BtBWDgBhEB0P1JPsuRUhxhJFKhIqPim1vrOvo=; b=dzZsL+xh0CHjvxwDaI+hV4FIN5fFUHX1WrKYQjZFxm4RYKqqVeck1w5kx78nhtlrNx4Q/E rPcGIJLpUAbcZZMdHe5qKqMXz7lhbLxDkcBhjxjBNxnC2PBSiATYwK6tL6YA2Nj6GmiF7Z aFlv+ojuiD5lFWHBZTX4O6h0Q/nSVqM= 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-564-akVG-CDjN96Sf3-1E93DVg-1; Thu, 22 Jul 2021 12:02:17 -0400 X-MC-Unique: akVG-CDjN96Sf3-1E93DVg-1 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 AAABF10AE605; Thu, 22 Jul 2021 16:01:24 +0000 (UTC) Received: from redhat.com (ovpn-114-245.ams2.redhat.com [10.36.114.245]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B4ED919711; Thu, 22 Jul 2021 16:01:21 +0000 (UTC) Date: Thu, 22 Jul 2021 17:01:18 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Yanan Wang Subject: Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero Message-ID: References: <20210722154326.1464-1-wangyanan55@huawei.com> <20210722154326.1464-2-wangyanan55@huawei.com> MIME-Version: 1.0 In-Reply-To: <20210722154326.1464-2-wangyanan55@huawei.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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 Content-Transfer-Encoding: 8bit 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=-1.472, 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Peter Maydell , Andrew Jones , Eduardo Habkost , Pierre Morel , Pankaj Gupta , Cornelia Huck , qemu-devel@nongnu.org, Markus Armbruster , wanghaibin.wang@huawei.com, yuzenghui@huawei.com, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jul 22, 2021 at 11:43:26PM +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. > > 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. > > Suggested-by: Andrew Jones > Signed-off-by: Yanan Wang > --- > hw/core/machine.c | 14 ++++++++++++++ > qapi/machine.json | 6 +++--- > qemu-options.hx | 12 +++++++----- > 3 files changed, 24 insertions(+), 8 deletions(-) > > diff --git a/hw/core/machine.c b/hw/core/machine.c > index 775add0795..db129d937b 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -829,6 +829,20 @@ 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 > + * 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, "parameters must be equal to or greater than one if provided"); I'd suggest a slight tweak since when seen it lacks context: $ ./qemu-system-x86_64 -smp 4,cores=0,sockets=2 qemu-system-x86_64: parameters must be equal to or greater than one if provided error_setg(errp, "CPU topology parameters must be equal to or greater than one if provided"); > 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 If you make the text changes, then feel free to add this when posting v2: Reviewed-by: Daniel P. Berrangé Tested-by: Daniel P. Berrangé 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 :|