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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 99B1CC4338F for ; Fri, 23 Jul 2021 08:41:13 +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 BE69D6069E for ; Fri, 23 Jul 2021 08:41:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BE69D6069E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:38730 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m6qk3-0006iL-Rv for qemu-devel@archiver.kernel.org; Fri, 23 Jul 2021 04:41:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38960) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m6qjD-000627-1O for qemu-devel@nongnu.org; Fri, 23 Jul 2021 04:40:19 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:2070) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m6qj9-0001OC-Eo for qemu-devel@nongnu.org; Fri, 23 Jul 2021 04:40:18 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GWN2z234PzchZF; Fri, 23 Jul 2021 16:36:43 +0800 (CST) Received: from dggpemm500023.china.huawei.com (7.185.36.83) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 23 Jul 2021 16:40:07 +0800 Received: from [10.174.187.128] (10.174.187.128) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Fri, 23 Jul 2021 16:40:06 +0800 Subject: Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero To: Markus Armbruster , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210722154326.1464-1-wangyanan55@huawei.com> <20210722154326.1464-2-wangyanan55@huawei.com> <87o8atcva4.fsf@dusky.pond.sub.org> From: "wangyanan (Y)" Message-ID: <553158b7-3705-8570-d3b8-e772ae49ed2c@huawei.com> Date: Fri, 23 Jul 2021 16:40:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <87o8atcva4.fsf@dusky.pond.sub.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.187.128] X-ClientProxiedBy: dggeme720-chm.china.huawei.com (10.1.199.116) To dggpemm500023.china.huawei.com (7.185.36.83) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.188; envelope-from=wangyanan55@huawei.com; helo=szxga02-in.huawei.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.203, RCVD_IN_DNSWL_MED=-2.3, 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 , Eduardo Habkost , Pierre Morel , Pankaj Gupta , Cornelia Huck , qemu-devel@nongnu.org, 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 2021/7/23 16:02, Markus Armbruster wrote: > Daniel P. Berrangé writes: > >> 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"); > Let's scratch "if provided". > > I'd replace "must be equal to or greater than one" by "must be > positive", or maybe "must be greater than zero". How about we use "must be greater than zero" ? After a grep search of these two sentences in QEMU, they both show up in several places. "must be positive" always reports an invalid value that is "< 0". While the check in this patch actually reject an invalid zero value. >>> 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 > "positive" again. Thanks, Yanan >>> + 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 > .