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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 128F0E6C60F for ; Tue, 3 Dec 2024 07:18:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tINB0-0008Ar-Fq; Tue, 03 Dec 2024 02:18:30 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tINAy-00089v-SY; Tue, 03 Dec 2024 02:18:28 -0500 Received: from mgamail.intel.com ([192.198.163.17]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tINAx-0007OV-Bo; Tue, 03 Dec 2024 02:18:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733210307; x=1764746307; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=g1p7ypTgbIDo2kAakWW29oZ132lTGOCrVOm0ThfGnhA=; b=Tkhk9U7+2x3UXuYrqnq4/ahLzw0aqCVpVxuTFjyzmTUnbh2CS9g6EJx4 JTv5fqDUrCV7zBUMuCrVSmK+zQdneyOqBYeOfFUYMMn3J5BWK8Ks+89DG 88f1Tu6EKy3OBvtS2ehLHO9bXMEZdC+TU6oAMmM8wugZ6RCIo/ET+omsu 6tTtZ4No7I8HpwfTYa1FMJGY1ijo/Q8BUEucGnVnBpAdUAl/5+WlHIjtv SGfHlMs9TeUSWbbzzakESKNZr0SMcXkT/lVOqlvfvd9EZowhjaF67bN7e 3RgQjPhf4d5z9ZOoFZuTfDQQss3k1VuM8L5olqCGi+OF1ZF9QoHM/74Qw g==; X-CSE-ConnectionGUID: dEnMzftHTl6OaI35Pj7QbA== X-CSE-MsgGUID: oGVSreouRi2T6rzcp/Y61A== X-IronPort-AV: E=McAfee;i="6700,10204,11274"; a="33332364" X-IronPort-AV: E=Sophos;i="6.12,204,1728975600"; d="scan'208";a="33332364" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Dec 2024 23:18:25 -0800 X-CSE-ConnectionGUID: WR1f7qTFT0+mdhuFGPYDpA== X-CSE-MsgGUID: RGRB0EFDToK4dt+4P3QvXg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,199,1725346800"; d="scan'208";a="98362748" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by orviesa003.jf.intel.com with ESMTP; 02 Dec 2024 23:18:22 -0800 Date: Tue, 3 Dec 2024 15:36:33 +0800 From: Zhao Liu To: Chuang Xu Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, imammedo@redhat.com, xieyongji@bytedance.com, chaiwen.cc@bytedance.com, qemu-stable@nongnu.org, Guixiong Wei , Yipeng Yin Subject: Re: [PATCH v6] i386/cpu: fixup number of addressable IDs for logical processors in the physical package Message-ID: References: <20241009035638.59330-1-xuchuangxclwt@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241009035638.59330-1-xuchuangxclwt@bytedance.com> Received-SPF: pass client-ip=192.198.163.17; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -73 X-Spam_score: -7.4 X-Spam_bar: ------- X-Spam_report: (-7.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Chuang, Could I pick this fix in my later series (with another overflow fix)? I can help you push this fix forward :-). Regards, Zhao On Wed, Oct 09, 2024 at 11:56:38AM +0800, Chuang Xu wrote: > Date: Wed, 9 Oct 2024 11:56:38 +0800 > From: Chuang Xu > Subject: [PATCH v6] i386/cpu: fixup number of addressable IDs for logical > processors in the physical package > X-Mailer: git-send-email 2.39.3 (Apple Git-146) > > When QEMU is started with: > -cpu host,migratable=on,host-cache-info=on,l3-cache=off > -smp 180,sockets=2,dies=1,cores=45,threads=2 > > On Intel platform: > CPUID.01H.EBX[23:16] is defined as "max number of addressable IDs for > logical processors in the physical package". > > When executing "cpuid -1 -l 1 -r" in the guest, we obtain a value of 90 for > CPUID.01H.EBX[23:16], whereas the expected value is 128. Additionally, > executing "cpuid -1 -l 4 -r" in the guest yields a value of 63 for > CPUID.04H.EAX[31:26], which matches the expected result. > > As (1+CPUID.04H.EAX[31:26]) rounds up to the nearest power-of-2 integer, > we'd beter round up CPUID.01H.EBX[23:16] to the nearest power-of-2 > integer too. Otherwise we may encounter unexpected results in guest. > > For example, when QEMU is started with CLI above and xtopology is disabled, > guest kernel 5.15.120 uses CPUID.01H.EBX[23:16]/(1+CPUID.04H.EAX[31:26]) to > calculate threads-per-core in detect_ht(). Then guest will get "90/(1+63)=1" > as the result, even though threads-per-core should actually be 2. > > And on AMD platform: > CPUID.01H.EBX[23:16] is defined as "Logical processor count". Current > result meets our expectation. > > So let us round up CPUID.01H.EBX[23:16] to the nearest power-of-2 integer > only for Intel platform to solve the unexpected result. > > Reviewed-by: Zhao Liu > Acked-by: Igor Mammedov > Signed-off-by: Guixiong Wei > Signed-off-by: Yipeng Yin > Signed-off-by: Chuang Xu