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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD3D5EE4993 for ; Mon, 21 Aug 2023 09:11:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234278AbjHUJLY (ORCPT ); Mon, 21 Aug 2023 05:11:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230367AbjHUJLX (ORCPT ); Mon, 21 Aug 2023 05:11:23 -0400 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65567C4; Mon, 21 Aug 2023 02:11:21 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=hao.xiang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VqEqKAv_1692609076; Received: from 30.221.109.103(mailfrom:hao.xiang@linux.alibaba.com fp:SMTPD_---0VqEqKAv_1692609076) by smtp.aliyun-inc.com; Mon, 21 Aug 2023 17:11:17 +0800 Message-ID: <6d10dcf7-7912-25a2-8d8e-ef7d71a4ce83@linux.alibaba.com> Date: Mon, 21 Aug 2023 17:11:16 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] kvm: x86: emulate MSR_PLATFORM_INFO msr bits Content-Language: en-US To: Chao Gao Cc: kvm@vger.kernel.org, shannon.zhao@linux.alibaba.com, pbonzini@redhat.com, seanjc@google.com, linux-kernel@vger.kernel.org References: <1692588392-58155-1-git-send-email-hao.xiang@linux.alibaba.com> From: Hao Xiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org For reason that, The turbo frequency info depends on specific machine type. And the msr value of MSR_PLATFORM_INFO may be diferent on diffrent generation machine. Get following msr bits (needed by turbostat on intel platform) by rdmsr MSR_PLATFORM_INFO directly in KVM is more reasonable. And set these msr bits as vcpu->arch.msr_platform_info default value. -bit 15:8, Maximum Non-Turbo Ratio (MAX_NON_TURBO_LIM_RATIO) -bit 47:40, Maximum Efficiency Ratio (MAX_EFFICIENCY_RATIO) On 2023/8/21 15:52, Chao Gao wrote: > On Mon, Aug 21, 2023 at 11:26:32AM +0800, Hao Xiang wrote: >> For intel platform, The BzyMhz field of Turbostat shows zero >> due to the missing of part msr bits of MSR_PLATFORM_INFO. >> >> Acquire necessary msr bits, and expose following msr info to guest, >> to make sure guest can get correct turbo frequency info. > > Userspace VMM (e.g., QEMU) can configure this MSR for guests. Please refer to > tools/testing/selftests/kvm/x86_64/platform_info_test.c. > > The question is why KVM needs this patch given KVM already provides interfaces > for QEMU to configure the MSR.