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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 CA34DC433DB for ; Fri, 15 Jan 2021 08:20:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81A3C22287 for ; Fri, 15 Jan 2021 08:20:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732506AbhAOIT5 (ORCPT ); Fri, 15 Jan 2021 03:19:57 -0500 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:38489 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726375AbhAOIT4 (ORCPT ); Fri, 15 Jan 2021 03:19:56 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0ULnMmPw_1610698747; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0ULnMmPw_1610698747) by smtp.aliyun-inc.com(127.0.0.1); Fri, 15 Jan 2021 16:19:09 +0800 Subject: Re: [RESEND v13 00/10] KVM: x86/pmu: Guest Last Branch Recording Enabling To: Like Xu , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Cc: Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H . Peter Anvin" , ak@linux.intel.com, wei.w.wang@intel.com, kan.liang@intel.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210108013704.134985-1-like.xu@linux.intel.com> From: Alex Shi Message-ID: <3deac361-05fa-60a5-0d88-4f6b968f10bf@linux.alibaba.com> Date: Fri, 15 Jan 2021 16:19:06 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20210108013704.134985-1-like.xu@linux.intel.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2021/1/8 ÉÏÎç9:36, Like Xu дµÀ: > Because saving/restoring tens of LBR MSRs (e.g. 32 LBR stack entries) in > VMX transition brings too excessive overhead to frequent vmx transition > itself, the guest LBR event would help save/restore the LBR stack msrs > during the context switching with the help of native LBR event callstack > mechanism, including LBR_SELECT msr. > Sounds the feature is much helpful for VMM guest performance tunning. Good job! Thanks Alex