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 2469BC3601E for ; Thu, 10 Apr 2025 09:26:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u2o9u-0006xx-Lq; Thu, 10 Apr 2025 05:25:18 -0400 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 1u2o9l-0006si-UX; Thu, 10 Apr 2025 05:25:10 -0400 Received: from mgamail.intel.com ([192.198.163.12]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u2o9j-00026A-9F; Thu, 10 Apr 2025 05:25:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1744277107; x=1775813107; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=vWFTCAHyc4ZZSNblinRf0t8BBfuIQYEI8cO6hq8NbrA=; b=CAGLPQl78R5F/0eb8DNCrhKsax4H8oLxcWT2JI5YQkfjoPvE6V3ZsJZs z6DogORdau5iKKoShp6lla52jwJmoJPjtQ7uqxf+1nPyxt3JNrHHEzdP7 OIkum8zy1tUayGCMXP/NY6axmXrwUjjHoBhxooKmShKeatvnl5hzegPUG F3katX1LpNIjL8ETP0+30y+R/SLTxC0OSxqZh0qlORH9BwUH3p/lMBl9U n3vMKzwlJMmIbUmphPOQrtEKDYCtYTETaKAPTJGWC4MWJLq1eJiR/99jr 8QIq0jIjVJa0ITghG3jyOYj5mX86KDQIvyydEc+VwrbOG+pG323l7xoIo A==; X-CSE-ConnectionGUID: Xx6nNb4dTQGIrOXlLCgZuA== X-CSE-MsgGUID: hE6bzLpVRNKkM6EHcckQPw== X-IronPort-AV: E=McAfee;i="6700,10204,11399"; a="49625375" X-IronPort-AV: E=Sophos;i="6.15,202,1739865600"; d="scan'208";a="49625375" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Apr 2025 02:25:00 -0700 X-CSE-ConnectionGUID: 7EFLD+8sQoiP2fdPZgk4+Q== X-CSE-MsgGUID: aiCRLBNDQsqVw5PNhNlRAg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,202,1739865600"; d="scan'208";a="129685784" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.39]) by fmviesa009.fm.intel.com with ESMTP; 10 Apr 2025 02:24:51 -0700 Date: Thu, 10 Apr 2025 17:45:41 +0800 From: Zhao Liu To: Dongli Zhang Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, qemu-arm@nongnu.org, qemu-ppc@nongnu.org, qemu-riscv@nongnu.org, qemu-s390x@nongnu.org, pbonzini@redhat.com, mtosatti@redhat.com, sandipan.das@amd.com, babu.moger@amd.com, likexu@tencent.com, like.xu.linux@gmail.com, groug@kaod.org, khorenko@virtuozzo.com, alexander.ivanov@virtuozzo.com, den@virtuozzo.com, davydov-max@yandex-team.ru, xiaoyao.li@intel.com, dapeng1.mi@linux.intel.com, joe.jin@oracle.com, peter.maydell@linaro.org, gaosong@loongson.cn, chenhuacai@kernel.org, philmd@linaro.org, aurelien@aurel32.net, jiaxun.yang@flygoat.com, arikalo@gmail.com, npiggin@gmail.com, danielhb413@gmail.com, palmer@dabbelt.com, alistair.francis@wdc.com, liwei1518@gmail.com, zhiwei_liu@linux.alibaba.com, pasic@linux.ibm.com, borntraeger@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, iii@linux.ibm.com, thuth@redhat.com, flavra@baylibre.com, ewanhai-oc@zhaoxin.com, ewanhai@zhaoxin.com, cobechen@zhaoxin.com, louisqi@zhaoxin.com, liamni@zhaoxin.com, frankzhu@zhaoxin.com, silviazhao@zhaoxin.com Subject: Re: [PATCH v3 10/10] target/i386/kvm: don't stop Intel PMU counters Message-ID: References: <20250331013307.11937-1-dongli.zhang@oracle.com> <20250331013307.11937-11-dongli.zhang@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250331013307.11937-11-dongli.zhang@oracle.com> Received-SPF: pass client-ip=192.198.163.12; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -48 X-Spam_score: -4.9 X-Spam_bar: ---- X-Spam_report: (-4.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.505, 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 On Sun, Mar 30, 2025 at 06:32:29PM -0700, Dongli Zhang wrote: > Date: Sun, 30 Mar 2025 18:32:29 -0700 > From: Dongli Zhang > Subject: [PATCH v3 10/10] target/i386/kvm: don't stop Intel PMU counters > X-Mailer: git-send-email 2.43.5 > > The kvm_put_msrs() sets the MSRs using KVM_SET_MSRS. The x86 KVM processes > these MSRs one by one in a loop, only saving the config and triggering the > KVM_REQ_PMU request. This approach does not immediately stop the event > before updating PMC. This is ture after KVM's 68fb4757e867 (v6.2). QEMU even supports v4.5 (docs/system/target-i386.rst)... I'm not sure whether it is outdated, but it's better to mention the Linux version. > In additional, PMU MSRs are set only at levels >= KVM_PUT_RESET_STATE, > excluding runtime. Therefore, updating these MSRs without stopping events > should be acceptable. I agree. > Finally, KVM creates kernel perf events with host mode excluded > (exclude_host = 1). While the events remain active, they don't increment > the counter during QEMU vCPU userspace mode. > > No Fixed tag is going to be added for the commit 0d89436786b0 ("kvm: > migrate vPMU state"), because this isn't a bugfix. > > Signed-off-by: Dongli Zhang > --- > target/i386/kvm/kvm.c | 9 --------- > 1 file changed, 9 deletions(-) Fine for me, Reviewed-by: Zhao Liu