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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,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 D346FC433ED for ; Tue, 6 Apr 2021 03:19:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92291613BC for ; Tue, 6 Apr 2021 03:19:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243532AbhDFDTn (ORCPT ); Mon, 5 Apr 2021 23:19:43 -0400 Received: from mga07.intel.com ([134.134.136.100]:37950 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231620AbhDFDTi (ORCPT ); Mon, 5 Apr 2021 23:19:38 -0400 IronPort-SDR: bJnfiOWR15TmoSqnQjYYgKh9FUMOMFRPOjettzB6PzUHVZCWb0o2xHqOvXwkrMvv9SXtAcx3Uy SsOKvo3q2xHg== X-IronPort-AV: E=McAfee;i="6000,8403,9945"; a="256957998" X-IronPort-AV: E=Sophos;i="5.81,308,1610438400"; d="scan'208";a="256957998" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2021 20:19:30 -0700 IronPort-SDR: qFrrEfOaOypP8Es0u+Z0lLUPd6o7qANb9FjPShyZMpOjW6lvn9MwNHMEN1bb5U9XtiYo9dVD1N PmfjpNOGlgdQ== X-IronPort-AV: E=Sophos;i="5.81,308,1610438400"; d="scan'208";a="421005662" Received: from likexu-mobl1.ccr.corp.intel.com (HELO [10.238.4.93]) ([10.238.4.93]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2021 20:19:25 -0700 Subject: Re: [PATCH v4 00/16] KVM: x86/pmu: Add basic support to enable Guest PEBS via DS To: peterz@infradead.org, Sean Christopherson , Paolo Bonzini Cc: eranian@google.com, andi@firstfloor.org, kan.liang@linux.intel.com, wei.w.wang@intel.com, Wanpeng Li , Vitaly Kuznetsov , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Like Xu References: <20210329054137.120994-1-like.xu@linux.intel.com> From: "Xu, Like" Message-ID: <4a39a825-7d18-b9ca-b0c3-eafec57b3921@intel.com> Date: Tue, 6 Apr 2021 11:19:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210329054137.120994-1-like.xu@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi all, do we have any comments on this patch set? On 2021/3/29 13:41, Like Xu wrote: > The guest Precise Event Based Sampling (PEBS) feature can provide > an architectural state of the instruction executed after the guest > instruction that exactly caused the event. It needs new hardware > facility only available on Intel Ice Lake Server platforms. This > patch set enables the basic PEBS via DS feature for KVM guests on ICX. > > We can use PEBS feature on the Linux guest like native: > > # perf record -e instructions:ppp ./br_instr a > # perf record -c 100000 -e instructions:pp ./br_instr a > > To emulate guest PEBS facility for the above perf usages, > we need to implement 2 code paths: > > 1) Fast path > > This is when the host assigned physical PMC has an identical index as > the virtual PMC (e.g. using physical PMC0 to emulate virtual PMC0). > This path is used in most common use cases. > > 2) Slow path > > This is when the host assigned physical PMC has a different index > from the virtual PMC (e.g. using physical PMC1 to emulate virtual PMC0) > In this case, KVM needs to rewrite the PEBS records to change the > applicable counter indexes to the virtual PMC indexes, which would > otherwise contain the physical counter index written by PEBS facility, > and switch the counter reset values to the offset corresponding to > the physical counter indexes in the DS data structure. > > The previous version [0] enables both fast path and slow path, which > seems a bit more complex as the first step. In this patchset, we want > to start with the fast path to get the basic guest PEBS enabled while > keeping the slow path disabled. More focused discussion on the slow > path [1] is planned to be put to another patchset in the next step. > > Compared to later versions in subsequent steps, the functionality > to support host-guest PEBS both enabled and the functionality to > emulate guest PEBS when the counter is cross-mapped are missing > in this patch set (neither of these are typical scenarios). > > With the basic support, the guest can retrieve the correct PEBS > information from its own PEBS records on the Ice Lake servers. > And we expect it should work when migrating to another Ice Lake > and no regression about host perf is expected. > > Here are the results of pebs test from guest/host for same workload: > > perf report on guest: > # Samples: 2K of event 'instructions:ppp', # Event count (approx.): 1473377250 > # Overhead Command Shared Object Symbol > 57.74% br_instr br_instr [.] lfsr_cond > 41.40% br_instr br_instr [.] cmp_end > 0.21% br_instr [kernel.kallsyms] [k] __lock_acquire > > perf report on host: > # Samples: 2K of event 'instructions:ppp', # Event count (approx.): 1462721386 > # Overhead Command Shared Object Symbol > 57.90% br_instr br_instr [.] lfsr_cond > 41.95% br_instr br_instr [.] cmp_end > 0.05% br_instr [kernel.vmlinux] [k] lock_acquire > Conclusion: the profiling results on the guest are similar tothat on the host. > > Please check more details in each commit and feel free to comment. > > Previous: > [0] https://lore.kernel.org/kvm/20210104131542.495413-1-like.xu@linux.intel.com/ > [1] https://lore.kernel.org/kvm/20210115191113.nktlnmivc3edstiv@two.firstfloor.org/ > > v3->v4 Changelog: > - Update this cover letter and propose a new upstream plan; > [PERF] > - Drop check host DS and move handler to handle_pmi_common(); > - Pass "struct kvm_pmu *" to intel_guest_get_msrs(); > - Propose new assignment logic for perf_guest_switch_msr(); > - Introduce x86_pmu.pebs_vmx for future capability maintenance; > [KVM] > - Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability; > - Raising PEBS PMI only when OVF_BIT 62 is not set; > - Make vmx_icl_pebs_cpu specific for PEBS-PDIR emulation; > - Fix a bug for fixed_ctr_ctrl_mask; > - Add two minor refactoring patches for reuse; > > Like Xu (16): > perf/x86/intel: Add x86_pmu.pebs_vmx for Ice Lake Servers > perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest > perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values > KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled > KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter > KVM: x86/pmu: Reprogram guest PEBS event to emulate guest PEBS counter > KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS > KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to manage guest DS buffer > KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS > KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled > KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter > KVM: x86/pmu: Move pmc_speculative_in_use() to arch/x86/kvm/pmu.h > KVM: x86/pmu: Disable guest PEBS before vm-entry in two cases > KVM: x86/pmu: Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability > KVM: x86/cpuid: Refactor host/guest CPU model consistency check > KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 > > arch/x86/events/core.c | 5 +- > arch/x86/events/intel/core.c | 93 +++++++++++++++++++++++--- > arch/x86/events/perf_event.h | 5 +- > arch/x86/include/asm/kvm_host.h | 16 +++++ > arch/x86/include/asm/msr-index.h | 6 ++ > arch/x86/include/asm/perf_event.h | 5 +- > arch/x86/kvm/cpuid.c | 24 ++----- > arch/x86/kvm/cpuid.h | 5 ++ > arch/x86/kvm/pmu.c | 49 ++++++++++---- > arch/x86/kvm/pmu.h | 37 +++++++++++ > arch/x86/kvm/vmx/capabilities.h | 26 ++++++-- > arch/x86/kvm/vmx/pmu_intel.c | 105 ++++++++++++++++++++++++------ > arch/x86/kvm/vmx/vmx.c | 25 ++++++- > arch/x86/kvm/vmx/vmx.h | 2 +- > arch/x86/kvm/x86.c | 14 ++-- > 15 files changed, 339 insertions(+), 78 deletions(-) >