Re: [PATCH v12 00/11] Guest Last Branch Recording Enabling

From: Like Xu <like.xu@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	ak@linux.intel.com, wei.w.wang@intel.com,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v12 00/11] Guest Last Branch Recording Enabling
Date: Wed, 1 Jul 2020 10:38:54 +0800	[thread overview]
Message-ID: <49040dda-cf81-94f8-d1e3-cc5b523deece@linux.intel.com> (raw)
In-Reply-To: <dc1c7ef1-5ab4-0f7b-5036-457193bc722c@linux.intel.com>

Ping friendly.

If there is room for improvement, please let me know.

On 2020/6/23 21:13, Like Xu wrote:
> On 2020/6/13 16:09, Like Xu wrote:
>> Hi all,
>>
>> Please help review this new version for the Kenrel 5.9 release.
>>
>> Now, you may apply the last two qemu-devel patches to the upstream
>> qemu and try the guest LBR feature with '-cpu host' command line.
>>
>> v11->v12 Changelog:
>> - apply "Signed-off-by" form PeterZ and his codes for the perf subsystem;
>> - add validity checks before expose LBR via MSR_IA32_PERF_CAPABILITIES;
>> - refactor MSR_IA32_DEBUGCTLMSR emulation with validity check;
>> - reorder "perf_event_attr" fields according to how they're declared;
>> - replace event_is_oncpu() with "event->state" check;
>> - make LBR emualtion specific to vmx rather than x86 generic;
>> - move pass-through LBR code to vmx.c instead of pmu_intel.c;
>> - add vmx_lbr_en/disable_passthrough layer to make code readable;
>> - rewrite pmu availability check with vmx_passthrough_lbr_msrs();
>>
>> You may check more details in each commit.
>>
>> Previous:
>> https://lore.kernel.org/kvm/20200514083054.62538-1-like.xu@linux.intel.com/
>>
>> ---
> ...
>>
>> Wei Wang (1):
>>   perf/x86: Fix variable types for LBR registers > Like Xu (10):
>>    perf/x86/core: Refactor hw->idx checks and cleanup
>>    perf/x86/lbr: Add interface to get LBR information
>>    perf/x86: Add constraint to create guest LBR event without hw counter
>>    perf/x86: Keep LBR records unchanged in host context for guest usage
> 
> Hi Peter,
> Would you like to add "Acked-by" to the first three perf patches ?
> 
>>    KVM: vmx/pmu: Expose LBR to guest via MSR_IA32_PERF_CAPABILITIES
>>    KVM: vmx/pmu: Unmask LBR fields in the MSR_IA32_DEBUGCTLMSR emualtion
>>    KVM: vmx/pmu: Pass-through LBR msrs when guest LBR event is scheduled
>>    KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI
>>    KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation
>>    KVM: vmx/pmu: Release guest LBR event via lazy release mechanism
>>
> 
> Hi Paolo,
> Would you like to take a moment to review the KVM part for this feature ?
> 
> Thanks,
> Like Xu
> 
>>
>> Qemu-devel:
>>    target/i386: add -cpu,lbr=true support to enable guest LBR
>>
>>   arch/x86/events/core.c            |  26 +--
>>   arch/x86/events/intel/core.c      | 109 ++++++++-----
>>   arch/x86/events/intel/lbr.c       |  51 +++++-
>>   arch/x86/events/perf_event.h      |   8 +-
>>   arch/x86/include/asm/perf_event.h |  34 +++-
>>   arch/x86/kvm/pmu.c                |  12 +-
>>   arch/x86/kvm/pmu.h                |   5 +
>>   arch/x86/kvm/vmx/capabilities.h   |  23 ++-
>>   arch/x86/kvm/vmx/pmu_intel.c      | 253 +++++++++++++++++++++++++++++-
>>   arch/x86/kvm/vmx/vmx.c            |  86 +++++++++-
>>   arch/x86/kvm/vmx/vmx.h            |  17 ++
>>   arch/x86/kvm/x86.c                |  13 --
>>   12 files changed, 559 insertions(+), 78 deletions(-)
>>
> 