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

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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@xxxxxxxxxxxxxxx/

---
...

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(-)





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