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Date:   Thu,  6 Jun 2019 15:02:19 +0800
From:   Wei Wang <>
Subject: [PATCH v6 00/12] Guest LBR Enabling

Last Branch Recording (LBR) is a performance monitor unit (PMU) feature
on Intel CPUs that captures branch related info. This patch series enables
this feature to KVM guests.

Here is a conclusion of the fundamental methods that we use:
1) the LBR feature is enabled per guest via QEMU setting of
2) the LBR stack is passed through to the guest for direct accesses after
   the guest's first access to any of the lbr related MSRs;
3) the host will help save/resotre the LBR stack when the vCPU is
   scheduled out/in.

    - perf/x86:
        - Patch 7:
                - define "no counter" as a new PERF_EV cap and keep it
                  used in the kernel, instead of esposing it in the user
                  ABI (if defined in perf_event_attr)
                - add a new API, perf_event_create, which can be used to
                  create a perf event without counter assignment (e.g.
                  a perf event simply to get the perf core's help of
                  switching lbr stack on thread switching, please see
                  patch 8)
    - KVM/vPMU:
	- Patch 8: use perf_event_create to create a perf event without
                   the need of a perf counter
	- Patch 12: set the GLOBAL_STATUS_COUNTERS_FROZEN bit when
                   injecting a vPMI.

Like Xu (1):
  KVM/x86/vPMU: Add APIs to support host save/restore the guest lbr

Wei Wang (11):
  perf/x86: fix the variable type of the LBR MSRs
  perf/x86: add a function to get the lbr stack
  KVM/x86: intel_pmu_lbr_enable
  KVM/x86/vPMU: tweak kvm_pmu_get_msr
  KVM/x86: expose MSR_IA32_PERF_CAPABILITIES to the guest
  perf/x86: no counter allocation support
  perf/x86: save/restore LBR_SELECT on vCPU switching
  KVM/x86/lbr: lazy save the guest lbr stack
  KVM/x86: remove the common handling of the debugctl msr

 arch/x86/events/core.c            |  12 ++
 arch/x86/events/intel/lbr.c       |  43 ++++-
 arch/x86/events/perf_event.h      |   6 +-
 arch/x86/include/asm/kvm_host.h   |   5 +
 arch/x86/include/asm/perf_event.h |  16 ++
 arch/x86/kvm/cpuid.c              |   2 +-
 arch/x86/kvm/cpuid.h              |   8 +
 arch/x86/kvm/pmu.c                |  29 ++-
 arch/x86/kvm/pmu.h                |  12 +-
 arch/x86/kvm/pmu_amd.c            |   7 +-
 arch/x86/kvm/vmx/pmu_intel.c      | 397 +++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/vmx/vmx.c            |   4 +-
 arch/x86/kvm/vmx/vmx.h            |   2 +
 arch/x86/kvm/x86.c                |  32 +--
 include/linux/perf_event.h        |  13 ++
 include/uapi/linux/kvm.h          |   1 +
 kernel/events/core.c              |  37 ++--
 17 files changed, 574 insertions(+), 52 deletions(-)


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