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Subject[PATCH v6 00/12] Guest LBR Enabling
Date
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
KVM_CAP_X86_GUEST_LBR;
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.

ChangeLog:
- 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.
previous:
https://lkml.org/lkml/2019/2/14/210

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

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: KVM_CAP_X86_GUEST_LBR
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
KVM/VMX/vPMU: support to report GLOBAL_STATUS_LBRS_FROZEN

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(-)

--
2.7.4

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