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:
pmu.c:
- patch 4: remove guest_cpuid_is_intel, which can be avoided by
directly checking pmu_ops->lbr_enable.
pmu_intel.c:
- patch 10: include MSR_LBR_SELECT into is_lbr_msr check, and pass
this msr through to the guest, instead of trapping
accesses.
- patch 12: fix the condition check of setting LBRS_FROZEN and
COUNTERS_FROZEN;
update the global_ovf_ctrl_mask for LBRS_FROZEN and
COUNTERS_FROZEN.
previous:
https://lkml.org/lkml/2019/6/6/133
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/pmu.c | 29 ++-
arch/x86/kvm/pmu.h | 12 +-
arch/x86/kvm/pmu_amd.c | 7 +-
arch/x86/kvm/vmx/pmu_intel.c | 393 +++++++++++++++++++++++++++++++++++++-
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 ++--
16 files changed, 562 insertions(+), 52 deletions(-)
--
2.7.4
