KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI
The current vPMU only supports Architecture Version 2. According to Intel SDM "17.4.7 Freezing LBR and Performance Counters on PMI", if IA32_DEBUGCTL.Freeze_LBR_On_PMI = 1, the LBR is frozen on the virtual PMI and the KVM would emulate to clear the LBR bit (bit 0) in IA32_DEBUGCTL. Also, guest needs to re-enable IA32_DEBUGCTL.LBR to resume recording branches. Signed-off-by: NLike Xu <like.xu@linux.intel.com> Reviewed-by: NAndi Kleen <ak@linux.intel.com> Message-Id: <20210201051039.255478-9-like.xu@linux.intel.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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