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...ose the PERF capabilities MSR? > > That's normally needed for LBR too to report the version > number. > It was missed, thanks for pointing it out. I also found KVM/QEMU doesn't expose CPUID.PDCM, will add that too. Since for now we are enabling LBR, I plan to expose only "PERF_CAP & 0x3f" to the guest, which reports the LBR format only. On the other side, it seems that the (guest) kernel driver also works without the above being supported, should we change it to report error and stop using the PMU features when the check of the above two fails (at intel_pmu_init(...

...ose the PERF capabilities MSR? > > That's normally needed for LBR too to report the version > number. > It was missed, thanks for pointing it out. I also found KVM/QEMU doesn't expose CPUID.PDCM, will add that too. Since for now we are enabling LBR, I plan to expose only "PERF_CAP & 0x3f" to the guest, which reports the LBR format only. On the other side, it seems that the (guest) kernel driver also works without the above being supported, should we change it to report error and stop using the PMU features when the check of the above two fails (at intel_pmu_init(...

This patch series enables the Last Branch Recording feature for the guest. Instead of trapping each LBR stack MSR access, the MSRs are passthroughed to the guest. Those MSRs are switched (i.e. load and saved) on VMExit and VMEntry. Test: Try "perf record -b ./test_program" on guest. Wei Wang (4): KVM/vmx: re-write the msr auto switch feature KVM/vmx: auto switch

This patch series enables the Last Branch Recording feature for the guest. Instead of trapping each LBR stack MSR access, the MSRs are passthroughed to the guest. Those MSRs are switched (i.e. load and saved) on VMExit and VMEntry. Test: Try "perf record -b ./test_program" on guest. Wei Wang (4): KVM/vmx: re-write the msr auto switch feature KVM/vmx: auto switch