Because, this depends on the kernel tracepoint "kvm_hv:kvm_guest_exit".
perf_prepare_sample() in the kernel side sets the event->header.misc
PERF_RECORD_MISC_KERNEL through perf_misc_flags(pt_regs). In case of
tracepoints which always get hit in the host kernel context, the
perf_misc_flags() will always return PERF_RECORD_MISC_KERNEL.
IMHO we will rather have to set the cpumode in the user space for this
and we can't depend on the event->header.misc field for this case.
What would you suggest?