INTEL_MSR_PERF_MASK
ctl &= ~INTEL_MSR_PERF_MASK;
ctl |= (pstate->st_cval & INTEL_MSR_PERF_MASK);
sval = rdmsr(INTEL_MSR_PERF_STATUS) & INTEL_MSR_PERF_MASK;
if ((pstates[i].st_sval & INTEL_MSR_PERF_MASK) == sval)