cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
- !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
+ !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
+ !mwait_substates)
return -ENODEV;
pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);