--- arch/x86/kernel/acpi/cstate.c

+++ arch/x86/kernel/acpi/cstate.c

@@ -145,6 +145,15 @@ int acpi_processor_ffh_cstate_probe(unsi

percpu_entry->states[cx->index].eax = cx->address;

percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;

}

+

+ /*

+ * For _CST FFH on Intel, if GAS.access_size bit 1 is cleared,

+ * then we should skip checking BM_STS for this C-state.

+ * ref: "Intel Processor Vendor-Specific ACPI Interface Specification"

+ */

+ if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))

+ cx->bm_sts_skip = 1;

+

return retval;

}

EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);