# HG changeset patch
# User Keir Fraser <keir@xen.org>
# Date 1290453180 0
# Node ID 0cc4ed1ce1f34ce442ed4da106e555931c895395
# Parent  899131a8f9d2b99acc4bbe18593952d30446e71b
x86: Check for MWAIT in CPUID before using it in ACPI idle code.

Signed-off-by: Keir Fraser <keir@xen.org>

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -717,7 +717,8 @@ static void set_cx(
     {
     case ACPI_ADR_SPACE_FIXED_HARDWARE:
         if ( xen_cx->reg.bit_width == VENDOR_INTEL &&
-             xen_cx->reg.bit_offset == NATIVE_CSTATE_BEYOND_HALT )
+             xen_cx->reg.bit_offset == NATIVE_CSTATE_BEYOND_HALT &&
+             boot_cpu_has(X86_FEATURE_MWAIT) )
             cx->entry_method = ACPI_CSTATE_EM_FFH;
         else
             cx->entry_method = ACPI_CSTATE_EM_HALT;