x86: Check for MWAIT in CPUID before using it in ACPI idle code.

Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset:   22416:0cc4ed1ce1f3
xen-unstable date:        Mon Nov 22 19:13:00 2010 +0000

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index e6bf303b32a7ca4bd180860b89611bfadf79a14f..4e35e40d0d18abb45cfca0e446fa29d6f13d3e0b 100644 (file)
--- 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;