xen/ACPI: allow passing down C1 information if no other C-states exist

Otherwise Xen may end up not using MWAIT despite its availability.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Keir Fraser <keir@xen.org>

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 8c042f5b1089f56cd299649f9017756ec8ad388b..1b44138832913181a850f3abecc56962ed72c998 100644 (file)
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -780,7 +780,7 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
                          current_count));
 
        /* Validate number of power states discovered */
-       if (current_count < 2)
+       if (current_count < (processor_pm_external() ? 1 : 2))
                status = -EFAULT;
 
       end: