x86: Disable cpuidle by default unless hpet broadcast is available.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

xen/arch/x86/setup.c

@@ -89,7 +89,7 @@ boolean_param("noapic", skip_ioapic_setup);
 
 /* **** Linux config option: propagated to domain0. */
 /* xen_cpuidle: xen control cstate. */
-/*static*/ int xen_cpuidle = 1;
+/*static*/ int xen_cpuidle = -1;
 boolean_param("cpuidle", xen_cpuidle);
 
 int early_boot = 1;

xen/arch/x86/time.c

@@ -1279,8 +1279,17 @@ static int disable_pit_irq(void)
         hpet_broadcast_init();
         if ( !hpet_broadcast_is_available() )
         {
-            printk("HPET broadcast init failed, turn to PIT broadcast.\n");
-            return 0;
+            if ( xen_cpuidle == -1 )
+            {
+                xen_cpuidle = 0;
+                printk("CPUIDLE: disabled due to no HPET. "
+                       "Force enable with 'cpuidle'.\n");
+            }
+            else
+            {
+                printk("HPET broadcast init failed, turn to PIT broadcast.\n");
+                return 0;
+            }
         }
     }