merge with xen-unstable.hg (staging)

1 files changed, 27 insertions, 4 deletions

diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c
index 31fc8adbe6..550faf069b 100644
--- a/xen/arch/x86/smp.c
+++ b/xen/arch/x86/smp.c
@@ -279,6 +279,19 @@ int on_selected_cpus(
 
     ASSERT(local_irq_is_enabled());
 
+    /* Legacy UP system with no APIC to deliver IPIs? */
+    if ( unlikely(!cpu_has_apic) )
+    {
+        ASSERT(num_online_cpus() == 1);
+        if ( cpu_isset(0, selected) )
+        {
+            local_irq_disable();
+            func(info);
+            local_irq_enable();
+        }
+        return 0;
+    }
+
     if ( nr_cpus == 0 )
         return 0;
 
@@ -306,23 +319,33 @@ int on_selected_cpus(
 
 static void stop_this_cpu (void *dummy)
 {
-    cpu_clear(smp_processor_id(), cpu_online_map);
-
-    local_irq_disable();
     disable_local_APIC();
     hvm_cpu_down();
 
+    cpu_clear(smp_processor_id(), cpu_online_map);
+
     for ( ; ; )
         __asm__ __volatile__ ( "hlt" );
 }
 
+/*
+ * Stop all CPUs and turn off local APICs and the IO-APIC, so other OSs see a 
+ * clean IRQ state.
+ */
 void smp_send_stop(void)
 {
-    /* Stop all other CPUs in the system. */
+    int timeout = 10;
+
     smp_call_function(stop_this_cpu, NULL, 1, 0);
 
+    /* Wait 10ms for all other CPUs to go offline. */
+    while ( (num_online_cpus() > 1) && (timeout-- > 0) )
+        mdelay(1);
+
     local_irq_disable();
     disable_local_APIC();
+    disable_IO_APIC();
+    hvm_cpu_down();
     local_irq_enable();
 }