diff -uNr xen-unstable.hg-orig/xen/arch/x86/hvm/rtc.c xen-unstable.hg-rtcfix/xen/arch/x86/hvm/rtc.c
--- xen-unstable.hg-orig/xen/arch/x86/hvm/rtc.c	2007-11-15 10:38:18.000000000 -0800
+++ xen-unstable.hg-rtcfix/xen/arch/x86/hvm/rtc.c	2007-11-15 12:48:13.000000000 -0800
@@ -128,7 +128,6 @@
         {
             /* set mode: reset UIP mode */
             s->hw.cmos_data[RTC_REG_A] &= ~RTC_UIP;
-            data &= ~RTC_UIE;
         }
         else
         {
@@ -350,7 +349,7 @@
     }
 
     /* update ended interrupt */
-    if ( s->hw.cmos_data[RTC_REG_B] & RTC_UIE )
+    if ( ( s->hw.cmos_data[RTC_REG_B] & RTC_UIE ) && !(s->hw.cmos_data[RTC_REG_B] & RTC_SET) )
     {
         s->hw.cmos_data[RTC_REG_C] |= 0x90; 
         hvm_isa_irq_deassert(d, RTC_IRQ);