diff -r 1d7221667204 xen/drivers/passthrough/io.c
--- a/xen/drivers/passthrough/io.c	Thu Oct 08 09:24:32 2009 +0100
+++ b/xen/drivers/passthrough/io.c	Fri Oct 16 16:38:06 2009 +0800
@@ -26,6 +26,7 @@
 #include <xen/hvm/irq.h>
 
 static void hvm_dirq_assist(unsigned long _d);
+static void __msi_pirq_eoi(struct domain *d, int pirq);
 
 static int pt_irq_need_timer(uint32_t flags)
 {
@@ -194,7 +195,9 @@
 	            spin_unlock(&d->event_lock);
         	    return -EBUSY;
             }
- 
+
+            __msi_pirq_eoi(d, pirq);
+
             /* if pirq is already mapped as vmsi, update the guest data/addr */
             old_gvec = hvm_irq_dpci->mirq[pirq].gmsi.gvec;
             hvm_irq_dpci->mirq[pirq].gmsi.gvec = pt_irq_bind->u.msi.gvec;