diff -Nurp custom-source-xen.orig/drivers/xen/core/evtchn.c custom-source-xen/drivers/xen/core/evtchn.c
--- custom-source-xen.orig/drivers/xen/core/evtchn.c	2011-03-29 13:34:19.025232010 +0000
+++ custom-source-xen/drivers/xen/core/evtchn.c	2011-03-29 14:39:23.824587517 +0000
@@ -245,7 +245,7 @@ asmlinkage void evtchn_do_upcall(struct 
 
 #ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
 		/* Clear master flag /before/ clearing selector flag. */
-		rmb();
+		wmb();
 #endif
 		l1 = xchg(&vcpu_info->evtchn_pending_sel, 0);
 
@@ -279,6 +279,8 @@ asmlinkage void evtchn_do_upcall(struct 
 
 				/* process port */
 				port = (l1i * BITS_PER_LONG) + l2i;
+				mask_evtchn(port);
+				clear_evtchn(port);
 				if ((irq = evtchn_to_irq[port]) != -1)
 					do_IRQ(irq, regs);
 				else {
@@ -701,24 +703,12 @@ static void mask_dynirq(unsigned int irq
 		mask_evtchn(evtchn);
 }
 
-static void ack_dynirq(unsigned int irq)
-{
-	int evtchn = evtchn_from_irq(irq);
-
-	move_native_irq(irq);
-
-	if (VALID_EVTCHN(evtchn)) {
-		mask_evtchn(evtchn);
-		clear_evtchn(evtchn);
-	}
-}
-
 static void end_dynirq(unsigned int irq)
 {
-	int evtchn = evtchn_from_irq(irq);
-
-	if (VALID_EVTCHN(evtchn) && !(irq_desc[irq].status & IRQ_DISABLED))
-		unmask_evtchn(evtchn);
+	if (!(irq_desc[irq].status & IRQ_DISABLED)) {
+		move_masked_irq(irq);
+		unmask_dynirq(irq);
+	}
 }
 
 static struct irq_chip dynirq_chip = {
@@ -726,8 +716,7 @@ static struct irq_chip dynirq_chip = {
 	.startup  = startup_dynirq,
 	.mask     = mask_dynirq,
 	.unmask   = unmask_dynirq,
-	.mask_ack = ack_dynirq,
-	.ack      = ack_dynirq,
+	.ack      = end_dynirq,
 	.end      = end_dynirq,
 #ifdef CONFIG_SMP
 	.set_affinity = set_affinity_irq,
@@ -816,30 +805,18 @@ static void unmask_pirq(unsigned int irq
 
 static void mask_pirq(unsigned int irq)
 {
-}
-
-static void ack_pirq(unsigned int irq)
-{
-	int evtchn = evtchn_from_irq(irq);
-
-	move_native_irq(irq);
-
-	if (VALID_EVTCHN(evtchn)) {
-		mask_evtchn(evtchn);
-		clear_evtchn(evtchn);
-	}
+	mask_dynirq(irq);
 }
 
 static void end_pirq(unsigned int irq)
 {
-	int evtchn = evtchn_from_irq(irq);
-
 	if ((irq_desc[irq].status & (IRQ_DISABLED|IRQ_PENDING)) ==
 	    (IRQ_DISABLED|IRQ_PENDING)) {
 		shutdown_pirq(irq);
-	} else if (VALID_EVTCHN(evtchn)) {
-		unmask_evtchn(evtchn);
-		pirq_unmask_notify(irq_to_pirq(irq));
+	} else {
+		if (!(irq_desc[irq].status & IRQ_DISABLED))
+			move_masked_irq(irq);
+		unmask_pirq(irq);
 	}
 }
 
@@ -850,8 +827,7 @@ static struct irq_chip pirq_chip = {
 	.shutdown = shutdown_pirq,
 	.mask     = mask_pirq,
 	.unmask   = unmask_pirq,
-	.mask_ack = ack_pirq,
-	.ack      = ack_pirq,
+	.ack      = end_pirq,
 	.end      = end_pirq,
 #ifdef CONFIG_SMP
 	.set_affinity = set_affinity_irq,
@@ -1034,7 +1010,7 @@ void __init xen_init_IRQ(void)
 		irq_desc[dynirq_to_irq(i)].action = NULL;
 		irq_desc[dynirq_to_irq(i)].depth = 1;
 		set_irq_chip_and_handler_name(dynirq_to_irq(i), &dynirq_chip,
-		                              handle_level_irq, "level");
+		                              handle_edge_irq, "edge");
 	}
 
 	/* Phys IRQ space is statically bound (1:1 mapping). Nail refcnts. */
@@ -1051,6 +1027,6 @@ void __init xen_init_IRQ(void)
 		irq_desc[pirq_to_irq(i)].action = NULL;
 		irq_desc[pirq_to_irq(i)].depth = 1;
 		set_irq_chip_and_handler_name(pirq_to_irq(i), &pirq_chip,
-		                              handle_level_irq, "level");
+		                              handle_edge_irq, "edge");
 	}
 }