diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 6aba2a23e2c3..7e8d3bc80af6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1174,6 +1174,15 @@ asmlinkage void __init xen_start_kernel(void)
 
 	xen_smp_init();
 
+#ifdef CONFIG_ACPI_NUMA
+	/*
+	 * The pages we from Xen are not related to machine pages, so
+	 * any NUMA information the kernel tries to get from ACPI will
+	 * be meaningless.  Prevent it from trying.
+	 */
+	acpi_numa = -1;
+#endif
+
 	pgd = (pgd_t *)xen_start_info->pt_base;
 
 	if (!xen_initial_domain())
diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index 4abb0b9ed653..3e6934d4bea8 100644
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -562,26 +562,24 @@ static void xenfb_init_shared_page(struct xenfb_info *info,
 static int xenfb_connect_backend(struct xenbus_device *dev,
 				 struct xenfb_info *info)
 {
-	int ret, evtchn;
+	int ret, evtchn, irq;
 	struct xenbus_transaction xbt;
 
 	ret = xenbus_alloc_evtchn(dev, &evtchn);
 	if (ret)
 		return ret;
-	ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
+	irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
 					0, dev->devicetype, info);
-	if (ret < 0) {
+	if (irq < 0) {
 		xenbus_free_evtchn(dev, evtchn);
 		xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
-		return ret;
+		return irq;
 	}
-	info->irq = ret;
-
  again:
 	ret = xenbus_transaction_start(&xbt);
 	if (ret) {
 		xenbus_dev_fatal(dev, ret, "starting transaction");
-		return ret;
+		goto unbind_irq;
 	}
 	ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
 			    virt_to_mfn(info->page));
@@ -603,20 +601,25 @@ static int xenfb_connect_backend(struct xenbus_device *dev,
 		if (ret == -EAGAIN)
 			goto again;
 		xenbus_dev_fatal(dev, ret, "completing transaction");
-		return ret;
+		goto unbind_irq;
 	}
 
 	xenbus_switch_state(dev, XenbusStateInitialised);
+	info->irq = irq;
 	return 0;
 
  error_xenbus:
 	xenbus_transaction_end(xbt, 1);
 	xenbus_dev_fatal(dev, ret, "writing xenstore");
+ unbind_irq:
+	unbind_from_irqhandler(irq, info);
 	return ret;
 }
 
 static void xenfb_disconnect_backend(struct xenfb_info *info)
 {
+	/* Prevent xenfb refresh */
+	info->update_wanted = 0;
 	if (info->irq >= 0)
 		unbind_from_irqhandler(info->irq, info);
 	info->irq = -1;
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 65f8637d13cf..74681478100a 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -170,6 +170,9 @@ static struct irq_info *info_for_irq(unsigned irq)
 
 static unsigned int evtchn_from_irq(unsigned irq)
 {
+	if (unlikely(WARN(irq < 0 || irq >= nr_irqs, "Invalid irq %d!\n", irq)))
+		return 0;
+
 	return info_for_irq(irq)->evtchn;
 }
 
@@ -405,15 +408,21 @@ static int find_unbound_irq(void)
 {
 	struct irq_data *data;
 	int irq, res;
-	int start = get_nr_hw_irqs();
+	int bottom = get_nr_hw_irqs();
+	int top = nr_irqs-1;
 
-	if (start == nr_irqs)
+	if (bottom == nr_irqs)
 		goto no_irqs;
 
-	/* nr_irqs is a magic value. Must not use it.*/
-	for (irq = nr_irqs-1; irq > start; irq--) {
+	/* This loop starts from the top of IRQ space and goes down.
+	 * We need this b/c if we have a PCI device in a Xen PV guest
+	 * we do not have an IO-APIC (though the backend might have them)
+	 * mapped in. To not have a collision of physical IRQs with the Xen
+	 * event channels start at the top of the IRQ space for virtual IRQs.
+	 */
+	for (irq = top; irq > bottom; irq--) {
 		data = irq_get_irq_data(irq);
-		/* only 0->15 have init'd desc; handle irq > 16 */
+		/* only 15->0 have init'd desc; handle irq > 16 */
 		if (!data)
 			break;
 		if (data->chip == &no_irq_chip)
@@ -424,7 +433,7 @@ static int find_unbound_irq(void)
 			return irq;
 	}
 
-	if (irq == start)
+	if (irq == bottom)
 		goto no_irqs;
 
 	res = irq_alloc_desc_at(irq, -1);