From aaca49642b92c8a57d3ca5029a5a94019c7af69f Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Fri, 20 Aug 2010 18:57:53 -0700
Subject: xen: use percpu interrupts for IPIs and VIRQs
 
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
 
commit aaca49642b92c8a57d3ca5029a5a94019c7af69f upstream.
 
IPIs and VIRQs are inherently per-cpu event types, so treat them as such:
 - use a specific percpu irq_chip implementation, and
 - handle them with handle_percpu_irq
 
This makes the path for delivering these interrupts more efficient
(no masking/unmasking, no locks), and it avoid problems with attempts
to migrate them.
 
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
 
---
 drivers/xen/events.c |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)
 
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -107,6 +107,7 @@ static inline unsigned long *cpu_evtchn_
 #define VALID_EVTCHN(chn)	((chn) != 0)
 
 static struct irq_chip xen_dynamic_chip;
+static struct irq_chip xen_percpu_chip;
 
 /* Constructor for packed IRQ information. */
 static struct irq_info mk_unbound_info(void)
@@ -389,8 +390,8 @@ static int bind_ipi_to_irq(unsigned int
 		if (irq < 0)
 			goto out;
 
-		set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
-					      handle_level_irq, "ipi");
+		set_irq_chip_and_handler_name(irq, &xen_percpu_chip,
+					      handle_percpu_irq, "ipi");
 
 		bind_ipi.vcpu = cpu;
 		if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
@@ -430,8 +431,8 @@ static int bind_virq_to_irq(unsigned int
 
 		irq = find_unbound_irq();
 
-		set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
-					      handle_level_irq, "virq");
+		set_irq_chip_and_handler_name(irq, &xen_percpu_chip,
+					      handle_percpu_irq, "virq");
 
 		evtchn_to_irq[evtchn] = irq;
 		irq_info[irq] = mk_virq_info(evtchn, virq);
@@ -934,6 +935,16 @@ static struct irq_chip xen_dynamic_chip
 	.retrigger	= retrigger_dynirq,
 };
 
+static struct irq_chip xen_percpu_chip __read_mostly = {
+	.name		= "xen-percpu",
+
+	.disable	= disable_dynirq,
+	.mask		= disable_dynirq,
+	.unmask		= enable_dynirq,
+
+	.ack		= ack_dynirq,
+};
+
 void __init xen_init_IRQ(void)
 {
 	int i;