From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Sat, 21 Aug 2010 01:57:53 +0000 (-0700)
Subject: xen: use percpu interrupts for IPIs and VIRQs
X-Git-Tag: v2.6.36-rc3~26^2~1
X-Git-Url: https://bbs.cooldavid.org/git/?a=commitdiff_plain;h=aaca49642b92c8a57d3ca5029a5a94019c7af69f;p=net-next-2.6.git

xen: use percpu interrupts for IPIs and VIRQs

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>
Cc: Stable Kernel <stable@kernel.org>
---

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 72f91bff29c..0923ccb2612 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -112,6 +112,7 @@ static inline unsigned long *cpu_evtchn_mask(int cpu)
 #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)
@@ -403,8 +404,8 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 		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,
@@ -444,8 +445,8 @@ static int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 
 		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);
@@ -964,6 +965,16 @@ static struct irq_chip xen_dynamic_chip __read_mostly = {
 	.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,
+};
+
 int xen_set_callback_via(uint64_t via)
 {
 	struct xen_hvm_param a;