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Subject[004/129] xen: use percpu interrupts for IPIs and VIRQs
2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------
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 en_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;



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