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 72f91bf..0923ccb 100644 (file)
--- 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;