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From: Konrad Rzeszutek Wilk on 4 Aug 2010 14:30
From: Jeremy Fitzhardinge <jeremy.fitzhardinge(a)citrix.com>

Impact: preserve compat with native

Reserve the lower irq range for use for hardware interrupts so we
can identity-map them.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge(a)citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk(a)oracle.com>
---
drivers/xen/events.c | 23 +++++++++++++++++------
1 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 288077f..b6de004 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -32,6 +32,7 @@
#include <asm/ptrace.h>
#include <asm/irq.h>
#include <asm/idle.h>
+#include <asm/io_apic.h>
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
@@ -41,9 +42,6 @@
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>

-/* Leave low irqs free for identity mapping */
-#define LEGACY_IRQS 16
-
/*
* This lock protects updates to the following mapping and reference-count
* arrays. The lock does not need to be acquired to read the mapping tables.
@@ -345,12 +343,24 @@ static void unmask_evtchn(int port)
put_cpu();
}

+static int get_nr_hw_irqs(void)
+{
+ int ret = 1;
+
+#ifdef CONFIG_X86_IO_APIC
+ ret = get_nr_irqs_gsi();
+#endif
+
+ return ret;
+}
+
static int find_unbound_irq(void)
{
int irq;
struct irq_desc *desc;
+ int start = get_nr_hw_irqs();

- for (irq = LEGACY_IRQS; irq < nr_irqs; irq++)
+ for (irq = start; irq < nr_irqs; irq++)
if (irq_info[irq].type == IRQT_UNBOUND)
break;

@@ -368,8 +378,8 @@ static int find_unbound_irq(void)

static bool identity_mapped_irq(unsigned irq)
{
- /* only identity map legacy irqs */
- return irq < LEGACY_IRQS;
+ /* identity map all the hardware irqs */
+ return irq < get_nr_hw_irqs();
}

static void pirq_unmask_notify(int irq)
@@ -538,6 +548,7 @@ int xen_allocate_pirq(unsigned gsi)

if (identity_mapped_irq(gsi)) {
irq = gsi;
+ irq_to_desc_alloc_node(irq, 0);
dynamic_irq_init(irq);
} else
irq = find_unbound_irq();
--
1.7.0.1

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