xen: identity map gsi->irqs

Impact: preserve compat with native

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

[v2: Rebased on top tip/irq/core]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index bc69a9d92abc..1bb51e459ab2 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -33,6 +33,7 @@
 #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>
@@ -46,9 +47,6 @@
 #include <xen/interface/hvm/hvm_op.h>
 #include <xen/interface/hvm/params.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.
@@ -351,6 +349,17 @@ 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)
 {
         struct irq_data *data;
@@ -382,8 +391,8 @@ 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)
@@ -552,6 +561,7 @@ 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();