[PATCH v3] [Bugfix] x86/apic: Fix xen IRQ allocation failure caused by commit b81975eade8c

[Jiang Liu <jiang.liu@linux.intel.com>]

Commit b81975eade8c ("x86, irq: Clean up irqdomain transition code")
breaks xen IRQ allocation because xen_smp_prepare_cpus() doesn't invoke
setup_IO_APIC(), so no irqdomains created for IOAPICs and
mp_map_pin_to_irq() fails at the very beginning.

So move creating of IOAPIC irqdomains from setup_IO_APIC() into
arch_early_ioapic_init().

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reported-and-tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/kernel/apic/io_apic.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 3f5f60406ab1..1117c84cefe4 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -245,6 +245,8 @@ static void free_ioapic_saved_registers(int idx)
 	ioapics[idx].saved_registers = NULL;
 }
 
+static int mp_irqdomain_create(int ioapic);
+
 int __init arch_early_ioapic_init(void)
 {
 	struct irq_cfg *cfg;
@@ -253,8 +255,10 @@ int __init arch_early_ioapic_init(void)
 	if (!nr_legacy_irqs())
 		io_apic_irqs = ~0UL;
 
-	for_each_ioapic(i)
+	for_each_ioapic(i) {
+		BUG_ON(mp_irqdomain_create(i));
 		alloc_ioapic_saved_registers(i);
+	}
 
 	/*
 	 * For legacy IRQ's, start with assigning irq0 to irq15 to
@@ -2371,16 +2375,12 @@ static void ioapic_destroy_irqdomain(int idx)
 
 void __init setup_IO_APIC(void)
 {
-	int ioapic;
-
 	/*
 	 * calling enable_IO_APIC() is moved to setup_local_APIC for BP
 	 */
 	io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
 
 	apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
-	for_each_ioapic(ioapic)
-		BUG_ON(mp_irqdomain_create(ioapic));
 
 	/*
          * Set up IO-APIC IRQ routing.
@@ -2929,7 +2929,8 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
 	/*
 	 * If mp_register_ioapic() is called during early boot stage when
 	 * walking ACPI/SFI/DT tables, it's too early to create irqdomain,
-	 * we are still using bootmem allocator. So delay it to setup_IO_APIC().
+	 * we are still using bootmem allocator.So delay it to
+	 * arch_early_ioapic_init().
 	 */
 	if (hotplug) {
 		if (mp_irqdomain_create(idx)) {
-- 
1.7.10.4