[PATCH 4.4 62/86] xen/x86: actually allocate legacy interrupts on PV guests

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefano Stabellini <sstabellini@xxxxxxxxxx>

commit 702f926067d2a4b28c10a3c41a1172dd62d9e735 upstream.

b4ff8389ed14 is incomplete: relies on nr_legacy_irqs() to get the number
of legacy interrupts when actually nr_legacy_irqs() returns 0 after
probe_8259A(). Use NR_IRQS_LEGACY instead.

Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/pci/xen.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -488,8 +488,11 @@ int __init pci_xen_initial_domain(void)
 #endif
 	__acpi_register_gsi = acpi_register_gsi_xen;
 	__acpi_unregister_gsi = NULL;
-	/* Pre-allocate legacy irqs */
-	for (irq = 0; irq < nr_legacy_irqs(); irq++) {
+	/*
+	 * Pre-allocate the legacy IRQs.  Use NR_LEGACY_IRQS here
+	 * because we don't have a PIC and thus nr_legacy_irqs() is zero.
+	 */
+	for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
 		int trigger, polarity;
 
 		if (acpi_get_override_irq(irq, &trigger, &polarity) == -1)