[PATCH] PCI: don't move ioapics below PCI bridge

A recent Stratus x86_64 platform uses a system ioapic that is a PCI device
located below a PCI bridge.  Other platforms like this may exist.

This patch fixes a problem wherein the kernel's PCI setup code moves
the ioapic to an address other than that assigned by the BIOS.  It simply
adds another exclusion (which already includes classless devices and host
bridges) to the function pbus_assign_resources_sorted so that it will not
move the ioapic.

If the ioapic is moved, the fixmap mapping to it is broken, so the OS should
leave it alone.

From: Kimball Murray <kimball.murray@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/pci/setup-bus.c

@@ -55,9 +55,10 @@ pbus_assign_resources_sorted(struct pci_bus *bus)
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		u16 class = dev->class >> 8;
 
-		/* Don't touch classless devices and host bridges.  */
+		/* Don't touch classless devices or host bridges or ioapics.  */
 		if (class == PCI_CLASS_NOT_DEFINED ||
-		    class == PCI_CLASS_BRIDGE_HOST)
+		    class == PCI_CLASS_BRIDGE_HOST ||
+		    class == PCI_CLASS_SYSTEM_PIC)
 			continue;
 
 		pdev_sort_resources(dev, &head);