x86/apic: Fix UP boot crash

Commit 31b3c9d72340 ("xen/x86: Implement x86_apic_ops") implemented
this:

... without considering that on UP the function pointer might be NULL.

Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/n/tip-3pfty0ml4yp62phbkchichh0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 8526317c5f0b..7e67c5a71061 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1012,7 +1012,8 @@ void __init setup_arch(char **cmdline_p)
         init_cpu_to_node();
 
         init_apic_mappings();
-        x86_io_apic_ops.init();
+        if (x86_io_apic_ops.init)
+                x86_io_apic_ops.init();
 
         kvm_guest_init();