diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 42b8a59..1588d71 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -59,7 +59,8 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_mask);
 cpumask_t cpu_online_map __read_mostly;
 EXPORT_SYMBOL(cpu_online_map);
 
-struct cpuinfo_x86 cpu_data[NR_CPUS];
+struct cpuinfo_x86 cpu_data[NR_CPUS] =
+	{ [0 ... NR_CPUS-1] = { .phys_proc_id=-1 } };
 
 u32 x86_cpu_to_apicid[NR_CPUS] __read_mostly =
 	{ [0 ... NR_CPUS-1] = BAD_APICID };