diff --git a/xen/arch/x86/genapic/x2apic.c b/xen/arch/x86/genapic/x2apic.c
index 371dd100c742..fe8e664e1b63 100644
--- a/xen/arch/x86/genapic/x2apic.c
+++ b/xen/arch/x86/genapic/x2apic.c
@@ -30,8 +30,11 @@ static inline u32 x2apic_cluster(unsigned int cpu)
 static void cf_check init_apic_ldr_x2apic_cluster(void)
 {
     unsigned int cpu, this_cpu = smp_processor_id();
+    uint32_t id = apic_read(APIC_ID);
+    uint32_t ldr = apic_read(APIC_LDR);
 
-    per_cpu(cpu_2_logical_apicid, this_cpu) = apic_read(APIC_LDR);
+    ASSERT(x2apic_ldr_from_id(id) == ldr);
+    per_cpu(cpu_2_logical_apicid, this_cpu) = ldr;
 
     if ( per_cpu(cluster_cpus, this_cpu) )
     {
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 9cfc82666ae5..2a010a6363b7 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -1064,11 +1064,6 @@ static const struct hvm_mmio_ops vlapic_mmio_ops = {
     .write = vlapic_mmio_write,
 };
 
-static uint32_t x2apic_ldr_from_id(uint32_t id)
-{
-    return ((id & ~0xf) << 12) | (1 << (id & 0xf));
-}
-
 static void set_x2apic_id(struct vlapic *vlapic)
 {
     const struct vcpu *v = vlapic_vcpu(vlapic);
diff --git a/xen/arch/x86/include/asm/apic.h b/xen/arch/x86/include/asm/apic.h
index 7b5a0832c05e..8a892fa2fa5b 100644
--- a/xen/arch/x86/include/asm/apic.h
+++ b/xen/arch/x86/include/asm/apic.h
@@ -148,6 +148,11 @@ static inline void ack_APIC_irq(void)
 	apic_write(APIC_EOI, 0);
 }
 
+static inline uint32_t x2apic_ldr_from_id(uint32_t id)
+{
+    return ((id & ~0xf) << 12) | (1 << (id & 0xf));
+}
+
 extern int get_maxlvt(void);
 extern void clear_local_APIC(void);
 extern void connect_bsp_APIC (void);