diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index ace2eb054053..9ba53814ed6a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -219,13 +219,21 @@ static __read_mostly unsigned int cpuid_leaf5_edx_val;
 static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 		      unsigned int *cx, unsigned int *dx)
 {
-	unsigned maskebx = ~0;
+	unsigned int maskebx = ~0;
+	unsigned int or_ebx = 0;
 
 	/*
 	 * Mask out inconvenient features, to try and disable as many
 	 * unsupported kernel subsystems as possible.
 	 */
 	switch (*ax) {
+	case 0x1:
+		/* Replace initial APIC ID in bits 24-31 of EBX. */
+		/* See xen_pv_smp_config() for related topology preparations. */
+		maskebx = 0x00ffffff;
+		or_ebx = smp_processor_id() << 24;
+		break;
+
 	case CPUID_MWAIT_LEAF:
 		/* Synthesize the values.. */
 		*ax = 0;
@@ -248,6 +256,7 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 		: "0" (*ax), "2" (*cx));
 
 	*bx &= maskebx;
+	*bx |= or_ebx;
 }
 
 static bool __init xen_check_mwait(void)
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 27d1a5b7f571..ac41d83b38d3 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -154,9 +154,9 @@ static void __init xen_pv_smp_config(void)
 	u32 apicid = 0;
 	int i;
 
-	topology_register_boot_apic(apicid++);
+	topology_register_boot_apic(apicid);
 
-	for (i = 1; i < nr_cpu_ids; i++)
+	for (i = 0; i < nr_cpu_ids; i++)
 		topology_register_apic(apicid++, CPU_ACPIID_INVALID, true);
 
 	/* Pretend to be a proper enumerated system */