Index: head/sys/arm/arm/platform.c
===================================================================
--- head/sys/arm/arm/platform.c
+++ head/sys/arm/arm/platform.c
@@ -177,3 +177,18 @@
 	PLATFORM_LATE_INIT(plat_obj);
 }
 
+#if defined(SMP) && defined(PLATFORM_SMP)
+void
+platform_mp_setmaxid(void)
+{
+
+	PLATFORM_MP_SETMAXID(plat_obj);
+}
+
+void
+platform_mp_start_ap(void)
+{
+
+	PLATFORM_MP_START_AP(plat_obj);
+}
+#endif
Index: head/sys/arm/arm/platform_if.m
===================================================================
--- head/sys/arm/arm/platform_if.m
+++ head/sys/arm/arm/platform_if.m
@@ -57,6 +57,12 @@
 	{
 		return;
 	}
+
+	static void platform_default_mp_setmaxid(platform_t plat)
+	{
+		mp_ncpus = 1;
+		mp_maxid = 0;
+	}
 };
 
 /**
@@ -114,3 +120,16 @@
 	platform_t	_plat;
 };
 
+/**
+ * @brief Called by cpu_mp_setmaxid() to set mp_maxid and mp_ncpus.
+ */
+METHOD void mp_setmaxid {
+	platform_t	_plat;
+} DEFAULT platform_default_mp_setmaxid;
+
+/**
+ * @brief Called by cpu_mp_start to start the secondary processors.
+ */
+METHOD void mp_start_ap {
+	platform_t	_plat;
+};
Index: head/sys/arm/conf/VIRT
===================================================================
--- head/sys/arm/conf/VIRT
+++ head/sys/arm/conf/VIRT
@@ -26,6 +26,7 @@
 options 	HZ=100
 options 	SCHED_ULE		# 4BSD scheduler
 options 	PLATFORM
+options 	PLATFORM_SMP
 options 	SMP			# Enable multiple cores
 
 # Debugging for use in -current
Index: head/sys/arm/qemu/virt_machdep.c
===================================================================
--- head/sys/arm/qemu/virt_machdep.c
+++ head/sys/arm/qemu/virt_machdep.c
@@ -41,6 +41,8 @@
 #include <machine/platform.h>
 #include <machine/platformvar.h>
 
+#include <arm/qemu/virt_mp.h>
+
 #include "platform_if.h"
 
 struct arm32_dma_range *
@@ -86,6 +88,11 @@
 	PLATFORMMETHOD(platform_devmap_init,	virt_devmap_init),
 	PLATFORMMETHOD(platform_lastaddr,	virt_lastaddr),
 
+#ifdef SMP
+	PLATFORMMETHOD(platform_mp_start_ap,	virt_mp_start_ap),
+	PLATFORMMETHOD(platform_mp_setmaxid,	virt_mp_setmaxid),
+#endif
+
 	PLATFORMMETHOD_END,
 };
 
Index: head/sys/arm/qemu/virt_mp.h
===================================================================
--- head/sys/arm/qemu/virt_mp.h
+++ head/sys/arm/qemu/virt_mp.h
@@ -0,0 +1,35 @@
+/*-
+ * Copyright (c) 2016 Andrew Turner
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _QEMU_VIRT_MP_H_
+#define	_QEMU_VIRT_MP_H_
+
+void virt_mp_start_ap(platform_t plat);
+void virt_mp_setmaxid(platform_t plat);
+
+#endif /* _QEMU_VIRT_MP_H_ */
Index: head/sys/arm/qemu/virt_mp.c
===================================================================
--- head/sys/arm/qemu/virt_mp.c
+++ head/sys/arm/qemu/virt_mp.c
@@ -38,12 +38,15 @@
 #include <vm/pmap.h>
 
 #include <machine/intr.h>
+#include <machine/platformvar.h>
 #include <machine/smp.h>
 
 #include <dev/ofw/openfirm.h>
 #include <dev/ofw/ofw_cpu.h>
 #include <dev/psci/psci.h>
 
+#include <arm/qemu/virt_mp.h>
+
 static int running_cpus;
 
 static boolean_t
@@ -57,7 +60,7 @@
 }
 
 void
-platform_mp_setmaxid(void)
+virt_mp_setmaxid(platform_t plat)
 {
 
 	mp_maxid = PCPU_GET(cpuid);
@@ -85,7 +88,7 @@
 }
 
 void
-platform_mp_start_ap(void)
+virt_mp_start_ap(platform_t plat)
 {
 
 	ofw_cpu_early_foreach(virt_start_ap, true);
Index: head/sys/conf/options.arm
===================================================================
--- head/sys/conf/options.arm
+++ head/sys/conf/options.arm
@@ -34,6 +34,7 @@
 LOADERRAMADDR		opt_global.h
 PHYSADDR		opt_global.h
 PLATFORM		opt_global.h
+PLATFORM_SMP		opt_global.h
 SOCDEV_PA		opt_global.h
 SOCDEV_VA		opt_global.h
 PV_STATS		opt_pmap.h