diff --git a/xen/common/timer.c b/xen/common/timer.c
index 376581bd54..12fcd952fd 100644
--- a/xen/common/timer.c
+++ b/xen/common/timer.c
@@ -601,6 +601,20 @@ static void migrate_timers_from_cpu(unsigned int old_cpu)
 
 static struct timer *dummy_heap;
 
+static void free_percpu_timers(unsigned int cpu)
+{
+    struct timers *ts = &per_cpu(timers, cpu);
+
+    ASSERT(GET_HEAP_SIZE(ts->heap) == 0);
+    if ( GET_HEAP_LIMIT(ts->heap) )
+    {
+        xfree(ts->heap);
+        ts->heap = &dummy_heap;
+    }
+    else
+        ASSERT(ts->heap == &dummy_heap);
+}
+
 static int cpu_callback(
     struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
@@ -610,14 +624,28 @@ static int cpu_callback(
     switch ( action )
     {
     case CPU_UP_PREPARE:
-        INIT_LIST_HEAD(&ts->inactive);
-        spin_lock_init(&ts->lock);
-        ts->heap = &dummy_heap;
+        /* Only initialise ts once. */
+        if ( !ts->heap )
+        {
+            INIT_LIST_HEAD(&ts->inactive);
+            spin_lock_init(&ts->lock);
+            ts->heap = &dummy_heap;
+        }
         break;
+
     case CPU_UP_CANCELED:
     case CPU_DEAD:
         migrate_timers_from_cpu(cpu);
+
+        if ( !park_offline_cpus && system_state != SYS_STATE_suspend )
+            free_percpu_timers(cpu);
         break;
+
+    case CPU_REMOVE:
+        if ( park_offline_cpus )
+            free_percpu_timers(cpu);
+        break;
+
     default:
         break;
     }
diff --git a/xen/include/asm-arm/smp.h b/xen/include/asm-arm/smp.h
index 3c122681d7..fdbcefa241 100644
--- a/xen/include/asm-arm/smp.h
+++ b/xen/include/asm-arm/smp.h
@@ -14,6 +14,12 @@ DECLARE_PER_CPU(cpumask_var_t, cpu_core_mask);
 
 #define raw_smp_processor_id() (get_processor_id())
 
+/*
+ * Do we, for platform reasons, need to actually keep CPUs online when we
+ * would otherwise prefer them to be off?
+ */
+#define park_offline_cpus false
+
 extern void noreturn stop_cpu(void);
 
 extern int arch_smp_init(void);
diff --git a/xen/include/asm-x86/smp.h b/xen/include/asm-x86/smp.h
index 09c55458df..9f533f9072 100644
--- a/xen/include/asm-x86/smp.h
+++ b/xen/include/asm-x86/smp.h
@@ -26,6 +26,10 @@ DECLARE_PER_CPU(cpumask_var_t, cpu_sibling_mask);
 DECLARE_PER_CPU(cpumask_var_t, cpu_core_mask);
 DECLARE_PER_CPU(cpumask_var_t, scratch_cpumask);
 
+/*
+ * Do we, for platform reasons, need to actually keep CPUs online when we
+ * would otherwise prefer them to be off?
+ */
 extern bool park_offline_cpus;
 
 void smp_send_nmi_allbutself(void);