diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index a9ca09acb2..e4439b2397 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -46,6 +46,8 @@ static void do_idle(void)
 {
     unsigned int cpu = smp_processor_id();
 
+    rcu_quiet_enter();
+
     sched_tick_suspend();
     /* sched_tick_suspend() can raise TIMER_SOFTIRQ. Process it now. */
     process_pending_softirqs();
@@ -59,6 +61,8 @@ static void do_idle(void)
     local_irq_enable();
 
     sched_tick_resume();
+
+    rcu_quiet_exit();
 }
 
 void idle_loop(void)
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 1d2b762e22..5158a03746 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2007,6 +2007,8 @@ void enter_hypervisor_from_guest(void)
 {
     struct vcpu *v = current;
 
+    rcu_quiet_exit();
+
     /*
      * If we pended a virtual abort, preserve it until it gets cleared.
      * See ARM ARM DDI 0487A.j D1.14.3 (Virtual Interrupts) for details,
@@ -2264,6 +2266,8 @@ static void check_for_vcpu_work(void)
  */
 void leave_hypervisor_to_guest(void)
 {
+    rcu_quiet_enter();
+
     local_irq_disable();
 
     check_for_vcpu_work();
diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index 836f524ef4..3d8dcec143 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -647,7 +647,8 @@ static void acpi_processor_idle(void)
     cpufreq_dbs_timer_suspend();
 
     sched_tick_suspend();
-    /* sched_tick_suspend() can raise TIMER_SOFTIRQ. Process it now. */
+    rcu_quiet_enter();
+    /* rcu_quiet_enter() can raise TIMER_SOFTIRQ. Process it now. */
     process_pending_softirqs();
 
     /*
@@ -660,6 +661,7 @@ static void acpi_processor_idle(void)
     {
         local_irq_enable();
         sched_tick_resume();
+        rcu_quiet_exit();
         cpufreq_dbs_timer_resume();
         return;
     }
@@ -785,6 +787,7 @@ static void acpi_processor_idle(void)
         power->last_state = &power->states[0];
         local_irq_enable();
         sched_tick_resume();
+        rcu_quiet_exit();
         cpufreq_dbs_timer_resume();
         return;
     }
@@ -793,6 +796,7 @@ static void acpi_processor_idle(void)
     power->last_state = &power->states[0];
 
     sched_tick_resume();
+    rcu_quiet_exit();
     cpufreq_dbs_timer_resume();
 
     if ( cpuidle_current_governor->reflect )
diff --git a/xen/arch/x86/cpu/mwait-idle.c b/xen/arch/x86/cpu/mwait-idle.c
index 52413e6da1..2657ec76f4 100644
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -756,7 +756,8 @@ static void mwait_idle(void)
 	cpufreq_dbs_timer_suspend();
 
 	sched_tick_suspend();
-	/* sched_tick_suspend() can raise TIMER_SOFTIRQ. Process it now. */
+	rcu_quiet_enter();
+	/* rcu_quiet_enter() can raise TIMER_SOFTIRQ. Process it now. */
 	process_pending_softirqs();
 
 	/* Interrupts must be disabled for C2 and higher transitions. */
@@ -765,6 +766,7 @@ static void mwait_idle(void)
 	if (!cpu_is_haltable(cpu)) {
 		local_irq_enable();
 		sched_tick_resume();
+		rcu_quiet_exit();
 		cpufreq_dbs_timer_resume();
 		return;
 	}
@@ -807,6 +809,7 @@ static void mwait_idle(void)
 		lapic_timer_on();
 
 	sched_tick_resume();
+	rcu_quiet_exit();
 	cpufreq_dbs_timer_resume();
 
 	if ( cpuidle_current_governor->reflect )
diff --git a/xen/common/rcupdate.c b/xen/common/rcupdate.c
index 42ab9dbbd6..a9c24b5889 100644
--- a/xen/common/rcupdate.c
+++ b/xen/common/rcupdate.c
@@ -52,8 +52,8 @@ static struct rcu_ctrlblk {
     int  next_pending;  /* Is the next batch already waiting?         */
 
     spinlock_t  lock __cacheline_aligned;
-    cpumask_t   cpumask; /* CPUs that need to switch in order ...   */
-    cpumask_t   ignore_cpumask; /* ... unless they are already idle */
+    cpumask_t   cpumask; /* CPUs that need to switch in order...      */
+    cpumask_t   ignore_cpumask; /* ...unless already idle or in guest */
     /* for current batch to proceed.        */
 } __cacheline_aligned rcu_ctrlblk = {
     .cur = -300,
@@ -85,7 +85,7 @@ struct rcu_data {
     struct rcu_head barrier;
     long            last_rs_qlen;     /* qlen during the last resched */
 
-    /* 3) idle CPUs handling */
+    /* 3) idle (or in guest mode) CPUs handling */
     struct timer cb_timer;
     bool cb_timer_active;
 };
@@ -107,6 +107,12 @@ struct rcu_data {
  * 3) it is stopped immediately, if the CPU wakes up from idle and
  *    resumes 'normal' execution.
  *
+ * Note also that the same happens if a CPU starts executing a guest that
+ * (almost) never comes back into the hypervisor. This may be the case if
+ * the guest uses "idle=poll" / "vwfi=native". Therefore, we need to handle
+ * guest entry events in the same way as the CPU going idle, i.e., consider
+ * it quiesced and arm the timer.
+ *
  * About how far in the future the timer should be programmed each time,
  * it's hard to tell (guess!!). Since this mimics Linux's periodic timer
  * tick, take values used there as an indication. In Linux 2.6.21, tick
@@ -304,9 +310,10 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp)
         * Make sure the increment of rcp->cur is visible so, even if a
         * CPU that is about to go idle, is captured inside rcp->cpumask,
         * rcu_pending() will return false, which then means cpu_quiet()
-        * will be invoked, before the CPU would actually enter idle.
+        * will be invoked, before the CPU would actually go idle (or
+	* enter a guest).
         *
-        * This barrier is paired with the one in rcu_idle_enter().
+        * This barrier is paired with the one in rcu_quiet_enter().
         */
         smp_mb();
         cpumask_andnot(&rcp->cpumask, &cpu_online_map, &rcp->ignore_cpumask);
@@ -463,14 +470,15 @@ int rcu_needs_cpu(int cpu)
  * periodically poke rcu_pedning(), so that it will invoke the callback
  * not too late after the end of the grace period.
  */
-static void cb_timer_start(void)
+static void cb_timer_start(unsigned int cpu)
 {
-    struct rcu_data *rdp = &this_cpu(rcu_data);
+    struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
 
     /*
      * Note that we don't check rcu_pending() here. In fact, we don't want
      * the timer armed on CPUs that are in the process of quiescing while
-     * going idle, unless they really are the ones with a queued callback.
+     * going idle or entering guest mode, unless they really have queued
+     * callbacks.
      */
     if (likely(!rdp->curlist))
         return;
@@ -479,9 +487,9 @@ static void cb_timer_start(void)
     rdp->cb_timer_active = true;
 }
 
-static void cb_timer_stop(void)
+static void cb_timer_stop(unsigned int cpu)
 {
-    struct rcu_data *rdp = &this_cpu(rcu_data);
+    struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
 
     if (likely(!rdp->cb_timer_active))
         return;
@@ -635,11 +643,14 @@ void __init rcu_init(void)
 }
 
 /*
- * The CPU is becoming idle, so no more read side critical
- * sections, and one more step toward grace period.
+ * The CPU is becoming about to either idle or enter the guest. In any of
+ * these cases, it can't have any outstanding read side critical sections
+ * so this is one step toward the end of the grace period.
  */
-void rcu_idle_enter(unsigned int cpu)
+void rcu_quiet_enter()
 {
+    unsigned int cpu = smp_processor_id();
+
     ASSERT(!cpumask_test_cpu(cpu, &rcu_ctrlblk.ignore_cpumask));
     cpumask_set_cpu(cpu, &rcu_ctrlblk.ignore_cpumask);
     /*
@@ -652,11 +663,15 @@ void rcu_idle_enter(unsigned int cpu)
      */
     smp_mb();
     cb_timer_start();
+    cb_timer_start(cpu);
 }
 
-void rcu_idle_exit(unsigned int cpu)
+
+void rcu_quiet_exit()
 {
-    cb_timer_stop();
+    unsigned int cpu = smp_processor_id();
+
+    cb_timer_stop(cpu);
     ASSERT(cpumask_test_cpu(cpu, &rcu_ctrlblk.ignore_cpumask));
     cpumask_clear_cpu(cpu, &rcu_ctrlblk.ignore_cpumask);
 }
diff --git a/xen/include/xen/rcupdate.h b/xen/include/xen/rcupdate.h
index 13850865ed..63db0f9887 100644
--- a/xen/include/xen/rcupdate.h
+++ b/xen/include/xen/rcupdate.h
@@ -145,8 +145,8 @@ void call_rcu(struct rcu_head *head,
 
 int rcu_barrier(void);
 
-void rcu_idle_enter(unsigned int cpu);
-void rcu_idle_exit(unsigned int cpu);
+void rcu_quiet_enter(void);
+void rcu_quiet_exit(void);
 
 void rcu_idle_timer_start(void);
 void rcu_idle_timer_stop(void);