hv: handle cpu offline request in idle thread

Change need_scheduled fileds of schedule context to flags because
it's not only used for need_schedule check.

Add two functions to request/handle cpu offline.

The reason we only handle cpu offline request in idle thread is
that we should pause the vcpu running on target pcpu. Then it's
only possible that target pcpu get cpu offline request in idle
thread.

Signed-off-by: Yin Fegnwei <fengwei.yin@intel.com>
Acked-by: Eddie Dong <Eddie.dong@intel.com>

Author: fyin1

hypervisor/common/hv_main.c

@@ -44,7 +44,7 @@ void vcpu_thread(struct vcpu *vcpu)
 			continue;
 		}
 
-		if (need_rescheduled(vcpu->pcpu_id)) {
+		if (need_reschedule(vcpu->pcpu_id)) {
 			/*
 			 * In extrem case, schedule() could return. Which
 			 * means the vcpu resume happens before schedule()

hypervisor/common/schedule.c

@@ -17,7 +17,7 @@ void init_scheduler(void)
 		spinlock_init(&per_cpu(sched_ctx, i).runqueue_lock);
 		spinlock_init(&per_cpu(sched_ctx, i).scheduler_lock);
 		INIT_LIST_HEAD(&per_cpu(sched_ctx, i).runqueue);
-		per_cpu(sched_ctx, i).need_scheduled = 0;
+		per_cpu(sched_ctx, i).flags= 0;
 		per_cpu(sched_ctx, i).curr_vcpu = NULL;
 	}
 }
@@ -90,15 +90,15 @@ static struct vcpu *select_next_vcpu(int pcpu_id)
 
 void make_reschedule_request(struct vcpu *vcpu)
 {
-	bitmap_set(NEED_RESCHEDULED,
-		&per_cpu(sched_ctx, vcpu->pcpu_id).need_scheduled);
+	bitmap_set(NEED_RESCHEDULE,
+		&per_cpu(sched_ctx, vcpu->pcpu_id).flags);
 	send_single_ipi(vcpu->pcpu_id, VECTOR_NOTIFY_VCPU);
 }
 
-int need_rescheduled(int pcpu_id)
+int need_reschedule(int pcpu_id)
 {
-	return bitmap_test_and_clear(NEED_RESCHEDULED,
-		&per_cpu(sched_ctx, pcpu_id).need_scheduled);
+	return bitmap_test_and_clear(NEED_RESCHEDULE,
+		&per_cpu(sched_ctx, pcpu_id).flags);
 }
 
 static void context_switch_out(struct vcpu *vcpu)
@@ -136,13 +136,28 @@ static void context_switch_in(struct vcpu *vcpu)
 	 */
 }
 
+void make_pcpu_offline(int pcpu_id)
+{
+	bitmap_set(NEED_OFFLINE,
+		&per_cpu(sched_ctx, pcpu_id).flags);
+	send_single_ipi(pcpu_id, VECTOR_NOTIFY_VCPU);
+}
+
+int need_offline(int pcpu_id)
+{
+	return bitmap_test_and_clear(NEED_OFFLINE,
+		&per_cpu(sched_ctx, pcpu_id).flags);
+}
+
 void default_idle(void)
 {
 	int pcpu_id = get_cpu_id();
 
 	while (1) {
-		if (need_rescheduled(pcpu_id))
+		if (need_reschedule(pcpu_id))
 			schedule();
+		else if (need_offline(pcpu_id))
+			cpu_dead(pcpu_id);
 		else
 			__asm __volatile("pause" ::: "memory");
 	}

hypervisor/include/common/schedule.h

@@ -7,12 +7,13 @@
 #ifndef	_HV_CORE_SCHEDULE_
 #define	_HV_CORE_SCHEDULE_
 
-#define	NEED_RESCHEDULED	(1)
+#define	NEED_RESCHEDULE		(1)
+#define	NEED_OFFLINE		(2)
 
 struct sched_context {
 	spinlock_t runqueue_lock;
 	struct list_head runqueue;
-	unsigned long need_scheduled;
+	unsigned long flags;
 	struct vcpu *curr_vcpu;
 	spinlock_t scheduler_lock;
 };
@@ -31,7 +32,10 @@ void remove_vcpu_from_runqueue(struct vcpu *vcpu);
 void default_idle(void);
 
 void make_reschedule_request(struct vcpu *vcpu);
-int need_rescheduled(int pcpu_id);
+int need_reschedule(int pcpu_id);
+void make_pcpu_offline(int pcpu_id);
+int need_offline(int pcpu_id);
+
 void schedule(void);
 
 void vcpu_thread(struct vcpu *vcpu);