drm/i915/gvt: Support event based scheduling

This patch decouple the time slice calculation and scheduler, let
other event be able to trigger scheduling without impact the
calculation for QoS.

v2: add only one new enum definition.
v3: fix typo.
Signed-off-by: Ping Gao <ping.a.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/gvt.c

@@ -147,7 +147,9 @@ static int gvt_service_thread(void *data)
 			mutex_unlock(&gvt->lock);
 		}
 
-		if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED,
+		if (test_bit(INTEL_GVT_REQUEST_SCHED,
+				(void *)&gvt->service_request) ||
+			test_bit(INTEL_GVT_REQUEST_EVENT_SCHED,
 					(void *)&gvt->service_request)) {
 			intel_gvt_schedule(gvt);
 		}

drivers/gpu/drm/i915/gvt/gvt.h

@@ -256,7 +256,12 @@ static inline struct intel_gvt *to_gvt(struct drm_i915_private *i915)
 
 enum {
 	INTEL_GVT_REQUEST_EMULATE_VBLANK = 0,
+
+	/* Scheduling trigger by timer */
 	INTEL_GVT_REQUEST_SCHED = 1,
+
+	/* Scheduling trigger by event */
+	INTEL_GVT_REQUEST_EVENT_SCHED = 2,
 };
 
 static inline void intel_gvt_request_service(struct intel_gvt *gvt,

drivers/gpu/drm/i915/gvt/sched_policy.c

@@ -198,11 +198,6 @@ static void tbs_sched_func(struct gvt_sched_data *sched_data)
 	struct intel_gvt_workload_scheduler *scheduler = &gvt->scheduler;
 	struct vgpu_sched_data *vgpu_data;
 	struct intel_vgpu *vgpu = NULL;
-	static uint64_t timer_check;
-
-	if (!(timer_check++ % GVT_TS_BALANCE_PERIOD_MS))
-		gvt_balance_timeslice(sched_data);
-
 	/* no active vgpu or has already had a target */
 	if (list_empty(&sched_data->lru_runq_head) || scheduler->next_vgpu)
 		goto out;
@@ -227,9 +222,19 @@ static void tbs_sched_func(struct gvt_sched_data *sched_data)
 void intel_gvt_schedule(struct intel_gvt *gvt)
 {
 	struct gvt_sched_data *sched_data = gvt->scheduler.sched_data;
+	static uint64_t timer_check;
 
 	mutex_lock(&gvt->lock);
+
+	if (test_and_clear_bit(INTEL_GVT_REQUEST_SCHED,
+				(void *)&gvt->service_request)) {
+		if (!(timer_check++ % GVT_TS_BALANCE_PERIOD_MS))
+			gvt_balance_timeslice(sched_data);
+	}
+	clear_bit(INTEL_GVT_REQUEST_EVENT_SCHED, (void *)&gvt->service_request);
+
 	tbs_sched_func(sched_data);
+
 	mutex_unlock(&gvt->lock);
 }