drm/i915/gvt: Use force single submit flag to distinguish gvt request from i915 request

In my previous Commit ab9da627906a ("drm/i915: make context status
notifier head be per engine") rely on scheduler->current_workload[x]
to distinguish gvt spacial request from i915 request. But this is
not always true since no synchronization between workload_thread and
lrc irq handler.

    lrc irq handler               workload_thread
         ----                          ----
  pick i915 requests;
                                intel_vgpu_submit_execlist();
                                current_workload[x] = xxx;
  shadow_context_status_change();

Then current_workload[x] is not null but current request is of i915 self.
So instead we check ctx flag CONTEXT_FORCE_SINGLE_SUBMISSION. Only gvt
request set this flag and always set.

v2: Reverse the order of multi-condition 'if' statement.

Fixes: ab9da6279 ("drm/i915: make context status notifier head be per engine")
Signed-off-by: Changbin Du <changbin.du@intel.com>
Reviewed-by: Yulei Zhang <yulei.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -127,6 +127,11 @@ static int populate_shadow_context(struct intel_vgpu_workload *workload)
 	return 0;
 }
 
+static inline bool is_gvt_request(struct drm_i915_gem_request *req)
+{
+	return i915_gem_context_force_single_submission(req->ctx);
+}
+
 static int shadow_context_status_change(struct notifier_block *nb,
 		unsigned long action, void *data)
 {
@@ -139,7 +144,7 @@ static int shadow_context_status_change(struct notifier_block *nb,
 	struct intel_vgpu_workload *workload =
 		scheduler->current_workload[req->engine->id];
 
-	if (unlikely(!workload))
+	if (!is_gvt_request(req) || unlikely(!workload))
 		return NOTIFY_OK;
 
 	switch (action) {