drm/i915/gvt: Only assign ppgtt root at dispatch time

This moves ppgtt root hook out of scan and shadow function,
as it's only required at dispatch time. Also make sure this
checks against shadow mm to be ready, otherwise bail to fail
earlier.
Reviewed-by: Xiong Zhang <xiong.y.zhang@intel.com>
Cc: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -345,7 +345,7 @@ static int set_context_ppgtt_from_shadow(struct intel_vgpu_workload *workload,
 	int i = 0;
 
 	if (mm->type != INTEL_GVT_MM_PPGTT || !mm->ppgtt_mm.shadowed)
-		return -1;
+		return -EINVAL;
 
 	if (mm->ppgtt_mm.root_entry_type == GTT_TYPE_PPGTT_ROOT_L4_ENTRY) {
 		px_dma(&ppgtt->pml4) = mm->ppgtt_mm.shadow_pdps[0];
@@ -409,12 +409,6 @@ int intel_gvt_scan_and_shadow_workload(struct intel_vgpu_workload *workload)
 	if (workload->shadow)
 		return 0;
 
-	ret = set_context_ppgtt_from_shadow(workload, shadow_ctx);
-	if (ret < 0) {
-		gvt_vgpu_err("workload shadow ppgtt isn't ready\n");
-		return ret;
-	}
-
 	/* pin shadow context by gvt even the shadow context will be pinned
 	 * when i915 alloc request. That is because gvt will update the guest
 	 * context from shadow context when workload is completed, and at that
@@ -677,6 +671,8 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
 {
 	struct intel_vgpu *vgpu = workload->vgpu;
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
+	struct intel_vgpu_submission *s = &vgpu->submission;
+	struct i915_gem_context *shadow_ctx = s->shadow_ctx;
 	struct i915_request *rq;
 	int ring_id = workload->ring_id;
 	int ret;
@@ -687,6 +683,12 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
 	mutex_lock(&vgpu->vgpu_lock);
 	mutex_lock(&dev_priv->drm.struct_mutex);
 
+	ret = set_context_ppgtt_from_shadow(workload, shadow_ctx);
+	if (ret < 0) {
+		gvt_vgpu_err("workload shadow ppgtt isn't ready\n");
+		goto err_req;
+	}
+
 	ret = intel_gvt_workload_req_alloc(workload);
 	if (ret)
 		goto err_req;