drm/i915/gvt: refactor function intel_vgpu_submit_execlist

The function intel_vgpu_submit_execlist could be more simpler. It
actually does:
  1) validate the submission. The first context must be valid,
     and all two must be privilege_access.
  2) submit valid contexts. The first one need emulate schedule_in.

We do not need a bitmap, valid desc copy valid_desc. Local variable
emulate_schedule_in also can be optimized out.

v2: dump desc content in err msg (Zhi Wang)
Signed-off-by: Changbin Du <changbin.du@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -708,53 +708,43 @@ static int submit_context(struct intel_vgpu *vgpu, int ring_id,
 int intel_vgpu_submit_execlist(struct intel_vgpu *vgpu, int ring_id)
 {
 	struct intel_vgpu_execlist *execlist = &vgpu->execlist[ring_id];
-	struct execlist_ctx_descriptor_format *desc[2], valid_desc[2];
-	unsigned long valid_desc_bitmap = 0;
-	bool emulate_schedule_in = true;
-	int ret;
-	int i;
+	struct execlist_ctx_descriptor_format desc[2];
+	int i, ret;
 
-	memset(valid_desc, 0, sizeof(valid_desc));
+	desc[0] = *get_desc_from_elsp_dwords(&execlist->elsp_dwords, 1);
+	desc[1] = *get_desc_from_elsp_dwords(&execlist->elsp_dwords, 0);
 
-	desc[0] = get_desc_from_elsp_dwords(&execlist->elsp_dwords, 1);
-	desc[1] = get_desc_from_elsp_dwords(&execlist->elsp_dwords, 0);
+	if (!desc[0].valid) {
+		gvt_vgpu_err("invalid elsp submission, desc0 is invalid\n");
+		goto inv_desc;
+	}
 
-	for (i = 0; i < 2; i++) {
-		if (!desc[i]->valid)
+	for (i = 0; i < ARRAY_SIZE(desc); i++) {
+		if (!desc[i].valid)
 			continue;
-
-		if (!desc[i]->privilege_access) {
+		if (!desc[i].privilege_access) {
 			gvt_vgpu_err("unexpected GGTT elsp submission\n");
-			return -EINVAL;
+			goto inv_desc;
 		}
-
-		/* TODO: add another guest context checks here. */
-		set_bit(i, &valid_desc_bitmap);
-		valid_desc[i] = *desc[i];
-	}
-
-	if (!valid_desc_bitmap) {
-		gvt_vgpu_err("no valid desc in a elsp submission\n");
-		return -EINVAL;
-	}
-
-	if (!test_bit(0, (void *)&valid_desc_bitmap) &&
-			test_bit(1, (void *)&valid_desc_bitmap)) {
-		gvt_vgpu_err("weird elsp submission, desc 0 is not valid\n");
-		return -EINVAL;
 	}
 
 	/* submit workload */
-	for_each_set_bit(i, (void *)&valid_desc_bitmap, 2) {
-		ret = submit_context(vgpu, ring_id, &valid_desc[i],
-				emulate_schedule_in);
+	for (i = 0; i < ARRAY_SIZE(desc); i++) {
+		if (!desc[i].valid)
+			continue;
+		ret = submit_context(vgpu, ring_id, &desc[i], i == 0);
 		if (ret) {
-			gvt_vgpu_err("fail to schedule workload\n");
+			gvt_vgpu_err("failed to submit desc %d\n", i);
 			return ret;
 		}
-		emulate_schedule_in = false;
 	}
+
 	return 0;
+
+inv_desc:
+	gvt_vgpu_err("descriptors content: desc0 %08x %08x desc1 %08x %08x\n",
+		     desc[0].udw, desc[0].ldw, desc[1].udw, desc[1].ldw);
+	return -EINVAL;
 }
 
 static void init_vgpu_execlist(struct intel_vgpu *vgpu, int ring_id)