drm/i915/gvt: Refine error handling for prepare_execlist_workload

refine the error handling for prepare_execlist_workload to restore to the
original states once error occurs.

only release the shadowed batch buffer and wa ctx when the workload is
completed successfully.

v2:
- split the mixed several error paths for better review. (Zhenyu)

v3:
- handle prepare batch buffer/wa ctx pin errors and
- emulate_schedule_in null issue. (Zhenyu)

v4:
- no need to handle emulate_schedule_in null issue. (Zhenyu)

v5:
- release the shadowed batch buffer and wa ctx only for the
  successful workload. (Zhenyu)

v6:
- polish the return style. (Zhenyu)
Signed-off-by: fred gao <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -368,7 +368,7 @@ static void free_workload(struct intel_vgpu_workload *workload)
 #define get_desc_from_elsp_dwords(ed, i) \
 	((struct execlist_ctx_descriptor_format *)&((ed)->data[i * 2]))
 
-static void prepare_shadow_batch_buffer(struct intel_vgpu_workload *workload)
+static int prepare_shadow_batch_buffer(struct intel_vgpu_workload *workload)
 {
 	const int gmadr_bytes = workload->vgpu->gvt->device_info.gmadr_bytes_in_cmd;
 	struct intel_shadow_bb_entry *entry_obj;
@@ -379,7 +379,7 @@ static void prepare_shadow_batch_buffer(struct intel_vgpu_workload *workload)
 
 		vma = i915_gem_object_ggtt_pin(entry_obj->obj, NULL, 0, 4, 0);
 		if (IS_ERR(vma)) {
-			return;
+			return PTR_ERR(vma);
 		}
 
 		/* FIXME: we are not tracking our pinned VMA leaving it
@@ -392,6 +392,7 @@ static void prepare_shadow_batch_buffer(struct intel_vgpu_workload *workload)
 		if (gmadr_bytes == 8)
 			entry_obj->bb_start_cmd_va[2] = 0;
 	}
+	return 0;
 }
 
 static int update_wa_ctx_2_shadow_ctx(struct intel_shadow_wa_ctx *wa_ctx)
@@ -420,7 +421,7 @@ static int update_wa_ctx_2_shadow_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 	return 0;
 }
 
-static void prepare_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
+static int prepare_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 {
 	struct i915_vma *vma;
 	unsigned char *per_ctx_va =
@@ -428,12 +429,12 @@ static void prepare_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 		wa_ctx->indirect_ctx.size;
 
 	if (wa_ctx->indirect_ctx.size == 0)
-		return;
+		return 0;
 
 	vma = i915_gem_object_ggtt_pin(wa_ctx->indirect_ctx.obj, NULL,
 				       0, CACHELINE_BYTES, 0);
 	if (IS_ERR(vma)) {
-		return;
+		return PTR_ERR(vma);
 	}
 
 	/* FIXME: we are not tracking our pinned VMA leaving it
@@ -447,26 +448,7 @@ static void prepare_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 	memset(per_ctx_va, 0, CACHELINE_BYTES);
 
 	update_wa_ctx_2_shadow_ctx(wa_ctx);
-}
-
-static int prepare_execlist_workload(struct intel_vgpu_workload *workload)
-{
-	struct intel_vgpu *vgpu = workload->vgpu;
-	struct execlist_ctx_descriptor_format ctx[2];
-	int ring_id = workload->ring_id;
-
-	intel_vgpu_pin_mm(workload->shadow_mm);
-	intel_vgpu_sync_oos_pages(workload->vgpu);
-	intel_vgpu_flush_post_shadow(workload->vgpu);
-	prepare_shadow_batch_buffer(workload);
-	prepare_shadow_wa_ctx(&workload->wa_ctx);
-	if (!workload->emulate_schedule_in)
-		return 0;
-
-	ctx[0] = *get_desc_from_elsp_dwords(&workload->elsp_dwords, 1);
-	ctx[1] = *get_desc_from_elsp_dwords(&workload->elsp_dwords, 0);
-
-	return emulate_execlist_schedule_in(&vgpu->execlist[ring_id], ctx);
+	return 0;
 }
 
 static void release_shadow_batch_buffer(struct intel_vgpu_workload *workload)
@@ -489,6 +471,64 @@ static void release_shadow_batch_buffer(struct intel_vgpu_workload *workload)
 	}
 }
 
+static int prepare_execlist_workload(struct intel_vgpu_workload *workload)
+{
+	struct intel_vgpu *vgpu = workload->vgpu;
+	struct execlist_ctx_descriptor_format ctx[2];
+	int ring_id = workload->ring_id;
+	int ret;
+
+	ret = intel_vgpu_pin_mm(workload->shadow_mm);
+	if (ret) {
+		gvt_vgpu_err("fail to vgpu pin mm\n");
+		goto out;
+	}
+
+	ret = intel_vgpu_sync_oos_pages(workload->vgpu);
+	if (ret) {
+		gvt_vgpu_err("fail to vgpu sync oos pages\n");
+		goto err_unpin_mm;
+	}
+
+	ret = intel_vgpu_flush_post_shadow(workload->vgpu);
+	if (ret) {
+		gvt_vgpu_err("fail to flush post shadow\n");
+		goto err_unpin_mm;
+	}
+
+	ret = prepare_shadow_batch_buffer(workload);
+	if (ret) {
+		gvt_vgpu_err("fail to prepare_shadow_batch_buffer\n");
+		goto err_unpin_mm;
+	}
+
+	ret = prepare_shadow_wa_ctx(&workload->wa_ctx);
+	if (ret) {
+		gvt_vgpu_err("fail to prepare_shadow_wa_ctx\n");
+		goto err_shadow_batch;
+	}
+
+	if (!workload->emulate_schedule_in)
+		return 0;
+
+	ctx[0] = *get_desc_from_elsp_dwords(&workload->elsp_dwords, 1);
+	ctx[1] = *get_desc_from_elsp_dwords(&workload->elsp_dwords, 0);
+
+	ret = emulate_execlist_schedule_in(&vgpu->execlist[ring_id], ctx);
+	if (!ret)
+		goto out;
+	else
+		gvt_vgpu_err("fail to emulate execlist schedule in\n");
+
+	release_shadow_wa_ctx(&workload->wa_ctx);
+err_shadow_batch:
+	release_shadow_batch_buffer(workload);
+err_unpin_mm:
+	intel_vgpu_unpin_mm(workload->shadow_mm);
+out:
+	return ret;
+}
+
 static int complete_execlist_workload(struct intel_vgpu_workload *workload)
 {
 	struct intel_vgpu *vgpu = workload->vgpu;
@@ -502,8 +542,10 @@ static int complete_execlist_workload(struct intel_vgpu_workload *workload)
 	gvt_dbg_el("complete workload %p status %d\n", workload,
 			workload->status);
 
-	release_shadow_batch_buffer(workload);
-	release_shadow_wa_ctx(&workload->wa_ctx);
+	if (!workload->status) {
+		release_shadow_batch_buffer(workload);
+		release_shadow_wa_ctx(&workload->wa_ctx);
+	}
 
 	if (workload->status || (vgpu->resetting_eng & ENGINE_MASK(ring_id))) {
 		/* if workload->status is not successful means HW GPU