hv:refine prepare_vm0 api

-- fix MISRA-C violation "procedure has more than one exit point"
   for this api
-- change start_vm to void type since it is always return 0

Tracked-On: #861
Signed-off-by: Mingqiang Chi <mingqiang.chi@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

Author: mingqiangchi

hypervisor/arch/x86/guest/vm.c

@@ -242,7 +242,7 @@ int32_t shutdown_vm(struct acrn_vm *vm)
 /**
  *  * @pre vm != NULL
  */
-int32_t start_vm(struct acrn_vm *vm)
+void start_vm(struct acrn_vm *vm)
 {
 	struct acrn_vcpu *vcpu = NULL;
 
@@ -251,8 +251,6 @@ int32_t start_vm(struct acrn_vm *vm)
 	/* Only start BSP (vid = 0) and let BSP start other APs */
 	vcpu = vcpu_from_vid(vm, 0U);
 	schedule_vcpu(vcpu);
-
-	return 0;
 }
 
 /**
@@ -402,30 +400,32 @@ static int32_t prepare_vm0(void)
 	vm0_desc.vm_hw_num_cores = phys_cpu_num;
 
 	err = create_vm(&vm0_desc, &vm);
-	if (err != 0) {
-		return err;
-	}
 
-	/* Allocate all cpus to vm0 at the beginning */
-	for (i = 0U; i < vm0_desc.vm_hw_num_cores; i++) {
-		err = prepare_vcpu(vm, i);
-		if (err != 0) {
-			return err;
+	if (err == 0) {
+		/* Allocate all cpus to vm0 at the beginning */
+		for (i = 0U; i < vm0_desc.vm_hw_num_cores; i++) {
+			err = prepare_vcpu(vm, i);
+			if (err != 0) {
+				break;
+			}
 		}
-	}
 
-	if (vm_sw_loader == NULL) {
-		vm_sw_loader = general_sw_loader;
-	}
+		if (err == 0) {
 
-	if (is_vm0(vm)) {
-		(void )vm_sw_loader(vm);
-	}
+			if (vm_sw_loader == NULL) {
+				vm_sw_loader = general_sw_loader;
+			}
+
+			if (is_vm0(vm)) {
+				(void)vm_sw_loader(vm);
+			}
 
-	/* start vm0 BSP automatically */
-	err = start_vm(vm);
+			/* start vm0 BSP automatically */
+			start_vm(vm);
 
-	pr_acrnlog("Start VM0");
+			pr_acrnlog("Start VM0");
+		}
+	}
 
 	return err;
 }

hypervisor/common/hypercall.c

@@ -177,15 +177,15 @@ int32_t hcall_destroy_vm(uint16_t vmid)
  */
 int32_t hcall_start_vm(uint16_t vmid)
 {
-	int32_t ret;
+	int32_t ret = 0;
 	struct acrn_vm *target_vm = get_vm_from_vmid(vmid);
 
 	if (target_vm == NULL) {
 		ret = -1;
 	} else if (target_vm->sw.io_shared_page == NULL) {
 		ret = -1;
 	} else {
-		ret = start_vm(target_vm);
+		start_vm(target_vm);
 	}
 
 	return ret;

hypervisor/include/arch/x86/guest/vm.h

@@ -263,7 +263,7 @@ int32_t shutdown_vm(struct acrn_vm *vm);
 void pause_vm(struct acrn_vm *vm);
 void resume_vm(struct acrn_vm *vm);
 void resume_vm_from_s3(struct acrn_vm *vm, uint32_t wakeup_vec);
-int32_t start_vm(struct acrn_vm *vm);
+void start_vm(struct acrn_vm *vm);
 int32_t reset_vm(struct acrn_vm *vm);
 int32_t create_vm(struct vm_description *vm_desc, struct acrn_vm **rtn_vm);
 int32_t prepare_vm(uint16_t pcpu_id);