diff --git a/hypervisor/arch/x86/guest/vm.c b/hypervisor/arch/x86/guest/vm.c
index ee2804f2d..5d2471800 100644
--- a/hypervisor/arch/x86/guest/vm.c
+++ b/hypervisor/arch/x86/guest/vm.c
@@ -49,9 +49,12 @@ uint16_t get_vmid_by_uuid(const uint8_t *uuid)
 	return vm_id;
 }
 
+/**
+ * @pre vm != NULL
+ */
 bool is_valid_vm(const struct acrn_vm *vm)
 {
-	return (vm != NULL) && (vm->state != VM_STATE_INVALID);
+	return (vm->state != VM_STATE_INVALID);
 }
 
 bool is_sos_vm(const struct acrn_vm *vm)
diff --git a/hypervisor/arch/x86/guest/vmcall.c b/hypervisor/arch/x86/guest/vmcall.c
index cee479719..783a31a25 100644
--- a/hypervisor/arch/x86/guest/vmcall.c
+++ b/hypervisor/arch/x86/guest/vmcall.c
@@ -28,7 +28,10 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 	uint64_t param1 = vcpu_get_gpreg(vcpu, CPU_REG_RDI);
 	/* hypercall param2 from guest*/
 	uint64_t param2 = vcpu_get_gpreg(vcpu, CPU_REG_RSI);
-	int32_t ret;
+	/* in case hypercall param1 is a vm id */
+	uint16_t vm_id = (uint16_t)param1;
+	bool vmid_is_valid = (vm_id < CONFIG_MAX_VM_NUM) ? true : false;
+	int32_t ret = -1;
 
 	switch (hypcall_id) {
 	case HC_SOS_OFFLINE_CPU:
@@ -57,69 +60,89 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 
 	case HC_DESTROY_VM:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_destroy_vm((uint16_t)param1);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_destroy_vm(vm_id);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_START_VM:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_start_vm((uint16_t)param1);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_start_vm(vm_id);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_RESET_VM:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_reset_vm((uint16_t)param1);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_reset_vm(vm_id);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_PAUSE_VM:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_pause_vm((uint16_t)param1);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_pause_vm(vm_id);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_CREATE_VCPU:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_create_vcpu(vm, (uint16_t)param1, param2);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_create_vcpu(vm, vm_id, param2);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_SET_VCPU_REGS:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_set_vcpu_regs(vm, (uint16_t)param1, param2);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_set_vcpu_regs(vm, vm_id, param2);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_SET_IRQLINE:
 		/* param1: vmid */
-		ret = hcall_set_irqline(vm, (uint16_t)param1,
-				(struct acrn_irqline_ops *)&param2);
+		if (vmid_is_valid) {
+			ret = hcall_set_irqline(vm, vm_id,
+					(struct acrn_irqline_ops *)&param2);
+		}
 		break;
 
 	case HC_INJECT_MSI:
 		/* param1: vmid */
-		ret = hcall_inject_msi(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_inject_msi(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_SET_IOREQ_BUFFER:
 		/* param1: vmid */
-		spinlock_obtain(&vmm_hypercall_lock);
-		ret = hcall_set_ioreq_buffer(vm, (uint16_t)param1, param2);
-		spinlock_release(&vmm_hypercall_lock);
+		if (vmid_is_valid) {
+			spinlock_obtain(&vmm_hypercall_lock);
+			ret = hcall_set_ioreq_buffer(vm, vm_id, param2);
+			spinlock_release(&vmm_hypercall_lock);
+		}
 		break;
 
 	case HC_NOTIFY_REQUEST_FINISH:
 		/* param1: vmid
 		 * param2: vcpu_id */
-		ret = hcall_notify_ioreq_finish((uint16_t)param1,
-			(uint16_t)param2);
+		if (vmid_is_valid) {
+			ret = hcall_notify_ioreq_finish(vm_id,
+				(uint16_t)param2);
+		}
 		break;
 
 	case HC_VM_SET_MEMORY_REGIONS:
@@ -127,7 +150,10 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 		break;
 
 	case HC_VM_WRITE_PROTECT_PAGE:
-		ret = hcall_write_protect_page(vm, (uint16_t)param1, param2);
+		/* param1: vmid */
+		if (vmid_is_valid) {
+			ret = hcall_write_protect_page(vm, vm_id, param2);
+		}
 		break;
 
 	/*
@@ -140,27 +166,37 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 
 	case HC_VM_GPA2HPA:
 		/* param1: vmid */
-		ret = hcall_gpa_to_hpa(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_gpa_to_hpa(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_ASSIGN_PTDEV:
 		/* param1: vmid */
-		ret = hcall_assign_ptdev(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_assign_ptdev(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_DEASSIGN_PTDEV:
 		/* param1: vmid */
-		ret = hcall_deassign_ptdev(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_deassign_ptdev(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_SET_PTDEV_INTR_INFO:
 		/* param1: vmid */
-		ret = hcall_set_ptdev_intr_info(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_set_ptdev_intr_info(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_RESET_PTDEV_INTR_INFO:
 		/* param1: vmid */
-		ret = hcall_reset_ptdev_intr_info(vm, (uint16_t)param1, param2);
+		if (vmid_is_valid) {
+			ret = hcall_reset_ptdev_intr_info(vm, vm_id, param2);
+		}
 		break;
 
 	case HC_WORLD_SWITCH:
@@ -180,7 +216,10 @@ static int32_t dispatch_hypercall(struct acrn_vcpu *vcpu)
 		break;
 
 	case HC_VM_INTR_MONITOR:
-		ret = hcall_vm_intr_monitor(vm, (uint16_t)param1, param2);
+		/* param1: vmid */
+		if (vmid_is_valid) {
+			ret = hcall_vm_intr_monitor(vm, vm_id, param2);
+		}
 		break;
 
 	default:
diff --git a/hypervisor/debug/vuart.c b/hypervisor/debug/vuart.c
index 2328fd080..f85f8358e 100644
--- a/hypervisor/debug/vuart.c
+++ b/hypervisor/debug/vuart.c
@@ -428,11 +428,11 @@ struct acrn_vuart *vuart_console_active(void)
 
 	if (console_vmid < CONFIG_MAX_VM_NUM) {
 		vm = get_vm_from_vmid(console_vmid);
+		if (is_valid_vm(vm)) {
+			vu = vm_console_vuart(vm);
+		}
 	}
 
-	if (is_valid_vm(vm)) {
-		vu = vm_console_vuart(vm);
-	}
 	return (vu && vu->active) ? vu : NULL;
 }