Aspects of the disclosure provide for mechanisms for securing virtual machines in a computer system. A method of the disclosure includes: receiving a first resource request initiated by an application running on a virtual machine during initialization of the application; allocating, by a hypervisor, a resource to the application in view of the first resource; and in response to receiving a message indicating completion of the initialization of the application, blocking, by the hypervisor, at least one hypercall initiated by the virtual machine. The completion of the initialization of the application may correspond to initiation of execution of the application using the allocated resource.