1. In a computing device executing a hypervisor hosting a trusted virtual machine, a non-trusted virtual machine, and a third virtual machine, a method for establishing a secure communication channel between the non-trusted virtual machine and the trusted virtual machine, comprising: writing, by a non-trusted virtual machine executed by a processor of a computing device, a first string of data to a region of memory of the computing device; detecting, by a trusted virtual machine executed by the processor of the computing device, the first string of data written to the region of memory; and establishing a communication channel between the trusted virtual machine and the non-trusted virtual machine by locking, by the trusted virtual machine and responsive to the detection, the region of memory for the duration of the communication to prevent a third virtual machine executed by the processor of the computing device from accessing the region of memory.