An example method of updating a virtual machine (VM) identifier (ID) stored in a memory buffer allocated from guest memory includes supplying firmware to a guest running on a VM that is executable on a host machine. The firmware includes instructions to allocate a memory buffer. The method also includes obtaining a buffer address of the memory buffer. The memory buffer is in guest memory and stores a VM ID that identifies a first instance of the VM. The method further includes storing the buffer address into hypervisor memory. The method also includes receiving an indication that the VM ID has been updated. The method further includes using the buffer address stored in hypervisor memory to update the VM ID.