Power management for host with devices assigned to virtual machines

A method of removing power from a device, the method comprising:

• receiving a request from a virtual machine to remove power from a device assigned to the virtual machine, wherein the virtual machine runs on a host machine and runs a guest operating system;
• scheduling the request to remove power from the device to be executed after receiving an indication that first state information of the device has been saved to a memory, the first state information maintained by the virtual machine;
• receiving the indication from the virtual machine that the first state information of the device has been saved to the memory;
• and
• after the request has been satisfied, sending a communication to the host machine to cause the host machine to remove power from the device.

A non-transitory machine-readable medium comprising a first plurality of machine-readable instructions that executed by one or more processors are adapted to cause the one or more processors to perform a method comprising:

• receiving an indication that a host machine will be suspended;
• scheduling one or more instructions, to suspend the host machine, to be executed after removal of power from a device assigned to a virtual machine, wherein the virtual machine runs on the host machine and runs a guest operating system;
• responsive to receiving the indication that the host machine will be suspended, sending a first communication to the virtual machine to cause the virtual machine to stop using the device, to further cause the virtual machine to save first state information maintained by the virtual machine to memory, and to further cause the virtual machine to suspend, wherein the first state information is associated with the device;
• receiving an indication that the virtual machine has been suspended;
• responsive to receiving the indication that the virtual machine has been suspended, saving second state information maintained by the host machine to memory, wherein the second state information is associated with the device;
• after saving the second state information, sending a second communication to the host machine to cause the host machine to remove power from the device;
• determining that power has been removed from the device;
• and
• responsive to the removal of power from the device, sending a third communication to the host machine to cause the host machine to suspend.