A method and system of host to guest (H2G) notification are disclosed. H2G is provided via an instruction. The instruction is a send user inter-processor interrupt instruction. An exemplary processor includes decoder circuitry to decode a single instruction and execute the decoded single instruction according to the at least the opcode to cause a host to guest notification from a virtual device running in a host machine on the first physical processor to a virtual device driver running on a virtual processor in a guest machine on a second physical processor.