1. In a system comprising one or more processors implementing a plurality of virtual machines, a method comprising: performing a translation lookaside buffer (TLB) lookup using a first search key and a second search key, the first search key representing a first identifier of an operating system executed in association with a corresponding virtual machine of the plurality of virtual machines, the first search key having fewer bits than the first identifier, and the second search key representing a second identifier of a virtual address space managed by the operating system, the second search key having fewer bits than the second identifier.