A system provides virtual per-processor timers based on a timer such as a platform timer. To virtualize a timer to be used by each processor independently, a data structure is maintained in memory for the timer. The data structure has an entry for each interrupt to be produced for each processor using the timer, specifying the processor and the due time, with the entries sorted by due time. If the virtualized timer is a platform timer that maintains context during power transitions, a processor can switch to the virtual per-processor timer upon a context-losing power transition.