A method for computing includes running a plurality of virtual machines on a computer having one or more cores and a memory. Upon occurrence of an event pertaining to a given virtual machine during a period in which the given virtual machine is unable to receive an interrupt, an interrupt message is written to a pre-assigned interrupt address in the memory. When the given virtual machine is able to receive the interrupt, after writing of the interrupt message, a context of the given virtual machine is copied from the memory to a given core on which the given virtual machine is running, and a hardware interrupt is automatically raised on the given core responsively to the interrupt message in the memory.