Determining a virtual interrupt source number from a physical interrupt source number

A computer-readable storage medium encoded with instructions, wherein the instructions when executed comprise:

• receiving a request from a virtual machine that specifies a first virtual interrupt source number and a first hardware resource;
• selecting a first physical interrupt source number that is assigned to the first hardware resource;
• assigning the first physical interrupt source number to the first virtual interrupt source number as an assigned pair that comprises the first physical interrupt source number and the first virtual interrupt source number;
• saving the assigned pair;
• sending the request and the first physical interrupt source number to the first hardware resource, wherein the first hardware resource performs the request;
• receiving a physical interrupt from the first hardware resource that specifies the first physical interrupt source number;
• in response to the receiving the physical interrupt that specifies the first physical interrupt source number, determining the virtual machine and the first virtual interrupt source number that is assigned to the first physical interrupt source number from the physical interrupt and the assigned pair, wherein the determining the virtual machine determines the virtual machine from among a plurality of virtual machines;
• and
• in response to the determining the virtual machine and the first virtual interrupt source number that is assigned to the first physical interrupt source number, sending a virtual interrupt that comprises that first virtual interrupt source number to the virtual machine, wherein the virtual machine invokes a routine identified by the virtual interrupt source number in response to receiving the virtual interrupt.

A computer comprising:

• a processor;
• a hardware resource;
• and
• memory communicatively coupled to the processor and the hardware resource, wherein the memory is encoded with instructions, and wherein the instructions when executed on the processor comprise
• receiving a request from a virtual machine that specifies a first virtual interrupt source number and a first hardware resource,
• selecting a first physical interrupt source number that is assigned to the first hardware resource,
• assigning the first physical interrupt source number to the first virtual interrupt source number as an assigned pair that comprises the first physical interrupt source number and the first virtual interrupt source number,
• saving the assigned pair,
• sending the request and the first physical interrupt source number to the first hardware resource, wherein the first hardware resource performs the request,
• receiving a physical interrupt from the first hardware resource that specifies the first physical interrupt source number,
• in response to the receiving the physical interrupt that specifies the first physical interrupt source number, determining the virtual machine and the first virtual interrupt source number that is assigned to the first physical interrupt source number from the physical interrupt and the assigned pair, wherein the determining the virtual machine determines the virtual machine from among a plurality of virtual machines, and
• in response to the determining the virtual machine and the first virtual interrupt source number that is assigned to the first physical interrupt source number, sending a virtual interrupt that comprises that first virtual interrupt source number to the virtual machine, wherein the virtual machine invokes a routine identified by the virtual interrupt source number in response to receiving the virtual interrupt.