Inter-VM Interrupt Handling via Posted Descriptors
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Solution Overview
Problem
Current virtualization systems incur overhead due to VM exits when sending interrupts between virtual machines, which can lead to inefficiencies in communication and resource management.
Innovation Solution
The implementation of an inter-VM-IPI instruction that allows notifications or interrupts to be sent between virtual machines without causing a VM exit, using a processor with virtualization extensions and a posted-interrupt descriptor format to manage interrupts efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional interrupt handling between virtual machines is used, then interrupts can be sent between VMs, but VM exits are triggered causing overhead and inefficiency
Solution Approach 1:
The patent introduces a posted interrupt descriptor as an intermediary data structure that enables interrupt notification between VMs without triggering VM exits. The descriptor contains interrupt information and is posted to a memory location accessible by the target VM, allowing the interrupt to be handled directly by the guest OS without hypervisor involvement.
Solution Approach 2:
The patent extracts the interrupt notification mechanism from the traditional VM exit path. By using posted interrupt descriptors that are directly accessible to guest VMs, the interrupt handling is separated from the hypervisor control flow, eliminating the need for VM exits while maintaining interrupt delivery functionality.
2Reliability
If VM exits are used for inter-VM communication, then interrupts can be delivered between VMs, but system overhead increases
Solution Approach 1:
The patent enables VMs to self-service interrupt handling by posting interrupt descriptors to memory locations that are directly accessible to the target VM. The guest OS can autonomously process these interrupts without requiring hypervisor mediation, reducing system complexity while maintaining reliable interrupt delivery.
Solution Approach 2:
The patent prepares interrupt descriptors in advance and posts them to predetermined memory locations before the interrupt needs to be handled. This preliminary action allows the target VM to immediately process the interrupt when it occurs, eliminating the need for complex runtime hypervisor intervention.
3Ease of operation
If traditional interrupt mechanisms are used, then interrupts can be handled, but resource management efficiency decreases
Solution Approach 1:
The patent replaces the mechanical VM exit mechanism with a memory-based posted interrupt descriptor system. This substitution eliminates the overhead of context switching and hypervisor intervention, improving resource management efficiency while maintaining the simplicity of interrupt handling through standardized descriptor formats.
Data Source
AI summary
Embodiments of an invention interrupts between virtual machines are disclosed. In an embodiment, a processor includes an instruction unit and an execution unit, both implemented at least partially in hardware of the processor. The instruction unit is to receive an instruction to send an interrupt to a target virtual machine. The execution unit is to execute the instruction on a sending virtual machine without exiting the sending virtual machine. Execution of the instruction includes using a handle specified by the instruction to find a posted interrupt descriptor.