Virtual Interrupt Routing via Hardware GIC Without VM-Exit

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Solution Overview

Problem

Existing interrupt handling processes in virtualization technologies involve delays due to the virtual machine monitor (VMM) triggering a VM-exit to write virtual interrupts into system registers, causing temporary suspension of virtual processors.

Innovation Solution

A system and method that utilize a hardware layer with a physical interrupt translation service (ITS) and a physical generic interrupt controller (GIC) to directly transfer virtual interrupt identifiers to target virtual processors without requiring the processors to exit, using preconfigured mapping relationships to ensure accurate interrupt handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the VMM writes the virtual interrupt into the system register corresponding to the virtual CPU by triggering VM-exit, then the virtual interrupt can be delivered to the virtual processor, but the virtual processor temporarily stops running and processing delay is increased

Engineering Contradiction:

Improvevirtual interrupt deliveryVSAvoidprocessing delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces a hardware intermediary component (hardware interrupt controller) between the VMM and the virtual processor. This hardware layer receives virtual interrupt information from the VMM and directly delivers it to the virtual processor without requiring VM-exit, thereby eliminating the processing delay while ensuring reliable interrupt delivery.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the software-based interrupt delivery mechanism (relying on VM-exit and system register writes) with a hardware-based interrupt controller. This substitution eliminates the need for virtual processor suspension and enables direct hardware-level interrupt delivery, significantly reducing processing delay.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If the VMM proactively triggers VM-exit to write virtual interrupt into system register, then the virtual interrupt can be written timely, but the virtual processor must temporarily exit and suspend execution

Engineering Contradiction:

Improveinterrupt writing timingVSAvoidvirtual processor execution continuity

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The hardware interrupt controller acts as an intermediary that receives virtual interrupt information from the VMM and directly delivers it to the virtual processor without requiring the processor to exit. This maintains both timely interrupt writing and continuous processor execution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the software-based VM-exit mechanism with a hardware-based interrupt delivery system. The hardware interrupt controller can write virtual interrupt information into the virtual processor's register directly without suspending execution, thereby maintaining productivity while ensuring timely interrupt handling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If conventional software-based interrupt virtualization is used, then the system can provide virtual interrupt controller and translation service, but multiple processing steps are required and processing delay is increased

Engineering Contradiction:

Improveinterrupt virtualization capabilityVSAvoidprocessing steps

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the software-based interrupt virtualization mechanism with a hardware-based solution. The hardware interrupt controller directly handles virtual interrupt translation and delivery, eliminating multiple software processing steps while maintaining interrupt virtualization capability. This reduces device complexity and processing delay.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the interrupt translation and delivery function from the software layer and implements it at the hardware level. By taking out these critical functions to the hardware layer, the system eliminates unnecessary software processing steps while preserving interrupt virtualization capabilities.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20260079742A1System and interrupt handling method

Publication Date: 2026.03.19 HUAWEI TECH CO LTD

AI summary

Embodiments of the present disclosure disclose a computing device, and are applied to the field of computing devices. In the present disclosure, a virtual interrupt obtained by a host machine is mapped to a physical interrupt of a physical layer, and a virtual interrupt identifier corresponding to the physical interrupt is transferred to a virtual processor by using the physical layer. When a hardware layer transparently transmits the virtual interrupt identifier to the virtual processor, the virtual processor does not need to exit. This decreases a delay caused by exit of the virtual processor when software implements virtual interrupt routing.