IOMMU Power Management With Synchronized Device Control
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Solution Overview
Problem
Conventional power management systems for IOMMUs suffer from security holes and slow responses due to asynchronous power-on/off synchronization between device managers and IOMMUs, and high workload on OS and hypervisor during recovery operations.
Innovation Solution
A power management system and method that integrates a device controller to manage the life cycle of IOMMUs and devices, with optional recovery engines to handle recovery operations, ensuring synchronized power management and reducing OS and hypervisor workload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If independent device manager and AC manager run on OS through software to manage device power and IOMMU power separately, then power management flexibility is improved, but security holes occur due to lack of synchronization between device power-on/off and IOMMU power-on/off
Solution Approach 1:
The patent merges the device manager and AC manager into a unified device controller that is integrated with the IOMMU. This unified controller ensures that device power states and IOMMU power states are synchronized, eliminating security holes while maintaining power management flexibility through integrated control logic.
Solution Approach 2:
The patent introduces a unified device controller as an intermediary between the OS and the IOMMU/device pair. This intermediary coordinates power management actions, ensuring that device power transitions are properly synchronized with IOMMU power transitions, thus preventing security vulnerabilities.
2Adaptability or versatility
If AC manager and another AC manager are used to manage IOMMU power according to trigger signals, then power control capability is improved, but response speed deteriorates due to preemption by other processing
Solution Approach 1:
The unified device controller is designed to autonomously manage IOMMU power states based on device power states without requiring continuous intervention from the OS or hypervisor. The controller self-monitors and self-adjusts power states, eliminating preemption delays and improving response speed while maintaining comprehensive power control capability.
Solution Approach 2:
By merging multiple AC managers into a single unified device controller, the patent eliminates the coordination overhead and preemption issues associated with multiple independent managers. The unified controller processes power management requests in a single thread, ensuring fast response while maintaining full power control functionality.
3Reliability
If OS and hypervisor execute recovery operations for IOMMU to ensure proper power management, then reliability is improved, but system performance deteriorates due to increased workload on processor
Solution Approach 1:
The unified device controller autonomously performs recovery operations for the IOMMU when power state inconsistencies are detected, without requiring intervention from the OS or hypervisor. This self-service capability maintains power management reliability while eliminating the performance penalty associated with processor-executed recovery operations.
Solution Approach 2:
The unified device controller acts as an intermediary that handles recovery operations locally, preventing the need for OS/hypervisor involvement in routine power management tasks. This intermediary approach maintains system reliability through proper error handling while preserving overall system performance by offloading recovery tasks from the main processor.
Data Source
AI summary
A power management system includes at least one device, at least one memory management unit (MMU), a processor, and at least one device controller, wherein the at least one MMU corresponds to the at least one device, respectively. The processor is arranged to execute at least one access control power manager, an operating system (OS), and a hypervisor, wherein the OS is arranged to generate a trigger signal, and the hypervisor is arranged to generate a first hint according to the trigger signal. The at least one device controller is arranged to control the at least one access control power manager according to the first hint, to manage at least one power of the at least one MMU.