Virtual Machine Data Logging via DMA Controller
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Solution Overview
Problem
Existing electronic control units for vehicles fail to securely manage virtual machines, leading to data loss when an abnormality occurs in a virtual machine, as they block communication without recording data intended for the affected machine.
Innovation Solution
An electronic control unit with a hypervisor-managed CPU resource allocation system that detects abnormalities in virtual machines, stops CPU resource allocation, and uses a DMA controller to transfer data to a common memory, ensuring security and data logging even after CPU resources are stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CPU resource allocation is stopped for an abnormal virtual machine to ensure security, then other virtual machines are protected from being affected, but data intended for the abnormal virtual machine is lost and cannot be recorded
Solution Approach 1:
The system separates the data reception function from the CPU processing function by introducing a DMA controller. The DMA controller independently receives data intended for the abnormal virtual machine and stores it in a separate reception buffer, while the CPU resource allocation is stopped to protect other virtual machines. This segmentation allows data to be preserved without requiring the abnormal virtual machine's CPU to be active.
Solution Approach 2:
The reception buffer acts as an intermediary between the communication interface and the virtual machine memory. It temporarily stores data intended for the abnormal virtual machine, allowing the data to be captured and preserved even when the virtual machine's CPU resources are stopped. This intermediary component bridges the gap between data reception and data processing requirements.
2Reliability
If communication is blocked when an abnormality occurs in a virtual machine, then security is improved, but data logging capability is lost
Solution Approach 1:
The system performs preliminary action by allocating a reception buffer in advance for each virtual machine and configuring the DMA controller to direct data to the appropriate buffer. When an abnormality occurs, the data logging function is already in place and can immediately capture data without requiring any additional setup or CPU intervention from the abnormal virtual machine.
Solution Approach 2:
The DMA controller performs self-service by autonomously managing data reception and transfer to the reception buffer without requiring CPU intervention. This allows the system to continue logging data for the abnormal virtual machine independently, even when the virtual machine itself cannot process data due to the abnormality.
3Loss of information
If CPU resources are continuously allocated to monitor and handle abnormal virtual machines, then data can be recorded, but security risks increase and system performance decreases
Solution Approach 1:
The system extracts the data reception function from the virtual machine's CPU by assigning it to the DMA controller. This extraction allows data to be captured and stored in the reception buffer without requiring the abnormal virtual machine's CPU to remain active or allocate resources, thereby maintaining security isolation while preserving data logging capability.
Solution Approach 2:
The system replaces the traditional CPU-based data reception and processing mechanism with a dedicated DMA controller that operates independently. This substitution eliminates the need for the abnormal virtual machine's CPU to be involved in data reception, allowing security isolation to be maintained while data continues to be recorded through the hardware-level DMA operation.
Data Source
AI summary
An electronic control unit is configured to perform: allocating CPU resources to provide a plurality of virtual machines under a management by a hypervisor; monitoring an abnormality that occurs in one specific virtual machine by another virtual machine different from the specific virtual machine; outputting a stop request that requests stop of the allocation of the CPU resources to the specific virtual machine in a case that the abnormality is detected; and stopping allocation of the CPU resources to the specific virtual machine, by the hypervisor, in response to the stop request. The electronic control unit further comprises a DMA controller. The DMA controller transfers data transmitted to the specific virtual machine to a common memory which is common among a plurality of virtual machines.