Interrupt Filter Blocks Unauthorized System Management Interrupts
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Solution Overview
Problem
Computer systems face performance issues due to frequent system management interrupts (SMIs) from unreliable peripheral devices, which can lead to SMI storms, causing denial-of-service attacks and slowing down application program execution.
Innovation Solution
An interrupt filter system that determines the source and type of interrupt signals and blocks unauthorized SMIs using a comparator and logic circuit, with a register set to maintain a list of permitted devices, preventing invalid SMIs from reaching the processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processor allows all interrupt signals from peripheral devices, then system responsiveness to urgent matters is improved, but processor performance deteriorates due to excessive interrupt handling
Solution Approach 1:
The patent introduces an interrupt filter as an intermediary component between peripheral devices and the processor. This filter examines interrupt signals before they reach the processor, determining whether to allow or block them based on source identity and interrupt type. The filter acts as a mediator that protects the processor from harmful interrupts while permitting legitimate ones, thus maintaining system responsiveness without sacrificing processor performance.
2Productivity
If the processor blocks all interrupt signals from unauthorized sources, then processor performance is improved by preventing SMI storms, but system responsiveness to legitimate urgent matters deteriorates
Solution Approach 1:
The interrupt filter applies different treatment to different interrupt sources and types. Instead of a blanket block or allow policy, the filter examines each interrupt signal individually, identifying its source and type, then applies appropriate filtering rules. This localized quality control ensures that legitimate interrupts from authorized devices are permitted while blocking only the harmful ones, thus maintaining both processor performance and system responsiveness.
3Adaptability or versatility
If guest operating systems have direct access to peripheral devices, then system adaptability and device utilization are improved, but security vulnerabilities increase allowing DoS attacks
Solution Approach 1:
The interrupt filter serves as a security intermediary that sits between guest operating systems and peripheral devices. Even though guest OSes have direct access to devices, the filter monitors and controls interrupt signals from these devices before they reach the processor. This intermediary layer prevents malicious guest OSes from generating SMI storms through peripheral devices, thus maintaining security while preserving the adaptability benefits of direct device access.
Data Source
AI summary
A method and apparatus are provided for controlling system management interrupts is disclosed. An interrupt filter comprises a memory, a comparator and a logic circuit. The memory is adapted to contain a list indicating one or more devices with permission associated with an interrupt signal. The comparator is adapted to receive an interrupt signal containing type information from the one or more devices. The comparator is adapted to compare the interrupt type against the list to determine if the one or more devices is permitted to send the interrupt signal. The logic circuit blocks or passes the interrupt signal in response to the result of the comparison.