Confidential Computing Probe Filter for Key Mixing Hazards

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Solution Overview

Problem

Confidential computing environments face hazards due to the mixing of encryption keys, which can compromise data coherence and integrity when write operations attempt to store data using incorrect encryption keys without properly evicting stale data.

Innovation Solution

Implementing a probe filter within the cache hierarchy that detects access requests using a new encryption key, verifies the use of a previous encryption key at a memory address, and evicts references to the previous key to maintain data coherence and integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If write operations store data using a new encryption key without evicting stale data, then encryption key flexibility is improved, but data coherence and integrity deteriorate

Engineering Contradiction:

Improveencryption key flexibilityVSAvoiddata coherence and integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The probe filter performs preliminary action by detecting and evicting stale data references to previous encryption keys before the write operation completes. This ensures that when new data is written with a new encryption key, any stale references to the old key are removed in advance, preventing data coherence issues while allowing key flexibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The probe filter acts as an intermediary component between the write operation and the cache hierarchy. It intercepts write requests, checks for stale data using previous encryption keys, and mediates by evicting those stale references before allowing the new write to proceed, thus maintaining data integrity without restricting key changes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If stale data is not evicted before write operations, then write operation speed is improved, but data integrity deteriorates

Engineering Contradiction:

Improvewrite operation speedVSAvoiddata integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The probe filter implements a streamlined eviction mechanism that quickly identifies and removes stale data references without blocking the write operation. By using probe-based detection and rapid reference removal, the system achieves fast write operations while still ensuring data integrity through effective stale data eviction.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Reliability

If a probe filter is implemented to detect and evict stale data, then data integrity is improved, but device complexity increases

Engineering Contradiction:

Improvedata integrityVSAvoidcache hierarchy complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The probe filter is designed to serve multiple functions within the cache hierarchy: it detects stale data, evicts references to previous encryption keys, and enables secure key mixing. By consolidating these functions into a single filter mechanism, the system improves data integrity without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250240156A1Systems and methods relating to confidential computing key mixing hazard management

Publication Date: 2025.07.24 ADVANCED MICRO DEVICES INC

AI summary

A disclosed method can include (i) detecting, by a probe filter in a coherent fabric interconnect, an access request to a specific memory address of a cache hierarchy using a new encryption key, (ii) verifying, by the probe filter, that the specific memory address stores data encrypted using a previous and distinct encryption key, and (iii) evicting, by the probe filter in response to the verifying, references to the previous and distinct encryption key from the cache hierarchy. Various other methods, systems, and computer-readable media are also disclosed.