Arm CCA Realm guest attestation driver
A guest-side interface for Linux running as a "Realm" virtual machine on Arm CPUs with the Realm Management Extension. It exposes attestation services so cloud tenants can prove their VM is genuinely isolated from the hypervisor and host, as part of Arm's Confidential Compute Architecture on next-generation server silicon.
recommendation
It should stay because this is brand-new infrastructure for Arm's Confidential Compute Architecture, merged in October 2024 and still receiving follow-up work into 2025. Although real-world deployments are minimal today, Arm and partners like Fujitsu (with the 2025 MONAKA server CPU) are actively bringing first-generation RME silicon to market, and the code is under active upstream maintenance.
repository signals
sources
- git.kernel.org
Kernel history shows this directory is new, introduced in October 2024 and still receiving follow-up changes in late 2024 and 2025 rather than aging out.
- docs.kernel.org
The ARM64 maintainers entry lists drivers/virt/coco/arm-cca-guest under a maintained area, indicating current upstream ownership rather than deprecation.
- docs.kernel.org
Arm CCA support is for Linux running as a Realm guest on Arm systems with RME, so this is a specialized confidential-computing guest driver rather than legacy commodity hardware support.
- developer.arm.com
Arm stated in 2023 that partners were working on first silicon implementations of RME and expected it to become a mainstream feature in future CPU generations.
- developer.arm.com
Arm highlighted a 2025 Fujitsu MONAKA deployment case for Arm CCA, showing the technology is still appearing in new products in 2025.
codex reasoning notes (technical)
Local file inspection via shell showed a real module_init-based TSM driver that only loads in Realm world and exposes attestation. Upstream activity was checked with local shell git log using safe.directory; the cited kernel.org log URL is canonical recall for that same history. Web search found the Linux maintainers page and Arm CCA architecture doc, both showing maintained, current confidential-computing scope. Web search also found Arm official 2023 and 2025 blogs indicating ongoing/new Arm CCA hardware rollouts. No removal discussion surfaced in the available lore/web checks. This is niche and early-deployment infrastructure, but it is new and still relevant, so keep rather than deprecate/remove.