IBM enables hardware-accelerated ARM64 guest VMs on s390 via Linux KVM

IBM engineer Steffen Eiden presented at KVM Forum 2026 in Canada on the company's new capability to run ARM64 guest virtual machines directly on IBM s390 hardware with hardware acceleration. This cross-architecture virtualization stems from a collaboration between IBM and Arm on 'dual architecture' hardware, and requires substantial Linux KVM changes that have been submitted as patches over recent months. The initial code has been merged for Linux 7.4, making this the first kernel release with foundational support for the feature.

The implementation is described as technically complex, involving the translation or direct execution of ARM64 instruction streams on s390 processors. Eiden indicated that the work may expand to additional architectures beyond ARM64 and s390 in future iterations, and that guest ARM64 capabilities will continue to be enhanced. The presentation signals IBM's continued investment in mainframe virtualization flexibility and its willingness to bridge historically distinct processor ecosystems.

KVM and cross-architecture virtualization changes

• Linux KVM subsystem: Months of patches have been submitted to enable cross-architecture virtualization, with initial code now merged for the Linux 7.4 kernel series.
• s390 hardware acceleration: The ARM64 guest support relies on hardware-accelerated execution paths on IBM s390 rather than pure software emulation, reducing virtualization overhead.
• Dual architecture design: The feature requires coordination between IBM's s390 hardware platform and Arm's ARM64 instruction set architecture, representing a rare direct collaboration between the two companies.
• Future extensibility: IBM has indicated potential plans to extend the cross-architecture VM functionality to additional architectures beyond the current ARM64-on-s390 pairing.
• Guest capability roadmap: Further enhancements to ARM64 guest functionality and additional capabilities are planned beyond the initial Linux 7.4 implementation.

Why it matters

For Linux distribution maintainers and enterprise operators running s390 mainframes, this opens a path to consolidate ARM64 workloads onto existing IBM hardware without separate ARM64 server fleets, potentially simplifying heterogeneous data center management. The development also strengthens KVM's position as a cross-platform hypervisor capable of handling non-native architectures, which may influence future cloud provider offerings and mainframe Linux adoption patterns.