Microsoft’s OpenVMM is growing into a much-bigger open-source virtualization project

Microsoft’s OpenVMM is growing fast into a much larger open-source effort. Nearly 100 contributors and more than 200 forks now surround the Rust-based virtualization platform. Microsoft originally open-sourced OpenVMM in late 2024. Its latest update highlights expanded hardware support, stronger security, and growing industry participation.

OpenVMM expands across Windows, Linux, ARM and major virtualization platforms

OpenVMM is a cross-platform virtual machine manager written in Rust. It works across Windows, Linux, and macOS, while supporting both x64 and AArch64 systems. The project supports several virtualization backends, including Microsoft’s MSHV, WHP, Linux KVM, and Apple’s Hypervisor framework. That broad approach remains central to Microsoft’s OpenVMM strategy.

Intel and Arm have contributed to the project, alongside the wider developer community. New work includes AArch64 improvements, SMMUv3 emulation, CXL support, PCIe NUMA configuration, and newer device-assignment capabilities.

OpenVMM is also gaining attention around WSL. Community contributors are exploring it as a possible virtual machine manager backend for WSL workloads.

Microsoft is pushing OpenVMM toward stronger security

Confidential computing has become another major focus. Microsoft says Intel TDX support reached general availability, while performance overhead dropped from around 3% to roughly 1% in certain workloads.

Arm CCA Realm support is also underway. AMD SEV-SNP work continues through improvements involving Virtual NMI, logging, debugging, attestation, and sealing capabilities.

The project’s Rust foundation also plays into Microsoft’s security goals. Much of its virtualization functionality runs in user mode, while sandboxing separates sensitive components.

Microsoft says OpenVMM is not intended to replace every other virtual machine manager. Instead, it wants developers and customers to have more choices across different workloads and environments.