But there are other options, like OpenVMM and in the future OpenHCL:
OpenVMM is a Type-2 VM written in Rust. On Linux it runs on top of KVM, so it uses /dev/kvm as its acceleration backend, not MSHV. It's essentially an alternative to QEMU, but using Microsoft's Hyper-V device model (VMBus, storvsp, netvsp) instead of virtio/QEMU devices.
Microsoft itself warns that OpenVMM on the host is not yet ready to run end-user workloads, and should be treated as a development platform for implementing new OpenVMM features rather than a ready-to-deploy application.
So on Proxmox, OpenVMM would: use KVM underneath (same as QEMU), run VMs with Hyper-V compatible devices, but have zero integration with Proxmox's UI, storage, or networking stack. (I am a console guy anyway)
That can be already run on proxmox as a standalone binary, but with caveats :
Code:
# Install Rust (OpenVMM is Rust-only, no prebuilt packages)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source $HOME/.cargo/env
# Install build dependencies
apt install -y git build-essential protobuf-compiler \
pkg-config libssl-dev clang
git clone https://github.com/microsoft/openvmm.git
cd openvmm
# Fetch required packages (UEFI firmware, test kernels, protoc, etc.)
cargo xflowey restore-packages
# Build OpenVMM
cargo build --release -p openvmm
Run a VM (example: Alpine Linux) OpenVMM uses a CLI interface quite different from QEMU:
Code:
# Basic VM with KVM backend, using OpenVMM's bundled UEFI
./target/release/openvmm \
--backend kvm \
--memory 1024 \
--processors 2 \
--disk path=alpine.img \
--nic consomme # built-in NAT networking
The one realistic use case today: running Windows VMs with native Hyper-V devices without needing virtio drivers.
Since OpenVMM uses the Hyper-V device model natively, Windows guests see it as a Hyper-V environment and need no extra driver installation.
But again, it's not production-grade yet.
The more interesting future direction is OpenHCL: Microsoft's open-source paravisor that runs OpenVMM inside the guest at a higher privilege level. Microsoft has stated they are looking forward to developing OpenHCL support for KVM as a host, in collaboration with cloud providers and the Linux/KVM community. That would eventually bring confidential VM features to KVM-based hypervisors like Proxmox, but that's still future work.
Bottom line: For your Proxmox homelab, there's limited benefit to running OpenVMM today over QEMU/KVM.
It's worth watching for when OpenHCL/KVM support matures.
Anyway, I might give it a shot - long easter weekend is coming ....
