Alioth

Alioth /AL-lee-oth/ is an experimental KVM-based type-2 hypervisor (virtual machine monitor) in Rust implemented from scratch.

[!IMPORTANT]

Disclaimer: Alioth is not an officially supported Google product.

Quick start

• Install Alioth from source,

  cargo install alioth-cli --git https://github.com/google/alioth.git
  

• Make an initramfs with u-root.

• Boot a Linux kernel with 2 CPUs and 4 GiB memory,

  alioth -l info --log-to-file \
      boot \
      --kernel /path/to/vmlinuz \
      --cmd-line "console=ttyS0" \
      --initramfs /path/to/initramfs \
      --memory size=4G \
      --num-cpu 2
  

Features

• Runs on x86_64 and aarch64.
• Boots confidential VMs with AMD SEV, SEV-ES, or SEV-SNP, see coco.md for details.
• VirtIO devices
  • net backed by a tap device,
  • vsock backed by host /dev/vhost-vsock,
  • blk backed by a raw-formatted image,
  • entropy backed by host /dev/urandom,
  • fs backed by virtiofsd with experimental Direct Access (DAX),
  • (WIP) balloon with free page reporting.
• PCI device passthrough based on VFIO/IOMMUFD.
• Other devices
  • serial console: 16450 on x86_64, pl011 on aarch64,
  • fw_cfg (QEMU Firmware Configuration Device),
  • pvpanic.

TODOs

• explore a better solution to ACPI DSDT to replace the pre-compiled AML bytes,
• increase test coverage,
• add missing documents,
• (long term) port Alioth to Apple's Hypervisor framework,
• performance, performance, and performance!

Acknowledgment

The virtualization implementation in Alioth takes the following projects as references,

• QEMU
• crosvm
• Cloud Hypervisor
• xhyve

The error handling practice is inspired by GreptimeDB's stack_trace_debug.