RIKEN-RCCS / MilvusVisor

A thin-hypervisor that runs on aarch64 CPUs.

MilvusVisor

MilvusVisor is a thin hypervisor that runs on aarch64 CPUs.

The features of the MilvusVisor are the following.

• (Theoretically) Smaller footprint and overhead than typical VMM (e.g. QEMU/KVM, Xen)
• Support running only one guest OS simultaneously for keeping it simple and thin
• Written in Rust

MilvusVisor allows providing functions OS-independently without the overhead of device virtualization. We are currently developing MilvusVisor as a research activity to achieve HPC environments that provide root privilege to the users without virtualization overhead.

Functions

Currently, MilvusVisor provides the following function.

You can build with enabling some functions by make custom_all FEATURES=feature1,feautre2,....(featureN is described like Feature Name: feature_name in each section.)
If you want to build with extra features, you can build by make custom_all FEATURES=default,feature1,feature2,....

• Protecting non-volatile data in devices from guest OS (e.g. Firmware, MAC address)
  • Intel I210 (Feature Name: i210)
    • Protect EEPROM from writing access
  • Mellanox Technologies MT27800 (Feature Name: mt27800)
    • Protect from firmware update
• Protecting MilvusVisor itself against DMA attack (Feature Name: smmu)
  • Using SMMUv3 Stage 2 Page Translation to protect from DMA attack
  • Stage 1 translation is available from guest OS
• Fast restore: Fast restoring the guest environments without reboot the machine (Feature Name: fast_restore)
  • Taking a snapshot just before the first boot of the guest OS
  • Restoring it on rebooting/shutting down the guest OS
• Protecting ACPI Tables from write accesses (Feature Name: acpi_table_protection)
  • For the Fast Restore
• Linked-List Style Memory Allocator (Feature Name: advanced_memory_manager)
• Contiguous Bit (Feature Name: contiguous_bit)
  • Set contiguous bit enabled if available (TLB will be optimized by the contiguous bit)
  • Some machine may not work fine with the contiguous bit
• A64FX specific registers' initialization (Feature Name: a64fx)
  • Control some A64FX specific registers
• PXE Boot (Feature Name: tftp)
  • download hypervisor_kernel and payload(usually, bootloader) via TFTP
• Raspberry Pi (Feature Name: raspberrypi)
  • For running MilvusVisor on a Raspberry pi. See the document for details.

Tested machines

We have tested MilvusVisor on the following machines.

• FUJITSU FX700
• FUJITSU FX1000
• GIGABYTE E252-P30
• QEMU (>= 7.1.0)
• Bluefield-2
• Rasspberry pi 4 model B
  • The setup steps for Raspbrry pi are different from the other machines. So please also see the document when you try MilvusVisor on Raspberry pi.

The following table shows which feature worked on which machines.

Test items \ Machine	FX700	FX1000	E252-P30	QEMU	Bluefield-2	RPi4B
Booting Linux on MilvusVisor (Multi-core)	o	o	o	o	o	o
Protecting non-volatile data of Intel I210	o	-	-	-	-	-
Protecting firmware update of Mellanox Technologies MT27800	o	-	-	-	-	-
Protecting MilvusVisor itself against DMA attack	o	-	-	-	-	-
Fast Restore	o	o	-	-	-	-

How to build the hypervisor

By Rust toolchain

Requirements

• rustup command-line tool (you can install from https://rustup.rs/)

Steps (commands list)

rustup component add rust-src
cd path/to/repo-root/src
make

If you want to enable/disable specific features, please execute make custom_all FEATURES=(comma separated features). Please see src/hypervisor_kernel/Cargo.toml to know what features are available.

For example, if you want to build the hypervisor only with the device protection features, you should run the below command instead of make

make custom_all FEATURES=i210,mt27800

Next How to run the hypervisor

By docker

Requirements

• Docker (Tested by Docker version 20.10.8, build 3967b7d28e)
  • I tested by non-root users (See this to run docker command by non-root user)

Steps (commands list)

cd path/to/repo-root/src
./build_by_docker.sh # You can add arguments to pass the make command, like as `custom_all FEATURES=...`

For more detail, please see the scripts.

How to run the hypervisor

On QEMU

First, please install QEMU that supports emulating QEMU ARM Virtual Machine, a64fx CPU. Then, run the following command to run the built hypervisor.

cd path/to/repo-root/src
make QEMU_EFI=/usr/share/qemu-efi/QEMU_EFI.fd run #Please set the path of your QEMU_EFI.fd to QEMU_EFI

On a physical machine from a USB memory stick

Requirement

• Prepare a USB memory that has an EFI (FAT) partition that has /EFI/BOOT/ directory. Please confirm that there is no important file in the partition.
• Prepare a physical machine that has ARMv8.1-A or later, and UEFI firmware.

Steps

1. Attach your USB memory stick to the development machine which built the hypervisor binary.
2. Identify the EFI partition (in the following description, /dev/sdX1 is the EFI partition).
3. Run sudo make DEVICE=/dev/sdX1 write to copy the binary. !! Please be careful not to specify a wrong partition as DEVICE because the script mount/unmount the partition and copies the binary file with root privilege.!!
4. Detach the USB memory from the development machine, and attach it to the physical machine to run the hypervisor.
5. Boot the physical machine with UEFI, and specify BOOTAA64.EFI in the EFI partition as the EFI application to boot.

PXE Boot

Requirement

Modify each PATH in src/common/src/lib.rs.

• HYPERVISOR_TFTP_PATH : The absolute path of hypervisor_kernel at the tftp server
• UEFI_PAYLOAD_PATH : The absolute path of payload UEFI Application like OS bootloader at the tftp server

The default settings assume that files are deploy on tftp server likes below.

(tftp root)
`-- uefi
    |-- BOOTAA64.EFI
    |-- grubaa64.efi
    `-- hypervisor_kernel

Steps

1. Build MilvusVisor with tfp feature like make custom_all FEATURES=default,tftp
2. Deploy BOOTAA64.EFI and hypervisor_kernel on tftp server.(you can rename BOOTAA64.EFI)
3. Modify DHCP setting to change the boot file to BOOTAA64.EFI(if you renamed, adjust the name).

How to generate the documentation

You can generate the document by cargo doc in each cargo project directory.

If you want to see bootloader's document, please run the following command.

cd path/to/repo-root/src/hypervisor_bootloader
cargo doc --open # Browser will open

If you want to see kernel's document, please run the following command.

cd path/to/repo-root/src/hypervisor_kernel
cargo doc --open # Browser will open

Acknowledgment

This work was supported by JSPS KAKENHI Grant Number 21K17727.