DuVisor is a user-level hypervisor with high performance based on delegated virtualization. It deprivileges all the vulnerable subsystems of traditional hypervisors into user space, reducing the host kernel’s attack surface and preventing any of hypervisor's vulnerabilities from jeopardizing it. The Rust language and one-to-one model further ensures the isolation and reliability.

DuVisor

• DuVisor
  • Why DuVisor
  • Duvisor's Architecture
  • Quick Start
    • Prerequisite
    • Build DuVisor for QEMU
    • Run Example VM on QEMU
    • Build DuVisor for FireSim
  • Cite

Why DuVisor

Compared with traditional virtualization, DuVisor offers several advantages:

1. High Security: By using a deprivileged hypervisor, DuVisor eliminates the kernel's attack surface introduced by virtualization. Moreover, the one-to-one service model improves the isolation between virtual machines (VMs) and the fault tolerance of the system.

2. Near-native Performance: DuVisor eliminates redundant mode switching, thereby fully unleashing the potential performance of virtualization. The integrated design also improves cooperation between modules, making the code more efficient.

3. Agile Development: Because of the thriving software environment in user space, DuVisor is no longer constrained by kernel development environments and can freely choose programming languages and existing libraries. Currently, the project uses Rust to ensure security and takes advantage of its powerful testing framework to improve project quality.

4. Flexible Operations and Maintenance: DuVisor can be upgraded without rebooting the host system. New features and functionalities can be deployed more quickly. Cloud services will have better fault tolerance, benefiting from DuVisor's strong isolation.

Duvisor's Architecture

DuVisor adopts a one-to-one model to serve virtual machines (VMs) directly in user space, providing greater isolation to the entire system.

With a separate hypervisor process that only serves itself, each VM gains stronger isolation from other VMs and DuVisor processes. Additionally, the host kernel is no longer exposed to the hypervisor's security vulnerabilities.

Unlike traditional virtualization, all data interactions between the VM and the hypervisor are no longer mediated by the host kernel. DuVisor can directly handle VM traps in a more integrated way, reducing complexity while boosting performance.

DuVisor relies on a new hardware extension called DV-Ext to catch VM exits directly in user space. This hardware extension imports VM exits directly into the user state, providing virtualization-related registers that user-level software can use to access VM states and control VM behaviors.

Because DuVisor is developed in user space, it is more flexible than kernel modules. For instance, it uses the Rust language to build the main functionalities and therefore provides strong security. DuVisor can also quickly reuse existing off-the-shelf projects, such as Firecracker's I/O backend.

Note: All directories under ./src/ except for ./src/duvisor have been reused from I/O backend implementations of an early version of Firecracker.

Quick Start

Prerequisite

Hardware requirements:

• CPU: Commodity CPU with >= 4 cores which is able to run QEMU. Architecture is not limited.
• Memory: >8GB

First, clone this repository:

git clone https://github.com/IPADS-DuVisor/DuVisor
cd DuVisor
git submodule update --init --recursive

We provide a docker image to build the whole environment for x86-64 CPUs, as well as the Dockerfile of this image.

(Optional) To set up a native environment for building, you can follow the Dockerfile.

Install Docker: https://docs.docker.com/engine/install/ubuntu/

Prepare source code for guest VM:

wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.11.tar.xz
tar xf linux-5.11.tar.xz
mv linux-5.11 linux-guest

Prepare source code of busybox for rootfs:

mkdir -p prepare
cd prepare
git clone https://github.com/kvm-riscv/howto.git
wget https://busybox.net/downloads/busybox-1.33.1.tar.bz2
tar xf busybox-1.33.1.tar.bz2
mv busybox-1.33.1 rootfs
cd ..

Build DuVisor for QEMU

You can build DuVisor and other elements for executing DuVisor (host/guest Linux kernel, rootfs,OpenSBI) via one of the following two scripts:

Build via docker:

./scripts/quick_docker_build.sh

Native build:

./scripts/quick_native_build.sh

Run Example VM on QEMU

If you use the docker build in the last step:

./scripts/build/docker_exec_wrapper.sh ./scripts/run/example_boot.sh

# In QEMU
cd duvisor
./boot.sh

If you use the native build in the last step:

./scripts/run/example_boot.sh

# In QEMU
cd duvisor
./boot.sh

You would see DuVisor then.

Reference boot log:

bash> ./scripts/run/example_boot.sh

OpenSBI v0.8                                                                                                           
   ____                    _____ ____ _____                                                                            
  / __ \                  / ____|  _ \_   _|                                                                           
 | |  | |_ __   ___ _ __ | (___ | |_) || |                                                                             
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |                                                                             
 | |__| | |_) |  __/ | | |____) | |_) || |_                                                                            
  \____/| .__/ \___|_| |_|_____/|____/_____|                                                                           
        | |                                                                                                            
        |_|                                                                                                            
                                                                                                                       
Platform Name             : riscv-virtio,qemu

/* Skip some of the log */

[    0.299693] Key type dns_resolver registered
[    0.315945] Freeing unused kernel memory: 192K
[    0.328555] Run /init as init process
           _  _
          | ||_|
          | | _ ____  _   _  _  _ 
          | || |  _ \| | | |\ \/ /
          | || | | | | |_| |/    \
          |_||_|_| |_|\____|\_/\_/

               Busybox Rootfs

Please press Enter to activate this console. 
/ # cd duvisor
/duvisor # ./boot.sh                                                 
[debug] cmdline: append: root=/dev/ram console=ttyS0 earlycon=sbi
                                                                                                                       
                                                           
    ,------.         ,--.   ,--.,--.                               
    |  .-.  \ ,--.,--.\  `.'  / `--' ,---.  ,---. ,--.--.     
    |  |  \  :|  ||  | \     /  ,--.(  .-' | .-. ||  .--'     
    |  '--'  /'  ''  '  \   /   |  |.-'  `)' '-' '|  |    
    `-------'  `----'    `-'    `--'`----'  `---' `--'    
                                                           
                                                                  
Welcome to DUVISOR (QEMU)

/* Skip some of the log */

[    1.271158] Freeing unused kernel memory: 2144K
[    1.298522] Run /init as init process
           _  _
          | ||_|
          | | _ ____  _   _  _  _ 
          | || |  _ \| | | |\ \/ /
          | || | | | | |_| |/    \
          |_||_|_| |_|\____|\_/\_/

               Busybox Rootfs

Please press Enter to activate this console. 
/ # cat /proc/cpuinfo
processor       : 0
hart            : 1
isa             : rv64imafdcsu
mmu             : sv48

processor       : 1
hart            : 0
isa             : rv64imafdcsu
mmu             : sv48
/ # poweroff -f
[  120.441885] reboot: Power down
Poweroff the virtual machine by vcpu 1
[  127.298790] IOCTL_DUVISOR_UNREGISTER_VCPU: tid = 67
[  127.298805] IOCTL_DUVISOR_UNREGISTER_VCPU: tid = 68
DuVisor VM ended normally.
Finish vm running...
[  127.348446] vplic_dev_release:419 tgid = 66
[  127.348795] vplic_dev_release:406 tgid = 66 ulh_vm_data is NULL vplic!
[  127.349096] dv_driver_release:449 tgid = 66 ulh_vm_data is NULL!
/duvisor #

Build DuVisor for FireSim

To run DuVisor on the FireSim platform, you only need to checkout to the firesim branch and apply a firesim.patch to the guest kernel code. Other steps are the same as Build DuVisor for QEMU.

To apply firesim.patch to the guest kernel code:

wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.11.tar.xz
tar xf linux-5.11.tar.xz
mv linux-5.11 linux-guest
cd linux-guest
patch -p1 < ../firesim.patch

To run on FireSim, please use the Rocket-Chip with DV-ext enabled. We have provided a compiled hardware on AWS, you can refer to our AE for more details:

# config_runtime.ini
defaulthwconfig=firesim-rocket-quadcore-nic-l2-llc4mb-ddr3-ulh-VNA-4TLB-4PTW-IBCN-vssip

# config_hwdb.ini
[firesim-rocket-quadcore-nic-l2-llc4mb-ddr3-ulh-VNA-4TLB-4PTW-IBCN-vssip]
agfi=agfi-0e385553b7716f177
deploytripletoverride=None
customruntimeconfig=None

Cite

If you find this work helpful for your publication, please cite DuVisor's OSDI'23 paper:

@inproceedings {chen2023duvisor,
author = {Jiahao Chen and Dingji Li and Zeyu Mi and Yuxuan Liu and Binyu Zang and Haibing Guan and Haibo Chen},
title = {Security and Performance in the Delegated User-level Virtualization},
booktitle = {17th USENIX Symposium on Operating Systems Design and Implementation (OSDI 23)},
year = {2023},
isbn = {978-1-939133-34-2},
address = {Boston, MA},
pages = {209--226},
url = {https://www.usenix.org/conference/osdi23/presentation/chen},
publisher = {USENIX Association},
month = jul,
}