A micro hypervisor for RISC-V systems.

Quick Start

Building

rustup target add riscv64gc-unknown-none-elf
cargo build

running

There is a Makefile provided with targets for running various hosts in qemu.

Prerequisites

• rust toolchain from rustup
• rustup target add riscv64gc-unknown-none-elf
• install gcc-riscv64-unknown-elf for riscv64-unknown-elf-objcopy
• qemu-system-riscv64 - build using qemu instructions with --target-list=riscv64-softmmu

Test VM

A pair of test VMs are located in test-workloads.

tellus is a target build with cargo build --bin=tellus that runs in VS mode and provides the ability to send test API calls to salus running in HS mode.

guestvm is a test confidential guest. It is started by tellus and used for testing the guest side of the TSM API.

A makefile shortcut is provided:

make run_tellus

This will build salus, tellus, and the guestvm then boot them with the system-installed qemu.

Overview - Initial prototype

  +---U-mode--+ +-----VS-mode-----+ +-VS-mode-+
  |           | |                 | |         |
  |           | | +---VU-mode---+ | |         |
  |   Salus   | | | VMM(crosvm) | | |  Guest  |
  | Delegated | | +-------------+ | |         |
  |   Tasks   | |                 | |         |
  |           | |    Host(linux)  | |         |
  +-----------+ +-----------------+ +---------+
        |                |               |
   TBD syscall      SBI (TH-API)    SBI(TG-API)
        |                |               |
  +-------------HS-mode-----------------------+
  |       Salus                               |
  +-------------------------------------------+
                         |
                        SBI
                         |
  +----------M-mode---------------------------+
  |       Firmware(OpenSBI)                   |
  +-------------------------------------------+

Host

Normally Linux, this is the primary operating system for the device running in VS mode.

Responsibilities:

• Scheduling
• Memory allocation (except memory kept by firmware and salus at boot)
• Guest VM start/stop/scheduling via TEE TH-API provided by salus
• Device drivers and delegation

VMM

The virtual machine manager that runs in userspace of the host.

• qemu/kvm or crosvm
• configures memory and devices for guests
• runs any virtualized or para virtualized devices
• runs guests with vcpu_run.

Guests

VS-mode operating systems started by the host.

• Can run confidential or shared workloads.
• Uses memory shared from or donated by the host
• scheduled by the host
• can start sub-guests
• Confidential guests use TG-API for salus/host services

Salus

The code in this repository. An HS-mode hypervisor.

• starts the host and guests
• manages stage-2 translations and IOMMU configuration for guest isolation
• delegates some tasks such as attestation to u-mode helpers
• measured by the trusted firmware/RoT

Firmware

M-mode code.

OpenSBI currently - boots the system, loads salus to memory and passes it the device tree.