Understanding Rust VMM

We will try to understand vmm-reference, at least partially. Course project will build features on top of vmm-reference so please try to understand it well.

vmm-reference

Design. vmm-reference project uses kvm-ioctls, kvm-bindings, vm-memory, vm-superio, etc. vmm-reference is relatively simpler to understand since it does not support advanced features like VM pausing / resuming, snapshotting, and migration.

Introduction to rust vmm crates. Basically, vm-memory etc are generic interfaces which get implemented by the actual hypervisors. This is so that we can get reusability. Another point is to pick and choose. One can build a VMM without picking the block device Rust crate.

Setting up your system

Clone vmm-reference on your Linux machine. Make sure that you have KVM on your machine. You can check it by running the simple.rs from Lecture 6 and verify that it is indeed printing 4.

If you do not have a Linux machine, you can email course TAs to get access to one. One good way of using a remote machine, while getting IDE features, like jumping to a rust method is to use the SSH extension in VSCode.

Boot Linux VM

You can download a pre-built kernel image from here and launch vmm-reference as follows:

dell@abhilash:~/Documents/courses/col732/vmm-reference$ ./target/debug/vmm-reference --kernel path=~/Documents/courses/col732/vmm-reference/resources/kernel/bzimage-hello-busybox
....
[    0.673230] zswap: default zpool zbud not available
[    0.673738] zswap: pool creation failed
[    0.674195] Key type ._fscrypt registered
[    0.674621] Key type .fscrypt registered
[    0.675339] Key type encrypted registered
[    0.676273] Freeing unused decrypted memory: 2040K
[    0.677088] Freeing unused kernel image memory: 2800K
[    0.682218] Write protecting the kernel read-only data: 14336k
[    0.683567] Freeing unused kernel image memory: 2012K
[    0.684193] Freeing unused kernel image memory: 272K
[    0.684714] Run /init as init process
                                                   
                 _                                 
  _ __ _   _ ___| |_    __   ___ __ ___  _ __ ___  
 | '__| | | / __| __|___\ \ / / '_ \ _ \| '_ \ _ \ 
 | |  | |_| \__ \ ||_____\ V /| | | | | | | | | | |
 |_|   \__,_|___/\__|     \_/ |_| |_| |_|_| |_| |_|
                                                   
                                                   
Hello, world, from the rust-vmm reference VMM!
/ # ls
bin      etc      init     mnt      sbin     usr
dev      home     linuxrc  proc     sys
/ # echo "HELLO"
HELLO
/ #

You shall see messages like above. This means your VM is running!

Understanding vmm-reference

You can now start understanding the code. Start here:

[[vmm-reference-kvmvcpu]]
[[vmm-reference-kvmvm]]

The notes are not exhaustive. They are only to get you started on how to explore the code on your own. In this journey, ask from and listen to the following friends:

Miscellaneous

It might be easier to navigate this repo by cloning it locally, opening it in VSCode, and installing Foam extension in VSCode.