# SEV-Step Kernel

## Overview

This is a patched version of the Linux kernel that includes the changes for the SEV-Step framework.

The main part of the added code is in the `arch/x86/kvm/sev-step/` folder. However, as certain parts of the code
need to interface closely with VM entry and exit as well as the MMU, there is a little bit of code sprinkled through the kernel.
To get a full picture of the changes, do a diff against the git commit `c4daeffce56eebb52ec70ec59a202b879cd1c4fc`.

The IOCTL API used by the SEV-Step framework is defined/documented in
`include/uapi/linux/kvm.h` and the used data structures are defined in `include/uapi/linux/sev-step/sev-step.h`. These headers are part of the headers that are exported for userspace applications and can thus easily be used from C code.

If you want to use them in your own application just add `<sev step kernel dir>/kernel/usr/include` to the list of files that are searched for includes.
Afterward, you can e.g. use `#include "linux/kvm.h"` to include the `kvm.h` header.

## Build
See the main SEV-Step repo for information on building the kernel as well the compatible QEMU + OVMF versions.