Run liburing tests on emulated nvme in qemu

QEMU with nvme support is required (v5.1.0 and later)! See https://www.qemu.org/2020/08/11/qemu-5-1-0/

Since not everyone has access to the proper nvme HW, let alone on multiple architectures. This project aims to provide a convenient set of scripts to run liburing tests on qemu emulated nvme device with polling support on various architectures.

Currently only x86_64 and ppc64 is supported, but I hope to expand it soon.

This is still very much work-in-progress. Use with caution!

How it works

1. It takes an OS image (rpm based such as Fedora, or CentOS) and makes some initial system preparations after which it will boot into the system.
2. Qemu provides the system with a emulated nvme device with polling support.
3. When booting for the first time it will install required tools to build and test liburing, update kernel and optionally install provided rpm packages. Then it reboots, possibly into new kernel.
4. Assuming the installation was successful, it will create a partition on a nvme drive. One to use for block device testing and the other for a file based testing.
5. Clone the liburing from a git repository and build it.
6. Run the tests with make runtests
7. After the test the virtual machine is shut down and the logs are copied over to the local host.

Required tools

The following tools are required by the script:

• virt-sysprep
• qemu-system-x86_64
• qemu-system-ppc64
• wget
• virt-copy-out

On Fedora you should be able to install all of that with the following command:

dnf -y install libguestfs-tools-c qemu-system-x86-core qemu-system-ppc-core wget

How to use it

The configuration file provides a convenient way to have a different setup for a different OS and/or architecture.

For example you can have multiple configuration files like this:

• config.fedora.x86_64
• config.rhel.x86_64
• config.rhel.ppc64

Those can differ in ARCH, IMG etc. Additionally you can provide a custom rpm repository containing a custom kernel, or kernel rpm package directly and number of other options.

Conveniently the IMG can be URL and the image is downloaded automatically if it does not exist yet.

Then, you can run the tests for example like this:

./qemu-test-iouring.sh -C config.rhel.x86_64 -c

./qemu-test-iouring.sh -C config.fedora.x86_64 -c -p kernel-5.9.0_rc3+-1.x86_64.rpm

./qemu-test-iouring.sh -C config.rhel.ppc64 -c -r test.repo

Note that you can use the -c option to preserve the original OS image. Otherwise the image will be changed directly and it currently does not provide a way to reinstall kernel or add additional packaged once the image is initialized. This is likely to change in the future.

Configuration file

You can find example configuration file in config.example

# Configuration file for qemu-test-iouring. Copy this file to config.local,
# nncomment and specify values to change defaults.
#
# Default architecture
# ARCH="x86_64"
#
# Initialize the image before running virtual machine
# 1 - initialize the image (default)
# 0 - do not initialize the image
# IMG_INIT=1
#
# Do not run on spefified image, but rather create copy of it first
# and run on that.
# 0 - run on the provided image (default)
# 1 - run on the copy of the provided image
# COPY_IMG=0
#
# Specify additional file to copy into the virtual machine. See
# man virt-builder for more information on --copy-in option
# COPY_IN=""
#
# Default image to run with. Will be overridden by -I option
# IMG=""
#
# Default nvme image to run with. Will be overridden by -N option
# NVME_IMG=""
#
# Specify liburing git repository and optionaly branch
# GUEST_LIBURING_GIT="git://git.kernel.dk/liburing -b master"
#
# How many cpus should the guest virtual machine have.
# GUEST_CPUS=4
#
# How much memory should the quest virtual machine have.
# GUEST_MEMORY=2048
#
# In case you need setup configuration variable for liburing test itself,
# use this section and prepend the variable name with LIBURING_ it will be
# copied over when the test config file is create. Note that TEST_FILES
# will be overridden.
#
# List of excluded tests
# LIBURING_TEST_EXCLUDE=""
#

Usage

You can see what options are supported using help ./qemu-test-iouring.sh -h

Usage: ./qemu-test-iouring.sh [-h] [-n] [-d] [-c] [-a ARCH] [-I IMG] [-r REPO] [-N NVME]
	-h		Print this help
	-C CONFIG	Specify custom configuration file. This option
			can only be specified once. (Default "./config.local")
	-a ARCH		Specify architecture to run (default: x86_64).
			Supported: x86_64 ppc64
	-I IMG		OS image with Fedora, Centos or Rhel. Can be
			existing file, or http(s) url.
	-N NVME		Nvme image to run on. It needs to be at least
			1GB in size.
	-r REPO		Specify yum repository file to include in guest.
			Can be repeated to include multiple files and
			implies image initialization.
	-n		Do not initialize the image with virt-sysprep
	-d		Do not run liburing tests on startup. Implies
			image initialization.
	-c		Do not run on specified image, but rather create
			copy of it first.
	-e		Exclude test. Can be repeated to exclude
			multiple tests.
	-p PKG		RPM package to install in guest

Example: ././qemu-test-iouring.sh -a ppc64 -r test.repo -c -I fedora.img -N nvme.img