kvm-ioctls

The kvm-ioctls crate provides safe wrappers over the KVM API, a set of ioctls used for creating and configuring Virtual Machines (VMs) on Linux. The ioctls are accessible through four structures:

• Kvm - wrappers over system ioctls
• VmFd - wrappers over VM ioctls
• VcpuFd - wrappers over vCPU ioctls
• DeviceFd - wrappers over device ioctls

For further details check the KVM API as well as the code documentation.

Supported Platforms

The kvm-ioctls can be used on x86_64 and aarch64. Right now the aarch64 support is considered experimental. For a production ready version, please check the progress in the corresponding GitHub issue.

Running the tests

Our Continuous Integration (CI) pipeline is implemented on top of Buildkite. For the complete list of tests, check our CI pipeline.

Each individual test runs in a container. To reproduce a test locally, you can use the dev-container on both x86 and arm64.

docker run --device=/dev/kvm \
           -it \
           --security-opt seccomp=unconfined \
           --volume $(pwd)/kvm-ioctls:/kvm-ioctls \
           fandree/rust-vmm-dev
cd kvm-ioctls/
cargo test

Test Profiles

The integration tests support two test profiles:

• devel: this is the recommended profile for running the integration tests on a local development machine.
• ci (default option): this is the profile used when running the integration tests as part of the the Continuous Integration (CI).

The test profiles are applicable to tests that run using pytest. Currently only the coverage test follows this model as all the other integration tests are run using the Buildkite pipeline.

The difference between is declaring tests as passed or failed:

• with the devel profile the coverage test passes if the current coverage is equal or higher than the upstream coverage value. In case the current coverage is higher, the coverage file is updated to the new coverage value.
• with the ci profile the coverage test passes only if the current coverage is equal to the upstream coverage value.

Further details about the coverage test can be found in the Adaptive Coverage section.

Adaptive Coverage

The line coverage is saved in tests/coverage. To update the coverage before submitting a PR, run the coverage test:

docker run --device=/dev/kvm \
           -it \
           --security-opt seccomp=unconfined \
           --volume $(pwd)/kvm-ioctls:/kvm-ioctls \
           fandree/rust-vmm-dev
cd kvm-ioctls/
pytest --profile=devel tests/test_coverage.py

If the PR coverage is higher than the upstream coverage, the coverage file needs to be manually added to the commit before submitting the PR:

git add tests/coverage

Failing to do so will generate a fail on the CI pipeline when publishing the PR.

NOTE: The coverage file is only updated in the devel test profile. In the ci profile the coverage test will fail if the current coverage is higher than the coverage reported in tests/coverage.