kubevirt cpu allocation ratio is ignored for provisioned virtual machines

[soer3n]

Currently the machine-controller sets requests and limits for cpu and memory resources of a kubevirt virtual machine. (https://github.com/kubermatic/machine-controller/blob/main/pkg/cloudprovider/provider/kubevirt/provider.go#L755-#L762) Due to this kubevirt ignores to calculate the cpu ratio for the launcher pod.

To let kubevirt calculate the cpu requests for a launcher pod the configured cpus needs to be set in spec.domain.cpu instead of configuring the requested cpus and the limit in spec.domain.resources. This leads then to another challenge because then no limit would be set to the launcher pod by default. For that the kubevirt need to have cpu auto limit feature enabled which also requires additional configuration by either adding labels to namespaces or applying resource quotas for namespaces.

It would be nice to be able to use this kubevirt feature and to have a documentation regarding the requirements to use it.