There's a closed pull request on the void-packages repository

base-files+eudev: move kvm.rules from base-files to eudev
https://github.com/void-linux/void-packages/pull/24805

Description:
Prior to 33d781ff19 (base-files: update to 0.120., 2015-03-22).
We don't requires the existence of `kvm` groups.

Since that change, we ship a udev rule with `base-files`, hence the need
of `kvm` groups.

It's more than 5 years from the change, kvm should be available
in all installation.

Simply removing "system_accounts=kvm:24" from base-files may cause
problem with those very old installation.

Let move those statements and the udev rules to eudev instead.
When moving the rules, rename it to allow partial upgrade,
otherwise, we'll run into conflicts.