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

qemu : fixed firmware path
https://github.com/void-linux/void-packages/pull/23651

Description:
Hi,
the actual qemu version is built wrong. 
When libvirt start, it searchs firmware in **/usr/share/qemu/firmware** but the firmwares are installed in **/usr/lib/qemu/firmware** because it has been set **--data-lib=/usr/lib**.
Deleting this setting , now libvirt works correctly and i can choice uefi firmware.
Before this was not possible.
Regards