It is nvidia binary driver. Running LD_PRELOAD=/usr/lib64/libGL.so.1
Is there something that can be done/workarounded in qemu or should I just
patch libvirtd systemd unit file to include
LD_PRELOAD=/usr/lib64/libGL.so.1?
QEMU's just doing fork() and fork is supposed to work. If this driver
is supplied by Fedora I would suggest reporting the bug to them and
they can decide whether they want to get the driver fixed or work
around it in libvirt.
Otherwise if I were you I would uninstall the binary blob :-)