It looks like the issue has already been reported to the kernel: #897427 Feel free to close this bug here if nothing needs to be done in libvirt. Sorry for the noise.
- Bug#897634: Libvirt cannot start more than one vm afte... Sebastian Schweizer
- Bug#897634: libvirt-daemon: I also experience the... unsigned_nerd
- Bug#897634: [Pkg-libvirt-maintainers] Bug#897... Guido Günther
- Bug#897634: Libvirt cannot start more than one vm... Sebastian Schweizer

