Nikola Ciprich wrote...

it's been introduced by 4.14 and seems to be fixed by 2a266f23550be997d783f27e704b9b40c4010292 (no crash with it applied so far for me).

Thanks for sharing, running 4.14.19 with this additional one made all my problems go away, although they were a bit different: Using the "Resume" button in virt-manager after an earlier "Pause" caused the guest to freeze and using 100% CPU - especially when the guest is the grml rescue system, this happend almost always.

Christoph