Comment 2 for bug 1712534

Cross s390x was always as unsupported as possible to avoid people migrating off.
Never seen it working, but let me try your case.

A little matrix:

Host/Guest->
v amd64 s390x ppc64el
amd64 Y N Y
s390x Y Y slow-Y
ppc64el slow-Y N Y

I'd think it is just not meant to fully work.
It is a qemu crash after all so I could take a look, but knowing some history on how much good working s390x on x86 is "wanted" this is prio <low.

OTOH your Team has a set of real s390x KVM and z/VM systems, so for your testing try to use some of those?