Comment 20 for bug 1866870

@Boris - in your log I've seen that you also got the Penryn cpu which I find odd.
"-cpu Penryn,vme=on,vmx=on,x2apic=on,tsc-deadline=on,xsave=on,hypervisor=on,arat=on,tsc-adjust=on,arch-capabilities=on,skip-l1dfl-vmentry=on \"
Assuming you also only used default I wonder how it got to that, maybe the reason for that is the same reason that eventually triggers the error.
But virt-manager/libvirt would usually just do a best-fit (for me Haswell-noTSX-IBRS).

@Boris and @tstrike Could you both please report:
$ virsh capabilities
$ virsh domcapabilities
$ sudo qemu-system-x86_64 --enable-kvm --nographic --nodefaults -S -qmp-pretty stdio
{"execute":"qmp_capabilities"}
{"execute":"query-cpu-definitions"}
Note: the command seems to hang as you are on QMP, then just enter the two commands below one by one. This will add "qemu's explanation why a given cpu is usable or not"