Live migration for guests on hosts of different CPU classes?

[surfrock66]

I'm modernizing my environment and replacing some pretty old R710's with Intel(R) Xeon(R) X5687 CPU's with R6525's AMD EPYC 7252 CPU's. My VM's have all been set with the CPU type x86-64-v2-AES (v2 being the highest level my old Westmere CPUs support).

When I live migrate between the old and new hosts, my VM's lock up and need to be reset. I had done a bunch of reading and thought I understood that choosing kvm64 or x86-64-v2-AES would prevent that, but that is not the case.

I'm kind of stumped on my reading; I see a lot of stuff saying this should work, and a few places saying moving to kvm64 is better over x86-64-v2-AES. I'm having trouble gleaming an answer from the qemu docs and forum/reddit posts, and would like to get some opinions on how to best support live-migrating during this transition.

 

[fireon]

I have the same behavior here with 4 nodes. I can successfully move between the different CPU types within intel or amd online. But when I move e.g. an Intel to AMD or in reverse, it usually does not work. VM's crashes inside.
Sometimes it is even the case that the VM continues to run normally on the target host for 2-3 minutes, then it crashes.
Guest type does not matter, Windows and Linux VMs.

I can still remember that this worked with Qemu version 6. That was some time ago...