I've been slowly moving some old hyper-v vm's to unraid.  In each case I was selecting the Emulated CPU model.  However I just noticed that none of the vm's have emulated set and are all set to host pass through.  Worse, I can't change them back to emulated as it throws an error:
 

VM creation error

XML error: Non-empty feature list specified without CPU model

 

I've been searching the forum and it seems other people get this error, but doing the opposite.  Am I doing something wrong?  How do I not pass through cpu cores?

I was just doing this to test the CPU scheduling. What I did was just re-create the VMs (not the disks, but the configurations).

For my hackintosh though I just created a dummy VM config and copied over the cpu section (XML) since my XML had a lot of custom fields in it.

 

From my experience, changing from CPU passthrough to Emulated QEMU64 via the GUI always gave that error, so you should edit your XML manually instead (or create a new VM configuration for your disk).