For Intel I found this proxmox discussion: I tried it with proxmox as a VM on unraid and windows as a VM inside that and WSL inside that Windows VM. It worked (although very slow). However proxmox uses qemu instead of libvirt. So I think we just need to figure out how to correctly get these changes to work with libvirt:
args: -cpu Cooperlake,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time,+vmx
cpu: host