When using with QEMU v4.1.0-rc0<http://10.114.102.26/cgit/qemu/tag/?h=v4.1.0-rc0> or
newer, the patch
https://libvirt.org/git/?p=libvirt.git;a=commit;h=63acb7bfd56f117309e4fca...
cause some windows hyperv features cannot be enabled.
# virsh start win10
error: Failed to start domain win10
error: unsupported configuration: host doesn't support hyperv 'vpindex'
feature
<features>
<hyperv>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='4096'/>
<vpindex state='on'/>
<runtime state='on'/>
<synic state='on'/>
<reset state='on'/>
<frequencies state='on'/>
<reenlightenment state='on'/>
<tlbflush state='on'/>
<ipi state='on'/>
<evmcs state='on'/>
</hyperv>