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=63acb7bfd56f117309e4fcaf43... 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>