Nested KVM performance evaluation on Linux Manjaro 19.0 Guest on Virthost CentOS 8.1

UPDATE 03/05/2020
   Seems to work only on CentOS 8.1 
   Failure on F31, Manjaro GDM 19.0.1 ( bare metal)
END UPDATE

Performance appraisal has been done via attempt to set up Manjaro 19.0 Guest as KVM virtualization host installing Qemu && Libvirt via native command  `pacman -S`. After creating the Manjaro 19.0 virtual machine, edit its XML profile via `virsh edit`. Shut down VM && replace 'host-model' with 'host-passthrough' && VM restart. Set up KVM-Hypervisor on Manjaro 19 Guest

 $ sudo pacman -S qemu virt-manager virt-viewer \
   dnsmasq vde2 bridge-utils openbsd-netcat  
 $ sudo pacman -S ebtables iptables
 $ sudo systemctl enable libvirtd.service
 $ sudo systemctl start libvirtd.service

Tune /etc/libvirt/libvirtd.conf :   unix_sock_group = "libvirt" (line 85)  unix_sock_rw_perms = "0770" (line 102) When done restart libvirtd daemon. Changes been done will suppress  prompt for root password at Virt-Manager startup. They are, actually, optional.
 $ sudo usermod -a -G libvirt $(whoami)
 $ newgrp libvirt
 $ sudo systemctl restart libvirtd.service
Define network openstackvms.xml on the Manjaro Guest
# cat openstackvms.xml
<network>
   <name>openstackvms</name>
   <uuid>d0e9964a-f91a-40c0-b769-a609aee41bf2</uuid>
   <forward mode='nat'>
     <nat>
       <port start='1024' end='65535'/>
     </nat>
   </forward>
   <bridge name='virbr1' stp='on' delay='0' />
   <mac address='52:54:00:60:f8:6d'/>
   <ip address='192.169.142.1' netmask='255.255.255.0'>
     <dhcp>
       <range start='192.169.142.2' end='192.169.142.254' />
     </dhcp>
   </ip>
 </network>

Now create VM F31 inside Guest

   At this point verify status of libvirtd.service 

  Sequence of DHCP requests and responses for "virbr1"  is clearly shown via `systemctl status libvirtd.service` command

  Now just try to watch movie (via YouTube) on F31 guest running inside Manjaro 19 Guest  (nested KVM has been set up ) on VirtHost CentOS 8.1.  Spice console is working fine even running on the F31 guest inside Manjaro 19.0 KVM guest .