virsh network

To avoid hardcoding the PCI address of a VF into a guest’s configuration, a libvirt network with a device pool containing all of the VFs of an SR-IOV device is created. The guest then references this network, such that on guest startup, a VF is assigned from the pool:

 [root@rhel-tiger-14-6 ~]# touch /var/lib/libvirt/network/ens4f0.xml

 [root@rhel-tiger-14-6 ~]# chown root:root /var/lib/libvirt/network/ens4f0.xml

 [root@rhel-tiger-14-6 ~]# chmod 644 /var/lib/libvirt/network/ens4f0.xml

 [root@rhel-tiger-14-6 ~]# cat /var/lib/libvirt/network/ens4f0.xml
 <network>
   <name>ens4f0-pool</name>
   <forward mode='hostdev' managed='yes'>
     <pf dev=ens4f0/>
   </forward>
 </network>

 [root@rhel-tiger-14-6 ~]# virsh net-define /var/lib/libvirt/network/ens4f0.xml
 Network ens4f0-pool defined from /var/lib/libvirt/network/ens4f0.xml

 [root@rhel-tiger-14-6 ~]# virsh net-autostart ens4f0-pool
 Network ens4f0-pool marked as autostarted

 [root@rhel-tiger-14-6 ~]# virsh net-start ens4f0-pool
 Network ens4f0-pool started

 [root@rhel-tiger-14-6 libvirt]# virsh net-list
  Name          State    Autostart   Persistent
 ------------------------------------------------
  default       active   yes         yes
  ens4f0-pool   active   yes         yes
  ens4f1-pool   active   yes         yes
  ens4f2-pool   active   yes         yes
  ens4f3-pool   active   yes         yes
  ens5f0-pool   active   yes         yes
  ens5f1-pool   active   yes         yes
  ens5f2-pool   active   yes         yes
  ens5f3-pool   active   yes         yes

 [root@rhel-tiger-14-6 ~]# virsh net-dumpxml ens4f0-pool 
 <network>
   <name>ens4f0-pool</name>
   <uuid>bcb39207-503f-4af8-824c-45bf3756facf</uuid>
   <forward mode='hostdev' managed='yes'>
     <pf dev='ens4f0'/>
     <address type='pci' domain='0x0000' bus='0xaf' slot='0x02' function='0x0'/>
     <address type='pci' domain='0x0000' bus='0xaf' slot='0x02' function='0x1'/>
   </forward>
 </network>

Because these networks are configured as autostart, you must ensure that the VFs have been created before the libvirtd service is started.