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.