I think this is just noise in the journal; not a real problem (it's an annoyance).
Fedora Server 29 running two docker containers: pihole and battery historian. When I do 'sysmtectl start libvirtd' I immediately start getting the following in the journal every 5s.
Feb 11 13:53:23 fnuc.local dnsmasq[32033]: failed to create listening socket for 192.168.122.1: Address already in use
That continues until I both stop libvirtd and also remove the virbr0 link. I'm kinda wondering if this is suboptimal behavior that constitutes a bug? I don't know why it's failing to create a socket for 192.168.122.1, maybe docker owns it. But then why doesn't libvirtd just fallback to some other address and notify in the journal, rather than spamming the journal? In any case I'm still able to ssh into and out of any VM I create. I'm also able to connect via virt-manager and spice to any VM. So its seems like it's just noise and not an actual problem.
fnuc.local chris ~ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether b8:ae:ed:77:ea:51 brd ff:ff:ff:ff:ff:ff inet 10.0.0.250/24 brd 10.0.0.255 scope global dynamic noprefixroute enp3s0 valid_lft 377745sec preferred_lft 377745sec inet6 2601:282:700:8c78:3cef:4672:2da9:af30/64 scope global dynamic noprefixroute valid_lft 252404sec preferred_lft 252404sec inet6 fe80::91f1:7594:6bae:99ea/64 scope link noprefixroute valid_lft forever preferred_lft forever 3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether fe:b0:a1:f2:be:c4 brd ff:ff:ff:ff:ff:ff 4: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default link/ether 02:42:7a:65:7b:b6 brd ff:ff:ff:ff:ff:ff inet 172.17.0.1/16 scope global docker0 valid_lft forever preferred_lft forever inet6 fe80::42:7aff:fe65:7bb6/64 scope link valid_lft forever preferred_lft forever 6: vethe8a3f14@if5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default link/ether d2:b4:ca:37:f7:3a brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet6 fe80::d0b4:caff:fe37:f73a/64 scope link valid_lft forever preferred_lft forever 8: veth1b171f3@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default link/ether 9a:f4:98:f3:08:1c brd ff:ff:ff:ff:ff:ff link-netnsid 1 inet6 fe80::98f4:98ff:fef3:81c/64 scope link valid_lft forever preferred_lft forever 9: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000 link/ether 52:54:00:24:e3:cf brd ff:ff:ff:ff:ff:ff inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0 valid_lft forever preferred_lft forever 10: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel master virbr0 state DOWN group default qlen 1000 link/ether 52:54:00:24:e3:cf brd ff:ff:ff:ff:ff:ff fnuc.local chris ~