symptom: after schedule restart due to kernel upgrade to 3.10.0-327.28.2.el7.x86_64, something wrong happen to our guest KVM. Some network devices were disappeared. No more ensX device anymore.
Solution:
Note: this solution tested via host server (using virsh console) and ssh
Install Network Manager Text User Interface (TUI) 
# yum install NetworkManager-tui
Check your device status using Network Manager Command Line Interface (nmcli)
# nmcli dev statusDEVICE  TYPE      STATE         CONNECTIONeth0    ethernet  connected     eth0ens4    ethernet  disconnected  --lo      loopback  unmanaged     --
Edit your available/connected network using Network Manager TUI
# nmtui edit eth0
make sure to check 
- Require IPv4 addressing for this connection
 - Automatically connected
 - Available to all users
 
References:
- http://ask.xmodulo.com/configure-static-ip-address-centos7.html
 - https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Networking_Guide/sec-Using_the_NetworkManager_Command_Line_Tool_nmcli.html