The CentOS VIrtualization Special Interest Group wants to remind everyone that the End of Life for the Xen-4.4 branch (currently 4.4.4-19) will be March 31st, 2017.
This is because the Xen Project will no longer support Xen-4.4 after that date, based on this link:
https://wiki.xenproject.org/wiki/Xen_Project_Release_Features
Xen-4.6 is still available and will be maintained until October 2018 (on both CentOS-6 and CentOS-7) and Xen-4.8 will be available soon.
Thanks, Johnny Hughes