CentOS 7 Xen PV guests failing to boot with kernel 3.10.0-693.17.1.el7
After updating one of my VPS's I experienced the adrenaline rush of rebooting, waiting, panicking and rolling back a kernel update. Normally updates on CentOS are stable and nothing to worry about. However after all the fast patches to the kernel due to the new Intel/CPU based vulnerabilities I was rightly cautious to run the updates on a non-vital server first.
Kernel Update 3.10.0-693.17.1.el7 was the culprit, and as of today (2018-02-12) the CentOS repos including Plus still haven't pushed a fixed version.