You can run an independent clock for your XEN VM . That will fix the hardware clock problem, unless you don’t have access to host node. It is always best to keep the hardware clock of Dom0 with synchronization . But if your server provider won’t give support for you , please set it as follows,
Setup the wall clock in /proc
echo 1 > /proc/sys/xen/independent_wallclock
And to keep the setting between reboots, just add it to the /etc/sysctl.conf
xen.independent_wallclock = 1
This will fix the issue.