This is an old revision of the document!
http://www.ingmarverheij.com/damn-you-c-states-unexpected-xenserver-reboot/
http://support.citrix.com/article/CTX127395
Disable all power management in the BIOS:
Disable all C-states, including C1E.
A result above 2
indicates you need to disable power management in the BIOS:
xenpm get-cpuidle-states | grep total | uniq