It seems some of the smaller hypervisor companies didn't get the memo, and they are blocking the msr write to to set the chicken bit.
They block it by raising an exception. They should IGNORE that bit if they allow setting it. I also have a strong suspicion some of them do not have the firmware fixes, and that the chickenbit-off state we read is true. Anyways, a brand new errata to skip setting the chickenbit on such hypervisors is going out the door right now.
