We may choose to do bug 526862, in which case this bug can be dupped to that one.
NONSTOP_TSC is probably a good idea to mask even from dom0, but maybe not CONSTANT_TSC. It may regress cpu freq scaling.
We opted to do bug 526862 which now zeros all registers for leaf 80000007, so this bug can be duped to that. *** This bug has been marked as a duplicate of bug 526862 ***