x86/xstate: Make errors in xstate calculations more obvious by crashing the domain

x86/xstate: Make errors in xstate calculations more obvious by crashing the domain

If xcr0_max exceeds xfeature_mask, then something is broken with the CPUID
policy derivation or auditing logic.  If hardware rejects new_bv, then
something is broken with Xen's xstate logic.

In both cases, crash the domain with an obvious error message, to help
highlight the issues.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: d6371ccb93012db4ad6615fe666205b86308cb4e
master date: 2018-07-19 19:57:26 +0100