x86/pv: disallow access to unknown MSRs

x86/pv: disallow access to unknown MSRs

Change the catch-all behavior for MSR not explicitly handled. Instead
of allow full read-access to the MSR space and silently dropping
writes return an exception when the MSR is not explicitly handled.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>