platform/x86/intel/ifs: Add stub driver for In-Field Scan

Cloud Service Providers that operate fleets of servers have reported
[1] occasions where they can detect that a CPU has gone bad due to
effects like electromigration, or isolated manufacturing defects.
However, that detection method is A/B testing seemingly random
application failures looking for a pattern. In-Field Scan (IFS) is
a driver for a platform capability to load a crafted 'scan image'
to run targeted low level diagnostics outside of the CPU's architectural
error detection capabilities.

Stub version of driver just does initial part of check for the IFS
feature. MSR_IA32_CORE_CAPS must enumerate the presence of the
MSR_INTEGRITY_CAPS MSR.

[1]: https://www.youtube.com/watch?v=QMF3rqhjYuM



Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220506225410.1652287-5-tony.luck@intel.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>