x86/microcode/intel: Save the microcode only after a successful late-load

commit 2a1dada3 upstream

There are situations where the late microcode is loaded into memory but
is not applied:

  1) The rendezvous fails
  2) The microcode is rejected by the CPUs

If any of this happens then the pointer which was updated at firmware
load time is stale and subsequent CPU hotplug operations either fail to
update or create inconsistent microcode state.

Save the loaded microcode in a separate pointer before the late load is
attempted and when successful, update the hotplug pointer accordingly
via a new microcode_ops callback.

Remove the pointless fallback in the loader to a microcode pointer which
is never populated.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115902.505491309@linutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>