x86/l1tf: Handle EPT disabled state proper

x86/l1tf: Handle EPT disabled state proper

If Extended Page Tables (EPT) are disabled or not supported, no L1D
flushing is required. The setup function can just avoid setting up the L1D
flush for the EPT=n case.

Invoke it after the hardware setup has be done and enable_ept has the
correct state and expose the EPT disabled state in the mitigation status as
well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142322.612160168@linutronix.de
Orabug: 28220625
CVE: CVE-2018-3620

(cherry picked from commit a7b9020b06ec6d7c3f3b0d4ef1a9eba12654f4f7)

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Conflicts:
	arch/x86/kernel/cpu/bugs_64.c
	arch/x86/kvm/vmx.c
Contextual: different content; Modified arch/x86/kernel/cpu/bugs_64.c
instead of arch/x86/kernel/cpu/bugs.c.