x86/speculation/mds: Add SMT warning message

x86/speculation/mds: Add SMT warning message

commit 39226ef02bfb43248b7db12a4fdccb39d95318e3 upstream

MDS is vulnerable with SMT.  Make that clear with a one-time printk
whenever SMT first gets enabled.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
(cherry picked from commit 2dad2dcf7f7eab0e6d10d560e22fddd0a08b37b3)

Orabug: 29526900
CVE: CVE-2018-12126
CVE: CVE-2018-12130
CVE: CVE-2018-12127

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Conflicts:
	arch/x86/kernel/cpu/bugs.c
bugs.c vs bugs_64.c: we do not have arch_smt_update. Squash the check in mds_select_mitigation.