x86/speculation/mds: Add mds=full,nosmt cmdline option

x86/speculation/mds: Add mds=full,nosmt cmdline option

commit d71eb0ce109a124b0fa714832823b9452f2762cf upstream

Add the mds=full,nosmt cmdline option.  This is like mds=full, but with
SMT disabled if the CPU is vulnerable.

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 623b724d5e50c15d160799446956ba0d23d4f978)

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:
	Documentation/admin-guide/kernel-parameters.txt
	arch/x86/kernel/cpu/bugs.c
bugs.64 vs bugs_64.c: different boot command line parsing code
Documentation/admin-guide/kernel-parameters.txt vs Documentation/kernel-parameters.txt