commit 0b22930e upstream.

I found the nested NMI documentation to be difficult to follow.
Improve the comments.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 4.0: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[ luis: backported to 3.16: Used Ben's backport to 4.0 ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>