Re: [PATCH] x86/microcode: Add an option to reload microcode even if revision is unchanged

From: Borislav Petkov
Date: Fri Sep 06 2019 - 13:17:28 EST

On Fri, Sep 06, 2019 at 09:52:07AM -0700, Johannes Erdfelt wrote:
> That doesn't mean that late loading isn't still useful.

If it weren't useful, it would've been gone a long time ago. No one is
arguing whether it is useful or not.

> Just as I can't know for sure that every future microcode update will be
> safely late loadable, you can't know for sure that every future microcode
> update won't be safely late loadable.

Well, you know what can happen so good luck, I guess.

> We do use other techniques as well particularly when it's not time
> sensitive.

So you reboot or not? Do you do reboot-similar techniques where you can
potentially do early microcode loading too?

> It very much makes it right because it's still a tool that can be used
> safely in the right cases. Just because it can't be used 100% of the time
> (even if it is close to that in practice) doesn't make it magically unsafe
> either.

As I said, good luck with that. It's not like you haven't been warned
about what can happen.