Messages in this thread | | | Date | Fri, 26 Jan 2018 10:40:37 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH v4 6/7] x86/cpufeature: Blacklist SPEC_CTRL on early Spectre v2 microcodes |
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* David Woodhouse <dwmw2@infradead.org> wrote:
> On Thu, 2018-01-25 at 12:34 +0100, Thomas Gleixner wrote: > > > > This stuff is really a master piece of trainwreck engineering. > > > > So yeah, whatever we do we end up with a proper mess. Lets go for a > > blacklist and hope that we'll have something which holds at some > > foreseeable day in the future. > > > > The other concern I have is IBRS vs. IBPB. Are we sufficiently sure that > > IBPB is working on those IBRS blacklisted ucode revisions? Or should we > > just play safe and not touch any of this at all when we detect a > > blacklisted one? > > That isn't sufficiently clear to me. I've changed it back to blacklist > *everything* for now, to be safe. If at any point Intel want to get > their act together and give us coherent information to the contrary, we > can change to separate IBPB/IBRS blacklists.
Yes.
I also agree that blacklists are the fundamentally correct approach here: a bit-rotting blacklist is far better to users than a bit-rotting whitelist, assuming that the number of CPU and microcode bugs goes down with time.
Thanks,
Ingo
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