Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation

From: Linus Torvalds
Date: Sun Jan 21 2018 - 17:28:14 EST

On Sun, Jan 21, 2018 at 2:00 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
>> The patches do things like add the garbage MSR writes to the kernel
>> entry/exit points. That's insane. That says "we're trying to protect
>> the kernel". We already have retpoline there, with less overhead.
> You're looking at IBRS usage, not IBPB. They are different things.

Ehh. Odd intel naming detail.

If you look at this series, it very much does that kernel entry/exit
stuff. It was patch 10/10, iirc. In fact, the patch I was replying to
was explicitly setting that garbage up.

And I really don't want to see these garbage patches just mindlessly
sent around.