Re: [PATCH v7 02/26] x86/fpu/xstate: Refine CET user xstate bit enabling

From: Edgecombe, Rick P
Date: Mon Nov 27 2023 - 20:32:17 EST


On Fri, 2023-11-24 at 10:40 +0100, Peter Zijlstra wrote:
> So booting a host with "ibt=off" will clear the FEATURE_IBT, this was
> fine before this patch-set, but possibly not with.
>
> That kernel argument really only wants to tell the kernel not to use
> IBT
> itself, but not inhibit IBT from being used by guests.

Should we add a SW bit for it then? ibt=off sounds like it should be
turning off the whole feature though. It doesn't sound like kernel IBT
specifically.