Re: [PATCH] x86/bugs: Add force_cpu_bug= cmdline param

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Dec 17, 2024 at 12:17:52PM +0100, Borislav Petkov wrote:
> On Mon, Dec 16, 2024 at 06:58:24PM +0100, Brendan Jackman wrote:
> > OK yeah, tainting definitely makes sense, I think that goes quite a
> > long way to avoid bogus bug reports?
> 
> It was my feeble attempt back then to leave enough breadcrumbs so that when
> I see a bug report, I can say: "well, then don't do that then" and mark it as
> invalid. :)
> 
> > I will also update the docs to sound scarier.
> 
> Right.

Perhaps issue a pr_warn() for every bit set? People tend to not like
WARN/ERR in their production logs much :-)

> > So do you think we should allow setting arbitrary cpu features? That
> > seems like a much bigger footgun. But then again, the difference
> > between "big footgun" and "very big footgun" is not that important,
> > either way it needs to be clear to users that this is a scary red
> > button.
> 
> Yeah, with your patch we're half-way there. Might as well do the whole thing
> but again, this is only my opinion. Probably should hear what others have to
> say first...

Given I'm the one that did the retbleed=force thing (and other force
options), I'm in favour.