Re: [PATCH -v2.1] x86/msr: Filter MSR writes

[Matthew Garrett]

On Tue, Jul 14, 2020 at 9:04 AM Chris Down <chris@xxxxxxxxxxxxxx> wrote:
> Either way, again, this isn't really the point. :-) The point is that there
> _are_ currently widespread cases involving poking MSRs from userspace, however
> sacrilegious or ugly (which I agree with!), and while people should be told
> about that, it's excessive to have the potential to take up 80% of kmsg in the
> default configuration. It doesn't take thousands of messages to get the message
> across, that's what a custom printk ratelimit is for.

Agreed - we should now offer all the necessary interfaces to avoid
userspace having to hit MSRs directly for thermal management, but that
wasn't always the case, and as a result there's tooling that still
behaves this way.