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

[Chris Down]

Borislav Petkov writes:
> On Tue, Jul 14, 2020 at 05:04:48PM +0100, Chris Down wrote:
> > Since the issue involves DPTF which is only supported via binary blobs, I
> > can't say for certain what the issue is. As I understand it, when the
> > throttling behaviour isn't explicitly configured by the OS kernel, the
> > default policy is extremely overeager. Matthew also had a look at it[0], but
> > I don't know if anything eventually happened there. I've cc'ed him.
> >
> > 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.
>
> Ok, feel free to suggest a fix, better yet send a patch. Otherwise,
> you'd have to wait for my vacation to end first. :-)

Sure thing, I'll send a patch tomorrow, then. :-)