* Bryan O'Donoghue <[email protected]> wrote:
> On Thu, 2016-02-18 at 08:58 +0100, Ingo Molnar wrote:
> > So why not simply do the patch below? Very few people use boot
> > parameters, and the
> > complexity does not seem to be worth it.
> >
> > Furthermore I think an IMR range in itself is safe enough - it's not
> > like such
> > register state is going to be randomly corrupted, even with the
> > 'lock' bit unset.
>
>
> Hi Ingo.
>
> I agree - to flip the lock bit you need to be in ring-0 anyway.
>
> > So it's a perfectly fine protective measure against accidental memory
> > corruption
> > from the DMA space. It should not try to be more than that.
> >
> > And once we do this, I suggest we get rid of the 'lock' parameter
> > altogether -
> > that will further simplify the code.
> >
> > Thanks,
> >
> > Ingo
>
> That was the V1 of this patch
>
> https://groups.google.com/forum/#!topic/linux.kernel/6ZuVOF3TJow
heh ;-)
> Andriy asked for the boot parameter to control the state of the IMR
> lock bit, I'm just as happy to go back to that version TBH
I really think it's over-engineered - especially considering that with the
kernel
lock-down removed there's no other IMR area that is really locked down - so we
could get rid of the whole 'locked' logic that would simplify the code
throughout.
Yeah, it's a nice looking hardware feature - but I don't think it's
particularly
useful in terms of extra protection.
Thanks,
Ingo
