Re: [PATCH 2/3] x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural

From: Luck, Tony
Date: Fri Apr 17 2020 - 13:06:10 EST


On Fri, Apr 17, 2020 at 12:04:36PM +0200, Thomas Gleixner wrote:
> Tony Luck <tony.luck@xxxxxxxxx> writes:
> > + m = x86_match_cpu(split_lock_cpu_ids);
> > + if (!m)
> > + return;
> > +
> > + if (m->driver_data && cpu_has(c, X86_FEATURE_CORE_CAPABILITIES))
> > {
>
> This condition results in the following:
>
> driver_data MSR_CORE_CAPS MSR_CORE_CAPS_SLD SLD available
>
> 1 0 Don't care Don't care Y
> 2 1 N Don't care Y
> 3 1 Y Y Y
> 4 1 Y N N
>
> #2 does not make any sense to me.

Nor to me :-(

I got too clever trying to combine tests.

New version taking cases one at a time so my "stuck inside the
house for six weeks now" brain can follow the steps.

-Tony