Re: [patch v2 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect

[Xiaoyao Li]

On 4/3/2020 12:25 AM, Peter Zijlstra wrote:
> Learn to trim your replies already!

Sorry.

> On Fri, Apr 03, 2020 at 12:20:08AM +0800, Xiaoyao Li wrote:
> > On 4/2/2020 11:23 PM, Peter Zijlstra wrote:
>
> > > +bad_module:
> > > +	pr_warn("disabled due to VMX in module: %s\n", me->name);
> > > +	sld_state = sld_off;
> >
> > shouldn't we remove the __ro_after_init of sld_state?
>
> Oh, that's probably a good idea. I can't actually test this due to no
> hardware.
>
> > And, shouldn't we clear X86_FEATURE_SPLIT_LOCK_DETECT flag?
>
> Don't think you can do that this late. Also, the hardware has the MSR
> and it works, it's just that we should not.

Actually, I agree to keep this flag.

But, during the previous patch review, tglx wants to make

	sld_off = no X86_FEATURE_SPLIT_LOCK_DETECT

I'm not sure whether he still insists on it now.

I really want to decouple sld_off and X86_FEATURE_SPLIT_LOCK_DETECT.
So if X86_FEATURE_SPLIT_LOCK_DETECT is set, we can virtualize and expose 
it to guest even when host is sld_off.