Re: [Xen-devel] [PATCH v1 02/47] x86: mtrr: generalize run time disabling of MTRR

["Luis R. Rodriguez" <mcgrof@xxxxxxxx>]

On Fri, Mar 27, 2015 at 02:40:17PM -0600, Toshi Kani wrote:
> On Fri, 2015-03-20 at 16:17 -0700, Luis R. Rodriguez wrote:
>  :
> > @@ -734,6 +742,7 @@ void __init mtrr_bp_init(void)
> >     }
> >  
> >     if (mtrr_if) {
> > +           mtrr_enabled = true;
> >             set_num_var_ranges();
> >             init_table();
> >             if (use_intel()) {
>                         get_mtrr_state();
> 
> After setting mtrr_enabled to true, get_mtrr_state() reads
> MSR_MTRRdefType and sets 'mtrr_state.enabled', which also indicates if
> MTRRs are enabled or not on the system.  So, potentially, we could have
> a case that mtrr_enabled is set to true, but mtrr_state.enabled is set
> to disabled when MTRRs are disabled by BIOS.

Thanks for the review, in this case then we should update mtrr_enabled to false.

> ps.
> I recently cleaned up this part of the MTRR code in the patch below,
> which is currently available in the -mm & -next trees.
> https://lkml.org/lkml/2015/3/24/1063

Great I will rebase and work with that and try to address this
consideration you have raised.

  Luis

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