Re: [PATCH v6 00/16] x86/mtrr: fix handling with PAT but without MTRR

[Juergen Gross <jgross@xxxxxxxx>]

On 31.05.23 19:48, Borislav Petkov wrote:
> On Wed, May 31, 2023 at 04:20:08PM +0200, Juergen Gross wrote:
> > One other note: why does mtrr_cleanup() think that using 8 instead of 6
> > variable MTRRs would be an "optimal setting"?
> Maybe the more extensive debug output below would help answer that...
Patch 2 wants this diff on top:

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c 
b/arch/x86/kernel/cpu/mtrr/generic.c
index 59b48bd8380c..ce254ca89c62 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -655,7 +655,7 @@ static bool set_mtrr_var_ranges(unsigned int index, struct 
mtrr_var_range *vr)
        bool changed = false;

        rdmsr(MTRRphysBase_MSR(index), lo, hi);
-       if ((vr->base_lo & MTRR_PHYSBASE_RSVD) != (lo & MTRR_PHYSBASE_RSVD)
+       if ((vr->base_lo & ~MTRR_PHYSBASE_RSVD) != (lo & ~MTRR_PHYSBASE_RSVD)
            || (vr->base_hi & ~phys_hi_rsvd) != (hi & ~phys_hi_rsvd)) {

                mtrr_wrmsr(MTRRphysBase_MSR(index), vr->base_lo, vr->base_hi);
@@ -664,7 +664,7 @@ static bool set_mtrr_var_ranges(unsigned int index, struct 
mtrr_var_range *vr)
        rdmsr(MTRRphysMask_MSR(index), lo, hi);

-       if ((vr->mask_lo & MTRR_PHYSMASK_RSVD) != (lo & MTRR_PHYSMASK_RSVD)
+       if ((vr->mask_lo & ~MTRR_PHYSMASK_RSVD) != (lo & ~MTRR_PHYSMASK_RSVD)
            || (vr->mask_hi & ~phys_hi_rsvd) != (hi & ~phys_hi_rsvd)) {
                mtrr_wrmsr(MTRRphysMask_MSR(index), vr->mask_lo, vr->mask_hi);
                changed = true;



Juergen

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