Re: [PATCH 12/15] KVM: MTRR: introduce mtrr_for_each_mem_type

[Xiao Guangrong]

On 06/09/2015 08:36 AM, David Matlack wrote:
> On Sat, May 30, 2015 at 3:59 AM, Xiao Guangrong
> <guangrong.xiao@xxxxxxxxxxxxxxx> wrote:
> > It walks all MTRRs and gets all the memory cache type setting for the
> > specified range also it checks if the range is fully covered by MTRRs
> >
> > Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/mtrr.c | 183 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 183 insertions(+)
> >
> > diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
> > index e59d138..35f86303 100644
> > --- a/arch/x86/kvm/mtrr.c
> > +++ b/arch/x86/kvm/mtrr.c
> > @@ -395,6 +395,189 @@ void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
> >          INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
> >   }
> >
> > +struct mtrr_looker {
> > +       /* input fields. */
> > +       struct kvm_mtrr *mtrr_state;
> > +       u64 start;
> > +       u64 end;
> > +
> > +       /* output fields. */
> > +       int mem_type;
> > +       /* [start, end) is fully covered in MTRRs? */
>
> s/fully/not fully/ ?

Yup, thanks for pointing it out.

> > +       bool partial_map;
> > +
> > +       /* private fields. */
> > +       union {
> > +               /* used for fixed MTRRs. */
> > +               struct {
> > +                       int index;
> > +                       int seg;
> > +               };
> > +
> > +               /* used for var MTRRs. */
> > +               struct {
> > +                       struct kvm_mtrr_range *range;
> > +                       /* max address has been covered in var MTRRs. */
> > +                       u64 start_max;
> > +               };
> > +       };
> > +
> > +       bool fixed;
> > +};
> > +
> > +static void mtrr_lookup_init(struct mtrr_looker *looker,
> > +                            struct kvm_mtrr *mtrr_state, u64 start, u64 end)
> > +{
> > +       looker->mtrr_state = mtrr_state;
> > +       looker->start = start;
> > +       looker->end = end;
> > +}
> > +
> > +static u64 fixed_mtrr_range_end_addr(int seg, int index)
> > +{
> > +       struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
> > +
> > +        return mtrr_seg->start + mtrr_seg->range_size * index;
>
> Should be (index + 1)?

Good eyes, will fix.

> > +}
> > +
> > +static bool mtrr_lookup_fixed_start(struct mtrr_looker *looker)
> > +{
> > +       int seg, index;
> > +
> > +       if (!looker->mtrr_state->fixed_mtrr_enabled)
> > +               return false;
> > +
> > +       seg = fixed_mtrr_addr_to_seg(looker->start);
> > +       if (seg < 0)
> > +               return false;
> > +
> > +       looker->fixed = true;
> > +       index = fixed_mtrr_addr_seg_to_range_index(looker->start, seg);
> > +       looker->index = index;
> > +       looker->seg = seg;
> > +       looker->mem_type = looker->mtrr_state->fixed_ranges[index];
> > +       looker->start = fixed_mtrr_range_end_addr(seg, index);
> > +       return true;
> > +}
> > +
> > +static bool match_var_range(struct mtrr_looker *looker,
> > +                           struct kvm_mtrr_range *range)
> > +{
> > +       u64 start, end;
> > +
> > +       var_mtrr_range(range, &start, &end);
> > +       if (!(start >= looker->end || end <= looker->start)) {
> > +               looker->range = range;
> > +               looker->mem_type = range->base & 0xff;
> > +
> > +               /*
> > +                * the function is called when we do kvm_mtrr.head walking
> > +                * that means range has the minimum base address interleaves
> > +                * with [looker->start_max, looker->end).
> > +                */
>
> I'm having trouble understanding this comment. I think this is what you
> are trying to say:
>
>    this function is called when we do kvm_mtrr.head walking. range has the
>    minimum base address which interleaves [looker->start_max, looker->end).
>
> Let me know if I parsed it wrong.

Yes, it is, will improve the comment.

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