Re: [PATCH 6/6] KVM: MMU: Avoid handling same rmap_pde inkvm_handle_hva_range()

From: Takuya Yoshikawa
Date: Sun Jul 01 2012 - 09:19:10 EST


On Sun, 01 Jul 2012 10:41:05 +0300
Avi Kivity <avi@xxxxxxxxxx> wrote:

> >> > Note: in the new code we could not use trace_kvm_age_page(), so we just
> >> > dropped the point from kvm_handle_hva_range().
> >> >
> >>
> >> Can't it be pushed to handler()?
> >
> > Yes, but it will be changed to print rmap, not hva and gfn.
> > I will do in the next version.
>
> We should try to avoid changing the tracepoint ABI. If we pass the
> memslot to handler(), we should be able to reconstruct the gfn and hva.

That's not enough because we only know rmapp in the handler: we also need
level or something. I agree that passing memslot for keeping the ABI is
good, but how about two more arguments?

BTW, trace_kvm_age_page() is tracing every handler, not just kvm_age_rmapp().
Is this intentional?

If we trace in the caller, in kvm_age_hva(), we know hva, but not gfn.

Thanks,
Takuya
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