Re: [PATCH 11/11] KVM/MMU: Flush tlb in the kvm_age_rmapp()

[Tianyu Lan <lantianyu1986@gmail.com>]

Hi Paolo:
               Thanks for your review.

On Tue, Jan 8, 2019 at 12:31 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 07/01/19 04:42, Tianyu Lan wrote:
> >> I'm assuming you're
> >> clearing young to avoid the flush in kvm_mmu_notifier_clear_flush_young(),
> >> but keeping that flush is silly since it will never be invoked.  Just
> >> squash this patch with patch 10/11 so that you can remove the unnecessary
> >> flush in kvm_mmu_notifier_clear_flush_young() and preserve young.
> >>
> > The platform may provide tlb flush with address range as granularity. My changes
> > are to use range flush when it's available. kvm_mmu_notifier_clear_flush_young()
> > is common function for all platforms and most platforms still need the
> > flush in the
> > kvm_mmu_notifier_clear_flush_young(). I think it's better to separate
> > flush request and
> > "young" from return value of kvm_age_hva(). New flush parameter I
> > added in the patch 10
> > can be changed to a pointer and kvm_age_hva() can use it to return
> > flush request.
>
> There are two possibilities:
>
> - pass a "bool *flush".  If NULL, kvm_age_hva should not flush.  If not
> NULL, kvm_age_hva should receive a true *flush, and should change it to
> false if kvm_age_hva takes care of the flush
>
> - pass a "bool flush".  In patch 10, change all kvm_age_hva
> implementation to do the flush if they return 1.
>
> I think I prefer the latter, in this case the small code duplication is
> offset by a simpler API.
>

From my understanding, this means to move the flush in the
kvm_mmu_notifier_clear_flush_young()
to kvm_age_hva() and do flush in kvm_age_hva() when young is >0 and "flush"
parameter is true, right?
-- 
Best regards
Tianyu Lan