linux-kernel - Re: [Patch v4 06/18] KVM: x86/mmu: Shrink split_shadow_page

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Date:   Thu, 9 Mar 2023 11:59:48 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     Zhi Wang <zhi.wang.linux@...il.com>
Cc:     seanjc@...gle.com, pbonzini@...hat.com, bgardon@...gle.com,
        dmatlack@...gle.com, jmattson@...gle.com, mizhang@...gle.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Patch v4 06/18] KVM: x86/mmu: Shrink split_shadow_page_cache via
 MMU shrinker

On Thu, Mar 9, 2023 at 8:01 AM Zhi Wang <zhi.wang.linux@...il.com> wrote:
>
> On Mon,  6 Mar 2023 14:41:15 -0800
> Vipin Sharma <vipinsh@...gle.com> wrote:
>
> > Use MMU shrinker to free unused pages in split_shadow_page_cache.
> > Refactor the code and make common function to try emptying the page cache.
> >
> > Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
> > ---
> >  arch/x86/kvm/mmu/mmu.c | 34 +++++++++++++++++++++-------------
> >  1 file changed, 21 insertions(+), 13 deletions(-)
> >
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index 0ebb8a2eaf47..73a0ac9c11ce 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -6696,13 +6696,24 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
> >       }
> >  }
> >
>
> After adding the lock in the kvm_mmu_memory_cache, the cache_lock doesn't need
> to be passed here and in mmu_shrink_scan().
>
Agree. Let us see what is the decision on moving the lock inside the cache.