linux-kernel - Re: [PATCH v4 4/4] KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats

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Message-ID: <87k0b4i7se.wl-maz@kernel.org>
Date:   Mon, 02 May 2022 10:49:05 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Oliver Upton <oupton@...gle.com>
Cc:     Yosry Ahmed <yosryahmed@...gle.com>, Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Zefan Li <lizefan.x@...edance.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v4 4/4] KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats

On Mon, 02 May 2022 08:24:28 +0100,
Oliver Upton <oupton@...gle.com> wrote:
> 
> Hi Yosry,
> 
> On Fri, Apr 29, 2022 at 08:11:31PM +0000, Yosry Ahmed wrote:
> > Count the pages used by KVM in arm64 for stage2 mmu in secondary pagetable
> > stats.
> > 
> > Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
> > ---
> >  arch/arm64/kvm/mmu.c | 35 +++++++++++++++++++++++++++++++----
> >  1 file changed, 31 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 53ae2c0640bc..fc5030307cce 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -92,9 +92,13 @@ static bool kvm_is_device_pfn(unsigned long pfn)
> >  static void *stage2_memcache_zalloc_page(void *arg)
> >  {
> >  	struct kvm_mmu_memory_cache *mc = arg;
> > +	void *virt;
> >  
> >  	/* Allocated with __GFP_ZERO, so no need to zero */
> > -	return kvm_mmu_memory_cache_alloc(mc);
> > +	virt = kvm_mmu_memory_cache_alloc(mc);
> > +	if (virt)
> > +		kvm_account_pgtable_pages(virt, +1);
> 
> Sorry I didn't say it last time around, would now be a good time to
> clean up the funky sign convention of kvm_mod_used_mmu_pages()? Or limit
> the funk to just x86 :)

Indeed. I pointed this out in my initial review of this series, and
expected these to be gone by now.

	M.

-- 
Without deviation from the norm, progress is not possible.