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: <Ym+HLD/U0wwrxtaB@google.com>
Date:   Mon, 2 May 2022 07:24:28 +0000
From:   Oliver Upton <oupton@...gle.com>
To:     Yosry Ahmed <yosryahmed@...gle.com>
Cc:     Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Marc Zyngier <maz@...nel.org>,
        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

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 :)

--
Thanks,
Oliver