linux-kernel - Re: [PATCH 02/21] KVM: x86/mmu: Consolidate "page" variant of memory cache helpers

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Date:   Tue, 9 Jun 2020 15:54:04 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Marc Zyngier <maz@...nel.org>, Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-mips@...r.kernel.org, kvm@...r.kernel.org,
        kvm-ppc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Peter Feiner <pfeiner@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Christoffer Dall <christoffer.dall@....com>
Subject: Re: [PATCH 02/21] KVM: x86/mmu: Consolidate "page" variant of memory
 cache helpers

On Fri, Jun 5, 2020 at 2:39 PM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:
>
> Drop the "page" variants of the topup/free memory cache helpers, using
> the existence of an associated kmem_cache to select the correct alloc
> or free routine.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Reviewed-by: Ben Gardon <bgardon@...gle.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 37 +++++++++++--------------------------
>  1 file changed, 11 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 0830c195c9ed..cbc101663a89 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1067,7 +1067,10 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min)
>         if (cache->nobjs >= min)
>                 return 0;
>         while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> -               obj = kmem_cache_zalloc(cache->kmem_cache, GFP_KERNEL_ACCOUNT);
> +               if (cache->kmem_cache)
> +                       obj = kmem_cache_zalloc(cache->kmem_cache, GFP_KERNEL_ACCOUNT);
> +               else
> +                       obj = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
>                 if (!obj)
>                         return cache->nobjs >= min ? 0 : -ENOMEM;
>                 cache->objects[cache->nobjs++] = obj;
> @@ -1082,30 +1085,12 @@ static int mmu_memory_cache_free_objects(struct kvm_mmu_memory_cache *cache)
>
>  static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
>  {
> -       while (mc->nobjs)
> -               kmem_cache_free(mc->kmem_cache, mc->objects[--mc->nobjs]);
> -}
> -
> -static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache,
> -                                      int min)
> -{
> -       void *page;
> -
> -       if (cache->nobjs >= min)
> -               return 0;
> -       while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> -               page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
> -               if (!page)
> -                       return cache->nobjs >= min ? 0 : -ENOMEM;
> -               cache->objects[cache->nobjs++] = page;
> +       while (mc->nobjs) {
> +               if (mc->kmem_cache)
> +                       kmem_cache_free(mc->kmem_cache, mc->objects[--mc->nobjs]);
> +               else
> +                       free_page((unsigned long)mc->objects[--mc->nobjs]);
>         }
> -       return 0;
> -}
> -
> -static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc)
> -{
> -       while (mc->nobjs)
> -               free_page((unsigned long)mc->objects[--mc->nobjs]);
>  }
>
>  static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
> @@ -1116,7 +1101,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
>                                    8 + PTE_PREFETCH_NUM);
>         if (r)
>                 goto out;
> -       r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);
> +       r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_cache, 8);
>         if (r)
>                 goto out;
>         r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, 4);
> @@ -1127,7 +1112,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
>  static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
>  {
>         mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
> -       mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache);
> +       mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
>         mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
>  }
>
> --
> 2.26.0
>