Re: [PATCH 01/21] KVM: x86/mmu: Track the associated kmem_cache in the MMU caches

[Ben Gardon]

On Fri, Jun 5, 2020 at 2:39 PM Sean Christopherson
<sean.j.christopherson@xxxxxxxxx> wrote:
>
> Track the kmem_cache used for non-page KVM MMU memory caches instead of
> passing in the associated kmem_cache when filling the cache.  This will
> allow consolidating code and other cleanups.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/kvm_host.h |  1 +
>  arch/x86/kvm/mmu/mmu.c          | 24 +++++++++++-------------
>  2 files changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 1da5858501ca..16347b050754 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -251,6 +251,7 @@ struct kvm_kernel_irq_routing_entry;
>   */
>  struct kvm_mmu_memory_cache {
>         int nobjs;
> +       struct kmem_cache *kmem_cache;
>         void *objects[KVM_NR_MEM_OBJS];
>  };
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index fdd05c233308..0830c195c9ed 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1060,15 +1060,14 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
>         local_irq_enable();
>  }
>
> -static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
> -                                 struct kmem_cache *base_cache, int min)
> +static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min)
>  {
>         void *obj;
>
>         if (cache->nobjs >= min)
>                 return 0;
>         while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> -               obj = kmem_cache_zalloc(base_cache, GFP_KERNEL_ACCOUNT);
> +               obj = kmem_cache_zalloc(cache->kmem_cache, GFP_KERNEL_ACCOUNT);
>                 if (!obj)
>                         return cache->nobjs >= min ? 0 : -ENOMEM;
>                 cache->objects[cache->nobjs++] = obj;
> @@ -1081,11 +1080,10 @@ static int mmu_memory_cache_free_objects(struct kvm_mmu_memory_cache *cache)
>         return cache->nobjs;
>  }
>
> -static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc,
> -                                 struct kmem_cache *cache)
> +static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
>  {
>         while (mc->nobjs)
> -               kmem_cache_free(cache, mc->objects[--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,
> @@ -1115,25 +1113,22 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
>         int r;
>
>         r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
> -                                  pte_list_desc_cache, 8 + PTE_PREFETCH_NUM);
> +                                  8 + PTE_PREFETCH_NUM);
>         if (r)
>                 goto out;
>         r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);
>         if (r)
>                 goto out;
> -       r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
> -                                  mmu_page_header_cache, 4);
> +       r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, 4);
>  out:
>         return r;
>  }
>
>  static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
>  {
> -       mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
> -                               pte_list_desc_cache);
> +       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_header_cache,
> -                               mmu_page_header_cache);
> +       mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
>  }
>
>  static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> @@ -5684,6 +5679,9 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
>         uint i;
>         int ret;
>
> +       vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> +       vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> +
>         vcpu->arch.mmu = &vcpu->arch.root_mmu;
>         vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
>
> --
> 2.26.0
>