Re: [PATCH 15/21] KVM: Move x86's MMU memory cache helpers to common KVM code

From: Ben Gardon <bgardon@google.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
	kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	kvmarm@lists.cs.columbia.edu,
	Janosch Frank <frankja@linux.ibm.com>,
	Marc Zyngier <maz@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Junaid Shahid <junaids@google.com>,
	kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Jim Mattson <jmattson@google.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Peter Shier <pshier@google.com>,
	linux-mips@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Peter Feiner <pfeiner@google.com>
Subject: Re: [PATCH 15/21] KVM: Move x86's MMU memory cache helpers to common KVM code
Date: Wed, 10 Jun 2020 13:24:18 -0700	[thread overview]
Message-ID: <CANgfPd_oGhO4dpkejhzh1PaAc-0U068kVdoHj4_fiQveW8yXLg@mail.gmail.com> (raw)
In-Reply-To: <20200605213853.14959-16-sean.j.christopherson@intel.com>

On Fri, Jun 5, 2020 at 2:39 PM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> Move x86's memory cache helpers to common KVM code so that they can be
> reused by arm64 and MIPS in future patches.
>
> Suggested-by: Christoffer Dall <christoffer.dall@arm.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
> ---
>  arch/x86/kvm/mmu/mmu.c   | 53 --------------------------------------
>  include/linux/kvm_host.h |  7 +++++
>  virt/kvm/kvm_main.c      | 55 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 62 insertions(+), 53 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index b85d3e8e8403..a627437f73fd 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1060,47 +1060,6 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
>         local_irq_enable();
>  }
>
> -static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
> -                                              gfp_t gfp_flags)
> -{
> -       gfp_flags |= mc->gfp_zero;
> -
> -       if (mc->kmem_cache)
> -               return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
> -       else
> -               return (void *)__get_free_page(gfp_flags);
> -}
> -
> -static int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> -{
> -       void *obj;
> -
> -       if (mc->nobjs >= min)
> -               return 0;
> -       while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> -               obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> -               if (!obj)
> -                       return mc->nobjs >= min ? 0 : -ENOMEM;
> -               mc->objects[mc->nobjs++] = obj;
> -       }
> -       return 0;
> -}
> -
> -static int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
> -{
> -       return mc->nobjs;
> -}
> -
> -static void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> -{
> -       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]);
> -       }
> -}
> -
>  static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
>  {
>         int r;
> @@ -1132,18 +1091,6 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
>         kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
>  }
>
> -static void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> -{
> -       void *p;
> -
> -       if (WARN_ON(!mc->nobjs))
> -               p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT);
> -       else
> -               p = mc->objects[--mc->nobjs];
> -       BUG_ON(!p);
> -       return p;
> -}
> -
>  static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
>  {
>         return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index d38d6b9c24be..802b9e2306f0 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -815,6 +815,13 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool usermode_vcpu_not_eligible);
>  void kvm_flush_remote_tlbs(struct kvm *kvm);
>  void kvm_reload_remote_mmus(struct kvm *kvm);
>
> +#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
> +int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
> +int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc);
> +void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc);
> +void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
> +#endif
> +
>  bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
>                                  struct kvm_vcpu *except,
>                                  unsigned long *vcpu_bitmap, cpumask_var_t tmp);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4db151f6101e..fead5f1d5594 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -342,6 +342,61 @@ void kvm_reload_remote_mmus(struct kvm *kvm)
>         kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
>  }
>
> +#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
> +static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
> +                                              gfp_t gfp_flags)
> +{
> +       gfp_flags |= mc->gfp_zero;
> +
> +       if (mc->kmem_cache)
> +               return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
> +       else
> +               return (void *)__get_free_page(gfp_flags);
> +}
> +
> +int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> +{
> +       void *obj;
> +
> +       if (mc->nobjs >= min)
> +               return 0;
> +       while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> +               obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> +               if (!obj)
> +                       return mc->nobjs >= min ? 0 : -ENOMEM;
> +               mc->objects[mc->nobjs++] = obj;
> +       }
> +       return 0;
> +}
> +
> +int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
> +{
> +       return mc->nobjs;
> +}
> +
> +void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> +{
> +       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]);
> +       }
> +}
> +
> +void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> +{
> +       void *p;
> +
> +       if (WARN_ON(!mc->nobjs))
> +               p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT);
> +       else
> +               p = mc->objects[--mc->nobjs];
> +       BUG_ON(!p);
> +       return p;
> +}
> +#endif
> +
>  static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
>  {
>         mutex_init(&vcpu->mutex);
> --
> 2.26.0
>
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