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 <Y64eAvm4JglT1au4@google.com> <CALzav=fGmy=YmpA6u=b0-p8zxnKbF2rt5mQUo-DWm2wYBU7dzA@mail.gmail.com>
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From:   Vipin Sharma <vipinsh@google.com>
Date:   Tue, 3 Jan 2023 10:45:50 -0800
Message-ID: <CAHVum0fdz8HmgQd5z2n9eAzWuTjtBPA5_aVrY123K=kAMdJvhw@mail.gmail.com>
Subject: Re: [Patch v3 6/9] KVM: Provide NUMA node support to kvm_mmu_memory_cache{}
To:     David Matlack <dmatlack@google.com>
Cc:     seanjc@google.com, pbonzini@redhat.com, bgardon@google.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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On Thu, Dec 29, 2022 at 3:12 PM David Matlack <dmatlack@google.com> wrote:
>
> On Thu, Dec 29, 2022 at 3:08 PM David Matlack <dmatlack@google.com> wrote:
> >
> > On Wed, Dec 21, 2022 at 06:34:54PM -0800, Vipin Sharma wrote:
> > > Add 'node' variable in kvm_mmu_memory_cache{} to denote which NUMA node
> > > this cache should allocate memory from. Default initialize to
> > > NUMA_NO_NODE in all architectures.
> > >
> > > Signed-off-by: Vipin Sharma <vipinsh@google.com>
> > > ---
> > >  arch/arm64/kvm/arm.c      |  2 +-
> > >  arch/arm64/kvm/mmu.c      |  4 +++-
> > >  arch/mips/kvm/mips.c      |  2 ++
> > >  arch/riscv/kvm/mmu.c      |  2 +-
> > >  arch/riscv/kvm/vcpu.c     |  2 +-
> > >  arch/x86/kvm/mmu/mmu.c    | 22 ++++++++++++----------
> > >  include/linux/kvm_host.h  |  6 ++++++
> > >  include/linux/kvm_types.h |  2 ++
> > >  8 files changed, 28 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > > index 9c5573bc4614..52a41f4532e2 100644
> > > --- a/arch/arm64/kvm/arm.c
> > > +++ b/arch/arm64/kvm/arm.c
> > > @@ -340,7 +340,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > >       vcpu->arch.target = -1;
> > >       bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
> > >
> > > -     vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_cache, NULL, NUMA_NO_NODE);
> > >
> > >       /*
> > >        * Default value for the FP state, will be overloaded at load
> > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > > index 31d7fa4c7c14..bd07155e17fa 100644
> > > --- a/arch/arm64/kvm/mmu.c
> > > +++ b/arch/arm64/kvm/mmu.c
> > > @@ -894,12 +894,14 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > >  {
> > >       phys_addr_t addr;
> > >       int ret = 0;
> > > -     struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
> > > +     struct kvm_mmu_memory_cache cache;
> > >       struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> > >       enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> > >                                    KVM_PGTABLE_PROT_R |
> > >                                    (writable ? KVM_PGTABLE_PROT_W : 0);
> > >
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&cache, NULL, NUMA_NO_NODE);
> >
> > This is not any better than setting cache.node = NUMA_NO_NODE directly.
> > Yes it's less lines of code, but it's harder to read (what does NULL
> > mean here?), and every user of kvm_mmu_memory_cache still has to know to
> > pass NUMA_NO_NODE.
> >
> > When I originally gave this suggestion, I intended to suggest that
> > INIT_KVM_MMU_MEMORY_CACHE() provide just default initialization.
> > Non-default initialization for gfp_zero, gfp_custom, kmem_cache, and
> > node would remain as they are.
> >
> > Yes this adds some more lines, but keeps things readable, and doesn't
> > every initialization site of kvm_mmu_memory_cache to know what to pass
> > for gfp_zero, node, and kmem_cache. It only needs to set the fields
> > *it* cares about.
>
> And to offset the extra lines to call INIT_KVM_MMU_MEMORY_CACHE(), we
> could finally invert the meaning of gfp_zero so that caches use
> __GFP_ZERO by default. The majority of caches want __GFP_ZERO, so that
> should cut down a bunch of lines.
>

Can you clarify what you mean by invert?

Caches which don't want __GFP_ZERO will explicitly set gfp_zero to 0.
Is this what you intend?


> >
> > Here's what I mean specifically, based on INIT_LIST_HEAD. I don't think
> > I got all the kvm_mmu_memory_cache users, but you get the point.
> >
> >
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 9c5573bc4614..0e138dcaf4d4 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -340,6 +340,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >         vcpu->arch.target = -1;
> >         bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_cache);
> >         vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >
> >         /*
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 31d7fa4c7c14..f5fd78a4f084 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -894,12 +894,14 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> >  {
> >         phys_addr_t addr;
> >         int ret = 0;
> > -       struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
> > +       KVM_MMU_MEMORY_CACHE(cache);
> >         struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> >         enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> >                                      KVM_PGTABLE_PROT_R |
> >                                      (writable ? KVM_PGTABLE_PROT_W : 0);
> >
> > +       cache.gfp_zero = __GFP_ZERO;
> > +
> >         if (is_protected_kvm_enabled())
> >                 return -EPERM;
> >
> > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> > index 34b57e0be2ef..7915a5a2d104 100644
> > --- a/arch/riscv/kvm/mmu.c
> > +++ b/arch/riscv/kvm/mmu.c
> > @@ -351,10 +351,11 @@ int kvm_riscv_gstage_ioremap(struct kvm *kvm, gpa_t gpa,
> >         int ret = 0;
> >         unsigned long pfn;
> >         phys_addr_t addr, end;
> > -       struct kvm_mmu_memory_cache pcache = {
> > -               .gfp_custom = (in_atomic) ? GFP_ATOMIC | __GFP_ACCOUNT : 0,
> > -               .gfp_zero = __GFP_ZERO,
> > -       };
> > +       KVM_MMU_MEMORY_CACHE(pcache);
> > +
> > +       pcache.gfp_zero = __GFP_ZERO;
> > +       if (in_atomic)
> > +               pcache.gfp_custom = GFP_ATOMIC | __GFP_ACCOUNT;
> >
> >         end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> >         pfn = __phys_to_pfn(hpa);
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 7c08567097f0..3d73ab3ec9a4 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -161,6 +161,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >
> >         /* Mark this VCPU never ran */
> >         vcpu->arch.ran_atleast_once = false;
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_header_cache);
> >         vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >         bitmap_zero(vcpu->arch.isa, RISCV_ISA_EXT_MAX);
> >
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index 254bc46234e0..d4cd8e64cc03 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -5909,14 +5909,19 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> >  {
> >         int ret;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_pte_list_desc_cache);
> >         vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> >         vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_header_cache);
> >         vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> >         vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_shadow_page_cache);
> >         vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_shadowed_info_cache);
> > +
> >         vcpu->arch.mmu = &vcpu->arch.root_mmu;
> >         vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
> >
> > @@ -6083,11 +6088,14 @@ int kvm_mmu_init_vm(struct kvm *kvm)
> >         node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
> >         kvm_page_track_register_notifier(kvm, node);
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_page_header_cache);
> >         kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
> >         kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_shadow_page_cache);
> >         kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO;
> >
> > +       INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_desc_cache);
> >         kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
> >         kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
> >
> > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> > index 76de36e56cdf..eb7ff9afa5c7 100644
> > --- a/include/linux/kvm_types.h
> > +++ b/include/linux/kvm_types.h
> > @@ -98,6 +98,17 @@ struct kvm_mmu_memory_cache {
> >         int capacity;
> >         void **objects;
> >  };
> > +
> > +#define KVM_MMU_MEMORY_CACHE_INIT() (struct kvm_mmu_memory_cache) { \
> > +}
> > +
> > +#define KVM_MMU_MEMORY_CACHE(_name) \
> > +       struct kvm_mmu_memory_cache _name = KVM_MMU_MEMORY_CACHE_INIT()
> > +
> > +static inline void INIT_KVM_MMU_MEMORY_CACHE(struct kvm_mmu_memory_cache *cache)
> > +{
> > +       *cache = KVM_MMU_MEMORY_CACHE_INIT();
> > +}
> >  #endif
> >
> >  #define HALT_POLL_HIST_COUNT                   32
> >
> > > +
> > >       if (is_protected_kvm_enabled())
> > >               return -EPERM;
> > >
> > > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> > > index a25e0b73ee70..b017c29a9340 100644
> > > --- a/arch/mips/kvm/mips.c
> > > +++ b/arch/mips/kvm/mips.c
> > > @@ -304,6 +304,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > >                    HRTIMER_MODE_REL);
> > >       vcpu->arch.comparecount_timer.function = kvm_mips_comparecount_wakeup;
> > >
> > > +     vcpu->arch.mmu_page_cache.node = NUMA_NO_NODE;
> > > +
> > >       /*
> > >        * Allocate space for host mode exception handlers that handle
> > >        * guest mode exits
> > > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> > > index 34b57e0be2ef..119de4520cc6 100644
> > > --- a/arch/riscv/kvm/mmu.c
> > > +++ b/arch/riscv/kvm/mmu.c
> > > @@ -353,9 +353,9 @@ int kvm_riscv_gstage_ioremap(struct kvm *kvm, gpa_t gpa,
> > >       phys_addr_t addr, end;
> > >       struct kvm_mmu_memory_cache pcache = {
> > >               .gfp_custom = (in_atomic) ? GFP_ATOMIC | __GFP_ACCOUNT : 0,
> > > -             .gfp_zero = __GFP_ZERO,
> > >       };
> > >
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&pcache, NULL, NUMA_NO_NODE);
> > >       end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> > >       pfn = __phys_to_pfn(hpa);
> > >
> > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > > index 7c08567097f0..189b14feb365 100644
> > > --- a/arch/riscv/kvm/vcpu.c
> > > +++ b/arch/riscv/kvm/vcpu.c
> > > @@ -161,7 +161,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > >
> > >       /* Mark this VCPU never ran */
> > >       vcpu->arch.ran_atleast_once = false;
> > > -     vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_cache, NULL, NUMA_NO_NODE);
> > >       bitmap_zero(vcpu->arch.isa, RISCV_ISA_EXT_MAX);
> > >
> > >       /* Setup ISA features available to VCPU */
> > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > > index 6f6a10d7a871..23a3b82b2384 100644
> > > --- a/arch/x86/kvm/mmu/mmu.c
> > > +++ b/arch/x86/kvm/mmu/mmu.c
> > > @@ -5954,13 +5954,14 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> > >  {
> > >       int ret;
> > >
> > > -     vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> > > -     vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_pte_list_desc_cache,
> > > +                               pte_list_desc_cache, NUMA_NO_NODE);
> > >
> > > -     vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> > > -     vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_page_header_cache,
> > > +                               mmu_page_header_cache, NUMA_NO_NODE);
> > >
> > > -     vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&vcpu->arch.mmu_shadow_page_cache,
> > > +                               NULL, NUMA_NO_NODE);
> > >       spin_lock_init(&vcpu->arch.mmu_shadow_page_cache_lock);
> > >
> > >       vcpu->arch.mmu = &vcpu->arch.root_mmu;
> > > @@ -6124,14 +6125,15 @@ int kvm_mmu_init_vm(struct kvm *kvm)
> > >       node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
> > >       kvm_page_track_register_notifier(kvm, node);
> > >
> > > -     kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
> > > -     kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_page_header_cache,
> > > +                               mmu_page_header_cache, NUMA_NO_NODE);
> > >
> > > -     kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_shadow_page_cache,
> > > +                               NULL, NUMA_NO_NODE);
> > >       spin_lock_init(&kvm->arch.split_shadow_page_cache_lock);
> > >
> > > -     kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
> > > -     kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
> > > +     INIT_KVM_MMU_MEMORY_CACHE(&kvm->arch.split_desc_cache,
> > > +                               pte_list_desc_cache, NUMA_NO_NODE);
> > >
> > >       return 0;
> > >  }
> > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > > index a262e15ebd19..719687a37ef7 100644
> > > --- a/include/linux/kvm_host.h
> > > +++ b/include/linux/kvm_host.h
> > > @@ -2302,4 +2302,10 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr)
> > >  /* Max number of entries allowed for each kvm dirty ring */
> > >  #define  KVM_DIRTY_RING_MAX_ENTRIES  65536
> > >
> > > +#define INIT_KVM_MMU_MEMORY_CACHE(_cache, _kmem_cache, _node) ({     \
> > > +     (_cache)->kmem_cache = _kmem_cache;                             \
> > > +     (_cache)->gfp_zero = __GFP_ZERO;                                \
> > > +     (_cache)->node = _node;                                         \
> > > +})
> > > +
> > >  #endif
> > > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> > > index 76de36e56cdf..9c70ce95e51f 100644
> > > --- a/include/linux/kvm_types.h
> > > +++ b/include/linux/kvm_types.h
> > > @@ -97,6 +97,8 @@ struct kvm_mmu_memory_cache {
> > >       struct kmem_cache *kmem_cache;
> > >       int capacity;
> > >       void **objects;
> > > +     /* Node on which memory should be allocated by default */
> > > +     int node;
> > >  };
> > >  #endif
> > >
> > > --
> > > 2.39.0.314.g84b9a713c41-goog
> > >