Re: [Patch v3 6/9] KVM: Provide NUMA node support to kvm_mmu_memory_cache{}

From: Ben Gardon
Date: Thu Dec 29 2022 - 13:23:07 EST

On Wed, Dec 28, 2022 at 2:08 PM Vipin Sharma <vipinsh@xxxxxxxxxx> wrote:
>
> On Tue, Dec 27, 2022 at 11:10 AM Ben Gardon <bgardon@xxxxxxxxxx> wrote:
> >
> > On Wed, Dec 21, 2022 at 6:35 PM Vipin Sharma <vipinsh@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > ---
> > > 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);
> > > +
> > > 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;
> > > +
> >
> > It looks weird to have MIPS not using the initialization MACRO. Should
> > it just have a GFP_ZERO parameter?
>
> MIPS is not setting GFP_ZERO explicitly before my series, so, I didn't
> make it GFP_ZERO. I am not sure if MIPS needs it or not, I tried to
> keep the same functionality in my patch.
>
> May be someone from MIPS can tell more about it.

That makes sense, I just don't want to see MIPS get left behind
because we move the cache init logic to a macro or function. Folks
might update the init function but forget to update MIPS too.

>
> >
> > > /*
> > > * 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; \
> > > +})
> > > +
> >
> > Given that this initialization is probably not happening in a super
> > hot path, is there any downside to just using a function for the
> > initialization?
> >
>
> It can totally be a function as well. I will make it function in the
> next version.

Awesome, thanks.

>
>
> > > #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
> > >