Re: [PATCH 10/21] KVM: x86/mmu: Make __GFP_ZERO a property of the memory cache
From: Ben Gardon <hidden>
Date: 2020-06-10 18:57:48
Also in:
kvm, kvmarm, linux-mips, lkml
On Fri, Jun 5, 2020 at 2:39 PM Sean Christopherson [off-list ref] wrote:
Add a gfp_zero flag to 'struct kvm_mmu_memory_cache' and use it to control __GFP_ZERO instead of hardcoding a call to kmem_cache_zalloc(). A future patch needs such a flag for the __get_free_page() path, as gfn arrays do not need/want the allocator to zero the memory. Convert the kmem_cache paths to __GFP_ZERO now so as to avoid a weird and inconsistent API in the future. No functional change intended. Signed-off-by: Sean Christopherson <redacted>
Reviewed-by: Ben Gardon <redacted>
quoted hunk ↗ jump to hunk
--- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu/mmu.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-)diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index e7a427547557..fb99e6776e27 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; + gfp_t gfp_zero;
This would make more sense to me if it could be used for general extra gfp flags and was called gfp_flags or something, or it was a boolean that was later translated into the flag being set. Storing the gfp_zero flag here is a little counter-intuitive. Probably not worth changing unless you're sending out a v2 for some other reason.
quoted hunk ↗ jump to hunk
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 d245acece3cd..6b0ec9060786 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c@@ -1063,8 +1063,10 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) 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_zalloc(mc->kmem_cache, gfp_flags); + return kmem_cache_alloc(mc->kmem_cache, gfp_flags); else return (void *)__get_free_page(gfp_flags); }@@ -5680,7 +5682,10 @@ 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; + vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; + vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; --2.26.0
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