linux-kernel - [PATCH v2 10/21] KVM: x86/mmu: Make __GFP

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Date:   Mon, 22 Jun 2020 13:08:11 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Marc Zyngier <maz@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
        Arnd Bergmann <arnd@...db.de>
Cc:     James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-mips@...r.kernel.org, kvm@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ben Gardon <bgardon@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Christoffer Dall <christoffer.dall@....com>
Subject: [PATCH v2 10/21] KVM: x86/mmu: Make __GFP_ZERO a property of the memory cache

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.

Reviewed-by: Ben Gardon <bgardon@...gle.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 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 376e1653ac41..67b84aa2984e 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;
 	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