linux-kernel - [PATCH v2 20/45] KVM: x86: Remove spurious kvm_mmu

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Message-Id: <20191218215530.2280-21-sean.j.christopherson@intel.com>
Date:   Wed, 18 Dec 2019 13:55:05 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Marc Zyngier <maz@...nel.org>, James Hogan <jhogan@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.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-ppc@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Kurz <groug@...d.org>
Subject: [PATCH v2 20/45] KVM: x86: Remove spurious kvm_mmu_unload() from vcpu destruction path

x86 does not load its MMU until KVM_RUN, which cannot be invoked until
after vCPU creation succeeds.  Given that kvm_arch_vcpu_destroy() is
called if and only if vCPU creation fails, it is impossible for the MMU
to be loaded.

Note, the bogus kvm_mmu_unload() call was added during an unrelated
refactoring of vCPU allocation, i.e. was presumably added as an
opportunstic "fix" for a perceived leak.

Fixes: fb3f0f51d92d1 ("KVM: Dynamically allocate vcpus")
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/x86.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8973037eb2fa..19c14b786255 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9178,10 +9178,6 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.apf.msr_val = 0;
 
-	vcpu_load(vcpu);
-	kvm_mmu_unload(vcpu);
-	vcpu_put(vcpu);
-
 	kvm_arch_vcpu_free(vcpu);
 }
 
-- 
2.24.1