linux-kernel - [PATCH 4.19 80/87] KVM: x86: Remove spurious kvm_mmu

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Date:   Tue,  3 Mar 2020 18:44:11 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 4.19 80/87] KVM: x86: Remove spurious kvm_mmu_unload() from vcpu destruction path

From: Sean Christopherson <sean.j.christopherson@...el.com>

commit 9d979c7e6ff43ca3200ffcb74f57415fd633a2da upstream.

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>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kvm/x86.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8695,10 +8695,6 @@ void kvm_arch_vcpu_destroy(struct kvm_vc
 {
 	vcpu->arch.apf.msr_val = 0;
 
-	vcpu_load(vcpu);
-	kvm_mmu_unload(vcpu);
-	vcpu_put(vcpu);
-
 	kvm_arch_vcpu_free(vcpu);
 }