[PATCH v4 21/23] KVM: nVMX: Don't switch to vmcs01 when freeing a vCPU

Now that neither free_nested() nor vmx_vcpu_free() relies on vmcs01 being
the active VMCS, don't bother switching to L1 and thus vmcs01 when freeing
nested state.

Temporarily keep the vcpu_{load,put}() pair even though the only reason the
vCPU needed to be loaded was to be able to do vmx_switch_vmcs(), as there
was at least one *known* side effect of doing vcpu_load() that KVM was
subtly relying on (taking the vCPU off the PI wakeup list).  I.e. defer
dropping the superfluous load+put to a separate patch so that there's a
dedicated bisection point if there are more lurking dependencies.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/nested.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 553915015a75..4a8f57eb3277 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c

@@ -393,19 +393,9 @@ static void nested_vmx_do_vmxoff(struct kvm_vcpu *vcpu)
 	free_nested(vcpu);
 }
 
-/*
- * Ensure that the current vmcs of the logical processor is the
- * vmcs01 of the vcpu before calling free_nested().
- */
 void nested_vmx_free_vcpu(struct kvm_vcpu *vcpu)
 {
-	struct vcpu_vmx *vmx = to_vmx(vcpu);
-
 	vcpu_load(vcpu);
-	if (is_guest_mode(vcpu)) {
-		leave_guest_mode(vcpu);
-		vmx_switch_vmcs(vcpu, &vmx->vmcs01);
-	}
 	free_nested(vcpu);
 	vcpu_put(vcpu);
 }

-- 
2.56.0.385.gac671c819a-goog