From 4335edbbc1284259b17590f76a21fd4a162b4305 Mon Sep 17 00:00:00 2001
From: Zhenzhong Duan <zhenzhong.duan@intel.com>
Date: Fri, 11 Mar 2022 18:26:43 +0800
Subject: [PATCH] KVM: x86: Remove redundant vm_entry_controls_clearbit() call
When emulating exit from long mode, EFER_LMA is cleared with
vmx_set_efer(). This will already unset the VM_ENTRY_IA32E_MODE control
bit as requested by SDM, so there is no need to unset VM_ENTRY_IA32E_MODE
again in exit_lmode() explicitly. In case EFER isn't supported by
hardware, long mode isn't supported, so exit_lmode() cannot be reached.
Note that, thanks to the shadow controls mechanism, this change doesn't
eliminate vmread or vmwrite.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-3-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/vmx.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2d122416b1e87..04d170c4b61eb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2902,7 +2902,6 @@ static void enter_lmode(struct kvm_vcpu *vcpu)
static void exit_lmode(struct kvm_vcpu *vcpu)
{
- vm_entry_controls_clearbit(to_vmx(vcpu), VM_ENTRY_IA32E_MODE);
vmx_set_efer(vcpu, vcpu->arch.efer & ~EFER_LMA);
}
--
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