Commit 4335edbb authored by Zhenzhong Duan's avatar Zhenzhong Duan Committed by Paolo Bonzini
Browse files

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: default avatarZhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-3-zhenzhong.duan@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b76edfe9

arch/x86/kvm/vmx/vmx.c

+0 −1
Original line number Diff line number Diff line
@@ -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);

}