KVM: x86: Remove return code from enable_irq/nmi_window

It's no longer possible to enter enable_irq_window in guest mode when
L1 intercepts external interrupts and we are entering L2. This is now
caught in vcpu_enter_guest. So we can remove the check from the VMX
version of enable_irq_window, thus the need to return an error code from
both enable_irq_window and enable_nmi_window.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 64d9bb9..1e8616e 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3650,7 +3650,7 @@
 	return ret;
 }
 
-static int enable_irq_window(struct kvm_vcpu *vcpu)
+static void enable_irq_window(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
@@ -3664,16 +3664,15 @@
 		svm_set_vintr(svm);
 		svm_inject_irq(svm, 0x0);
 	}
-	return 0;
 }
 
-static int enable_nmi_window(struct kvm_vcpu *vcpu)
+static void enable_nmi_window(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	if ((svm->vcpu.arch.hflags & (HF_NMI_MASK | HF_IRET_MASK))
 	    == HF_NMI_MASK)
-		return 0; /* IRET will cause a vm exit */
+		return; /* IRET will cause a vm exit */
 
 	/*
 	 * Something prevents NMI from been injected. Single step over possible
@@ -3682,7 +3681,6 @@
 	svm->nmi_singlestep = true;
 	svm->vmcb->save.rflags |= (X86_EFLAGS_TF | X86_EFLAGS_RF);
 	update_db_bp_intercept(vcpu);
-	return 0;
 }
 
 static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr)