KVM: nSVM: extract svm_set_gif

Extract the code that is needed to implement CLGI and STGI,
so that we can run it from VMRUN and vmexit (and in the future,
KVM_SET_NESTED_STATE).  Skip the request for KVM_REQ_EVENT unless needed,
subsuming the evaluate_pending_interrupts optimization that is found
in enter_svm_guest_mode.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/irq.c

@@ -83,6 +83,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
 
 	return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
 }
+EXPORT_SYMBOL_GPL(kvm_cpu_has_injectable_intr);
 
 /*
  * check if there is pending interrupt without

arch/x86/kvm/svm/nested.c

@@ -333,10 +333,6 @@ static void nested_prepare_vmcb_control(struct vcpu_svm *svm)
 void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 			  struct vmcb *nested_vmcb)
 {
-	bool evaluate_pending_interrupts =
-		is_intercept(svm, INTERCEPT_VINTR) ||
-		is_intercept(svm, INTERCEPT_IRET);
-
 	svm->nested.vmcb = vmcb_gpa;
 	if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
 		svm->vcpu.arch.hflags |= HF_HIF_MASK;
@@ -347,21 +343,7 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	nested_prepare_vmcb_save(svm, nested_vmcb);
 	nested_prepare_vmcb_control(svm);
 
-	/*
-	 * If L1 had a pending IRQ/NMI before executing VMRUN,
-	 * which wasn't delivered because it was disallowed (e.g.
-	 * interrupts disabled), L0 needs to evaluate if this pending
-	 * event should cause an exit from L2 to L1 or be delivered
-	 * directly to L2.
-	 *
-	 * Usually this would be handled by the processor noticing an
-	 * IRQ/NMI window request.  However, VMRUN can unblock interrupts
-	 * by implicitly setting GIF, so force L0 to perform pending event
-	 * evaluation by requesting a KVM_REQ_EVENT.
-	 */
-	enable_gif(svm);
-	if (unlikely(evaluate_pending_interrupts))
-		kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+	svm_set_gif(svm, true);
 }
 
 int nested_svm_vmrun(struct vcpu_svm *svm)
@@ -505,7 +487,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm->vcpu.arch.mp_state = KVM_MP_STATE_RUNNABLE;
 
 	/* Give the current vmcb to the guest */
-	disable_gif(svm);
+	svm_set_gif(svm, false);
 
 	nested_vmcb->save.es     = vmcb->save.es;
 	nested_vmcb->save.cs     = vmcb->save.cs;

arch/x86/kvm/svm/svm.c

@@ -1981,29 +1981,39 @@ static int vmrun_interception(struct vcpu_svm *svm)
 	return nested_svm_vmrun(svm);
 }
 
-static int stgi_interception(struct vcpu_svm *svm)
+void svm_set_gif(struct vcpu_svm *svm, bool value)
 {
-	int ret;
-
-	if (nested_svm_check_permissions(svm))
-		return 1;
-
+	if (value) {
 		/*
 		 * If VGIF is enabled, the STGI intercept is only added to
 		 * detect the opening of the SMI/NMI window; remove it now.
+		 * Likewise, clear the VINTR intercept, we will set it
+		 * again while processing KVM_REQ_EVENT if needed.
 		 */
 		if (vgif_enabled(svm))
 			clr_intercept(svm, INTERCEPT_STGI);
-
-	ret = kvm_skip_emulated_instruction(&svm->vcpu);
-	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+		if (is_intercept(svm, SVM_EXIT_VINTR))
+			svm_clear_vintr(svm);
 
 		enable_gif(svm);
+		if (svm->vcpu.arch.smi_pending ||
+		    svm->vcpu.arch.nmi_pending ||
+		    kvm_cpu_has_injectable_intr(&svm->vcpu))
+			kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+	} else {
+		disable_gif(svm);
 
-	return ret;
+		/*
+		 * After a CLGI no interrupts should come.  But if vGIF is
+		 * in use, we still rely on the VINTR intercept (rather than
+		 * STGI) to detect an open interrupt window.
+		*/
+		if (!vgif_enabled(svm))
+			svm_clear_vintr(svm);
+	}
 }
 
-static int clgi_interception(struct vcpu_svm *svm)
+static int stgi_interception(struct vcpu_svm *svm)
 {
 	int ret;
 
@@ -2011,12 +2021,19 @@ static int clgi_interception(struct vcpu_svm *svm)
 		return 1;
 
 	ret = kvm_skip_emulated_instruction(&svm->vcpu);
+	svm_set_gif(svm, true);
+	return ret;
+}
 
-	disable_gif(svm);
+static int clgi_interception(struct vcpu_svm *svm)
+{
+	int ret;
 
-	/* After a CLGI no interrupts should come */
-	svm_clear_vintr(svm);
+	if (nested_svm_check_permissions(svm))
+		return 1;
 
+	ret = kvm_skip_emulated_instruction(&svm->vcpu);
+	svm_set_gif(svm, false);
 	return ret;
 }
 

arch/x86/kvm/svm/svm.h

@@ -357,6 +357,7 @@ void disable_nmi_singlestep(struct vcpu_svm *svm);
 bool svm_smi_blocked(struct kvm_vcpu *vcpu);
 bool svm_nmi_blocked(struct kvm_vcpu *vcpu);
 bool svm_interrupt_blocked(struct kvm_vcpu *vcpu);
+void svm_set_gif(struct vcpu_svm *svm, bool value);
 
 /* nested.c */