KVM: x86: Add a return code to kvm_apic_accept_events

No functional change intended. At present, the only negative value
returned by kvm_check_nested_events is -EBUSY.

Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20210604172611.281819-6-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -2872,28 +2872,28 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data, unsigned long len)
 	return kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, addr, new_len);
 }
 
-void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
+int kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	u8 sipi_vector;
 	int r;
 	unsigned long pe;
 
 	if (!lapic_in_kernel(vcpu))
-		return;
+		return 0;
 
 	/*
 	 * Read pending events before calling the check_events
 	 * callback.
 	 */
 	pe = smp_load_acquire(&apic->pending_events);
 	if (!pe)
-		return;
+		return 0;
 
 	if (is_guest_mode(vcpu)) {
 		r = kvm_check_nested_events(vcpu);
 		if (r < 0)
-			return;
+			return r == -EBUSY ? 0 : r;
 		/*
 		 * If an event has happened and caused a vmexit,
 		 * we know INITs are latched and therefore
@@ -2914,7 +2914,7 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 		WARN_ON_ONCE(vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED);
 		if (test_bit(KVM_APIC_SIPI, &pe))
 			clear_bit(KVM_APIC_SIPI, &apic->pending_events);
-		return;
+		return 0;
 	}
 
 	if (test_bit(KVM_APIC_INIT, &pe)) {
@@ -2935,6 +2935,7 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
 		}
 	}
+	return 0;
 }
 
 void kvm_lapic_exit(void)

arch/x86/kvm/lapic.h

@@ -76,7 +76,7 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu);
 int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu);
 int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu);
 int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu);
-void kvm_apic_accept_events(struct kvm_vcpu *vcpu);
+int kvm_apic_accept_events(struct kvm_vcpu *vcpu);
 void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event);
 u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu);
 void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8);

arch/x86/kvm/x86.c

@@ -9335,7 +9335,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win ||
 	    kvm_xen_has_interrupt(vcpu)) {
 		++vcpu->stat.req_event;
-		kvm_apic_accept_events(vcpu);
+		r = kvm_apic_accept_events(vcpu);
+		if (r < 0) {
+			r = 0;
+			goto out;
+		}
 		if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
 			r = 1;
 			goto out;
@@ -9547,7 +9551,8 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
 			return 1;
 	}
 
-	kvm_apic_accept_events(vcpu);
+	if (kvm_apic_accept_events(vcpu) < 0)
+		return 0;
 	switch(vcpu->arch.mp_state) {
 	case KVM_MP_STATE_HALTED:
 	case KVM_MP_STATE_AP_RESET_HOLD:
@@ -9771,7 +9776,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 			goto out;
 		}
 		kvm_vcpu_block(vcpu);
-		kvm_apic_accept_events(vcpu);
+		if (kvm_apic_accept_events(vcpu) < 0) {
+			r = 0;
+			goto out;
+		}
 		kvm_clear_request(KVM_REQ_UNHALT, vcpu);
 		r = -EAGAIN;
 		if (signal_pending(current)) {
@@ -9973,22 +9981,29 @@ int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
+	int r;
+
 	vcpu_load(vcpu);
 	if (kvm_mpx_supported())
 		kvm_load_guest_fpu(vcpu);
 
-	kvm_apic_accept_events(vcpu);
+	r = kvm_apic_accept_events(vcpu);
+	if (r < 0)
+		goto out;
+	r = 0;
+
 	if ((vcpu->arch.mp_state == KVM_MP_STATE_HALTED ||
 	     vcpu->arch.mp_state == KVM_MP_STATE_AP_RESET_HOLD) &&
 	    vcpu->arch.pv.pv_unhalted)
 		mp_state->mp_state = KVM_MP_STATE_RUNNABLE;
 	else
 		mp_state->mp_state = vcpu->arch.mp_state;
 
+out:
 	if (kvm_mpx_supported())
 		kvm_put_guest_fpu(vcpu);
 	vcpu_put(vcpu);
-	return 0;
+	return r;
 }
 
 int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,