KVM: arm/arm64: vgic-v3: Retire pending interrupts on disabling LPIs

When disabling LPIs (for example on reset) at the redistributor
level, it is expected that LPIs that was pending in the CPU
interface are eventually retired.

Currently, this is not what is happening, and these LPIs will
stay in the ap_list, eventually being acknowledged by the vcpu
(which didn't quite expect this behaviour).

The fix is thus to retire these LPIs from the list of pending
interrupts as we disable LPIs.
Reported-by: Heyi Guo <guoheyi@huawei.com>
Tested-by: Heyi Guo <guoheyi@huawei.com>
Fixes: 0e4e82f1 ("KVM: arm64: vgic-its: Enable ITS emulation as a virtual MSI controller")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

virt/kvm/arm/vgic/vgic-mmio-v3.c

@@ -200,6 +200,9 @@ static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu,
 
 	vgic_cpu->lpis_enabled = val & GICR_CTLR_ENABLE_LPIS;
 
+	if (was_enabled && !vgic_cpu->lpis_enabled)
+		vgic_flush_pending_lpis(vcpu);
+
 	if (!was_enabled && vgic_cpu->lpis_enabled)
 		vgic_enable_lpis(vcpu);
 }

virt/kvm/arm/vgic/vgic.c

@@ -151,6 +151,27 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 	kfree(irq);
 }
 
+void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_irq *irq, *tmp;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
+
+	list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
+		if (irq->intid >= VGIC_MIN_LPI) {
+			raw_spin_lock(&irq->irq_lock);
+			list_del(&irq->ap_list);
+			irq->vcpu = NULL;
+			raw_spin_unlock(&irq->irq_lock);
+			vgic_put_irq(vcpu->kvm, irq);
+		}
+	}
+
+	raw_spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
+}
+
 void vgic_irq_set_phys_pending(struct vgic_irq *irq, bool pending)
 {
 	WARN_ON(irq_set_irqchip_state(irq->host_irq,

virt/kvm/arm/vgic/vgic.h

@@ -238,6 +238,7 @@ void vgic_v3_put(struct kvm_vcpu *vcpu);
 bool vgic_has_its(struct kvm *kvm);
 int kvm_vgic_register_its_device(void);
 void vgic_enable_lpis(struct kvm_vcpu *vcpu);
+void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu);
 int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi);
 int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr);
 int vgic_v3_dist_uaccess(struct kvm_vcpu *vcpu, bool is_write,