KVM: arm/arm64: Do not inject spurious interrupts

When lowering a level-triggered line from userspace, we forgot to lower
the pending bit on the emulated CPU interface and we also did not
re-compute the pending_on_cpu bitmap for the CPU affected by the change.

Update vgic_update_irq_pending() to fix the two issues above and also
raise a warning in vgic_quue_irq_to_lr if we encounter an interrupt
pending on a CPU which is neither marked active nor pending.

  [ Commit text reworked completely - Christoffer ]

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 6bd1c9bf7ae7..596455a394af 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1132,7 +1132,8 @@ static void vgic_queue_irq_to_lr(struct kvm_vcpu *vcpu, int irq,
                 kvm_debug("Set active, clear distributor: 0x%x\n", vlr.state);
                 vgic_irq_clear_active(vcpu, irq);
                 vgic_update_state(vcpu->kvm);
-        } else if (vgic_dist_irq_is_pending(vcpu, irq)) {
+        } else {
+                WARN_ON(!vgic_dist_irq_is_pending(vcpu, irq));
                 vlr.state |= LR_STATE_PENDING;
                 kvm_debug("Set pending: 0x%x\n", vlr.state);
         }
@@ -1607,8 +1608,12 @@ static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
         } else {
                 if (level_triggered) {
                         vgic_dist_irq_clear_level(vcpu, irq_num);
-                        if (!vgic_dist_irq_soft_pend(vcpu, irq_num))
+                        if (!vgic_dist_irq_soft_pend(vcpu, irq_num)) {
                                 vgic_dist_irq_clear_pending(vcpu, irq_num);
+                                vgic_cpu_irq_clear(vcpu, irq_num);
+                                if (!compute_pending_for_cpu(vcpu))
+                                        clear_bit(cpuid, dist->irq_pending_on_cpu);
+                        }
                 }
 
                 ret = false;