x86: ioapic: ignore level irq during processing

For level triggered interrupts, we will get Remote IRR bit cleared after
guest kernel finished processing specific request. Before that, we
should ignore the same interrupt from triggering again.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1469974685-4144-1-git-send-email-peterx@redhat.com>
[Push new "if" up so that it covers KVM split irqchip as well. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/intc/ioapic.c

@@ -117,21 +117,25 @@ static void ioapic_service(IOAPICCommonState *s)
                     s->ioredtbl[i] |= IOAPIC_LVT_REMOTE_IRR;
                 }
 
+                if (coalesce) {
+                    /* We are level triggered interrupts, and the
+                     * guest should be still working on previous one,
+                     * so skip it. */
+                    continue;
+                }
+
 #ifdef CONFIG_KVM
                 if (kvm_irqchip_is_split()) {
                     if (info.trig_mode == IOAPIC_TRIGGER_EDGE) {
                         kvm_set_irq(kvm_state, i, 1);
                         kvm_set_irq(kvm_state, i, 0);
                     } else {
-                        if (!coalesce) {
-                            kvm_set_irq(kvm_state, i, 1);
-                        }
+                        kvm_set_irq(kvm_state, i, 1);
                     }
                     continue;
                 }
-#else
-                (void)coalesce;
 #endif
+
                 /* No matter whether IR is enabled, we translate
                  * the IOAPIC message into a MSI one, and its
                  * address space will decide whether we need a