KVM: Report IRQ injection status to userspace.

IRQ injection status is either -1 (if there was no CPU found
that should except the interrupt because IRQ was masked or
ioapic was misconfigured or ...) or >= 0 in that case the
number indicates to how many CPUs interrupt was injected.
If the value is 0 it means that the interrupt was coalesced
and probably should be reinjected.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 28 insertions, 13 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 6bc7439eff6e..be8aba791554 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -29,22 +29,24 @@
 
 #include "ioapic.h"
 
-static void kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
-                            struct kvm *kvm, int level)
+static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
+                           struct kvm *kvm, int level)
 {
 #ifdef CONFIG_X86
-        kvm_pic_set_irq(pic_irqchip(kvm), e->irqchip.pin, level);
+        return kvm_pic_set_irq(pic_irqchip(kvm), e->irqchip.pin, level);
+#else
+        return -1;
 #endif
 }
 
-static void kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
-                               struct kvm *kvm, int level)
+static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
+                              struct kvm *kvm, int level)
 {
-        kvm_ioapic_set_irq(kvm->arch.vioapic, e->irqchip.pin, level);
+        return kvm_ioapic_set_irq(kvm->arch.vioapic, e->irqchip.pin, level);
 }
 
-static void kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
-                        struct kvm *kvm, int level)
+static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
+                       struct kvm *kvm, int level)
 {
         int vcpu_id;
         struct kvm_vcpu *vcpu;
@@ -88,13 +90,20 @@ static void kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
         default:
                 break;
         }
+        return 1;
 }
 
-/* This should be called with the kvm->lock mutex held */
-void kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
+/* This should be called with the kvm->lock mutex held
+ * Return value:
+ *  < 0   Interrupt was ignored (masked or not delivered for other reasons)
+ *  = 0   Interrupt was coalesced (previous irq is still pending)
+ *  > 0   Number of CPUs interrupt was delivered to
+ */
+int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
 {
         struct kvm_kernel_irq_routing_entry *e;
         unsigned long *irq_state, sig_level;
+        int ret = -1;
 
         if (irq < KVM_IOAPIC_NUM_PINS) {
                 irq_state = (unsigned long *)&kvm->arch.irq_states[irq];
@@ -113,8 +122,14 @@ void kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
          * writes to the unused one.
          */
         list_for_each_entry(e, &kvm->irq_routing, link)
-                if (e->gsi == irq)
-                        e->set(e, kvm, sig_level);
+                if (e->gsi == irq) {
+                        int r = e->set(e, kvm, sig_level);
+                        if (r < 0)
+                                continue;
+
+                        ret = r + ((ret < 0) ? 0 : ret);
+                }
+        return ret;
 }
 
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
@@ -232,7 +247,7 @@ int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
                         e->set = kvm_set_pic_irq;
                         break;
                 case KVM_IRQCHIP_PIC_SLAVE:
-                                e->set = kvm_set_pic_irq;
+                        e->set = kvm_set_pic_irq;
                         delta = 8;
                         break;
                 case KVM_IRQCHIP_IOAPIC: