KVM: switch irq injection/acking data structures to irq_lock

Protect irq injection/acking data structures with a separate irq_lock
mutex. This fixes the following deadlock:

CPU A                               CPU B
kvm_vm_ioctl_deassign_dev_irq()
  mutex_lock(&kvm->lock);            worker_thread()
  -> kvm_deassign_irq()                -> kvm_assigned_dev_interrupt_work_handler()
    -> deassign_host_irq()               mutex_lock(&kvm->lock);
      -> cancel_work_sync() [blocked]

[gleb: fix ia64 path]

Reported-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a23f42e550af..44f20cdb5709 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -424,7 +424,9 @@ static void apic_set_eoi(struct kvm_lapic *apic)
                 trigger_mode = IOAPIC_LEVEL_TRIG;
         else
                 trigger_mode = IOAPIC_EDGE_TRIG;
+        mutex_lock(&apic->vcpu->kvm->irq_lock);
         kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
+        mutex_unlock(&apic->vcpu->kvm->irq_lock);
 }
 
 static void apic_send_ipi(struct kvm_lapic *apic)
@@ -448,7 +450,9 @@ static void apic_send_ipi(struct kvm_lapic *apic)
                    irq.trig_mode, irq.level, irq.dest_mode, irq.delivery_mode,
                    irq.vector);
 
+        mutex_lock(&apic->vcpu->kvm->irq_lock);
         kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq);
+        mutex_unlock(&apic->vcpu->kvm->irq_lock);
 }
 
 static u32 apic_get_tmcct(struct kvm_lapic *apic)