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, 2 insertions, 2 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 977af7ab8193..3837db65d33e 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -654,10 +654,10 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
         struct kvm_vcpu *vcpu;
         int i;
 
-        mutex_lock(&kvm->lock);
+        mutex_lock(&kvm->irq_lock);
         kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
         kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
-        mutex_unlock(&kvm->lock);
+        mutex_unlock(&kvm->irq_lock);
 
         /*
          * Provides NMI watchdog support via Virtual Wire mode.