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/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 314012323afe..4092b8dcd510 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -57,10 +57,10 @@ irqfd_inject(struct work_struct *work)
         struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
         struct kvm *kvm = irqfd->kvm;
 
-        mutex_lock(&kvm->lock);
+        mutex_lock(&kvm->irq_lock);
         kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
         kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
-        mutex_unlock(&kvm->lock);
+        mutex_unlock(&kvm->irq_lock);
 }
 
 /*