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/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 319922137fdd..8dde36953af3 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1000,10 +1000,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
                         goto out;
                 if (irqchip_in_kernel(kvm)) {
                         __s32 status;
-                        mutex_lock(&kvm->lock);
+                        mutex_lock(&kvm->irq_lock);
                         status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
                                     irq_event.irq, irq_event.level);
-                        mutex_unlock(&kvm->lock);
+                        mutex_unlock(&kvm->irq_lock);
                         if (ioctl == KVM_IRQ_LINE_STATUS) {
                                 irq_event.status = status;
                                 if (copy_to_user(argp, &irq_event,