1 files changed, 34 insertions, 5 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fc1b58a72757..9c2fd025b8ae 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2533,21 +2533,50 @@ int kvm_io_bus_read(struct kvm_io_bus *bus, gpa_t addr, int len, void *val)
         return -EOPNOTSUPP;
 }
 
-void kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
+int kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
                              struct kvm_io_device *dev)
 {
+        int ret;
+
         down_write(&kvm->slots_lock);
-        __kvm_io_bus_register_dev(bus, dev);
+        ret = __kvm_io_bus_register_dev(bus, dev);
         up_write(&kvm->slots_lock);
+
+        return ret;
 }
 
 /* An unlocked version. Caller must have write lock on slots_lock. */
-void __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
-                             struct kvm_io_device *dev)
+int __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
+                              struct kvm_io_device *dev)
 {
-        BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));
+        if (bus->dev_count > NR_IOBUS_DEVS-1)
+                return -ENOSPC;
 
         bus->devs[bus->dev_count++] = dev;
+
+        return 0;
+}
+
+void kvm_io_bus_unregister_dev(struct kvm *kvm,
+                               struct kvm_io_bus *bus,
+                               struct kvm_io_device *dev)
+{
+        down_write(&kvm->slots_lock);
+        __kvm_io_bus_unregister_dev(bus, dev);
+        up_write(&kvm->slots_lock);
+}
+
+/* An unlocked version. Caller must have write lock on slots_lock. */
+void __kvm_io_bus_unregister_dev(struct kvm_io_bus *bus,
+                                 struct kvm_io_device *dev)
+{
+        int i;
+
+        for (i = 0; i < bus->dev_count; i++)
+                if (bus->devs[i] == dev) {
+                        bus->devs[i] = bus->devs[--bus->dev_count];
+                        break;
+                }
 }
 
 static struct notifier_block kvm_cpu_notifier = {