KVM: add vm refcounting
the main purpose of adding this functions is the abilaty to release the
spinlock that protect the kvm list while still be able to do operations
on a specific kvm in a safe way.
Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 41d4b65..93ed78b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -193,6 +193,7 @@
mutex_init(&kvm->lock);
kvm_io_bus_init(&kvm->mmio_bus);
init_rwsem(&kvm->slots_lock);
+ atomic_set(&kvm->users_count, 1);
spin_lock(&kvm_lock);
list_add(&kvm->vm_list, &vm_list);
spin_unlock(&kvm_lock);
@@ -242,11 +243,25 @@
mmdrop(mm);
}
+void kvm_get_kvm(struct kvm *kvm)
+{
+ atomic_inc(&kvm->users_count);
+}
+EXPORT_SYMBOL_GPL(kvm_get_kvm);
+
+void kvm_put_kvm(struct kvm *kvm)
+{
+ if (atomic_dec_and_test(&kvm->users_count))
+ kvm_destroy_vm(kvm);
+}
+EXPORT_SYMBOL_GPL(kvm_put_kvm);
+
+
static int kvm_vm_release(struct inode *inode, struct file *filp)
{
struct kvm *kvm = filp->private_data;
- kvm_destroy_vm(kvm);
+ kvm_put_kvm(kvm);
return 0;
}