KVM: protect kvm_usage_count with its own spinlock

The VM list need not be protected by a raw spinlock.  Separate the
two so that kvm_lock can be made non-raw.

Cc: kvm@vger.kernel.org
Cc: gleb@redhat.com
Cc: jan.kiszka@siemens.com
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index a9f366e73c8e..ba9e1c2150c2 100644
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -135,7 +135,11 @@ Name:		kvm_lock
 Type:           raw_spinlock
 Arch:           any
 Protects:       - vm_list
-                - hardware virtualization enable/disable
+
+Name:           kvm_count_lock
+Type:           raw_spinlock_t
+Arch:           any
+Protects:       - hardware virtualization enable/disable
 Comment:        'raw' because hardware enabling/disabling must be atomic /wrt
                 migration.