[PATCH -rt] kvm: lockdep annotate mmu_lock wait_lock

[Marcelo Tosatti <mtosatti@redhat.com>]

wait_lock for mmu_lock, being allocated in kmalloc memory,
can't be tracked by LOCKDEP. 

Disable LOCKDEP verification for it.

Fixes

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 0 PID: 12386 Comm: qemu-kvm Not tainted 3.10.0-631.rt56.546.el7.x86_64.debug #1
 Hardware name: To be filled by O.E.M. To be filled by O.E.M./PMH61ML, BIOS 4.6.4 07/14/2011
 0000000000000002 00000000ee340fa8 ffff88008e2d7bc0 ffffffffa57534fc
 ffff88008e2d7bd0 ffffffffa574ce9f ffff88008e2d7c50 ffffffffa510e565
 ffff88008e2d7bf8 00000001a50cf83d 0000000000000000 ffff880000000000
 Call Trace:
 [<ffffffffa57534fc>] dump_stack+0x19/0x1b
 [<ffffffffa574ce9f>] register_lock_class.part.27+0x38/0x3c
 [<ffffffffa510e565>] __lock_acquire+0xcc5/0xdc0
 [<ffffffffa510efb2>] lock_acquire+0xb2/0x230
 [<ffffffffa5759ccd>] ? rt_spin_lock_slowlock+0x6d/0x3c0
 [<ffffffffa575c5f0>] _raw_spin_lock_irqsave+0x70/0xc0
 [<ffffffffa5759ccd>] ? rt_spin_lock_slowlock+0x6d/0x3c0
 [<ffffffffa5759ccd>] rt_spin_lock_slowlock+0x6d/0x3c0
 [<ffffffffa575b7ac>] rt_spin_lock+0x2c/0x60
 [<ffffffffc09b387f>] kvm_page_track_register_notifier+0x1f/0x60 [kvm]
 [<ffffffffc099a8eb>] kvm_mmu_init_vm+0x2b/0x30 [kvm]
 [<ffffffffc0987e04>] kvm_arch_init_vm+0x264/0x290 [kvm]
 [<ffffffffc096a14e>] kvm_dev_ioctl+0xde/0x740 [kvm]
 [<ffffffffa5250d45>] do_vfs_ioctl+0x365/0x5b0
 [<ffffffffa5251031>] SyS_ioctl+0xa1/0xc0
 [<ffffffffa57656ed>] tracesys+0xdd/0xe2
 ---------------------------
 | preempt count: 00000001 ]
 | 1-level deep critical section nesting:
 ----------------------------------------
 .. [<ffffffffa575c5cd>] .... _raw_spin_lock_irqsave+0x4d/0xc0
 .....[<ffffffffa5759ccd>] ..   ( <= rt_spin_lock_slowlock+0x6d/0x3c0)


Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7e80f62..6375db8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -613,6 +613,8 @@ static struct kvm *kvm_create_vm(unsigned long type)
 		return ERR_PTR(-ENOMEM);
 
 	spin_lock_init(&kvm->mmu_lock);
+
+	lockdep_set_novalidate_class(&kvm->mmu_lock.lock.wait_lock);
 	mmgrab(current->mm);
 	kvm->mm = current->mm;
 	kvm_eventfd_init(kvm);