drm/i915: Differentiate between aliasing-ppgtt and ggtt pinning

	if (flags & PIN_GLOBAL)

		wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm);

	/* No more allocations allowed once we hold vm->mutex */

	err = mutex_lock_interruptible(&vma->vm->mutex);

	/*

	 * Differentiate between user/kernel vma inside the aliasing-ppgtt.

	 *

	 * We conflate the Global GTT with the user's vma when using the

	 * aliasing-ppgtt, but it is still vitally important to try and

	 * keep the use cases distinct. For example, userptr objects are

	 * not allowed inside the Global GTT as that will cause lock

	 * inversions when we have to evict them the mmu_notifier callbacks -

	 * but they are allowed to be part of the user ppGTT which can never

	 * be mapped. As such we try to give the distinct users of the same

	 * mutex, distinct lockclasses [equivalent to how we keep i915_ggtt

	 * and i915_ppgtt separate].

	 *

	 * NB this may cause us to mask real lock inversions -- while the

	 * code is safe today, lockdep may not be able to spot future

	 * transgressions.

	 */

	err = mutex_lock_interruptible_nested(&vma->vm->mutex,

					      !(flags & PIN_GLOBAL));

	if (err)

		goto err_fence;

	/* No more allocations allowed now we hold vm->mutex */

	if (unlikely(i915_vma_is_closed(vma))) {

		err = -ENOENT;

		goto err_unlock;

	if (err)

		goto out_rpm;

	err = mutex_lock_interruptible(&vm->mutex);

	err = mutex_lock_interruptible_nested(&vma->vm->mutex, !wakeref);

	if (err)

		goto out_rpm;