drm/i915/gt: Mark context->state vma as active while pinned

As we use the active state to keep the vma alive while we are reading
its contents during GPU error capture, we need to mark the
context->state vma as active during execution if we want to include it
in the error state.
Reported-by: NLionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: b1e3177b ("drm/i915: Coordinate i915_active with its own mutex")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: NLionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200110110402.1231745-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_context.c

@@ -160,6 +160,10 @@ static int __context_pin_state(struct i915_vma *vma)
 	if (err)
 		return err;
 
+	err = i915_active_acquire(&vma->active);
+	if (err)
+		goto err_unpin;
+
 	/*
 	 * And mark it as a globally pinned object to let the shrinker know
 	 * it cannot reclaim the object until we release it.
@@ -168,11 +172,16 @@ static int __context_pin_state(struct i915_vma *vma)
 	vma->obj->mm.dirty = true;
 
 	return 0;
+
+err_unpin:
+	i915_vma_unpin(vma);
+	return err;
 }
 
 static void __context_unpin_state(struct i915_vma *vma)
 {
 	i915_vma_make_shrinkable(vma);
+	i915_active_release(&vma->active);
 	__i915_vma_unpin(vma);
 }