drm/msm: Do not unpin/evict exported dma-buf's

Our initial logic for excluding dma-bufs was not quite right.  In
particular we want msm_gem_get/put_pages() path used for exported
dma-bufs to increment/decrement the pin-count.

Also, in case the importer is vmap'ing the dma-buf, we need to be
sure to update the object's status, because it is now no longer
potentially evictable.

Fixes: 63f17ef drm/msm: Support evicting GEM objects to swap
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20210426235326.1230125-1-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

Author: robclark

drivers/gpu/drm/msm/msm_gem.c

@@ -190,13 +190,25 @@ struct page **msm_gem_get_pages(struct drm_gem_object *obj)
 	}
 
 	p = get_pages(obj);
+
+	if (!IS_ERR(p)) {
+		msm_obj->pin_count++;
+		update_inactive(msm_obj);
+	}
+
 	msm_gem_unlock(obj);
 	return p;
 }
 
 void msm_gem_put_pages(struct drm_gem_object *obj)
 {
-	/* when we start tracking the pin count, then do something here */
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+
+	msm_gem_lock(obj);
+	msm_obj->pin_count--;
+	GEM_WARN_ON(msm_obj->pin_count < 0);
+	update_inactive(msm_obj);
+	msm_gem_unlock(obj);
 }
 
 int msm_gem_mmap_obj(struct drm_gem_object *obj,
@@ -646,6 +658,8 @@ static void *get_vaddr(struct drm_gem_object *obj, unsigned madv)
 			ret = -ENOMEM;
 			goto fail;
 		}
+
+		update_inactive(msm_obj);
 	}
 
 	return msm_obj->vaddr;

drivers/gpu/drm/msm/msm_gem.h

@@ -221,7 +221,7 @@ static inline bool is_active(struct msm_gem_object *msm_obj)
 /* imported/exported objects are not purgeable: */
 static inline bool is_unpurgeable(struct msm_gem_object *msm_obj)
 {
-	return msm_obj->base.dma_buf && msm_obj->base.import_attach;
+	return msm_obj->base.import_attach || msm_obj->pin_count;
 }
 
 static inline bool is_purgeable(struct msm_gem_object *msm_obj)
@@ -271,7 +271,7 @@ static inline void mark_unpurgeable(struct msm_gem_object *msm_obj)
 
 static inline bool is_unevictable(struct msm_gem_object *msm_obj)
 {
-	return is_unpurgeable(msm_obj) || msm_obj->pin_count || msm_obj->vaddr;
+	return is_unpurgeable(msm_obj) || msm_obj->vaddr;
 }
 
 static inline void mark_evictable(struct msm_gem_object *msm_obj)