drm/vmwgfx: Optimize the buffer object swap_notify callback somewhat.

Only try to unmap cached maps when the buffer is moved into or out from
vram. Otherwise the underlying pages stay the same.

Also when unbinding resources from MOBs about to move, make sure we're
really moving out of MOB memory.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_bo.c

@@ -1105,16 +1105,18 @@ void vmw_bo_move_notify(struct ttm_buffer_object *bo,
 	vbo = container_of(bo, struct vmw_buffer_object, base);
 
 	/*
-	 * Kill any cached kernel maps before move. An optimization could
-	 * be to do this iff source or destination memory type is in VRAM.
+	 * Kill any cached kernel maps before move to or from VRAM.
+	 * With other types of moves, the underlying pages stay the same,
+	 * and the map can be kept.
 	 */
-	vmw_bo_unmap(vbo);
+	if (mem->mem_type == TTM_PL_VRAM || bo->mem.mem_type == TTM_PL_VRAM)
+		vmw_bo_unmap(vbo);
 
 	/*
 	 * If we're moving a backup MOB out of MOB placement, then make sure we
 	 * read back all resource content first, and unbind the MOB from
 	 * the resource.
 	 */
-	if (mem->mem_type != VMW_PL_MOB)
+	if (mem->mem_type != VMW_PL_MOB && bo->mem.mem_type == VMW_PL_MOB)
 		vmw_resource_unbind_list(vbo);
 }