From WDK topic "EvtIoDeviceControl":
The EvtIoDeviceControl callback function can be called at IRQL <=
DISPATCH_LEVEL, unless the ExecutionLevel member of the device or driver's
WDF_OBJECT_ATTRIBUTES structure is set to WdfExecutionLevelPassive. (If your
driver is at the top of its driver stack, the callback function is called at
IRQL = PASSIVE_LEVEL.)

In OSR USB sample driver EvtIoDeviceControl is placed in the PAGE code
section, and contains PAGED_CODE macro. Driver doesn't set ExecutionLevel in
any place. Does this mean that this driver is at the top of driver stack, and
therefore, EvtIoDeviceControl is always called at PASSIVE_LEVEL? Is it
possible that such driver will be not at the top of driver stack?