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Level Zero Validation Layer

Introduction

The Level Zero driver implementations by design do minimal error checking and do not guard against invalid API programming.

The Level Zero Validation layer is intended to be the primary Level Zero API error handling mechanism. The validation layer can be enabled at runtime with environment settings. When validation layer is enabled, L0 loader will inject calls to validation layer into L0 API DDI tables. When validation layer is not enabled, it is completely removed from the call path and has no performance cost.

Usage

The validation layer is built into a shared library named libze_validation_layer.so or ze_validation_layer.dll. This library must be in your library search path.

The validation layer can be enabled at runtime by setting ZE_ENABLE_VALIDATION_LAYER=1

Level Zero Loader will read this environment settings when either zeInit or zesInit is called and set up the DDI function pointer tables accordingly.

By default, no validation modes will be enabled. The individual validation modes must be enabled with the following environment settings:

  • ZE_ENABLE_PARAMETER_VALIDATION
  • ZE_ENABLE_HANDLE_LIFETIME
  • ZE_ENABLE_MEMORY_TRACKER (Not yet Implemeneted)
  • ZE_ENABLE_THREADING_VALIDATION (Not yet Implemeneted)

Validation Modes

ZE_ENABLE_ALL_VALIDATION

ZE_ENABLE_PARAMETER_VALIDATION

Parameter Validation mode maintains no internal state. It performs the following checks on each API before calling into driver:

  • Non-optional input pointers must not be nullptr
  • Non-optional input handles must not be 0
  • Input flags must only have valid flag values set
  • Input enums values must not be greater than max defined value
  • (Planned) stype must be set to a valid ze_structure_type_t for struct
  • (Planned) pNext must be nullptr or point to a valid extension struct

If a check fails, the appropriate error code is returned and the driver API is not called.

ZE_ENABLE_HANDLE_LIFETIME

This mode maintains an internal mapping of each handle type to a state structure.

  • When handle is created it is added to map
  • When handle is destroyed it is removed from map
  • When application inputs a handle it is validated
  • validates handles are properly destroyed
  • Additional per handle state checks added as needed
    • Example - Check ze_cmdlist_handle_t open or closed

ZE_ENABLE_THREADING_VALIDATION (Not yet Implemeneted)

Validates:

  • Objects are not concurrently reused in free-threaded API calls

Testing

There is a small set of negative test cases designed to test the validation layer in the level zero tests repo.

It is desired to add new unit tests directly into validation layer repo that executes with null driver and does not have additional dependencies. Help Wanted!

Contributing

See CONTRIBUTING for more information.