xref: /dpdk/doc/guides/prog_guide/cryptodev_lib.rst (revision d2d7f0190bce57b2a07942e7c11a1e77a9c029ca)

..  SPDX-License-Identifier: BSD-3-Clause
    Copyright(c) 2016-2020 Intel Corporation.

Cryptography Device Library
===========================

The cryptodev library provides a Crypto device framework for management and
provisioning of hardware and software Crypto poll mode drivers, defining generic
APIs which support a number of different Crypto operations. The framework
currently only supports cipher, authentication, chained cipher/authentication
and AEAD symmetric and asymmetric Crypto operations.


Design Principles
-----------------

The cryptodev library follows the same basic principles as those used in DPDK's
Ethernet Device framework. The Crypto framework provides a generic Crypto device
framework which supports both physical (hardware) and virtual (software) Crypto
devices as well as a generic Crypto API which allows Crypto devices to be
managed and configured and supports Crypto operations to be provisioned on
Crypto poll mode driver.


Device Management
-----------------

Device Creation
~~~~~~~~~~~~~~~

Physical Crypto devices are discovered during the PCI probe/enumeration of the
EAL function which is executed at DPDK initialization, based on
their PCI device identifier, each unique PCI BDF (bus/bridge, device,
function). Specific physical Crypto devices, like other physical devices in DPDK
can be listed using the EAL command line options.

Virtual devices can be created by two mechanisms, either using the EAL command
line options or from within the application using an EAL API directly.

From the command line using the --vdev EAL option

.. code-block:: console

   --vdev  'crypto_aesni_mb0,max_nb_queue_pairs=2,socket_id=0'

.. Note::

   * If DPDK application requires multiple software crypto PMD devices then required
     number of ``--vdev`` with appropriate libraries are to be added.

   * An Application with crypto PMD instances sharing the same library requires unique ID.

   Example: ``--vdev  'crypto_aesni_mb0' --vdev  'crypto_aesni_mb1'``

Or using the rte_vdev_init API within the application code.

.. code-block:: c

   rte_vdev_init("crypto_aesni_mb",
                     "max_nb_queue_pairs=2,socket_id=0")

All virtual Crypto devices support the following initialization parameters:

* ``max_nb_queue_pairs`` - maximum number of queue pairs supported by the device.
* ``socket_id`` - socket on which to allocate the device resources on.


Device Identification
~~~~~~~~~~~~~~~~~~~~~

Each device, whether virtual or physical is uniquely designated by two
identifiers:

- A unique device index used to designate the Crypto device in all functions
  exported by the cryptodev API.

- A device name used to designate the Crypto device in console messages, for
  administration or debugging purposes. For ease of use, the port name includes
  the port index.


Device Configuration
~~~~~~~~~~~~~~~~~~~~

The configuration of each Crypto device includes the following operations:

- Allocation of resources, including hardware resources if a physical device.
- Resetting the device into a well-known default state.
- Initialization of statistics counters.

The rte_cryptodev_configure API is used to configure a Crypto device.

.. code-block:: c

   int rte_cryptodev_configure(uint8_t dev_id,
                               struct rte_cryptodev_config *config)

The ``rte_cryptodev_config`` structure is used to pass the configuration
parameters for socket selection and number of queue pairs.

.. literalinclude:: ../../../lib/cryptodev/rte_cryptodev.h
   :language: c
   :start-after: Structure rte_cryptodev_config 8<
   :end-before: >8 End of structure rte_cryptodev_config.


Configuration of Queue Pairs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Each Crypto devices queue pair is individually configured through the
``rte_cryptodev_queue_pair_setup`` API.
Each queue pairs resources may be allocated on a specified socket.

.. code-block:: c

    int rte_cryptodev_queue_pair_setup(uint8_t dev_id, uint16_t queue_pair_id,
                const struct rte_cryptodev_qp_conf *qp_conf,
                int socket_id)


.. literalinclude:: ../../../lib/cryptodev/rte_cryptodev.h
   :language: c
   :start-after: Structure rte_cryptodev_qp_conf 8<
   :end-before: >8 End of structure rte_cryptodev_qp_conf.


The field ``mp_session`` is used for creating temporary session to process
the crypto operations in the session-less mode.
They can be the same other different mempools. Please note not all Cryptodev
PMDs supports session-less mode.


Logical Cores, Memory and Queues Pair Relationships
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Crypto device Library as the Poll Mode Driver library support NUMA for when
a processor’s logical cores and interfaces utilize its local memory. Therefore
Crypto operations, and in the case of symmetric Crypto operations, the session
and the mbuf being operated on, should be allocated from memory pools created
in the local memory. The buffers should, if possible, remain on the local
processor to obtain the best performance results and buffer descriptors should
be populated with mbufs allocated from a mempool allocated from local memory.

The run-to-completion model also performs better, especially in the case of
virtual Crypto devices, if the Crypto operation and session and data buffer is
in local memory instead of a remote processor's memory. This is also true for
the pipe-line model provided all logical cores used are located on the same
processor.

Multiple logical cores should never share the same queue pair for enqueuing
operations or dequeuing operations on the same Crypto device since this would
require global locks and hinder performance. It is however possible to use a
different logical core to dequeue an operation on a queue pair from the logical
core which it was enqueued on. This means that a crypto burst enqueue/dequeue
APIs are a logical place to transition from one logical core to another in a
packet processing pipeline.


Device Features and Capabilities
---------------------------------

Crypto devices define their functionality through two mechanisms, global device
features and algorithm capabilities. Global devices features identify device
wide level features which are applicable to the whole device such as
the device having hardware acceleration or supporting symmetric and/or asymmetric
Crypto operations.

The capabilities mechanism defines the individual algorithms/functions which
the device supports, such as a specific symmetric Crypto cipher,
authentication operation or Authenticated Encryption with Associated Data
(AEAD) operation.


Device Features
~~~~~~~~~~~~~~~

Currently the following Crypto device features are defined:

* Symmetric Crypto operations
* Asymmetric Crypto operations
* Chaining of symmetric Crypto operations
* SSE accelerated SIMD vector operations
* AVX accelerated SIMD vector operations
* AVX2 accelerated SIMD vector operations
* AESNI accelerated instructions
* Hardware off-load processing


Device Operation Capabilities
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Crypto capabilities which identify particular algorithm which the Crypto PMD
supports are  defined by the operation type, the operation transform, the
transform identifier and then the particulars of the transform. For the full
scope of the Crypto capability see the definition of the structure in the
*DPDK API Reference*.

.. code-block:: c

   struct rte_cryptodev_capabilities;

Each Crypto poll mode driver defines its own private array of capabilities
for the operations it supports. Below is an example of the capabilities for a
PMD which supports the authentication algorithm SHA1_HMAC and the cipher
algorithm AES_CBC.

.. code-block:: c

    static const struct rte_cryptodev_capabilities pmd_capabilities[] = {
        {    /* SHA1 HMAC */
            .op = RTE_CRYPTO_OP_TYPE_SYMMETRIC,
            .sym = {
                .xform_type = RTE_CRYPTO_SYM_XFORM_AUTH,
                .auth = {
                    .algo = RTE_CRYPTO_AUTH_SHA1_HMAC,
                    .block_size = 64,
                    .key_size = {
                        .min = 64,
                        .max = 64,
                        .increment = 0
                    },
                    .digest_size = {
                        .min = 12,
                        .max = 12,
                        .increment = 0
                    },
                    .aad_size = { 0 },
                    .iv_size = { 0 }
                }
            }
        },
        {    /* AES CBC */
            .op = RTE_CRYPTO_OP_TYPE_SYMMETRIC,
            .sym = {
                .xform_type = RTE_CRYPTO_SYM_XFORM_CIPHER,
                .cipher = {
                    .algo = RTE_CRYPTO_CIPHER_AES_CBC,
                    .block_size = 16,
                    .key_size = {
                        .min = 16,
                        .max = 32,
                        .increment = 8
                    },
                    .iv_size = {
                        .min = 16,
                        .max = 16,
                        .increment = 0
                    }
                }
            }
        }
    }


Capabilities Discovery
~~~~~~~~~~~~~~~~~~~~~~

Discovering the features and capabilities of a Crypto device poll mode driver
is achieved through the ``rte_cryptodev_info_get`` function.

.. code-block:: c

   void rte_cryptodev_info_get(uint8_t dev_id,
                               struct rte_cryptodev_info *dev_info);

This allows the user to query a specific Crypto PMD and get all the device
features and capabilities. The ``rte_cryptodev_info`` structure contains all the
relevant information for the device.

.. literalinclude:: ../../../lib/cryptodev/rte_cryptodev.h
   :language: c
   :start-after: Structure rte_cryptodev_info 8<
   :end-before: >8 End of structure rte_cryptodev_info.


Operation Processing
--------------------

Scheduling of Crypto operations on DPDK's application data path is
performed using a burst oriented asynchronous API set. A queue pair on a Crypto
device accepts a burst of Crypto operations using enqueue burst API. On physical
Crypto devices the enqueue burst API will place the operations to be processed
on the devices hardware input queue, for virtual devices the processing of the
Crypto operations is usually completed during the enqueue call to the Crypto
device. The dequeue burst API will retrieve any processed operations available
from the queue pair on the Crypto device, from physical devices this is usually
directly from the devices processed queue, and for virtual device's from a
``rte_ring`` where processed operations are placed after being processed on the
enqueue call.


Private data
~~~~~~~~~~~~
For session-based operations, the set and get API provides a mechanism for an
application to store and retrieve the private user data information stored along
with the crypto session.

For example, suppose an application is submitting a crypto operation with a session
associated and wants to indicate private user data information which is required to be
used after completion of the crypto operation. In this case, the application can use
the set API to set the user data and retrieve it using get API.

.. code-block:: c

	int rte_cryptodev_sym_session_set_user_data(
		struct rte_cryptodev_sym_session *sess,	void *data, uint16_t size);

	void * rte_cryptodev_sym_session_get_user_data(
		struct rte_cryptodev_sym_session *sess);

Please note the ``size`` passed to set API cannot be bigger than the predefined
``user_data_sz`` when creating the session header mempool, otherwise the
function will return error. Also when ``user_data_sz`` was defined as ``0`` when
creating the session header mempool, the get API will always return ``NULL``.

For session-less mode, the private user data information can be placed along with the
``struct rte_crypto_op``. The ``rte_crypto_op::private_data_offset`` indicates the
start of private data information. The offset is counted from the start of the
rte_crypto_op including other crypto information such as the IVs (since there can
be an IV also for authentication).

User callback APIs
~~~~~~~~~~~~~~~~~~
The add APIs configures a user callback function to be called for each burst of crypto
ops received/sent on a given crypto device queue pair. The return value is a pointer
that can be used later to remove the callback using remove API. Application is expected
to register a callback function of type ``rte_cryptodev_callback_fn``. Multiple callback
functions can be added for a given queue pair. API does not restrict on maximum number of
callbacks.

Callbacks registered by application would not survive ``rte_cryptodev_configure`` as it
reinitializes the callback list. It is user responsibility to remove all installed
callbacks before calling ``rte_cryptodev_configure`` to avoid possible memory leakage.

So, the application is expected to add user callback after ``rte_cryptodev_configure``.
The callbacks can also be added at the runtime. These callbacks get executed when
``rte_cryptodev_enqueue_burst``/``rte_cryptodev_dequeue_burst`` is called.

.. code-block:: c

	struct rte_cryptodev_cb *
		rte_cryptodev_add_enq_callback(uint8_t dev_id, uint16_t qp_id,
					       rte_cryptodev_callback_fn cb_fn,
					       void *cb_arg);

	struct rte_cryptodev_cb *
		rte_cryptodev_add_deq_callback(uint8_t dev_id, uint16_t qp_id,
					       rte_cryptodev_callback_fn cb_fn,
					       void *cb_arg);

	uint16_t (* rte_cryptodev_callback_fn)(uint16_t dev_id, uint16_t qp_id,
					       struct rte_crypto_op **ops,
					       uint16_t nb_ops, void *user_param);

The remove API removes a callback function added by
``rte_cryptodev_add_enq_callback``/``rte_cryptodev_add_deq_callback``.

.. code-block:: c

	int rte_cryptodev_remove_enq_callback(uint8_t dev_id, uint16_t qp_id,
					      struct rte_cryptodev_cb *cb);

	int rte_cryptodev_remove_deq_callback(uint8_t dev_id, uint16_t qp_id,
					      struct rte_cryptodev_cb *cb);


Enqueue / Dequeue Burst APIs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The burst enqueue API uses a Crypto device identifier and a queue pair
identifier to specify the Crypto device queue pair to schedule the processing on.
The ``nb_ops`` parameter is the number of operations to process which are
supplied in the ``ops`` array of ``rte_crypto_op`` structures.
The enqueue function returns the number of operations it actually enqueued for
processing, a return value equal to ``nb_ops`` means that all packets have been
enqueued.

.. code-block:: c

   uint16_t rte_cryptodev_enqueue_burst(uint8_t dev_id, uint16_t qp_id,
                                        struct rte_crypto_op **ops, uint16_t nb_ops)

The dequeue API uses the same format as the enqueue API of processed but
the ``nb_ops`` and ``ops`` parameters are now used to specify the max processed
operations the user wishes to retrieve and the location in which to store them.
The API call returns the actual number of processed operations returned, this
can never be larger than ``nb_ops``.

.. code-block:: c

   uint16_t rte_cryptodev_dequeue_burst(uint8_t dev_id, uint16_t qp_id,
                                        struct rte_crypto_op **ops, uint16_t nb_ops)


Operation Representation
~~~~~~~~~~~~~~~~~~~~~~~~

An Crypto operation is represented by an rte_crypto_op structure, which is a
generic metadata container for all necessary information required for the
Crypto operation to be processed on a particular Crypto device poll mode driver.

.. figure:: img/crypto_op.*

The operation structure includes the operation type, the operation status
and the session type (session-based/less), a reference to the operation
specific data, which can vary in size and content depending on the operation
being provisioned. It also contains the source mempool for the operation,
if it allocated from a mempool.

If Crypto operations are allocated from a Crypto operation mempool, see next
section, there is also the ability to allocate private memory with the
operation for applications purposes.

Application software is responsible for specifying all the operation specific
fields in the ``rte_crypto_op`` structure which are then used by the Crypto PMD
to process the requested operation.


Operation Management and Allocation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The cryptodev library provides an API set for managing Crypto operations which
utilize the Mempool Library to allocate operation buffers. Therefore, it ensures
that the crypto operation is interleaved optimally across the channels and
ranks for optimal processing.
A ``rte_crypto_op`` contains a field indicating the pool that it originated from.
When calling ``rte_crypto_op_free(op)``, the operation returns to its original pool.

.. code-block:: c

   extern struct rte_mempool *
   rte_crypto_op_pool_create(const char *name, enum rte_crypto_op_type type,
                             unsigned nb_elts, unsigned cache_size, uint16_t priv_size,
                             int socket_id);

During pool creation ``rte_crypto_op_init()`` is called as a constructor to
initialize each Crypto operation which subsequently calls
``__rte_crypto_op_reset()`` to configure any operation type specific fields based
on the type parameter.


``rte_crypto_op_alloc()`` and ``rte_crypto_op_bulk_alloc()`` are used to allocate
Crypto operations of a specific type from a given Crypto operation mempool.
``__rte_crypto_op_reset()`` is called on each operation before being returned to
allocate to a user so the operation is always in a good known state before use
by the application.

.. code-block:: c

   struct rte_crypto_op *rte_crypto_op_alloc(struct rte_mempool *mempool,
                                             enum rte_crypto_op_type type)

   unsigned rte_crypto_op_bulk_alloc(struct rte_mempool *mempool,
                                     enum rte_crypto_op_type type,
                                     struct rte_crypto_op **ops, uint16_t nb_ops)

``rte_crypto_op_free()`` is called by the application to return an operation to
its allocating pool.

.. code-block:: c

   void rte_crypto_op_free(struct rte_crypto_op *op)


Symmetric Cryptography Support
------------------------------

The cryptodev library currently provides support for the following symmetric
Crypto operations; cipher, authentication, including chaining of these
operations, as well as also supporting AEAD operations.


Session and Session Management
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sessions are used in symmetric cryptographic processing to store the immutable
data defined in a cryptographic transform which is used in the operation
processing of a packet flow. Sessions are used to manage information such as
expand cipher keys and HMAC IPADs and OPADs, which need to be calculated for a
particular Crypto operation, but are immutable on a packet to packet basis for
a flow. Crypto sessions cache this immutable data in a optimal way for the
underlying PMD and this allows further acceleration of the offload of
Crypto workloads.

The Crypto device framework provides APIs to create session mempool and allocate
and initialize sessions for crypto devices, where sessions are mempool objects.
The application has to use ``rte_cryptodev_sym_session_pool_create()`` to
create the session mempool header and the private data with the size specified
by the user through the ``elt_size`` parameter in the function.
The session private data is for the driver to initialize and access
during crypto operations, hence the ``elt_size`` should be big enough
for all drivers that will share this mempool.
To obtain the proper session private data size of a crypto device,
the user can call ``rte_cryptodev_sym_get_private_session_size()`` function.
In case of heterogeneous crypto devices which will share the same session mempool,
the maximum session private data size of them should be passed.

Once the session mempools have been created, ``rte_cryptodev_sym_session_create()``
is used to allocate and initialize the session from the given mempool.
The created session can ONLY be used by the crypto devices sharing the same driver ID
as the device ID passed into the function as the parameter.
In addition, a symmetric transform chain is used to specify the operation and its parameters.
See the section below for details on transforms.

When a session is no longer used, user must call ``rte_cryptodev_sym_session_free()``
to uninitialize the session data and return the session
back to the mempool it belongs.


Transforms and Transform Chaining
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Symmetric Crypto transforms (``rte_crypto_sym_xform``) are the mechanism used
to specify the details of the Crypto operation. For chaining of symmetric
operations such as cipher encrypt and authentication generate, the next pointer
allows transform to be chained together. Crypto devices which support chaining
must publish the chaining of symmetric Crypto operations feature flag. Allocation of the
xform structure is in the application domain. To allow future API extensions in a
backwardly compatible manner, e.g. addition of a new parameter, the application should
zero the full xform struct before populating it.

Currently there are three transforms types cipher, authentication and AEAD.
Also it is important to note that the order in which the
transforms are passed indicates the order of the chaining.

.. literalinclude:: ../../../lib/cryptodev/rte_crypto_sym.h
   :language: c
   :start-after: Structure rte_crypto_sym_xform 8<
   :end-before: >8 End of structure rte_crypto_sym_xform.

The API does not place a limit on the number of transforms that can be chained
together but this will be limited by the underlying Crypto device poll mode
driver which is processing the operation.

.. figure:: img/crypto_xform_chain.*


Symmetric Operations
~~~~~~~~~~~~~~~~~~~~

The symmetric Crypto operation structure contains all the mutable data relating
to performing symmetric cryptographic processing on a referenced mbuf data
buffer. It is used for either cipher, authentication, AEAD and chained
operations.

As a minimum the symmetric operation must have a source data buffer (``m_src``),
a valid session (or transform chain if in session-less mode) and the minimum
authentication/ cipher/ AEAD parameters required depending on the type of operation
specified in the session or the transform
chain.

.. literalinclude:: ../../../lib/cryptodev/rte_crypto_sym.h
   :language: c
   :start-after: Structure rte_crypto_sym_op 8<
   :end-before: >8 End of structure rte_crypto_sym_op.


Synchronous mode
----------------

Some cryptodevs support synchronous mode alongside with a standard asynchronous
mode. In that case operations are performed directly when calling
``rte_cryptodev_sym_cpu_crypto_process`` method instead of enqueuing and
dequeuing an operation before. This mode of operation allows cryptodevs which
utilize CPU cryptographic acceleration to have significant performance boost
comparing to standard asynchronous approach. Cryptodevs supporting synchronous
mode have ``RTE_CRYPTODEV_FF_SYM_CPU_CRYPTO`` feature flag set.

To perform a synchronous operation a call to
``rte_cryptodev_sym_cpu_crypto_process`` has to be made with vectorized
operation descriptor (``struct rte_crypto_sym_vec``) containing:

- ``num`` - number of operations to perform,
- pointer to an array of size ``num`` containing a scatter-gather list
  descriptors of performed operations (``struct rte_crypto_sgl``). Each instance
  of ``struct rte_crypto_sgl`` consists of a number of segments and a pointer to
  an array of segment descriptors ``struct rte_crypto_vec``;
- pointers to arrays of size ``num`` containing IV, AAD and digest information
  in the ``cpu_crypto`` sub-structure,
- pointer to an array of size ``num`` where status information will be stored
  for each operation.

Function returns a number of successfully completed operations and sets
appropriate status number for each operation in the status array provided as
a call argument. Status different than zero must be treated as error.

For more details, e.g. how to convert an mbuf to an SGL, please refer to an
example usage in the IPsec library implementation.

Cryptodev Raw Data-path APIs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Crypto Raw data-path APIs are a set of APIs designed to enable external
libraries/applications to leverage the cryptographic processing provided by
DPDK crypto PMDs through the cryptodev API but in a manner that is not
dependent on native DPDK data structures (eg. rte_mbuf, rte_crypto_op, ... etc)
in their data-path implementation.

The raw data-path APIs have the following advantages:

- External data structure friendly design. The new APIs uses the operation
  descriptor ``struct rte_crypto_sym_vec`` that supports raw data pointer and
  IOVA addresses as input. Moreover, the APIs does not require the user to
  allocate the descriptor from mempool, nor requiring mbufs to describe input
  data's virtual and IOVA addresses. All these features made the translation
  from user's own data structure into the descriptor easier and more efficient.

- Flexible enqueue and dequeue operation. The raw data-path APIs gives the
  user more control to the enqueue and dequeue operations, including the
  capability of precious enqueue/dequeue count, abandoning enqueue or dequeue
  at any time, and operation status translation and set on the fly.

Cryptodev PMDs which support the raw data-path APIs will have
``RTE_CRYPTODEV_FF_SYM_RAW_DP`` feature flag presented. To use this feature,
the user shall create a local ``struct rte_crypto_raw_dp_ctx`` buffer and
extend to at least the length returned by ``rte_cryptodev_get_raw_dp_ctx_size``
function call. The created buffer is then initialized using
``rte_cryptodev_configure_raw_dp_ctx`` function with the ``is_update``
parameter as 0. The library and the crypto device driver will then set the
buffer and attach either the cryptodev sym session, the rte_security session,
or the cryptodev xform for session-less operation into the ctx buffer, and
set the corresponding enqueue and dequeue function handlers based on the
algorithm information stored in the session or xform. When the ``is_update``
parameter passed into ``rte_cryptodev_configure_raw_dp_ctx`` is 1, the driver
will not initialize the buffer but only update the session or xform and
the function handlers accordingly.

After the ``struct rte_crypto_raw_dp_ctx`` buffer is initialized, it is now
ready for enqueue and dequeue operation. There are two different enqueue
functions: ``rte_cryptodev_raw_enqueue`` to enqueue single raw data
operation, and ``rte_cryptodev_raw_enqueue_burst`` to enqueue a descriptor
with multiple operations. In case of the application uses similar approach to
``struct rte_crypto_sym_vec`` to manage its data burst but with different
data structure, using the ``rte_cryptodev_raw_enqueue_burst`` function may be
less efficient as this is a situation where the application has to loop over
all crypto operations to assemble the ``struct rte_crypto_sym_vec`` descriptor
from its own data structure, and then the driver will loop over them again to
translate every operation in the descriptor to the driver's specific queue data.
The ``rte_cryptodev_raw_enqueue`` should be used to save one loop for each data
burst instead.

The ``rte_cryptodev_raw_enqueue`` and ``rte_cryptodev_raw_enqueue_burst``
functions will return or set the enqueue status. ``rte_cryptodev_raw_enqueue``
will return the status directly, ``rte_cryptodev_raw_enqueue_burst`` will
return the number of operations enqueued or stored (explained as follows) and
set the ``enqueue_status`` buffer provided by the user. The possible
enqueue status values are:

- ``1``: the operation(s) is/are enqueued successfully.
- ``0``: the operation(s) is/are cached successfully in the crypto device queue
  but is not actually enqueued. The user shall call
  ``rte_cryptodev_raw_enqueue_done`` function after the expected operations
  are stored. The crypto device will then start enqueuing all of them at
  once.
- The negative integer: error occurred during enqueue.

Calling ``rte_cryptodev_configure_raw_dp_ctx`` with the parameter ``is_update``
set as 0 twice without the enqueue function returning or setting enqueue status
to 1 or ``rte_cryptodev_raw_enqueue_done`` function being called in between will
invalidate any operation stored in the device queue but not enqueued. This
feature is useful when the user wants to abandon partially enqueued operations
for a failed enqueue burst operation and try enqueuing in a whole later.

Similar as enqueue, there are two dequeue functions:
``rte_cryptodev_raw_dequeue`` for dequeuing single operation, and
``rte_cryptodev_raw_dequeue_burst`` for dequeuing a burst of operations (e.g.
all operations in a ``struct rte_crypto_sym_vec`` descriptor). The
``rte_cryptodev_raw_dequeue_burst`` function allows the user to provide callback
functions to retrieve dequeue count from the enqueued user data and write the
expected status value to the user data on the fly. The dequeue functions also
set the dequeue status:

- ``1``: the operation(s) is/are dequeued successfully.
- ``0``: the operation(s) is/are completed but is not actually dequeued (hence
  still kept in the device queue). The user shall call the
  ``rte_cryptodev_raw_dequeue_done`` function after the expected number of
  operations (e.g. all operations in a descriptor) are dequeued. The crypto
  device driver will then free them from the queue at once.
- The negative integer: error occurred during dequeue.

Calling ``rte_cryptodev_configure_raw_dp_ctx`` with the parameter ``is_update``
set as 0 twice without the dequeue functions execution changed dequeue_status
to 1 or ``rte_cryptodev_raw_dequeue_done`` function being called in between will
revert the crypto device queue's dequeue effort to the moment when the
``struct rte_crypto_raw_dp_ctx`` buffer is initialized. This feature is useful
when the user wants to abandon partially dequeued data and try dequeuing again
later in a whole.

There are a few limitations to the raw data path APIs:

* Only support in-place operations.
* APIs are NOT thread-safe.
* CANNOT mix the raw data-path API's enqueue with rte_cryptodev_enqueue_burst,
  or vice versa.

See *DPDK API Reference* for details on each API definitions.

Sample code
-----------

There are various sample applications that show how to use the cryptodev library,
such as the L2fwd with Crypto sample application (L2fwd-crypto) and
the IPsec Security Gateway application (ipsec-secgw).

While these applications demonstrate how an application can be created to perform
generic crypto operation, the required complexity hides the basic steps of
how to use the cryptodev APIs.

The following sample code shows the basic steps to encrypt several buffers
with AES-CBC (although performing other crypto operations is similar),
using one of the crypto PMDs available in DPDK.

.. code-block:: c

    /*
     * Simple example to encrypt several buffers with AES-CBC using
     * the Cryptodev APIs.
     */

    #define MAX_SESSIONS         1024
    #define NUM_MBUFS            1024
    #define POOL_CACHE_SIZE      128
    #define BURST_SIZE           32
    #define BUFFER_SIZE          1024
    #define AES_CBC_IV_LENGTH    16
    #define AES_CBC_KEY_LENGTH   16
    #define IV_OFFSET            (sizeof(struct rte_crypto_op) + \
                                 sizeof(struct rte_crypto_sym_op))

    struct rte_mempool *mbuf_pool, *crypto_op_pool;
    struct rte_mempool *session_pool, *session_priv_pool;
    unsigned int session_size;
    int ret;

    /* Initialize EAL. */
    ret = rte_eal_init(argc, argv);
    if (ret < 0)
        rte_exit(EXIT_FAILURE, "Invalid EAL arguments\n");

    uint8_t socket_id = rte_socket_id();

    /* Create the mbuf pool. */
    mbuf_pool = rte_pktmbuf_pool_create("mbuf_pool",
                                    NUM_MBUFS,
                                    POOL_CACHE_SIZE,
                                    0,
                                    RTE_MBUF_DEFAULT_BUF_SIZE,
                                    socket_id);
    if (mbuf_pool == NULL)
        rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");

    /*
     * The IV is always placed after the crypto operation,
     * so some private data is required to be reserved.
     */
    unsigned int crypto_op_private_data = AES_CBC_IV_LENGTH;

    /* Create crypto operation pool. */
    crypto_op_pool = rte_crypto_op_pool_create("crypto_op_pool",
                                            RTE_CRYPTO_OP_TYPE_SYMMETRIC,
                                            NUM_MBUFS,
                                            POOL_CACHE_SIZE,
                                            crypto_op_private_data,
                                            socket_id);
    if (crypto_op_pool == NULL)
        rte_exit(EXIT_FAILURE, "Cannot create crypto op pool\n");

    /* Create the virtual crypto device. */
    char args[128];
    const char *crypto_name = "crypto_aesni_mb0";
    snprintf(args, sizeof(args), "socket_id=%d", socket_id);
    ret = rte_vdev_init(crypto_name, args);
    if (ret != 0)
        rte_exit(EXIT_FAILURE, "Cannot create virtual device");

    uint8_t cdev_id = rte_cryptodev_get_dev_id(crypto_name);

    /* Get private session data size. */
    session_size = rte_cryptodev_sym_get_private_session_size(cdev_id);

    #ifdef USE_TWO_MEMPOOLS
    /* Create session mempool for the session header. */
    session_pool = rte_cryptodev_sym_session_pool_create("session_pool",
                                    MAX_SESSIONS,
                                    0,
                                    POOL_CACHE_SIZE,
                                    0,
                                    socket_id);

    /*
     * Create session private data mempool for the
     * private session data for the crypto device.
     */
    session_priv_pool = rte_mempool_create("session_pool",
                                    MAX_SESSIONS,
                                    session_size,
                                    POOL_CACHE_SIZE,
                                    0, NULL, NULL, NULL,
                                    NULL, socket_id,
                                    0);

    #else
    /* Use of the same mempool for session header and private data */
	session_pool = rte_cryptodev_sym_session_pool_create("session_pool",
                                    MAX_SESSIONS * 2,
                                    session_size,
                                    POOL_CACHE_SIZE,
                                    0,
                                    socket_id);

	session_priv_pool = session_pool;

    #endif

    /* Configure the crypto device. */
    struct rte_cryptodev_config conf = {
        .nb_queue_pairs = 1,
        .socket_id = socket_id
    };

    struct rte_cryptodev_qp_conf qp_conf = {
        .nb_descriptors = 2048,
        .mp_session = session_pool,
        .mp_session_private = session_priv_pool
    };

    if (rte_cryptodev_configure(cdev_id, &conf) < 0)
        rte_exit(EXIT_FAILURE, "Failed to configure cryptodev %u", cdev_id);

    if (rte_cryptodev_queue_pair_setup(cdev_id, 0, &qp_conf, socket_id) < 0)
        rte_exit(EXIT_FAILURE, "Failed to setup queue pair\n");

    if (rte_cryptodev_start(cdev_id) < 0)
        rte_exit(EXIT_FAILURE, "Failed to start device\n");

    /* Create the crypto transform. */
    uint8_t cipher_key[16] = {0};
    struct rte_crypto_sym_xform cipher_xform = {
        .next = NULL,
        .type = RTE_CRYPTO_SYM_XFORM_CIPHER,
        .cipher = {
            .op = RTE_CRYPTO_CIPHER_OP_ENCRYPT,
            .algo = RTE_CRYPTO_CIPHER_AES_CBC,
            .key = {
                .data = cipher_key,
                .length = AES_CBC_KEY_LENGTH
            },
            .iv = {
                .offset = IV_OFFSET,
                .length = AES_CBC_IV_LENGTH
            }
        }
    };

    /* Create crypto session and initialize it for the crypto device. */
    struct rte_cryptodev_sym_session *session;
    session = rte_cryptodev_sym_session_create(cdev_id, &cipher_xform,
                    session_pool);
    if (session == NULL)
        rte_exit(EXIT_FAILURE, "Session could not be created\n");

    /* Get a burst of crypto operations. */
    struct rte_crypto_op *crypto_ops[BURST_SIZE];
    if (rte_crypto_op_bulk_alloc(crypto_op_pool,
                            RTE_CRYPTO_OP_TYPE_SYMMETRIC,
                            crypto_ops, BURST_SIZE) == 0)
        rte_exit(EXIT_FAILURE, "Not enough crypto operations available\n");

    /* Get a burst of mbufs. */
    struct rte_mbuf *mbufs[BURST_SIZE];
    if (rte_pktmbuf_alloc_bulk(mbuf_pool, mbufs, BURST_SIZE) < 0)
        rte_exit(EXIT_FAILURE, "Not enough mbufs available");

    /* Initialize the mbufs and append them to the crypto operations. */
    unsigned int i;
    for (i = 0; i < BURST_SIZE; i++) {
        if (rte_pktmbuf_append(mbufs[i], BUFFER_SIZE) == NULL)
            rte_exit(EXIT_FAILURE, "Not enough room in the mbuf\n");
        crypto_ops[i]->sym->m_src = mbufs[i];
    }

    /* Set up the crypto operations. */
    for (i = 0; i < BURST_SIZE; i++) {
        struct rte_crypto_op *op = crypto_ops[i];
        /* Modify bytes of the IV at the end of the crypto operation */
        uint8_t *iv_ptr = rte_crypto_op_ctod_offset(op, uint8_t *,
                                                IV_OFFSET);

        generate_random_bytes(iv_ptr, AES_CBC_IV_LENGTH);

        op->sym->cipher.data.offset = 0;
        op->sym->cipher.data.length = BUFFER_SIZE;

        /* Attach the crypto session to the operation */
        rte_crypto_op_attach_sym_session(op, session);
    }

    /* Enqueue the crypto operations in the crypto device. */
    uint16_t num_enqueued_ops = rte_cryptodev_enqueue_burst(cdev_id, 0,
                                            crypto_ops, BURST_SIZE);

    /*
     * Dequeue the crypto operations until all the operations
     * are processed in the crypto device.
     */
    uint16_t num_dequeued_ops, total_num_dequeued_ops = 0;
    do {
        struct rte_crypto_op *dequeued_ops[BURST_SIZE];
        num_dequeued_ops = rte_cryptodev_dequeue_burst(cdev_id, 0,
                                        dequeued_ops, BURST_SIZE);
        total_num_dequeued_ops += num_dequeued_ops;

        /* Check if operation was processed successfully */
        for (i = 0; i < num_dequeued_ops; i++) {
            if (dequeued_ops[i]->status != RTE_CRYPTO_OP_STATUS_SUCCESS)
                rte_exit(EXIT_FAILURE,
                        "Some operations were not processed correctly");
        }

        rte_mempool_put_bulk(crypto_op_pool, (void **)dequeued_ops,
                                            num_dequeued_ops);
    } while (total_num_dequeued_ops < num_enqueued_ops);

Asymmetric Cryptography
-----------------------

The cryptodev library currently provides support for the following asymmetric
Crypto operations; RSA, Modular exponentiation and inversion, Diffie-Hellman and
Elliptic Curve Diffie-Hellman public and/or private key generation and shared
secret compute, DSA Signature generation and verification.

Session and Session Management
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sessions are used in asymmetric cryptographic processing to store the immutable
data defined in asymmetric cryptographic transform which is further used in the
operation processing. Sessions typically stores information, such as, public
and private key information or domain params or prime modulus data i.e. immutable
across data sets. Crypto sessions cache this immutable data in a optimal way for the
underlying PMD and this allows further acceleration of the offload of Crypto workloads.

Like symmetric, the Crypto device framework provides APIs to allocate and initialize
asymmetric sessions for crypto devices, where sessions are mempool objects.
It is the application's responsibility to create and manage the session mempools.
Application using both symmetric and asymmetric sessions should allocate and maintain
different sessions pools for each type.

An application can use ``rte_cryptodev_asym_session_pool_create()`` to create a mempool
with a specified number of elements. The element size will allow for the session header,
and the max private session size.
The max private session size is chosen based on available crypto devices,
the biggest private session size is used. This means any of those devices can be used,
and the mempool element will have available space for its private session data.

Once the session mempools have been created, ``rte_cryptodev_asym_session_create()``
is used to allocate and initialize an asymmetric session from the given mempool.
An asymmetric transform chain is used to specify the operation and its parameters.
See the section below for details on transforms.

When a session is no longer used, user must call ``rte_cryptodev_asym_session_clear()``
for each of the crypto devices that are using the session, to free all driver
private asymmetric session data. Once this is done, session should be freed using
``rte_cryptodev_asym_session_free()`` which returns them to their mempool.

Asymmetric Sessionless Support
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Asymmetric crypto framework supports session-less operations as well.

Fields that should be set by user are:

Member xform of struct rte_crypto_asym_op should point to the user created rte_crypto_asym_xform.
Note that rte_crypto_asym_xform should be immutable for the lifetime of associated crypto_op.

Member sess_type of rte_crypto_op should also be set to RTE_CRYPTO_OP_SESSIONLESS.

Transforms and Transform Chaining
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Asymmetric Crypto transforms (``rte_crypto_asym_xform``) are the mechanism used
to specify the details of the asymmetric Crypto operation. Next pointer within
xform allows transform to be chained together. Also it is important to note that
the order in which the transforms are passed indicates the order of the chaining. Allocation
of the xform structure is in the application domain. To allow future API extensions in a
backwardly compatible manner, e.g. addition of a new parameter, the application should
zero the full xform struct before populating it.

Not all asymmetric crypto xforms are supported for chaining. Currently supported
asymmetric crypto chaining is Diffie-Hellman private key generation followed by
public generation. Also, currently API does not support chaining of symmetric and
asymmetric crypto xforms.

Each xform defines specific asymmetric crypto algo. Currently supported are:
* RSA
* Modular operations (Exponentiation and Inverse)
* Diffie-Hellman
* DSA
* Elliptic Curve Diffie-Hellman
* None - special case where PMD may support a passthrough mode. More for diagnostic purpose

See *DPDK API Reference* for details on each rte_crypto_xxx_xform struct

Asymmetric Operations
~~~~~~~~~~~~~~~~~~~~~

The asymmetric Crypto operation structure contains all the mutable data relating
to asymmetric cryptographic processing on an input data buffer. It uses either
RSA, Modular, Diffie-Hellman or DSA operations depending upon session it is attached
to.

Every operation must carry a valid session handle which further carries information
on xform or xform-chain to be performed on op. Every xform type defines its own set
of operational params in their respective rte_crypto_xxx_op_param struct. Depending
on xform information within session, PMD picks up and process respective op_param
struct.
Unlike symmetric, asymmetric operations do not use mbufs for input/output.
They operate on data buffer of type ``rte_crypto_param``.

See *DPDK API Reference* for details on each rte_crypto_xxx_op_param struct

Private user data
~~~~~~~~~~~~~~~~~

Similar to symmetric above, asymmetric also has a set and get API that provides a
mechanism for an application to store and retrieve the private user data information
stored along with the crypto session.

.. code-block:: c

	int rte_cryptodev_asym_session_set_user_data(void *sess,
		void *data, uint16_t size);

	void * rte_cryptodev_asym_session_get_user_data(void *sess);

Please note the ``size`` passed to set API cannot be bigger than the predefined
``user_data_sz`` when creating the session mempool, otherwise the function will
return an error. Also when ``user_data_sz`` was defined as ``0`` when
creating the session mempool, the get API will always return ``NULL``.

Asymmetric crypto Sample code
-----------------------------

There's a unit test application test_cryptodev_asym.c inside unit test framework that
show how to setup and process asymmetric operations using cryptodev library.

The following code samples are taken from the test application mentioned above,
and show basic steps to compute modular exponentiation using an openssl PMD
available in DPDK (performing other crypto operations is similar except change
to respective op and xform setup).

.. note::
   The following code snippets are taken from multiple functions, so variable
   names may differ slightly between sections.

Configure the virtual device, queue pairs, crypto op pool and session mempool.

.. literalinclude:: ../../../app/test/test_cryptodev_asym.c
   :language: c
   :start-after: Device, op pool and session configuration for asymmetric crypto. 8<
   :end-before: >8 End of device, op pool and session configuration for asymmetric crypto section.
   :dedent: 1

Create MODEX data vectors.

.. literalinclude:: ../../../app/test/test_cryptodev_mod_test_vectors.h
   :language: c
   :start-after: MODEX data. 8<
   :end-before: >8 End of MODEX data.

Setup crypto xform to do modular exponentiation using data vectors.

.. literalinclude:: ../../../app/test/test_cryptodev_mod_test_vectors.h
   :language: c
   :start-after: MODEX vector. 8<
   :end-before: >8 End of MODEX vector.

Generate crypto op, create and attach a session, then process packets.

.. literalinclude:: ../../../app/test/test_cryptodev_asym.c
   :language: c
   :start-after: Create op, create session, and process packets. 8<
   :end-before: >8 End of create op, create session, and process packets section.
   :dedent: 1

.. note::
   The ``rte_cryptodev_asym_session`` struct is hidden from the application.
   The ``sess`` pointer used above is a void pointer.


Asymmetric Crypto Device API
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The cryptodev Library API is described in the
`DPDK API Reference <https://doc.dpdk.org/api/>`_


Device Statistics
-----------------

The Cryptodev library has support for displaying Crypto device information
through the Telemetry interface. Telemetry commands that can be used
are shown below.

#. Get the list of available Crypto devices by ID::

     --> /cryptodev/list
     {"/cryptodev/list": [0, 1, 2, 3]}

#. Get general information from a Crypto device::

     --> /cryptodev/info,0
     {"/cryptodev/info": {"device_name": "0000:1c:01.0_qat_sym",
     "max_nb_queue_pairs": 2}}

#. Get the statistics for a particular Crypto device::

     --> /cryptodev/stats,0
     {"/cryptodev/stats": {"enqueued_count": 0, "dequeued_count": 0,
     "enqueue_err_count": 0, "dequeue_err_count": 0}}

#. Get the capabilities of a particular Crypto device::

     --> /cryptodev/caps,0
     {"/cryptodev/caps": {"crypto_caps": [<array of serialized bytes of
     capabilities>], "crypto_caps_n": <number of capabilities>}}

For more information on how to use the Telemetry interface, see
the :doc:`../howto/telemetry`.