Re: [dpdk-dev] [v2 1/2] cryptodev: support enqueue callback functions

["Gujjar, Abhinandan S" <abhinandan.gujjar@intel.com>]

Hi Konstantin,

Please find some comments inline.

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Wednesday, September 16, 2020 7:10 PM
> To: Gujjar, Abhinandan S <abhinandan.gujjar@intel.com>; dev@dpdk.org
> Cc: Doherty, Declan <declan.doherty@intel.com>; jerinj@marvell.com;
> akhil.goyal@nxp.com; Vangati, Narender <narender.vangati@intel.com>;
> Gujjar, Abhinandan S <abhinandan.gujjar@intel.com>
> Subject: RE: [dpdk-dev] [v2 1/2] cryptodev: support enqueue callback
> functions
> 
> Hi Guijjar,
> 
> >
> > In an eventdev world, multiple workers (with ordered queue) will be
> > working on IPsec ESP processing. The ESP header's sequence number is
> > unique and has to be sequentially incremented in an orderly manner.
> > This rises a need for incrementing sequence number in crypto stage
> > especially in event crypto adapter. By adding a user callback to
> > cryptodev at enqueue burst, the user callback will get executed in the
> > context of event crypto adapter. This helps the application to
> > increment the ESP sequence number atomically and orderly manner.
> >
> > This patch adds APIs to add/remove callback functions. The callback
> > function will be called for each burst of crypto ops received on a
> > given crypto device queue pair.
> >
> > v1->v2:
> > Moved callback related members to the end of cryptodev struct Added
> > support for RCU
> >
> > Signed-off-by: Abhinandan Gujjar <abhinandan.gujjar@intel.com>
> > ---
> >  config/common_base                             |   1 +
> >  lib/librte_cryptodev/Makefile                  |   2 +-
> >  lib/librte_cryptodev/rte_cryptodev.c           | 157
> +++++++++++++++++++++++++
> >  lib/librte_cryptodev/rte_cryptodev.h           | 154
> +++++++++++++++++++++++-
> >  lib/librte_cryptodev/rte_cryptodev_version.map |   6 +
> >  5 files changed, 318 insertions(+), 2 deletions(-)
> >
> > diff --git a/config/common_base b/config/common_base index
> > fbf0ee7..f5ebde4 100644
> > --- a/config/common_base
> > +++ b/config/common_base
> > @@ -599,6 +599,7 @@
> CONFIG_RTE_LIBRTE_PMD_BBDEV_FPGA_5GNR_FEC=y
> >  #
> >  CONFIG_RTE_LIBRTE_CRYPTODEV=y
> >  CONFIG_RTE_CRYPTO_MAX_DEVS=64
> > +CONFIG_RTE_CRYPTODEV_CALLBACKS=y
> >
> >  #
> >  # Compile PMD for ARMv8 Crypto device diff --git
> > a/lib/librte_cryptodev/Makefile b/lib/librte_cryptodev/Makefile index
> > 73e77a2..514d552 100644
> > --- a/lib/librte_cryptodev/Makefile
> > +++ b/lib/librte_cryptodev/Makefile
> > @@ -10,7 +10,7 @@ LIB = librte_cryptodev.a  CFLAGS += -O3  CFLAGS +=
> > $(WERROR_FLAGS)  LDLIBS += -lrte_eal -lrte_mempool -lrte_ring
> > -lrte_mbuf -LDLIBS += -lrte_kvargs
> > +LDLIBS += -lrte_kvargs -lrte_rcu
> >
> >  # library source files
> >  SRCS-y += rte_cryptodev.c rte_cryptodev_pmd.c
> > cryptodev_trace_points.c diff --git
> > a/lib/librte_cryptodev/rte_cryptodev.c
> > b/lib/librte_cryptodev/rte_cryptodev.c
> > index 1dd795b..2fb3e35 100644
> > --- a/lib/librte_cryptodev/rte_cryptodev.c
> > +++ b/lib/librte_cryptodev/rte_cryptodev.c
> > @@ -38,6 +38,7 @@
> >  #include <rte_string_fns.h>
> >  #include <rte_compat.h>
> >  #include <rte_function_versioning.h>
> > +#include <rte_rcu_qsbr.h>
> >
> >  #include "rte_crypto.h"
> >  #include "rte_cryptodev.h"
> > @@ -499,6 +500,10 @@ struct
> rte_cryptodev_sym_session_pool_private_data {
> >  	return 0;
> >  }
> >
> > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > +/* spinlock for crypto device enq callbacks */ static rte_spinlock_t
> > +rte_cryptodev_enq_cb_lock = RTE_SPINLOCK_INITIALIZER; #endif
> >
> >  const char *
> >  rte_cryptodev_get_feature_name(uint64_t flag) @@ -1449,6 +1454,158
> @@
> > struct rte_cryptodev *
> >  	rte_spinlock_unlock(&rte_cryptodev_cb_lock);
> >  }
> >
> > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > +int
> > +rte_cryptodev_rcu_qsbr_add(uint8_t dev_id, struct rte_rcu_qsbr *qsbr)
> > +{
> > +
> > +	struct rte_cryptodev *dev;
> > +
> > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > +		return -EINVAL;
> > +	}
> > +
> > +	dev = &rte_crypto_devices[dev_id];
> > +	dev->qsbr = qsbr;
> > +	return 0;
> > +}
> 
> So if I understand your patch correctly you propose a new working model for
> crypto-devs:
> 1. Control-plane has to allocate/setup rcu_qsbr and do
> rte_cryptodev_rcu_qsbr_add().
> 2. Data-plane has somehow to obtain pointer to that rcu_qsbr and wrap
> cryptodev_enqueue()
>    with rcu_qsbr_quiescent()  or rcu_qsbr_online()/rcu_qsbr_offline().
Yes. I think, it is not a new model. It is same as RCU integration with LPM.
Please refer: https://patches.dpdk.org/cover/73673/

> 
> That seems quite a big change and I don't think it is acceptable for most
> users.
> From my perspective adding/installing call-backs to the dev has to be opaque
> to the data-plane code.
> Also note that different callbacks can be installed by different entities (libs)
> and might have no idea about each other.
> That's why I thought it would be better to make all this RCU stuff internal
> inside cryptodev:
>     hide all this rcu_qsbr allocation/setup inside cryptodev init/queue setup
>     invoke rcu_qsbr_online()/rcu_qsbr_offline() inside cryptodev_enqueue().
I have already tried exploring above stuffs. There are too many constraints.
The changes don't fit in, as per RCU design.
Moreover, having rcu api under enqueue_burst() will affect the performance.
The changes are more on control plane side, which is one time.
The data plane changes are minimal.

> 
> > +
> > +struct rte_cryptodev_enq_callback *
> > +rte_cryptodev_add_enq_callback(uint8_t dev_id,
> > +			       uint16_t qp_id,
> > +			       rte_cryptodev_enq_cb_fn cb_fn,
> > +			       void *cb_arg)
> > +{
> > +	struct rte_cryptodev *dev;
> > +	struct rte_cryptodev_enq_callback *cb, *tail;
> > +
> > +	if (!cb_fn)
> > +		return NULL;
> > +
> > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > +		return NULL;
> > +	}
> > +
> > +	dev = &rte_crypto_devices[dev_id];
> > +	if (qp_id >= dev->data->nb_queue_pairs) {
> > +		CDEV_LOG_ERR("Invalid queue_pair_id=%d", qp_id);
> > +		return NULL;
> > +	}
> > +
> > +	cb = rte_zmalloc(NULL, sizeof(*cb), 0);
> > +	if (cb == NULL) {
> > +		CDEV_LOG_ERR("Failed to allocate memory for callback on "
> > +			     "dev=%d, queue_pair_id=%d", dev_id, qp_id);
> > +		rte_errno = ENOMEM;
> > +		return NULL;
> > +	}
> > +
> > +	cb->fn = cb_fn;
> > +	cb->arg = cb_arg;
> > +
> > +	rte_spinlock_lock(&rte_cryptodev_enq_cb_lock);
> > +	if (dev->enq_cbs == NULL) {
> > +		dev->enq_cbs = rte_zmalloc(NULL, sizeof(cb) *
> > +					   dev->data->nb_queue_pairs, 0);
> > +		if (dev->enq_cbs == NULL) {
> > +			CDEV_LOG_ERR("Failed to allocate memory for
> callbacks");
> > +			rte_errno = ENOMEM;
> > +			rte_free(cb);
> > +			return NULL;
> > +		}
> > +	}
> > +
> > +	/* Add the callbacks in fifo order. */
> > +	tail = dev->enq_cbs[qp_id];
> > +	if (tail) {
> > +		while (tail->next)
> > +			tail = tail->next;
> > +		tail->next = cb;
> > +	} else
> > +		dev->enq_cbs[qp_id] = cb;
> > +
> > +	rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > +
> > +	return cb;
> > +}
> > +
> > +int
> > +rte_cryptodev_remove_enq_callback(uint8_t dev_id,
> > +				  uint16_t qp_id,
> > +				  struct rte_cryptodev_enq_callback *cb) {
> > +	struct rte_cryptodev *dev;
> > +	struct rte_cryptodev_enq_callback **prev_cb, *curr_cb;
> > +	uint16_t qp;
> > +	int free_mem;
> > +	int ret;
> > +
> > +	free_mem = 1;
> > +
> > +	if (!cb) {
> > +		CDEV_LOG_ERR("cb is NULL");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!rte_cryptodev_pmd_is_valid_dev(dev_id)) {
> > +		CDEV_LOG_ERR("Invalid dev_id=%" PRIu8, dev_id);
> > +		return -EINVAL;
> > +	}
> > +
> > +	dev = &rte_crypto_devices[dev_id];
> > +	if (qp_id >= dev->data->nb_queue_pairs) {
> > +		CDEV_LOG_ERR("Invalid queue_pair_id=%d", qp_id);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!dev->qsbr) {
> > +		CDEV_LOG_ERR("Rcu qsbr is NULL");
> > +		return -EINVAL;
> > +	}
> > +
> > +	rte_spinlock_lock(&rte_cryptodev_enq_cb_lock);
> > +	if (dev->enq_cbs == NULL) {
> > +		rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > +		return -EINVAL;
> > +	}
> > +
> > +	prev_cb = &dev->enq_cbs[qp_id];
> > +	for (; *prev_cb != NULL; prev_cb = &curr_cb->next) {
> > +		curr_cb = *prev_cb;
> > +		if (curr_cb == cb) {
> > +			/* Remove the user cb from the callback list. */
> > +			*prev_cb = curr_cb->next;
> > +			ret = 0;
> > +			break;
> > +		}
> > +	}
> > +
> > +	if (!ret) {
> > +		/* Call sync with invalid thread id as this is part of
> > +		 * control plane API */
> > +		rte_rcu_qsbr_synchronize(dev->qsbr,
> > +					 RTE_QSBR_THRID_INVALID);
> > +		rte_free(cb);
> > +	}
> > +
> > +	for (qp = 0; qp < dev->data->nb_queue_pairs; qp++)
> > +		if (dev->enq_cbs[qp] != NULL) {
> 
> Some reference count (number of callbacks) seems like a better approach
> here.
Ok.
> 
> > +			free_mem = 0;
> > +			break;
> > +		}
> > +
> > +	if (free_mem) {
> > +		rte_free(dev->enq_cbs);
> > +		dev->enq_cbs = NULL;
> > +	}
> > +
> > +	rte_spinlock_unlock(&rte_cryptodev_enq_cb_lock);
> > +
> > +	return ret;
> > +}
> > +#endif
> >
> >  int
> >  rte_cryptodev_sym_session_init(uint8_t dev_id, diff --git
> > a/lib/librte_cryptodev/rte_cryptodev.h
> > b/lib/librte_cryptodev/rte_cryptodev.h
> > index 7b3ebc2..2c7a47b 100644
> > --- a/lib/librte_cryptodev/rte_cryptodev.h
> > +++ b/lib/librte_cryptodev/rte_cryptodev.h
> > @@ -530,6 +530,32 @@ struct rte_cryptodev_qp_conf {  };
> >
> >  /**
> > + * Function type used for pre processing crypto ops when enqueue
> > +burst is
> > + * called.
> > + *
> > + * The callback function is called on enqueue burst immediately
> > + * before the crypto ops are put onto the hardware queue for processing.
> > + *
> > + * @param	dev_id		The identifier of the device.
> > + * @param	qp_id		The index of the queue pair in which ops are
> > + *				to be enqueued for processing. The value
> > + *				must be in the range [0, nb_queue_pairs - 1]
> > + *				previously supplied to
> > + *				*rte_cryptodev_configure*.
> > + * @param	ops		The address of an array of *nb_ops* pointers
> > + *				to *rte_crypto_op* structures which contain
> > + *				the crypto operations to be processed.
> > + * @param	nb_ops		The number of operations to process.
> > + * @param	user_param	The arbitrary user parameter passed in by the
> > + *				application when the callback was originally
> > + *				registered.
> > + * @return			The number of ops to be enqueued to the
> > + *				crypto device.
> > + */
> > +typedef uint16_t (*rte_cryptodev_enq_cb_fn)(uint16_t dev_id, uint16_t
> qp_id,
> > +		struct rte_crypto_op **ops, uint16_t nb_ops, void
> *user_param);
> > +
> > +/**
> >   * Typedef for application callback function to be registered by application
> >   * software for notification of device events
> >   *
> > @@ -853,7 +879,6 @@ struct rte_cryptodev_config {
> >  		enum rte_cryptodev_event_type event,
> >  		rte_cryptodev_cb_fn cb_fn, void *cb_arg);
> >
> > -
> >  typedef uint16_t (*dequeue_pkt_burst_t)(void *qp,
> >  		struct rte_crypto_op **ops,	uint16_t nb_ops);
> >  /**< Dequeue processed packets from queue pair of a device. */ @@
> > -870,6 +895,17 @@ typedef uint16_t (*enqueue_pkt_burst_t)(void *qp,
> >  /** Structure to keep track of registered callbacks */
> > TAILQ_HEAD(rte_cryptodev_cb_list, rte_cryptodev_callback);
> >
> > +/**
> > + * @internal
> > + * Structure used to hold information about the callbacks to be
> > +called for a
> > + * queue pair on enqueue.
> > + */
> > +struct rte_cryptodev_enq_callback {
> > +	struct rte_cryptodev_enq_callback *next;
> > +	rte_cryptodev_enq_cb_fn fn;
> > +	void *arg;
> > +};
> > +
> >  /** The data structure associated with each crypto device. */  struct
> > rte_cryptodev {
> >  	dequeue_pkt_burst_t dequeue_burst;
> > @@ -898,6 +934,14 @@ struct rte_cryptodev {
> >  	__extension__
> >  	uint8_t attached : 1;
> >  	/**< Flag indicating the device is attached */
> > +
> > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > +	struct rte_cryptodev_enq_callback **enq_cbs;
> > +	/**< User application callback for pre enqueue processing */
> > +
> > +	struct rte_rcu_qsbr *qsbr;
> > +	/** < RCU QSBR variable for rte_cryptodev_enq_callback */
> 
> Probably better to have both these fields per queue.
> Space for them can be allocated at dev_configure() or so.
enq_cbs is allocated during callback add.
Unlike ethdev, each cryptodev have their own max queue pair. There is no macro for that.
I think, single RCU should be good enough, as it has mechanism to track all its reporting threads.

> BTW, wouldn't it make sense to have ability to add callback for dequeue too?
As mentioned in the commit message, this patch was driven by a requirement.
If required, callback for the dequeue can be added in a separate patch. 
> 
> > +#endif
> >  } __rte_cache_aligned;
> >
> >  void *
> > @@ -1019,6 +1063,18 @@ struct rte_cryptodev_data {
> >  		struct rte_crypto_op **ops, uint16_t nb_ops)  {
> >  	struct rte_cryptodev *dev = &rte_cryptodevs[dev_id];
> > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > +	if (unlikely(dev->enq_cbs != NULL && dev->enq_cbs[qp_id] !=
> NULL)) {
> > +		struct rte_cryptodev_enq_callback *cb =
> > +			dev->enq_cbs[qp_id];
> > +
> > +		do {
> > +			nb_ops = cb->fn(dev_id, qp_id, ops, nb_ops,
> > +					cb->arg);
> > +			cb = cb->next;
> > +		} while (cb != NULL);
> > +	}
> > +#endif
> >
> >  	rte_cryptodev_trace_enqueue_burst(dev_id, qp_id, (void **)ops,
> nb_ops);
> >  	return (*dev->enqueue_burst)(
> > @@ -1351,6 +1407,102 @@ struct rte_cryptodev_asym_session *
> >  	struct rte_cryptodev_sym_session *sess, union rte_crypto_sym_ofs
> ofs,
> >  	struct rte_crypto_sym_vec *vec);
> >
> > +#ifdef RTE_CRYPTODEV_CALLBACKS
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change without prior notice
> > + *
> > + * Add a user callback for a given crypto device and queue pair which
> > +will be
> > + * called on crypto ops enqueue.
> > + *
> > + * This API configures a function to be called for each burst of
> > +crypto ops
> > + * received on a given crypto device queue pair. The return value is
> > +a pointer
> > + * that can be used later to remove the callback using
> > + * rte_cryptodev_remove_enq_callback().
> > + *
> > + * Multiple functions are called in the order that they are added.
> > + *
> > + * @param	dev_id		The identifier of the device.
> > + * @param	qp_id		The index of the queue pair in which ops are
> > + *				to be enqueued for processing. The value
> > + *				must be in the range [0, nb_queue_pairs - 1]
> > + *				previously supplied to
> > + *				*rte_cryptodev_configure*.
> > + * @param	cb_fn		The callback function
> > + * @param	cb_arg		A generic pointer parameter which will be
> passed
> > + *				to each invocation of the callback function on
> > + *				this crypto device and queue pair.
> > + *
> > + * @return
> > + *   NULL on error.
> > + *   On success, a pointer value which can later be used to remove the
> callback.
> > + */
> > +
> > +__rte_experimental
> > +struct rte_cryptodev_enq_callback *
> > +rte_cryptodev_add_enq_callback(uint8_t dev_id,
> > +			       uint16_t qp_id,
> > +			       rte_cryptodev_enq_cb_fn cb_fn,
> > +			       void *cb_arg);
> > +
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change without prior notice
> > + *
> > + * Remove a user callback function for given crypto device and queue pair.
> > + *
> > + * This function is used to removed callbacks that were added to a
> > +crypto
> > + * device queue pair using rte_cryptodev_add_enq_callback().
> > + *
> > + * Note: The callback expects a RCU QSBR to be configured to
> > +synchronize
> > + * to free the memory. Application is expected to configure RCU QSBR
> > +after
> > + * adding an enqueue callback.
> > + *
> > + *
> > + * @param	dev_id		The identifier of the device.
> > + * @param	qp_id		The index of the queue pair in which ops are
> > + *				to be enqueued for processing. The value
> > + *				must be in the range [0, nb_queue_pairs - 1]
> > + *				previously supplied to
> > + *				*rte_cryptodev_configure*.
> > + * @param	cb		Pointer to user supplied callback created via
> > + *				rte_cryptodev_add_enq_callback().
> > + *
> > + * @return
> > + *   - 0: Success. Callback was removed.
> > + *   - -EINVAL:  The dev_id or the qp_id is out of range, or the callback
> > + *               is NULL or not found for the crypto device queue pair.
> > + */
> > +
> > +__rte_experimental
> > +int rte_cryptodev_remove_enq_callback(uint8_t dev_id,
> > +				  uint16_t qp_id,
> > +				  struct rte_cryptodev_enq_callback *cb);
> > +
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change without prior notice
> > + *
> > + * Associate RCU QSBR variable with a cryptodev.
> > + *
> > + * This function is used to add RCU QSBR to a crypto device.
> > + * The purpose of RCU is to help multiple threads to synchronize
> > + * with each other before initiating adding/removing callback
> > + * while dataplane threads are running enqueue callbacks.
> > + *
> > + * @param	dev_id		The identifier of the device.
> > + * @param	qsr		RCU QSBR configuration
> > + * @return
> > + *   On success - 0
> > + *   On error - EINVAL.
> > + */
> > +
> > +__rte_experimental
> > +int rte_cryptodev_rcu_qsbr_add(uint8_t dev_id, struct rte_rcu_qsbr
> > +*qsbr); #endif
> > +
> >  #ifdef __cplusplus
> >  }
> >  #endif
> > diff --git a/lib/librte_cryptodev/rte_cryptodev_version.map
> > b/lib/librte_cryptodev/rte_cryptodev_version.map
> > index 02f6dcf..46de3ca 100644
> > --- a/lib/librte_cryptodev/rte_cryptodev_version.map
> > +++ b/lib/librte_cryptodev/rte_cryptodev_version.map
> > @@ -64,6 +64,7 @@ DPDK_20.0 {
> >  	rte_cryptodev_sym_capability_get;
> >  };
> >
> > +
> >  EXPERIMENTAL {
> >  	global:
> >
> > @@ -105,4 +106,9 @@ EXPERIMENTAL {
> >
> >  	# added in 20.08
> >  	rte_cryptodev_get_qp_status;
> > +
> > +	# added in 20.11
> > +	rte_cryptodev_add_enq_callback;
> > +	rte_cryptodev_remove_enq_callback;
> > +	rte_cryptodev_rcu_qsbr_add;
> >  };
> > --
> > 1.9.1