Re: [dpdk-dev] [RFC] eventdev: add crypto adapter API header

["Doherty, Declan" <declan.doherty@intel.com>]

On 29/11/2017 11:41 AM, Jerin Jacob wrote:
> -----Original Message-----

...

> 
> Adding Declan and Hemant.
> > IMO, RTE_EVENT_CRYPTO_ENQ_MULTI_EVENTQ may not be very useful
> from application perceptive as the scope is very limited.
> In real world use cases, we will be attaching destination event queue information
> to the session, not to the queue pair.
> 
> 
> IMO, RTE_EVENT_CRYPTO_ENQ_MBUF_MULTI_EVENTQ scheme may not very
> convenient for application writers as
> # it relies on mbuf private area memory. So it has additional memory alloc/free
> requirements.
> # additional overhead for application/PMD to write/read the event queue metadata
> information per packet.
> 
> Since we already have meta data structure in the crypto
> area, How about adding the destination event queue attributes
> in the PMD crypto session area and for, _session less_, we can add it
> in rte_crypto_op stricture? This will help in:
> 
> # Offloading HW specific meta data generation for event queue attributes
> to slow path.
> # From the application perspective, most likely the event queue parameters
> will be different for each session not per packet nor per event queue
> pair.
> 

Hey Jerin,

given my limited experience with eventdev, your proposed approach in 
general makes sense to me, in that a packet flow having crypto 
processing done will always be forwarded the same next stage event 
queue. So storing this state in the crypto session, or crypto op in the 
case of sessionless ops, seems sensible.

> Something like below to share my view. Exact details may be we can work it out.
> 

I terms of your proposed changes below, my main concern would be 
introducing dependencies on the eventdev library into cryptodev, as with 
this new crypto adpater you will have a dependency on cryptodev in 
eventdev.

I think the best approach would be to support opaque metadata in both 
the crypto op and crypto session structures, as this would allow other 
uses cases to be supported which aren't specific to eventdev to also 
store metadata across cryptodev processing.

> ➜ [master][dpdk.org] $ git diff
> diff --git a/lib/librte_cryptodev/rte_crypto.h
> b/lib/librte_cryptodev/rte_crypto.h
> index 3d672fe7d..b44ef673b 100644
> --- a/lib/librte_cryptodev/rte_crypto.h
> +++ b/lib/librte_cryptodev/rte_crypto.h
> @@ -115,6 +115,9 @@ struct rte_crypto_op {
>   
>          uint8_t reserved[5];
>          /**< Reserved bytes to fill 64 bits for future additions */
> 
> +#if 0
> + Crypto completion event attribute. For _session less_ crypto enqueue operation,
> + The will field shall be used by application to post the crypto completion event
> + upon the crypto enqueue operation complete.
> 
> + Note: In the case of session based crypto operation, SW based crypto adapter can use
> + this memory to store crypto event completion attributes from the PMD
> + specific session area.
> +
> + Note: ev.event_ptr will point to struct rte_crypto_op *op, So
> + that core can free the ops memory on event_dequeue().
> +#endif
> +
> +       struct rte_event ev;
> 
>          struct rte_mempool *mempool;
>          /**< crypto operation mempool which operation is allocated from
>   * */
>   
> diff --git a/lib/librte_cryptodev/rte_cryptodev.h
> b/lib/librte_cryptodev/rte_cryptodev.h
> index dade5548f..540b29e66 100644
> --- a/lib/librte_cryptodev/rte_cryptodev.h
> +++ b/lib/librte_cryptodev/rte_cryptodev.h
> @@ -945,6 +945,13 @@ rte_cryptodev_sym_session_init(uint8_t dev_id,
>                          struct rte_crypto_sym_xform *xforms,
>                          struct rte_mempool *mempool);
> 
> +#if 0
> + Create PMD specific session meta data for the destination event queue
> + attribute to post the crypto completion event on crypto work complete.
> +#endif
> +int
> +rte_cryptodev_sym_session_event_init(uint8_t dev_id,
> +                       struct rte_cryptodev_sym_session *sess,
> +                       struct rte_crypto_sym_xform *xforms,
> +                       struct rte_mempool *mempool,
> +                       struct rte_event ev);
> +
>   /**
>    * Frees private data for the device id, based on its device type,
>    * returning it to its mempool.
> 
> 
>> + *
>> + * The metadata offset is used to configure the location of the
>> + * rte_event_crypto_metadata structure within the mbuf's private metadata area.
>> + *
>> + * When the application sends crypto operations to the adapter,
>> + * the crypto queue pair identifier needs to be specified, similarly eventdev
>> + * parameters such as the flow id, scheduling type etc are needed by the
>> + * adapter when it enqueues mbufs from completed crypto operations to eventdev.
>> + */
>> +
>> +#ifdef __cplusplus
>> +extern "C" {
>> +#endif
>> +
>> +#include <stdint.h>
>> +#include <rte_service.h>
>> +
>> +#include "rte_eventdev.h"
>> +
>> +#define RTE_EVENT_CRYPTO_ADAPTER_MAX_INSTANCE 32
>> +
>> + /**
>> + * @warning
>> + * @b EXPERIMENTAL: this enum may change without prior notice
>> + *
>> + * Crypto event queue conf type
>> + */
>> +enum rte_event_crypto_conf_type {
>> +	RTE_EVENT_CRYPTO_CONF_TYPE_EVENT = 1,
>> +	/**< Refer RTE_EVENT_CRYPTO_ADAPTER_CAP_MULTI_EVENTQ */
>> +	RTE_EVENT_CRYPTO_CONF_TYPE_MBUF,
>> +	/**< Refer RTE_EVENT_CRYPTO_ADAPTER_CAP_MBUF_MULTI_EVENTQ */
>> +	RTE_EVENT_CRYPTO_CONF_TYPE_MAX
>> +};
> 
> See above.
> 
>> +
>> + /**
>> + * @warning
>> + * @b EXPERIMENTAL: this enum may change without prior notice
>> + *
>> + * Crypto event adapter type
>> + */
>> +enum rte_event_crypto_adapter_type {
>> +	RTE_EVENT_CRYPTO_ADAPTER_RX_ONLY = 1,
>> +	/**< Start only Rx part of crypto adapter.
>> +	* Packets dequeued from cryptodev are new to eventdev and
>> +	* events will be treated as RTE_EVENT_OP_NEW */
>> +	RTE_EVENT_CRYPTO_ADAPTER_RX_TX,
>> +	/**< Start both Rx & Tx part of crypto adapter.
>> +	* Packet's event context will be retained and
>> +	* event will be treated as RTE_EVENT_OP_FORWARD */
>> +};
> 
> How about leveraging ev.op based schematics as mentioned above?
>