Re: [dpdk-dev] [PATCH v4 1/5] ethdev: negotiate delivery of packet metadata from HW to PMD

[Ivan Malov <Ivan.Malov@oktetlabs.ru>]

Hi Ori,

On 05/10/2021 15:03, Ori Kam wrote:
> Hi Ivan,
> 
> Just a nit below.
> 
>> -----Original Message-----
>> From: Ivan Malov <ivan.malov@oktetlabs.ru>
>> Sent: Tuesday, October 5, 2021 2:50 AM
>> Subject: [PATCH v4 1/5] ethdev: negotiate delivery of packet metadata from
>> HW to PMD
>>
>> Provide an API to let the application control the NIC's ability to deliver specific
>> kinds of per-packet metadata to the PMD.
>>
>> Checks for the NIC's ability to set these kinds of metadata in the first place
>> (support for the flow actions) belong in flow API responsibility domain (flow
>> validate mechanism).
>> This topic is out of scope of the new API in question.
>>
>> The PMD's ability to deliver received metadata to the user by virtue of mbuf
>> fields should be covered by mbuf library.
>> It is also out of scope of the new API in question.
>>
> 
> +1 very clear.
> 
>> Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
>> Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
>> Reviewed-by: Andy Moreton <amoreton@xilinx.com>
>> Acked-by: Ray Kinsella <mdr@ashroe.eu>
>> Acked-by: Jerin Jacob <jerinj@marvell.com>
>> ---
> 
> [Snip]
> 
>> --- a/lib/ethdev/rte_ethdev.h
>> +++ b/lib/ethdev/rte_ethdev.h
>> @@ -4902,6 +4902,59 @@ __rte_experimental  int
>> rte_eth_representor_info_get(uint16_t port_id,
>>   				 struct rte_eth_representor_info *info);
>>
>> +/** The NIC is able to deliver flag (if set) with packets to the PMD.
>> +*/ #define RTE_ETH_RX_METADATA_USER_FLAG (UINT64_C(1) << 0)
>> +
>> +/** The NIC is able to deliver mark ID with packets to the PMD. */
>> +#define RTE_ETH_RX_METADATA_USER_MARK (UINT64_C(1) << 1)
>> +
>> +/** The NIC is able to deliver tunnel ID with packets to the PMD. */
>> +#define RTE_ETH_RX_METADATA_TUNNEL_ID (UINT64_C(1) << 2)
>> +
>> +/**
>> + * @warning
>> + * @b EXPERIMENTAL: this API may change without prior notice
>> + *
>> + * Negotiate the NIC's ability to deliver specific kinds of metadata to the PMD.
>> + *
>> + * Invoke this API before the first rte_eth_dev_configure() invocation
>> + * to let the PMD make preparations that are inconvenient to do later.
>> + *
>> + * The negotiation process is as follows:
>> + *
>> + * - the application requests features intending to use at least some
>> +of them;
>> + * - the PMD responds with the guaranteed subset of the requested
>> +feature set;
>> + * - the application can retry negotiation with another set of
>> +features;
>> + * - the application can pass zero to clear the negotiation result;
>> + * - the last negotiated result takes effect upon the ethdev start.
> 
> Not upon ethdev configure?

Well, technically, doing "configure()" just closes the negotiation 
window. I guess, "to take effect" is "to be activated", and activation 
of Rx features typically happens on Rx subsystem start.

I know it might seem a bit inconsistent, but in any case the API 
contract says clearly that invocations of "metadata_negotiate()" should 
be done before "configure()".

Andrew?

> 
>> + *
>> + * @note
>> + *   The PMD is supposed to first consider enabling the requested feature set
>> + *   in its entirety. Only if it fails to do so, does it have the right to
>> + *   respond with a smaller set of the originally requested features.
>> + *
>> + * @note
>> + *   Return code (-ENOTSUP) does not necessarily mean that the requested
>> + *   features are unsupported. In this case, the application should just
>> + *   assume that these features can be used without prior negotiations.
>> + *
>> + * @param port_id
>> + *   Port (ethdev) identifier
>> + *
>> + * @param[inout] features
>> + *   Feature selection buffer
>> + *
>> + * @return
>> + *   - (-EBUSY) if the port can't handle this in its current state;
>> + *   - (-ENOTSUP) if the method itself is not supported by the PMD;
>> + *   - (-ENODEV) if *port_id* is invalid;
>> + *   - (-EINVAL) if *features* is NULL;
>> + *   - (-EIO) if the device is removed;
>> + *   - (0) on success
>> + */
>> +__rte_experimental
>> +int rte_eth_rx_metadata_negotiate(uint16_t port_id, uint64_t
>> +*features);
>> +
>>   #include <rte_ethdev_core.h>
>>
>>   /**
>> diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h index
>> 7b1ed7f110..75656ff9f8 100644
>> --- a/lib/ethdev/rte_flow.h
>> +++ b/lib/ethdev/rte_flow.h
>> @@ -1904,6 +1904,10 @@ enum rte_flow_action_type {
>>   	 * PKT_RX_FDIR_ID mbuf flags.
>>   	 *
>>   	 * See struct rte_flow_action_mark.
>> +	 *
>> +	 * One should negotiate mark delivery from the NIC to the PMD.
>> +	 * @see rte_eth_rx_metadata_negotiate()
>> +	 * @see RTE_ETH_RX_METADATA_USER_MARK
>>   	 */
>>   	RTE_FLOW_ACTION_TYPE_MARK,
>>
>> @@ -1912,6 +1916,10 @@ enum rte_flow_action_type {
>>   	 * sets the PKT_RX_FDIR mbuf flag.
>>   	 *
>>   	 * No associated configuration structure.
>> +	 *
>> +	 * One should negotiate flag delivery from the NIC to the PMD.
>> +	 * @see rte_eth_rx_metadata_negotiate()
>> +	 * @see RTE_ETH_RX_METADATA_USER_FLAG
>>   	 */
>>   	RTE_FLOW_ACTION_TYPE_FLAG,
>>
>> @@ -4223,6 +4231,10 @@ rte_flow_tunnel_match(uint16_t port_id,
>>   /**
>>    * Populate the current packet processing state, if exists, for the given mbuf.
>>    *
>> + * One should negotiate tunnel metadata delivery from the NIC to the HW.
>> + * @see rte_eth_rx_metadata_negotiate()
>> + * @see RTE_ETH_RX_METADATA_TUNNEL_ID
>> + *
>>    * @param port_id
>>    *   Port identifier of Ethernet device.
>>    * @param[in] m
>> diff --git a/lib/ethdev/version.map b/lib/ethdev/version.map index
>> 904bce6ea1..2e638c680e 100644
>> --- a/lib/ethdev/version.map
>> +++ b/lib/ethdev/version.map
>> @@ -247,6 +247,9 @@ EXPERIMENTAL {
>>   	rte_mtr_meter_policy_delete;
>>   	rte_mtr_meter_policy_update;
>>   	rte_mtr_meter_policy_validate;
>> +
>> +	# added in 21.11
>> +	rte_eth_rx_metadata_negotiate;
>>   };
>>
>>   INTERNAL {
>> --
>> 2.20.1
> Best,
> Ori
> 

-- 
Ivan M