[dpdk-dev] [PATCH] RFC: ethdev: add reassembly offload

[Xu, Rosen]

Hi,

> -----Original Message-----
> From: dev <dev-bounces at dpdk.org> On Behalf Of Akhil Goyal
> Sent: Monday, August 23, 2021 18:03
> To: dev at dpdk.org
> Cc: anoobj at marvell.com; Nicolau, Radu <radu.nicolau at intel.com>; Doherty,
> Declan <declan.doherty at intel.com>; hemant.agrawal at nxp.com;
> matan at nvidia.com; Ananyev, Konstantin <konstantin.ananyev at intel.com>;
> thomas at monjalon.net; adwivedi at marvell.com; Yigit, Ferruh
> <ferruh.yigit at intel.com>; andrew.rybchenko at oktetlabs.ru; Akhil Goyal
> <gakhil at marvell.com>
> Subject: [dpdk-dev] [PATCH] RFC: ethdev: add reassembly offload
> 
> Reassembly is a costly operation if it is done in software, however, if it is
> offloaded to HW, it can considerably save application cycles.
> The operation becomes even more costlier if IP fragmants are encrypted.
> 
> To resolve above two issues, a new offload DEV_RX_OFFLOAD_REASSEMBLY
> is introduced in ethdev for devices which can attempt reassembly of packets
> in hardware.
> rte_eth_dev_info is added with the reassembly capabilities which a device
> can support.
> Now, if IP fragments are encrypted, reassembly can also be attempted while
> doing inline IPsec processing.
> This is controlled by a flag in rte_security_ipsec_sa_options to enable
> reassembly of encrypted IP fragments in the inline path.
> 
> The resulting reassembled packet would be a typical segmented mbuf in case
> of success.
> 
> And if reassembly of fragments is failed or is incomplete (if fragments do not
> come before the reass_timeout), the mbuf is updated with an ol_flag
> PKT_RX_REASSEMBLY_INCOMPLETE and mbuf is returned as is. Now
> application may decide the fate of the packet to wait more for fragments to
> come or drop.
> 
> Signed-off-by: Akhil Goyal <gakhil at marvell.com>
> ---
>  lib/ethdev/rte_ethdev.c     |  1 +
>  lib/ethdev/rte_ethdev.h     | 18 +++++++++++++++++-
>  lib/mbuf/rte_mbuf_core.h    |  3 ++-
>  lib/security/rte_security.h | 10 ++++++++++
>  4 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c index
> 9d95cd11e1..1ab3a093cf 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -119,6 +119,7 @@ static const struct {
>  	RTE_RX_OFFLOAD_BIT2STR(VLAN_FILTER),
>  	RTE_RX_OFFLOAD_BIT2STR(VLAN_EXTEND),
>  	RTE_RX_OFFLOAD_BIT2STR(JUMBO_FRAME),
> +	RTE_RX_OFFLOAD_BIT2STR(REASSEMBLY),
>  	RTE_RX_OFFLOAD_BIT2STR(SCATTER),
>  	RTE_RX_OFFLOAD_BIT2STR(TIMESTAMP),
>  	RTE_RX_OFFLOAD_BIT2STR(SECURITY),
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h index
> d2b27c351f..e89a4dc1eb 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -1360,6 +1360,7 @@ struct rte_eth_conf {
>  #define DEV_RX_OFFLOAD_VLAN_FILTER	0x00000200
>  #define DEV_RX_OFFLOAD_VLAN_EXTEND	0x00000400
>  #define DEV_RX_OFFLOAD_JUMBO_FRAME	0x00000800
> +#define DEV_RX_OFFLOAD_REASSEMBLY	0x00001000
>  #define DEV_RX_OFFLOAD_SCATTER		0x00002000
>  /**
>   * Timestamp is set by the driver in
> RTE_MBUF_DYNFIELD_TIMESTAMP_NAME @@ -1477,6 +1478,20 @@ struct
> rte_eth_dev_portconf {
>   */
>  #define RTE_ETH_DEV_SWITCH_DOMAIN_ID_INVALID
> 	(UINT16_MAX)
> 
> +/**
> + * Reassembly capabilities that a device can support.
> + * The device which can support reassembly offload should set
> + * DEV_RX_OFFLOAD_REASSEMBLY
> + */
> +struct rte_eth_reass_capa {
> +	/** Maximum time in ns that a fragment can wait for further
> fragments */
> +	uint64_t reass_timeout;
> +	/** Maximum number of fragments that device can reassemble */
> +	uint16_t max_frags;
> +	/** Reserved for future capabilities */
> +	uint16_t reserved[3];
> +};

IP reassembly occurs at the final recipient of the message, NIC attempts to do it has a fer challenges. The reason is that having NICs need to worry about reassembling fragments would increase their complexity, so most likely it only can handle range length of datagrams. Seems rte_eth_reass_capa miss the max original datagrams length which NIC can support, this features is better to be negotiated between NIC and SW as well.

>  /**
>   * Ethernet device associated switch information
>   */
> @@ -1582,8 +1597,9 @@ struct rte_eth_dev_info {
>  	 * embedded managed interconnect/switch.
>  	 */
>  	struct rte_eth_switch_info switch_info;
> +	/* Reassembly capabilities of a device for reassembly offload */
> +	struct rte_eth_reass_capa reass_capa;
> 
> -	uint64_t reserved_64s[2]; /**< Reserved for future fields */
>  	void *reserved_ptrs[2];   /**< Reserved for future fields */
>  };
> 
> diff --git a/lib/mbuf/rte_mbuf_core.h b/lib/mbuf/rte_mbuf_core.h index
> bb38d7f581..cea25c87f7 100644
> --- a/lib/mbuf/rte_mbuf_core.h
> +++ b/lib/mbuf/rte_mbuf_core.h
> @@ -200,10 +200,11 @@ extern "C" {
>  #define PKT_RX_OUTER_L4_CKSUM_BAD	(1ULL << 21)
>  #define PKT_RX_OUTER_L4_CKSUM_GOOD	(1ULL << 22)
>  #define PKT_RX_OUTER_L4_CKSUM_INVALID	((1ULL << 21) | (1ULL << 22))
> +#define PKT_RX_REASSEMBLY_INCOMPLETE	(1ULL << 23)
> 
>  /* add new RX flags here, don't forget to update PKT_FIRST_FREE */
> 
> -#define PKT_FIRST_FREE (1ULL << 23)
> +#define PKT_FIRST_FREE (1ULL << 24)
>  #define PKT_LAST_FREE (1ULL << 40)
> 
>  /* add new TX flags here, don't forget to update PKT_LAST_FREE  */ diff --git
> a/lib/security/rte_security.h b/lib/security/rte_security.h index
> 88d31de0a6..364eeb5cd4 100644
> --- a/lib/security/rte_security.h
> +++ b/lib/security/rte_security.h
> @@ -181,6 +181,16 @@ struct rte_security_ipsec_sa_options {
>  	 * * 0: Disable per session security statistics collection for this SA.
>  	 */
>  	uint32_t stats : 1;
> +
> +	/** Enable reassembly on incoming packets.
> +	 *
> +	 * * 1: Enable driver to try reassembly of encrypted IP packets for
> +	 *      this SA, if supported by the driver. This feature will work
> +	 *      only if rx_offload DEV_RX_OFFLOAD_REASSEMBLY is set in
> +	 *      inline ethernet device.
> +	 * * 0: Disable reassembly of packets (default).
> +	 */
> +	uint32_t reass_en : 1;
>  };
> 
>  /** IPSec security association direction */
> --
> 2.25.1