Re: [dpdk-dev] [PATCH 00/20] net/mlx5: implement extensive metadata feature

[Matan Azrad <matan@mellanox.com>]

From: Viacheslav Ovsiienko
> The modern networks operate on the base of the packet switching
> approach, and in-network environment data are transmitted as the packets.
> Within the host besides the data, actually transmitted on the wire as packets,
> there might some out-of-band data helping to process packets. These data
> are named as metadata, exist on a per-packet basis and are attached to each
> packet as some extra dedicated storage (in meaning it besides the packet
> data itself).
> 
> In the DPDK network data are represented as mbuf structure chains and go
> along the application/DPDK datapath. From the other side, DPDK provides
> Flow API to control the flow engine. Being precise, there are two kinds of
> metadata in the DPDK, the one is purely software metadata (as fields of
> mbuf - flags, packet types, data length, etc.), and the other is metadata
> within flow engine.
> In this scope, we cover the second type (flow engine metadata) only.
> 
> The flow engine metadata is some extra data, supported on the per-packet
> basis and usually handled by hardware inside flow engine.
> 
> Initially, there were proposed two metadata related actions:
> 
> - RTE_FLOW_ACTION_TYPE_FLAG
> - RTE_FLOW_ACTION_TYPE_MARK
> 
> These actions set the special flag in the packet metadata, MARK action stores
> some specified value in the metadata storage, and, on the packet receiving
> PMD puts the flag and value to the mbuf and applications can see the packet
> was threated inside flow engine according to the appropriate RTE flow(s).
> MARK and FLAG are like some kind of gateway to transfer some per-packet
> information from the flow engine to the application via receiving datapath.
> Also, there is the item of type RTE_FLOW_ITEM_TYPE_MARK provided. It
> allows us to extend the flow match pattern with the capability to match the
> metadata values set by MARK/FLAG actions on other flows.
> 
> From the datapath point of view, the MARK and FLAG are related to the
> receiving side only. It would useful to have the same gateway on the
> transmitting side and there was the feature of type
> RTE_FLOW_ITEM_TYPE_META was proposed. The application can fill the field
> in mbuf and this value will be transferred to some field in the packet
> metadata inside the flow engine.
> 
> It did not matter whether these metadata fields are shared because of
> MARK and META items belonged to different domains (receiving and
> transmitting) and could be vendor-specific.
> 
> So far, so good, DPDK proposes some entities to control metadata inside the
> flow engine and gateways to exchange these values on a per-packet basis via
> datapath.
> 
> As we can see, the MARK and META means are not symmetric, there is
> absent action which would allow us to set META value on the transmitting
> path. So, the action of type:
> 
> - RTE_FLOW_ACTION_TYPE_SET_META is proposed.
> 
> The next, applications raise the new requirements for packet metadata. The
> flow engines are getting more complex, internal switches are introduced,
> multiple ports might be supported within the same flow engine namespace.
> From the DPDK points of view, it means the packets might be sent on one
> eth_dev port and received on the other one, and the packet path inside the
> flow engine entirely belongs to the same hardware device. The simplest
> example is SR-IOV with PF, VFs and the representors. And there is a brilliant
> opportunity to provide some out-of-band channel to transfer some extra
> data from one port to another one, besides the packet data itself. And
> applications would like to use this opportunity.
> 
> Improving the metadata definitions it is proposed to:
> - suppose MARK and META metadata fields not shared, dedicated
> - extend applying area for MARK and META items/actions for all
>   flow engine domains - transmitting and receiving
>   - allow MARK and META metadata to be preserved while crossing
>     the flow domains (from transmit origin through flow database
>     inside (E-)switch to receiving side domain), in simple words,
>     to allow metadata to convey the packet thought entire flow
>     engine space.
> 
> Another new proposed feature is transient per-packet storage inside the
> flow engine. It might have a lot of use cases.
> For example, if there is VXLAN tunneled traffic and some flow performs
> VXLAN decapsulation and wishes to save information regarding the dropped
> header it could use this temporary transient storage. The tools to maintain
> this storage are traditional (for DPDK rte_flow API):
> 
> - RTE_FLOW_ACTION_TYPE_SET_TAG - to set value
> - RTE_FLOW_ACTION_TYPE_SET_ITEM - to match on
> 
> There are primary properties of the proposed storage:
> - the storage is presented as an array of 32-bit opaque values
> - the size of array (or even bitmap of available indices) is
>   vendor specific and is subject to run-time trial
> - it is transient, it means it exists only inside flow engine,
>   no gateways for interacting with datapath, applications have
>   way neither to specify these data on transmitting nor to get
>   these data on receiving
> 
> This patchset implements the abovementioned extensive metadata feature
> in the mlx5 PMD.
> 
> The patchset must be applied after public RTE API updates:
> 
> [1]
> https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> es.dpdk.org%2Fpatch%2F62354%2F&data=02%7C01%7Cmatan%40mella
> nox.com%7C3d761a21d7b24f6cc3f908d761c67b89%7Ca652971c7d2e4d9ba6a4
> d149256f461b%7C0%7C0%7C637085377412009134&sdata=J4RsC9w8BNn
> %2BawnLG%2F4UJPzeo%2BZ%2BTBfVxkZ6j4gheg0%3D&reserved=0
> [2]
> https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> es.dpdk.org%2Fpatch%2F62355%2F&data=02%7C01%7Cmatan%40mella
> nox.com%7C3d761a21d7b24f6cc3f908d761c67b89%7Ca652971c7d2e4d9ba6a4
> d149256f461b%7C0%7C0%7C637085377412009134&sdata=AXgzWWkU8I
> yr3zm5z%2FPW%2B9p%2Fein7d87Jdr2dclqe71s%3D&reserved=0
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>

For all the series:
Acked-by: Matan Azrad <matan@mellanox.com>

> Viacheslav Ovsiienko (20):
>   net/mlx5: convert internal tag endianness
>   net/mlx5: update modify header action translator
>   net/mlx5: add metadata register copy
>   net/mlx5: refactor flow structure
>   net/mlx5: update flow functions
>   net/mlx5: update meta register matcher set
>   net/mlx5: rename structure and function
>   net/mlx5: check metadata registers availability
>   net/mlx5: add devarg for extensive metadata support
>   net/mlx5: adjust shared register according to mask
>   net/mlx5: check the maximal modify actions number
>   net/mlx5: update metadata register id query
>   net/mlx5: add flow tag support
>   net/mlx5: extend flow mark support
>   net/mlx5: extend flow meta data support
>   net/mlx5: add meta data support to Rx datapath
>   net/mlx5: add simple hash table
>   net/mlx5: introduce flow splitters chain
>   net/mlx5: split Rx flows to provide metadata copy
>   net/mlx5: add metadata register copy table
> 
>  doc/guides/nics/mlx5.rst                 |   49 +
>  drivers/net/mlx5/mlx5.c                  |  135 ++-
>  drivers/net/mlx5/mlx5.h                  |   19 +-
>  drivers/net/mlx5/mlx5_defs.h             |    7 +
>  drivers/net/mlx5/mlx5_ethdev.c           |    8 +-
>  drivers/net/mlx5/mlx5_flow.c             | 1178 ++++++++++++++++++++++-
>  drivers/net/mlx5/mlx5_flow.h             |  108 ++-
>  drivers/net/mlx5/mlx5_flow_dv.c          | 1544
> ++++++++++++++++++++++++------
>  drivers/net/mlx5/mlx5_flow_verbs.c       |   55 +-
>  drivers/net/mlx5/mlx5_prm.h              |   45 +-
>  drivers/net/mlx5/mlx5_rxtx.c             |    6 +
>  drivers/net/mlx5/mlx5_rxtx_vec_altivec.h |   25 +-
>  drivers/net/mlx5/mlx5_rxtx_vec_neon.h    |   23 +
>  drivers/net/mlx5/mlx5_rxtx_vec_sse.h     |   27 +-
>  drivers/net/mlx5/mlx5_utils.h            |  115 ++-
>  15 files changed, 2922 insertions(+), 422 deletions(-)
> 
> --
> 1.8.3.1