Re: [dpdk-dev] [PATCH v4 1/2] ethdev: add packet integrity checks

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 4/14/2021 1:56 PM, Gregory Etelson wrote:
> From: Ori Kam <orika@nvidia.com>
> 
> Currently, DPDK application can offload the checksum check,
> and report it in the mbuf.
> 
> However, as more and more applications are offloading some or all
> logic and action to the HW, there is a need to check the packet
> integrity so the right decision can be taken.
> 
> The application logic can be positive meaning if the packet is
> valid jump / do  actions, or negative if packet is not valid
> jump to SW / do actions (like drop)  a, and add default flow
> (match all in low priority) that will direct the miss packet
> to the miss path.
> 
> Since currently rte_flow works in positive way the assumption is
> that the positive way will be the common way in this case also.
> 
> When thinking what is the best API to implement such feature,
> we need to considure the following (in no specific order):
> 1. API breakage.
> 2. Simplicity.
> 3. Performance.
> 4. HW capabilities.
> 5. rte_flow limitation.
> 6. Flexibility.
> 
> First option: Add integrity flags to each of the items.
> For example add checksum_ok to ipv4 item.
> 
> Pros:
> 1. No new rte_flow item.
> 2. Simple in the way that on each item the app can see
> what checks are available.
> 
> Cons:
> 1. API breakage.
> 2. increase number of flows, since app can't add global rule and
>     must have dedicated flow for each of the flow combinations, for example
>     matching on icmp traffic or UDP/TCP  traffic with IPv4 / IPv6 will
>     result in 5 flows.
> 
> Second option: dedicated item
> 
> Pros:
> 1. No API breakage, and there will be no for some time due to having
>     extra space. (by using bits)
> 2. Just one flow to support the icmp or UDP/TCP traffic with IPv4 /
>     IPv6.
> 3. Simplicity application can just look at one place to see all possible
>     checks.
> 4. Allow future support for more tests.
> 
> Cons:
> 1. New item, that holds number of fields from different items.
> 
> For starter the following bits are suggested:
> 1. packet_ok - means that all HW checks depending on packet layer have
>     passed. This may mean that in some HW such flow should be splited to
>     number of flows or fail.
> 2. l2_ok - all check for layer 2 have passed.
> 3. l3_ok - all check for layer 3 have passed. If packet doesn't have
>     l3 layer this check should fail.
> 4. l4_ok - all check for layer 4 have passed. If packet doesn't
>     have l4 layer this check should fail.
> 5. l2_crc_ok - the layer 2 crc is O.K.
> 6. ipv4_csum_ok - IPv4 checksum is O.K. it is possible that the
>     IPv4 checksum will be O.K. but the l3_ok will be 0. it is not
>     possible that checksum will be 0 and the l3_ok will be 1.
> 7. l4_csum_ok - layer 4 checksum is O.K.
> 8. l3_len_OK - check that the reported layer 3 len is smaller than the
>     frame len.
> 
> Example of usage:
> 1. check packets from all possible layers for integrity.
>     flow create integrity spec packet_ok = 1 mask packet_ok = 1 .....
> 
> 2. Check only packet with layer 4 (UDP / TCP)
>     flow create integrity spec l3_ok = 1, l4_ok = 1 mask l3_ok = 1 l4_ok = 1
> 
> Signed-off-by: Ori Kam <orika@nvidia.com>
> ---
>   doc/guides/prog_guide/rte_flow.rst     | 19 ++++++++++
>   doc/guides/rel_notes/release_21_05.rst |  5 +++
>   lib/librte_ethdev/rte_flow.h           | 48 ++++++++++++++++++++++++++
>   3 files changed, 72 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index e1b93ecedf..4b8723b84c 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -1398,6 +1398,25 @@ Matches a eCPRI header.
>   - ``hdr``: eCPRI header definition (``rte_ecpri.h``).
>   - Default ``mask`` matches nothing, for all eCPRI messages.
>   
> +Item: ``PACKET_INTEGRITY_CHECKS``
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Matches packet integrity.
> +Some devices require pre-enabling for this item before using it.
> +

"pre-enabling" may not be clear enough, what about updating it slightly:

"Some devices require enabling integration checks in HW before using this flow 
item."

For the record, the intention here is to highlight that if the requested 
integration check is not enabled in HW, creating flow rule will fail.
Application may need to enable the integration check in HW first.