Re: [PATCH iwl-next v3 13/13] iavf: add support for offloading tc U32 cls filters

[Simon Horman <horms@kernel.org>]

On Wed, Jul 10, 2024 at 02:40:15PM -0600, Ahmed Zaki wrote:
> Add support for offloading cls U32 filters. Only "skbedit queue_mapping"
> and "drop" actions are supported. Also, only "ip" and "802_3" tc
> protocols are allowed. The PF must advertise the VIRTCHNL_VF_OFFLOAD_TC_U32
> capability flag.
> 
> Since the filters will be enabled via the FD stage at the PF, a new type
> of FDIR filters is added and the existing list and state machine are used.
> 
> The new filters can be used to configure flow directors based on raw
> (binary) pattern in the rx packet.
> 
> Examples:
> 
> 0. # tc qdisc add dev enp175s0v0  ingress
> 
> 1. Redirect UDP from src IP 192.168.2.1 to queue 12:
> 
>     # tc filter add dev <dev> protocol ip ingress u32 \
> 	match u32 0x45000000 0xff000000 at 0  \
> 	match u32 0x00110000 0x00ff0000 at 8  \
> 	match u32 0xC0A80201 0xffffffff at 12 \
> 	match u32 0x00000000 0x00000000 at 24 \
> 	action skbedit queue_mapping 12 skip_sw
> 
> 2. Drop all ICMP:
> 
>     # tc filter add dev <dev> protocol ip ingress u32 \
> 	match u32 0x45000000 0xff000000 at 0  \
> 	match u32 0x00010000 0x00ff0000 at 8  \
> 	match u32 0x00000000 0x00000000 at 24 \
> 	action drop skip_sw
> 
> 3. Redirect ICMP traffic from MAC 3c:fd:fe:a5:47:e0 to queue 7
>    (note proto: 802_3):
> 
>    # tc filter add dev <dev> protocol 802_3 ingress u32 \
> 	match u32 0x00003CFD 0x0000ffff at 4   \
> 	match u32 0xFEA547E0 0xffffffff at 8   \
> 	match u32 0x08004500 0xffffff00 at 12  \
> 	match u32 0x00000001 0x000000ff at 20  \
> 	match u32 0x0000 0x0000 at 40          \
> 	action skbedit queue_mapping 7 skip_sw
> 
> Notes on matches:
> 1 - All intermediate fields that are needed to parse the correct PTYPE
>     must be provided (in e.g. 3: Ethernet Type 0x0800 in MAC, IP version
>     and IP length: 0x45 and protocol: 0x01 (ICMP)).
> 2 - The last match must provide an offset that guarantees all required
>     headers are accounted for, even if the last header is not matched.
>     For example, in #2, the last match is 4 bytes at offset 24 starting
>     from IP header, so the total is 14 (MAC) + 24 + 4 = 42, which is the
>     sum of MAC+IP+ICMP headers.
> 
> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
> Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>
> Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>

...

> diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h

...

>  /* Must be called with fdir_fltr_lock lock held */
>  static inline bool iavf_fdir_max_reached(struct iavf_adapter *adapter)
>  {
> -	return (adapter->fdir_active_fltr >= IAVF_MAX_FDIR_FILTERS);
> +	return (adapter->fdir_active_fltr + adapter->raw_fdir_active_fltr >=
> +			IAVF_MAX_FDIR_FILTERS);

nit: These parentheses seem unnecessary

> +}

...

> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c

...

> +/**
> + * iavf_add_cls_u32 - Add U32 classifier offloads
> + * @adapter: pointer to iavf adapter structure
> + * @cls_u32: pointer to tc_cls_u32_offload struct with flow info

Please document the return value with a "Return:" or "Returns:" section.
Likewise for iavf_del_cls_u32 and iavf_setup_tc_cls_u32.

...