Subject: Re: [PATCH net-next v2] ethtool: ice: Support for RSS settings to GTP from ethtool

From: Jakub Kicinski <[email-masked]>
Date: Mon, 16 Oct 2023 15:23:43 -0700

Thanks for the v2!

Adding Willem, Pablo, and Harald to CC (please CC them on future
versions).

On Thu, 12 Oct 2023 06:01:15 +0000 Takeru Hayasaka wrote:
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
> index f7fba0dc87e5..a2d4f2081cf3 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -2011,6 +2011,18 @@ static inline int ethtool_validate_duplex(__u8 duplex)
>  #define	IPV4_FLOW	0x10	/* hash only */
>  #define	IPV6_FLOW	0x11	/* hash only */
>  #define	ETHER_FLOW	0x12	/* spec only (ether_spec) */
> +#define GTPU_V4_FLOW 0x13	/* hash only */
> +#define GTPU_V6_FLOW 0x14	/* hash only */
> +#define GTPC_V4_FLOW 0x15	/* hash only */
> +#define GTPC_V6_FLOW 0x16	/* hash only */
> +#define GTPC_TEID_V4_FLOW 0x17	/* hash only */
> +#define GTPC_TEID_V6_FLOW 0x18	/* hash only */
> +#define GTPU_EH_V4_FLOW 0x19	/* hash only */
> +#define GTPU_EH_V6_FLOW 0x20	/* hash only */

nit: please note that these are hex numbers,
     next value after 0x19 is 0x1a, not 0x20.

> +#define GTPU_UL_V4_FLOW 0x21	/* hash only */
> +#define GTPU_UL_V6_FLOW 0x22	/* hash only */
> +#define GTPU_DL_V4_FLOW 0x23	/* hash only */
> +#define GTPU_DL_V6_FLOW 0x24	/* hash only */
>  /* Flag to enable additional fields in struct ethtool_rx_flow_spec */
>  #define	FLOW_EXT	0x80000000
>  #define	FLOW_MAC_EXT	0x40000000

What gives me pause here is the number of flow sub-types we define
for GTP hashing.

My understanding of GTP is limited to what I just read on Wikipedia.

IIUC the GTPC vs GTPU distinction comes down to the UDP port on
which the protocol runs? Are the frames also different?

I'm guessing UL/DL are uplink/downlink but what's EH?

How do GTPU_V4_FLOW, GTPU_EH_V4_FLOW, GTPU_UL_V4_FLOW, and
GTPU_DL_V4_FLOW differ?

Key question is - are there reasonable use cases that you can think of
for enabling GTP hashing for each one of those bits individually or can
we combine some of them?

> @@ -2025,6 +2037,7 @@ static inline int ethtool_validate_duplex(__u8 duplex)
>  #define	RXH_IP_DST	(1 << 5)
>  #define	RXH_L4_B_0_1	(1 << 6) /* src port in case of TCP/UDP/SCTP */
>  #define	RXH_L4_B_2_3	(1 << 7) /* dst port in case of TCP/UDP/SCTP */
> +#define	RXH_GTP_TEID	(1 << 8) /* teid in case of GTP */
>  #define	RXH_DISCARD	(1 << 31)