Re: [PATCH net 7/8] i40e: set supported_extts_flags for rising edge

[Jakub Kicinski <kuba@kernel.org>]

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---
i40e: set supported_extts_flags for rising edge

The i40e driver always supported only rising edge detection, so
advertise PTP_RISING_EDGE, and PTP_STRICT_FLAGS to ensure the
PTP core properly validates user requests.

> diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> index 7d07c389bb231..c4525bfab09c0 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> @@ -1344,6 +1344,8 @@ static int i40e_init_pin_config(struct i40e_pf *pf)
>  	pf->ptp_caps.n_ext_ts = 2;
>  	pf->ptp_caps.pps = 1;
>  	pf->ptp_caps.n_per_out = 2;
> +	pf->ptp_caps.supported_extts_flags = PTP_RISING_EDGE |
> +					     PTP_STRICT_FLAGS;

[Severity: High]
This isn't a bug introduced by this patch, but does the PTP external timestamp
event in i40e_ptp_extts0_work() incorrectly assign the PCI Physical Function
(PF) ID to the event index instead of the PTP hardware channel index?

Looking at i40e_ptp_extts0_work():

drivers/net/ethernet/intel/i40e/i40e_ptp.c:i40e_ptp_extts0_work() {
	...
	event.type = PTP_CLOCK_EXTTS;
	event.index = hw->pf_id;

	/* fire event */
	ptp_clock_event(pf->ptp_clock, &event);
}

The PTP core API expects the index field to correspond to the requested EXTTS
channel index (which should be 0 here).

Userspace applications rely on this index to associate the received timestamp
event with the requested channel.

For interfaces where pf_id is greater than 0 (e.g., dual or quad port NICs),
this dispatches the event to userspace with the wrong channel index, causing
applications to ignore the timestamp or misbehave, completely breaking EXTTS
functionality for those ports.

>  
>  	pf->ptp_caps.pin_config = kzalloc_objs(*pf->ptp_caps.pin_config,
>  					       pf->ptp_caps.n_pins);