netdev - Re: [Intel-wired-lan] [PATCH iwl-net v4 1/6] igc: fix PTM cycle trigger logic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z-0VoDTYP9HsSrsJ@calimero.vinschen.de>
Date: Wed, 2 Apr 2025 12:46:56 +0200
From: Corinna Vinschen <vinschen@...hat.com>
To: Jacob Keller <jacob.e.keller@...el.com>
Cc: Anthony Nguyen <anthony.l.nguyen@...el.com>, david.zage@...el.com,
	vinicius.gomes@...el.com, rodrigo.cadore@...coustics.com,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	Christopher S M Hall <christopher.s.hall@...el.com>,
	Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>,
	Mor Bar-Gabay <morx.bar.gabay@...el.com>,
	Avigail Dahan <avigailx.dahan@...el.com>
Subject: Re: [Intel-wired-lan] [PATCH iwl-net v4 1/6] igc: fix PTM cycle
 trigger logic

On Apr  1 16:35, Jacob Keller wrote:
> From: Christopher S M Hall <christopher.s.hall@...el.com>
> 
> Writing to clear the PTM status 'valid' bit while the PTM cycle is
> triggered results in unreliable PTM operation. To fix this, clear the
> PTM 'trigger' and status after each PTM transaction.
> 
> The issue can be reproduced with the following:
> 
> $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m
> 
> Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
> quickly reproduce the issue.
> 
> PHC2SYS exits with:
> 
> "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
>   fails
> 
> This patch also fixes a hang in igc_probe() when loading the igc
> driver in the kdump kernel on systems supporting PTM.
> 
> The igc driver running in the base kernel enables PTM trigger in
> igc_probe().  Therefore the driver is always in PTM trigger mode,
> except in brief periods when manually triggering a PTM cycle.
> 
> When a crash occurs, the NIC is reset while PTM trigger is enabled.
> Due to a hardware problem, the NIC is subsequently in a bad busmaster
> state and doesn't handle register reads/writes.  When running
> igc_probe() in the kdump kernel, the first register access to a NIC
> register hangs driver probing and ultimately breaks kdump.
> 
> With this patch, igc has PTM trigger disabled most of the time,
> and the trigger is only enabled for very brief (10 - 100 us) periods
> when manually triggering a PTM cycle.  Chances that a crash occurs
> during a PTM trigger are not 0, but extremly reduced.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> Tested-by: Mor Bar-Gabay <morx.bar.gabay@...el.com>
> Tested-by: Avigail Dahan <avigailx.dahan@...el.com>
> Signed-off-by: Christopher S M Hall <christopher.s.hall@...el.com>
> Reviewed-by: Corinna Vinschen <vinschen@...hat.com>
> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>

Tested-by: Corinna Vinschen <vinschen@...hat.com>