linux-kernel - Re: [PATCH v2 1/3] watchdog/hpwdt: Only claim UNKNOWN NMI if from iLO

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Message-ID: <9c7c6ba4-2140-4d1c-b2de-705b9f6b9e2e@roeck-us.net>
Date:   Wed, 13 Dec 2023 14:14:08 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jerry Hoemann <jerry.hoemann@....com>
Cc:     wim@...ux-watchdog.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] watchdog/hpwdt: Only claim UNKNOWN NMI if from iLO

On Wed, Dec 13, 2023 at 02:53:38PM -0700, Jerry Hoemann wrote:
> Avoid unnecessary crashes by claiming only NMIs that are due to
> ERROR signalling or generated by the hpwdt hardware device.
> 
> The code does this, but only for iLO5.
> 
> The intent was to preserve legacy, Gen9 and earlier, semantics of
> using hpwdt for error containtment as hardware/firmware would signal
> fatal IO errors as an NMI with the expectation of hpwdt crashing
> the system.  Howerver, these IO errors should be received by hpwdt
> as an NMI_IO_CHECK.  So the test is overly permissive and should
> not be limited to only ilo5.
> 
> We need to enable this protection for future iLOs not matching the
> current PCI IDs.
> 
> Fixes: 62290a5c194b ("watchdog: hpwdt: Claim NMIs generated by iLO5")
> Signed-off-by: Jerry Hoemann <jerry.hoemann@....com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/hpwdt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
> index f79f932bca14..79ed1626d8ea 100644
> --- a/drivers/watchdog/hpwdt.c
> +++ b/drivers/watchdog/hpwdt.c
> @@ -178,7 +178,7 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
>  		"3. OA Forward Progress Log\n"
>  		"4. iLO Event Log";
>  
> -	if (ilo5 && ulReason == NMI_UNKNOWN && !mynmi)
> +	if (ulReason == NMI_UNKNOWN && !mynmi)
>  		return NMI_DONE;
>  
>  	if (ilo5 && !pretimeout && !mynmi)
> -- 
> 2.41.0
>