[Skiboot] [PATCH] hmi: Clear unknown debug trigger

[Mahesh Jagannath Salgaonkar]

On 05/04/2018 09:36 AM, Michael Neuling wrote:
> From: Ryan Grimm <grimm at linux.vnet.ibm.com>
> 
> On some systems, seeing hangs like this when Linux starts:
>   [ 170.027252763,5] OCC: All Chip Rdy after 0 ms
>   [ 170.062930145,5] INIT: Starting kernel at 0x20011000, fdt at 0x30ae0530 366247 bytes)
>   [ 171.238270428,5] OPAL: Switch to little-endian OS
> 
> If you look at the in memory skiboot console (or do 'nvram -p
> ibm,skiboot --update-config log-level-driver=7') we see the console get
> spammed with:
>   [ 5209.109790675,7] HMI: Received HMI interrupt: HMER = 0x0000400000000000
>   [ 5209.109792716,7] HMI: Received HMI interrupt: HMER = 0x0000400000000000
>   [ 5209.109794695,7] HMI: Received HMI interrupt: HMER = 0x0000400000000000
>   [ 5209.109796689,7] HMI: Received HMI interrupt: HMER = 0x0000400000000000
> 
> We're taking the debug trigger (bit 17) early on, before the
> hmi_debug_trigger function in the kernel is set up.
> 
> This clears the HMI in Skiboot and reports to the kernel instead of
> bringing down the machine.
> 
> Signed-off-by: Ryan Grimm <grimm at linux.vnet.ibm.com>
> Signed-off-by: Michael Neuling <mikey at neuling.org>

Reviewed-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

> ---
>  core/hmi.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/core/hmi.c b/core/hmi.c
> index bd0fc13b80..9e80c54f47 100644
> --- a/core/hmi.c
> +++ b/core/hmi.c
> @@ -1258,6 +1258,16 @@ static int handle_hmi_exception(uint64_t hmer, struct OpalHMIEvent *hmi_evt,
>  			queue_hmi_event(hmi_evt, recover, out_flags);
>  		}
>  	}
> +	if (hmer & SPR_HMER_TRIG_FIR_HMI) {
> +		hmer &= ~SPR_HMER_TRIG_FIR_HMI;
> +
> +		hmi_print_debug("Clearing unknown debug trigger", hmer);
> +		if (hmi_evt) {
> +			hmi_evt->severity = OpalHMI_SEV_NO_ERROR;
> +			hmi_evt->type = OpalHMI_ERROR_DEBUG_TRIG_FIR,
> +				queue_hmi_event(hmi_evt, recover, out_flags);
> +		}
> +	}
> 
>  	if (recover == 0)
>  		disable_fast_reboot("Unrecoverable HMI");
>