ACK: [SRU][X][B][F][PATCH 1/1] powerpc/pseries: Do not initiate shutdown when system is running on UPS

[William Breathitt Gray]

On Mon, Sep 14, 2020 at 12:05:21PM -0300, patricia.domingues at canonical.com wrote:
> From: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1893897
> 
> As per PAPR we have to look for both EPOW sensor value and event
> modifier to identify the type of event and take appropriate action.
> 
> In LoPAPR v1.1 section 10.2.2 includes table 136 "EPOW Action Codes":
> 
>   SYSTEM_SHUTDOWN 3
> 
>   The system must be shut down. An EPOW-aware OS logs the EPOW error
>   log information, then schedules the system to be shut down to begin
>   after an OS defined delay internal (default is 10 minutes.)
> 
> Then in section 10.3.2.2.8 there is table 146 "Platform Event Log
> Format, Version 6, EPOW Section", which includes the "EPOW Event
> Modifier":
> 
>   For EPOW sensor value = 3
>   0x01 = Normal system shutdown with no additional delay
>   0x02 = Loss of utility power, system is running on UPS/Battery
>   0x03 = Loss of system critical functions, system should be shutdown
>   0x04 = Ambient temperature too high
>   All other values = reserved
> 
> We have a user space tool (rtas_errd) on LPAR to monitor for
> EPOW_SHUTDOWN_ON_UPS. Once it gets an event it initiates shutdown
> after predefined time. It also starts monitoring for any new EPOW
> events. If it receives "Power restored" event before predefined time
> it will cancel the shutdown. Otherwise after predefined time it will
> shutdown the system.
> 
> Commit 79872e35469b ("powerpc/pseries: All events of
> EPOW_SYSTEM_SHUTDOWN must initiate shutdown") changed our handling of
> the "on UPS/Battery" case, to immediately shutdown the system. This
> breaks existing setups that rely on the userspace tool to delay
> shutdown and let the system run on the UPS.
> 
> Fixes: 79872e35469b ("powerpc/pseries: All events of EPOW_SYSTEM_SHUTDOWN must initiate shutdown")
> Cc: stable at vger.kernel.org # v4.0+
> Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
> [mpe: Massage change log and add PAPR references]
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> Link: https://lore.kernel.org/r/20200820061844.306460-1-hegdevasant@linux.vnet.ibm.com
> (cherry picked from commit 90a9b102eddf6a3f987d15f4454e26a2532c1c98)
> Signed-off-by: Patricia Domingues <patricia.domingues at canonical.com>
> ---
>  arch/powerpc/platforms/pseries/ras.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index ebb075018c34..86d5cb3b435e 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -92,7 +92,6 @@ static void handle_system_shutdown(char event_modifier)
>  	case EPOW_SHUTDOWN_ON_UPS:
>  		pr_emerg("Loss of system power detected. System is running on"
>  			 " UPS/battery. Check RTAS error log for details\n");
> -		orderly_poweroff(true);
>  		break;
>  
>  	case EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS:
> -- 
> 2.17.1

Acked-by: William Breathitt Gray <william.gray at canonical.com>
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