Public bug reported:

Problem Description
==================================
I attempted to inject a Core Unit Checkstop error by flipping Core FIR bit 5 on 
a K80 (Nvidia) 42L Server ( FSP - gp4fp1.aus.stglabs.ibm.com ). I was expecting 
the server to crash due to a Sapphire assert ( PEL with SRC BB821410 ) and a 
Sapphire dump to be collected in the process.

However on injecting the error , the host ( Ubuntu NV ) crashed, and
never recovered. OPAL however seemed to stay up and there were a
plethora of mail box errors - B182953C logged by the FSP.

Error Inject
--------------
$ putscom pu.ex 10013100 5 1 1 -ib -p3 -c5
s1.ex   k0:n0:s0:p03:c5
ecmd_ppc putscom pu.ex 10013100 5 1 1 -ib -p3 -c5


Console message
--------------
[htx@gp4p01]  [1m/sys/devices/system/cpu# [0m [ 1652.976253] Fatal Hypervisor 
Maintenance interrupt [Not recovered]
[ 1652.976332]  Error detail: Malfunction Alert
[ 1652.976402]  HMER: 8040000000000000
[ 1652.976450] Kernel panic - not syncing: Unrecoverable HMI exception
[ 1652.976467] CPU: 24 PID: 1261 Comm: kworker/24:1 Tainted: P           OE 
3.16.0-37-generic #51~14.04.1-Ubuntu
[ 1652.976530] Workqueue: events hmi_event_handler
[ 1652.976561] Call Trace:
[ 1652.976571] [c0000000189bf9e0] [c000000000017330] show_stack+0x170/0x290 
(unreliable)
[ 1652.976647] [c0000000189bfac0] [c0000000009eb8e4] dump_stack+0x90/0xbc
[ 1652.976674] [c0000000189bfaf0] [c0000000009e2b5c] panic+0x104/0x2a8
[ 1652.976703] [c0000000189bfb80] [c00000000007306c] 
hmi_event_handler+0x19c/0x2b0
[ 1652.976732] [c0000000189bfc50] [c0000000000d62dc] 
process_one_work+0x1ac/0x4d0
[ 1652.976772] [c0000000189bfce0] [c0000000000d6b80] worker_thread+0x190/0x630
[ 1652.976800] [c0000000189bfd80] [c0000000000e0024] kthread+0x114/0x140
[ 1652.976837] [c0000000189bfe30] [c00000000000a468] 
ret_from_kernel_thread+0x5c/0x74
[ 1652.977085] ---[ end Kernel panic - not syncing: Unrecoverable HMI exception
 

.
.
.
.
|------------------------------------------------------------------------------|
| 0x50227CFC 06/14/2015 22:27:43 System Hypervisor Firmware               mbox |
| 0x50227CFC Processed           Predictive Error                     B182953C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227CDD 06/14/2015 22:27:21 System Hypervisor Firmware               spif |
| 0x50227CDD Processed           Predictive Error                     B182951C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227CC0 06/14/2015 22:26:57 System Hypervisor Firmware               mbox |
| 0x50227CC0 Processed           Predictive Error                     B182953C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C9E 06/14/2015 22:26:31 System Hypervisor Firmware               spif |
| 0x50227C9E Processed           Predictive Error                     B182951C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C88 06/14/2015 22:26:12 System Hypervisor Firmware               mbox |
| 0x50227C88 Processed           Predictive Error                     B182953C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C7E 06/14/2015 22:26:06 System Hypervisor Firmware               spif |
| 0x50227C7E Processed           Predictive Error                     B182951C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C4F 06/14/2015 22:25:27 System Hypervisor Firmware               mbox |
| 0x50227C4F Processed           Predictive Error                     B182953C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C40 06/14/2015 22:25:16 System Hypervisor Firmware               spif |
| 0x50227C40 Processed           Predictive Error                     B182951C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C17 06/14/2015 22:24:42 System Hypervisor Firmware               mbox |
| 0x50227C17 Processed           Predictive Error                     B182953C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x50227C01 06/14/2015 22:24:25 System Hypervisor Firmware               spif |
| 0x50227C01 Processed           Predictive Error                     B182951C 
| --> Unexpected mail box error , needs investigation 
|------------------------------------------------------------------------------|
| 0x501CF14F 06/11/2015 15:32:31 Processor Unit (CPU)                     prdf |
| 0x501CF14F Processed           Predictive Error                     B113E504 
|  --> Error log corresponding to injected Core Unit Checkstop error ( Core FIR 
[5] )
|------------------------------------------------------------------------------|

== Comment: #3 - MAHESH J. SALGAONKAR <[email protected]> - 
2015-06-16 14:06:56 ==
Ah! I see that panic timeout is set to 0 (zero). That means kernel will wait 
forever after panic. The behaviour reported in this BUG is as expected when 
panic timeout is set to 0. Hence it is not a BUG.

===================
root@gp4p01:/usr/lib/debug/boot# cat /proc/sys/kernel/panic
0
root@gp4p01:/usr/lib/debug/boot# echo 10 > /proc/sys/kernel/panic
root@gp4p01:/usr/lib/debug/boot# cat /proc/sys/kernel/panic
10
root@gp4p01:/usr/lib/debug/boot#

After setting panic_timeout to 10 seconds I see that system rebooted on
unrecoverable HMI:

[salgaonkarm@mars linux-2.6]$ fsp_cmd -i gp4fp1.aus.stglabs.ibm.com
Checking if system 'gp4fp1.aus.stglabs.ibm.com' is accesible (ping test)
spawn telnet gp4fp1.aus.stglabs.ibm.com
Trying 9.3.136.91...
Connected to gp4fp1.aus.stglabs.ibm.com.
Escape character is '^]'.

Linux 2.6.32-279.14.1.69.fsp_fld8_1.ppcnf-fsp2 (gp4fp1) (12:51 on
Friday, 08 October 2004)

gp4fp1 login: dev
Password: 
$ smgr mfgState
runtime
$ 
$ putscom pu.ex 10013100 5 1 1 -ib -p3 -c5
s1.ex   k0:n0:s0:p03:c5    
ecmd_ppc putscom pu.ex 10013100 5 1 1 -ib -p3 -c5 
$ smgr mfgState
runtime
$ smgr mfgState
ipling                     <= System rebooting.. 
===================


For system to reboot after panic, please set panic timeout to non-zero value 
and try injecting core checkstop again. You can do that in two ways:
1. Boot kernel with "panic=<secs>" kernel option (See below for valid values)
    OR
2. Once OS is booted, echo non-zero value to  /proc/sys/kernel/panic
    $ echo 10 >  /proc/sys/kernel/panic


Please refer to Documentation/kernel-parameters.txt for valid panic
values:

-----------------Documentation/kernel-parameters.txt----------------------------
        panic=          [KNL] Kernel behaviour on panic: delay <timeout>
                        timeout > 0: seconds before rebooting
                        timeout = 0: wait forever
                        timeout < 0: reboot immediately
                        Format: <timeout>
-----------------Documentation/kernel-parameters.txt----------------------------

== Comment: #8 - Stewart Smith <[email protected]> - 2015-09-17 20:03:51 ==
You should be able to provide panic_timeout=180 as a kernel argument as a 
workaround.
However, this is *completely* an ubuntu bug. Perhaps we want to modify the 
panic() handler in linux though.

== Comment: #9 - Luciano Chavez <[email protected]> - 2015-09-18 10:47:31 ==
I was speaking to Feroz and Donna this morning (and sent a note about the same 
thing last night) and to them the issue is not the panic but that it does not 
reboot after it hits it. As explained there are three methods to override the 
panic timeout (add kernel.panic= to sysctl,conf, echo value to 
/proc/sys/kernel/panic, or pass panic= to kernel command line). 

So, I hope Feroz can chime in but they want the hard coded
CONFIG_PANIC_TIMEOUT changed because the rationale customers would
likely not be aware to change it despite the previously mentioned ways
to do it.

So, if that is what they want, we will have to send this to Canonical
for their take on this.


Hi Canconical, 
Can you please comment  your take on this issue ?

Thank you.

** Affects: ubuntu
     Importance: Undecided
     Assignee: Taco Screen team (taco-screen-team)
         Status: New


** Tags: architecture-ppc64le bugnameltc-126343 severity-high 
targetmilestone-inin14043

** Tags added: architecture-ppc64le bugnameltc-126343 severity-high
targetmilestone-inin14043

** Changed in: ubuntu
     Assignee: (unassigned) => Taco Screen team (taco-screen-team)

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https://bugs.launchpad.net/bugs/1512593

Title:
  :Ubuntu NV: Panic timeout=0 means Ubuntu does not reboot and recover
  from HMI (e.g. Core Unit Checkstop)

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