skiboot 5.1.20 release notes

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
(cherry picked from commit 8a9c042997ee77d99db062f0a35da4e9b264dd6e)
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/doc/release-notes/skiboot-5.1.20.rst b/doc/release-notes/skiboot-5.1.20.rst
new file mode 100644
index 0000000..63105c3
--- /dev/null
+++ b/doc/release-notes/skiboot-5.1.20.rst
@@ -0,0 +1,173 @@
+skiboot-5.1.20
+--------------
+
+skiboot-5.1.20 was released on Friday 18th August 2017.
+
+skiboot-5.1.20 is the 21st stable release of 5.1, it follows skiboot-5.1.19
+(which was released 16th January 2017).
+
+This release contains a few minor bug fixes backported to the 5.1.x series.
+All of the fixes have previously appeared in the 5.4.x stable series.
+
+Changes are:
+
+- FSP/CONSOLE: Workaround for unresponsive ipmi daemon
+
+  In some corner cases, where FSP is active but not responding to
+  console MBOX message (due to buggy IPMI) and we have heavy console
+  write happening from kernel, then eventually our console buffer
+  becomes full. At this point OPAL starts sending OPAL_BUSY_EVENT to
+  kernel. Kernel will keep on retrying. This is creating kernel soft
+  lockups. In some extreme case when every CPU is trying to write to
+  console, user will not be able to ssh and thinks system is hang.
+
+  If we reset FSP or restart IPMI daemon on FSP, system recovers and
+  everything becomes normal.
+
+  This patch adds workaround to above issue by returning OPAL_HARDWARE
+  when cosole is full. Side effect of this patch is, we may endup dropping
+  latest console data. But better to drop console data than system hang.
+
+  Alternative approach is to drop old data from console buffer, make space
+  for new data. But in normal condition only FSP can update 'next_out'
+  pointer and if we touch that pointer, it may introduce some other
+  race conditions. Hence we decided to just new console write request.
+
+- FSP: Set status field in response message for timed out message
+
+  For timed out FSP messages, we set message status as "fsp_msg_timeout".
+  But most FSP driver users (like surviellance) are ignoring this field.
+  They always look for FSP returned status value in callback function
+  (second byte in word1). So we endup treating timed out message as success
+  response from FSP.
+
+  Sample output: ::
+
+    [69902.432509048,7] SURV: Sending the heartbeat command to FSP
+    [70023.226860117,4] FSP: Response from FSP timed out, word0 = d66a00d7, word1 = 0 state: 3
+    ....
+    [70023.226901445,7] SURV: Received heartbeat acknowledge from FSP
+    [70023.226903251,3] FSP: fsp_trigger_reset() entry
+
+  Here SURV code thought it got valid response from FSP. But actually we didn't
+  receive response from FSP.
+
+- FSP: Improve timeout message
+
+  Presently we print word0 and word1 in error log. word0 contains
+  sequence number and command class. One has to understand word0
+  format to identify command class.
+
+  Lets explicitly print command class, sub command etc.
+
+- FSP/RTC: Remove local fsp_in_reset variable
+
+  Now that we are using fsp_in_rr() to detect FSP reset/reload, fsp_in_reset
+  become redundant. Lets remove this local variable.
+
+- FSP/RTC: Fix possible FSP R/R issue in rtc write path
+
+  fsp_opal_rtc_write() checks FSP status before queueing message to FSP. But if
+  FSP R/R starts before getting response to queued message then we will continue
+  to return OPAL_BUSY_EVENT to host. In some extreme condition host may
+  experience hang. Once FSP is back we will repost message, get response from FSP
+  and return OPAL_SUCCESS to host.
+
+  This patch caches new values and returns OPAL_SUCCESS if FSP R/R is happening.
+  And once FSP is back we will send cached value to FSP.
+
+- hw/fsp/rtc: read/write cached rtc tod on fsp hir.
+
+  Currently fsp-rtc reads/writes the cached RTC TOD on an fsp
+  reset. Use latest fsp_in_rr() function to properly read the cached rtc
+  value when fsp reset initiated by the hir.
+
+  Below is the kernel trace when we set hw clock, when hir process starts. ::
+
+    [ 1727.775824] NMI watchdog: BUG: soft lockup - CPU#57 stuck for 23s! [hwclock:7688]
+    [ 1727.775856] Modules linked in: vmx_crypto ibmpowernv ipmi_powernv uio_pdrv_genirq ipmi_devintf powernv_op_panel uio ipmi_msghandler powernv_rng leds_powernv ip_tables x_tables autofs4 ses enclosure scsi_transport_sas crc32c_vpmsum lpfc ipr tg3 scsi_transport_fc
+    [ 1727.775883] CPU: 57 PID: 7688 Comm: hwclock Not tainted 4.10.0-14-generic #16-Ubuntu
+    [ 1727.775883] task: c000000fdfdc8400 task.stack: c000000fdfef4000
+    [ 1727.775884] NIP: c00000000090540c LR: c0000000000846f4 CTR: 000000003006dd70
+    [ 1727.775885] REGS: c000000fdfef79a0 TRAP: 0901   Not tainted  (4.10.0-14-generic)
+    [ 1727.775886] MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE>
+    [ 1727.775889]   CR: 28024442  XER: 20000000
+    [ 1727.775890] CFAR: c00000000008472c SOFTE: 1
+                   GPR00: 0000000030005128 c000000fdfef7c20 c00000000144c900 fffffffffffffff4
+                   GPR04: 0000000028024442 c00000000090540c 9000000000009033 0000000000000000
+                   GPR08: 0000000000000000 0000000031fc4000 c000000000084710 9000000000001003
+                   GPR12: c0000000000846e8 c00000000fba0100
+    [ 1727.775897] NIP [c00000000090540c] opal_set_rtc_time+0x4c/0xb0
+    [ 1727.775899] LR [c0000000000846f4] opal_return+0xc/0x48
+    [ 1727.775899] Call Trace:
+    [ 1727.775900] [c000000fdfef7c20] [c00000000090540c] opal_set_rtc_time+0x4c/0xb0 (unreliable)
+    [ 1727.775901] [c000000fdfef7c60] [c000000000900828] rtc_set_time+0xb8/0x1b0
+    [ 1727.775903] [c000000fdfef7ca0] [c000000000902364] rtc_dev_ioctl+0x454/0x630
+    [ 1727.775904] [c000000fdfef7d40] [c00000000035b1f4] do_vfs_ioctl+0xd4/0x8c0
+    [ 1727.775906] [c000000fdfef7de0] [c00000000035bab4] SyS_ioctl+0xd4/0xf0
+    [ 1727.775907] [c000000fdfef7e30] [c00000000000b184] system_call+0x38/0xe0
+    [ 1727.775908] Instruction dump:
+    [ 1727.775909] f821ffc1 39200000 7c832378 91210028 38a10020 39200000 38810028 f9210020
+    [ 1727.775911] 4bfffe6d e8810020 80610028 4b77f61d <60000000> 7c7f1b78 3860000a 2fbffff4
+
+  This is found when executing the `op-test-framework fspresetReload testcase <https://github.com/open-power/op-test-framework/blob/master/testcases/fspresetReload.py>`_
+
+  With this fix ran fsp hir torture testcase in the above test
+  which is working fine.
+
+- FSP/CHIPTOD: Return false in error path
+
+- On FSP platforms: notify FSP of Platform Log ID after Host Initiated Reset Reload
+  Trigging a Host Initiated Reset (when the host detects the FSP has gone
+  out to lunch and should be rebooted), would cause "Unknown Command" messages
+  to appear in the OPAL log.
+
+  This patch implements those messages.
+
+  Log showing unknown command: ::
+
+    / # cat /sys/firmware/opal/msglog | grep -i ,3
+    [  110.232114723,3] FSP: fsp_trigger_reset() entry
+    [  188.431793837,3] FSP #0: Link down, starting R&R
+    [  464.109239162,3] FSP #0: Got XUP with no pending message !
+    [  466.340598554,3] FSP-DPO: Unknown command 0xce0900
+    [  466.340600126,3] FSP: Unhandled message ce0900
+
+- hw/i2c: Fix early lock drop
+
+  When interacting with an I2C master the p8-i2c driver (common to p9)
+  aquires a per-master lock which it holds for the duration of it's
+  interaction with the master.  Unfortunately, when
+  p8_i2c_check_initial_status() detects that the master is busy with
+  another transaction it drops the lock and returns OPAL_BUSY. This is
+  contrary to the driver's locking strategy which requires that the
+  caller aquire and drop the lock. This leads to a crash due to the
+  double unlock(), which skiboot treats as fatal.
+
+- head.S: store all of LR and CTR
+
+  When saving the CTR and LR registers the skiboot exception handlers use the
+  'stw' instruction which only saves the lower 32 bits of the register. Given
+  these are both 64 bit registers this leads to some strange register dumps,
+  for example: ::
+
+    ***********************************************
+    Unexpected exception 200 !
+    SRR0 : 0000000030016968 SRR1 : 9000000000201000
+    HSRR0: 0000000000000180 HSRR1: 9000000000001000
+    LR   : 3003438830823f50 CTR  : 3003438800000018
+    CFAR : 00000000300168fc
+    CR   : 40004208  XER: 00000000
+
+  In this dump the upper 32 bits of LR and CTR are actually stack gunk
+  which obscures the underlying issue.
+
+- hw/fsp: Do not queue SP and SPCN class messages during reset/reload
+  In certain cases of communicating with the FSP (e.g. sensors), the OPAL FSP
+  driver returns a default code (async
+  completion) even though there is no known bound from the time of this error
+  return to the actual data being available. The kernel driver keeps waiting
+  leading to soft-lockup on the host side.
+
+  Mitigate both these (known) cases by returning OPAL_BUSY so the host driver
+  knows to retry later.