v5.9

skiboot-5.9

skiboot v5.9 was released on Tuesday October 31st 2017. It is the first
release of skiboot 5.9 and becomes the new stable release of skiboot
following the 5.8 release, first released August 31st 2017. In this cyle
we have had five release candidate releases, mostly centered around bug
fixing for POWER9 platforms.

This release should be considered suitable for early-access POWER9
systems.

skiboot v5.9 contains all bug fixes as of skiboot-5.4.8 and
skiboot-5.1.21 (the currently maintained stable releases). There may be
some 5.9.x stable releases, depending on what issues are found.

For how the skiboot stable releases work, see stable-rules for details.

Over skiboot-5.8, we have the following changes:

New Features

POWER8

• fast-reset by default (if possible)

  Currently, this is limited to POWER8 systems.

  A normal reboot will, rather than doing a full IPL, go through a
  fast reboot procedure. This reduces the "reboot to petitboot" time
  from minutes to a handful of seconds.

POWER9

Since skiboot-5.9-rc3:

• occ-sensors : Add OCC inband sensor region to exports (useful for
  debugging)

Two SRESET fixes (see below for feature description):

• core: direct-controls: Fix clearing of special wakeup

  'special_wakeup_count' is incremented on successfully asserting
  special wakeup. So we will never clear the special wakeup if we
  check 'special_wakeup_count' to be zero. Fix this issue by
  checking the 'special_wakeup_count' to 1 in
  dctl_clear_special_wakeup().

• core/direct-controls: increase special wakeup timeout on POWER9

  Some instances have been observed where the special wakeup assert
  times out. The current timeout is too short for deeper sleep states.
  Hostboot uses 100ms, so match that.

Since skiboot-5.9-rc2: - cpu: Add
OPAL_REINIT_CPUS_TM_SUSPEND_DISABLED

Add a new CPU reinit flag, "TM Suspend Disabled", which requests that
CPUs be configured so that TM (Transactional Memory) suspend mode is
disabled.

Currently this always fails, because skiboot has no way to query the
state. A future hostboot change will add a mechanism for skiboot to
determine the status and return an appropriate error code.

Since skiboot-5.8:

• POWER9 power management during boot

  Less power should be consumed during boot.

• OPAL_SIGNAL_SYSTEM_RESET for POWER9

  This implements OPAL_SIGNAL_SYSTEM_RESET, using scom registers to
  quiesce the target thread and raise a system reset exception on it.
  It has been tested on DD2 with stop0 ESL=0 and ESL=1 shallow power
  saving modes.

  DD1 is not implemented because it is sufficiently different as to
  make support difficult.

• Enable deep idle states for POWER9

  • SLW: Add support for p9_stop_api

    p9_stop_api's are used to set SPR state on a core wakeup form
    a deeper low power state. p9_stop_api uses low level platform
    formware and self-restore microcode to restore the sprs to
    requested values.

    Code is taken from :
    https://github.com/open-power/hostboot/tree/master/src/import/chips/p9/procedures/utils/stopreg

  • SLW: Removing timebase related flags for stop4

    When a core enters stop4, it does not loose decrementer and time
    base. Hence removing flags OPAL_PM_DEC_STOP and
    OPAL_PM_TIMEBASE_STOP.

  • SLW: Allow deep states if homer address is known

    Use a common variable has_wakeup_engine instead of has_slw to
    tell if the:

    • SLW image is populated in case of power8
    • CME image is populated in case of power9

    Currently we expect CME to be loaded if homer address is known (
    except for simulators)

  • SLW: Configure self-restore for HRMOR

    Make a stop api call using libpore to restore HRMOR register.
    HRMOR needs to be cleared so that when thread exits stop, they
    arrives at linux system_reset vector (0x100).

  • SLW: Add opal_slw_set_reg support for power9

  This OPAL call is made from Linux to OPAL to configure values in
  various SPRs after wakeup from a deep idle state.

• PHB4: CAPP recovery

  CAPP recovery is initiated when a CAPP Machine Check is detected.
  The capp recovery procedure is initiated via a Hypervisor
  Maintenance interrupt (HMI).

  CAPP Machine Check may arise from either an error that results in a
  PHB freeze or from an internal CAPP error with CAPP checkstop FIR
  action. An error that causes a PHB freeze will result in the link
  down signal being asserted. The system continues running and the
  CAPP and PSL will be re-initialized.

  This implements CAPP recovery for POWER9 systems

• Add wafer-location property for POWER9

  Extract wafer-location from ECID and add property under xscom node.

  • bits 64:71 are the chip x location (7:0)
  • bits 72:79 are the chip y location (7:0)

  Sample output: :

  [root@wsp xscom@623fc00000000]# lsprop ecid
  ecid             019a00d4 03100718 852c0000 00fd7911
  [root@wsp xscom@623fc00000000]# lsprop wafer-location
  wafer-location   00000085 0000002c
  

• Add wafer-id property for POWER9

  Wafer id is derived from ECID data.

  • bits 4:63 are the wafer id ( ten 6 bit fields each containing a
    code)

  Sample output: :

  [root@wsp xscom@623fc00000000]# lsprop ecid
  ecid             019a00d4 03100718 852c0000 00fd7911
  [root@wsp xscom@623fc00000000]# lsprop wafer-id
  wafer-id         "6Q0DG340SO"
  

• Add ecid property under xscom node for POWER9. Sample output: :

  [root@wsp xscom@623fc00000000]# lsprop ecid
  ecid             019a00d4 03100718 852c0000 00fd7911
  

• Add ibm,firmware-versions device tree node

  In P8, hostboot provides mini device tree. It contains
  /ibm,firmware-versions node which has various firmware component
  version details.

  In P9, OPAL is building device tree. This patch adds support to
  parse VERSION section of PNOR and create /ibm,firmware-versions
  device tree node.

  Sample output: :

  /sys/firmware/devicetree/base/ibm,firmware-versions # lsprop .
  occ              "6a00709"
  skiboot          "v5.7-rc1-p344fb62"
  buildroot        "2017.02.2-7-g23118ce"
  capp-ucode       "9c73e9f"
  petitboot        "v1.4.3-p98b6d83"
  sbe              "02021c6"
  open-power       "witherspoon-v1.17-128-gf1b53c7-dirty"
  ....
  ....
  

POWER9

Since skiboot-5.9-rc5:

• Suppress XSCOM chiplet-offline errors on P9

  Workaround on P9: PRD does operations it knows will fail with this
  error to work around a hardware issue where accesses via the PIB
  (FSI or OCC) work as expected, accesses via the ADU (what xscom goes
  through) do not. The chip logic will always return all FFs if there
  is any error on the scom.

• asm/head: initialize preferred DSCR value

  POWER7/8 use DSCR=0. POWER9 preferred value has "stride-N" enabled.

Since skiboot-5.9-rc4: - opal/hmi: Workaround Power9 hw logic bug for
couple of TFMR TB errors. - opal/hmi: Fix TB reside and HDEC parity
error recovery for power9

Since skiboot-5.9-rc2: - hw/imc: Fix IMC Catalog load for DD2.X
processors

Since skiboot-5.9-rc1: - xive: Fix VP free block group mode
false-positive parameter check

The check to ensure the buddy allocation idx is aligned to its
allocation order was not taking into account the allocation split.
This would result in opal_xive_free_vp_block failures despite
giving the same value as returned by opal_xive_alloc_vp_block.

E.g., starting then stopping 4 KVM guests gives the following pattern
in the host: :

opal_xive_alloc_vp_block(5)=0x45000020
opal_xive_alloc_vp_block(5)=0x45000040
opal_xive_alloc_vp_block(5)=0x45000060
opal_xive_alloc_vp_block(5)=0x45000080
opal_xive_free_vp_block(0x45000020)=-1
opal_xive_free_vp_block(0x45000040)=0
opal_xive_free_vp_block(0x45000060)=-1
opal_xive_free_vp_block(0x45000080)=0

• hw/imc: pause microcode at boot

  IMC nest counters has both in-band (ucode access) and out of band
  access to it. Since not all nest counter configurations are
  supported by ucode, out of band tools are used to characterize other
  configuration.

  So it is prefer to pause the nest microcode at boot to aid the nest
  out of band tools. If the ucode not paused and OS does not have IMC
  driver support, then out to band tools will race with ucode and end
  up getting undesirable values. Patch to check and pause the ucode at
  boot.

  OPAL provides APIs to control IMC counters.
  OPAL_IMC_COUNTERS_INIT is used to initialize these counters at
  boot. OPAL_IMC_COUNTERS_START and OPAL_IMC_COUNTERS_STOP API
  calls should be used to start and pause these IMC engines.
  doc/opal-api/opal-imc-counters.rst details the OPAL APIs and their
  usage.

• hdata/i2c: update the list of known i2c devs

  This updates the list of known i2c devices - as of HDAT spec
  v10.5e - so that they can be properly identified during the hdat
  parsing.

• hdata/i2c: log unknown i2c devices

  An i2c device is unknown if either the i2c device list is outdated
  or the device is marked as unknown (0xFF) in the hdat.

Since skiboot-5.8:

• Disable Transactional Memory on Power9 DD 2.1

  Update pa_features_p9[] to disable TM (Transactional Memory). On
  DD 2.1 TM is not usable by Linux without other workarounds, so
  skiboot must disable it.

• xscom: Do not print error message for 'chiplet offline' return
  values

  xscom_read/write operations returns CHIPLET_OFFLINE when chiplet
  is offline. Some multicast xscom_read/write requests from HBRT
  results in xscom operation on offline chiplet(s) and printing below
  warnings in OPAL console: :

  [ 135.036327572,3] XSCOM: Read failed, ret = -14
  [ 135.092689829,3] XSCOM: Read failed, ret = -14
  

  Some SCOM users can deal correctly with this error code (notably
  opal-prd), so the error message is (in practice) erroneous.

• IMC: Fix the core_imc_event_mask

  CORE_IMC_EVENT_MASK is a scom that contains bits to control event
  sampling for different machine state for core imc. The current
  event-mask setting sample events only on host kernel (hypervisor)
  and host userspace.

  Patch to enable the sampling of events in other machine states (like
  guest kernel and guest userspace).

• IMC: Update the nest_pmus array with occ/gpe microcode uav updates

  OOC/gpe nest microcode maintains the list of individual nest units
  supported. Sync the recent updates to the UAV with nest_pmus array.

  For reference occ/gpr microcode link for the UAV:
  https://github.com/open-power/occ/blob/master/src/occ_gpe1/gpe1_24x7.h

• Parse IOSLOT information from HDAT

  Add structure definitions that describe the physical PCIe topology
  of a system and parse them into the device-tree based PCIe slot
  description.

• idle: user context state loss flags fix for stop states

  The "lite" stop variants with PSSCR[ESL]=PSSCR[EC]=1 do not lose
  user context, while the non-lite variants do (ESL: enable state
  loss).

  Some of the POWER9 idle states had these wrong.

CAPI

• POWER9 DD2 update

  The CAPI initialization sequence has been updated in DD2. This patch
  adapts to the changes, retaining compatibility with DD1. The patch
  includes some changes to DD1 fix-ups as well.

• Load CAPP microcode for POWER9 DD2.0 and DD2.1

• capi: Mask Psl Credit timeout error for POWER9

  Mask the PSL credit timeout error in CAPP FIR Mask register bit(46).
  As per the h/w team this error is now deprecated and shouldn't cause
  any fir-action for P9.

NVLINK2

A notabale change is that we now generate the device tree description of
NVLINK based on the HDAT we get from hostboot. Since Hostboot will
generate HDAT based on VPD, you now MUST have correct VPD programmed
or we will default to a Sequoia layout, which will lead to random
problems if you are not booting a Sequoia Witherspoon planar. In the
case of booting with old VPD and/or Hostboot, we print a giant scary
warning in order to scare you.

Since skiboot-5.9-rc2: - Revert "npu2: Add vendor cap for IRQ testing"

This reverts commit 9817c9e which
seems to break setting the PCI dev flag and the link number in the
PCIe vendor specific config space. This leads to the device driver
attempting to re-init the DL when it shouldn't which can cause HMI's.

Since skiboot-5.8:

• npu2: Read slot label from the HDAT link node

  Binding GPU to emulated NPU PCI devices is done using the slot
  labels since the NPU devices do not have a patching slot node we
  need to copy the label in here.

• npu2: Copy link speed from the npu HDAT node

  This needs to be in the PCI device node so the speed of the NVLink
  can be passed to the GPU driver.

• npu2: hw-procedures: Add settings to PHY_RESET

  Set a few new values in the PHY_RESET procedure, as specified by
  our updated programming guide documentation.

• Parse NVLink information from HDAT

  Add the per-chip structures that descibe how the
  A-Bus/NVLink/OpenCAPI phy is configured. This generates the
  npu@xyz nodes for each chip on systems that support it.

• npu2: Add vendor cap for IRQ testing

  Provide a way to test recoverable data link interrupts via a new
  vendor capability byte.

• npu2: Enable recoverable data link (no-stall) interrupts

  Allow the NPU2 to trigger "recoverable data link" interrupts.

• npu2: Implement basic FLR (Function Level Reset)

• npu2: hw-procedures: Update PHY DC calibration procedure

• npu2: hw-procedures: Change rx_pr_phase_step value

XIVE

• xive: Fix opal_xive_dump_tm() to access W2 properly. The HW only
  supported limited access sizes.

• xive: Make opal_xive_allocate_irq() properly try all chips

  When requested via OPAL_XIVE_ANY_CHIP, we need to try all chips.
  We first try the current one (on which the caller sits) and if that
  fails, we iterate all chips until the allocation succeeds.

• xive: Fix initialization & cleanup of HW thread contexts

  Instead of trying to "pull" everything and clear VT (which didn't
  work and caused some FIRs to be set), instead just clear and then
  set the PTER thread enable bit. This has the side effect of
  completely resetting the corresponding thread context.

  This fixes the spurrious XIVE FIRs reported by PRD and fircheck

• xive: Add debug option for detecting misrouted IPI in emulation

  This is high overhead so we don't enable it by default even in debug
  builds, it's also a bit messy, but it allowed me to detect and debug
  a locking issue earlier so it can be useful.

• xive: Increase the interrupt "gap" on debug builds

  We normally allocate IPIs from 0x10. Make that 0x1000 on debug
  builds to limit the chances of overlapping with Linux interrupt
  numbers which makes debugging code that confuses them easier.

  Also add a warning in emulation if we get an interrupt in the queue
  whose number is below the gap.

• xive: Fix locking around cache scrub & watch

  Thankfully the missing locking only affects debug code and init code
  that doesn't run concurrently. Also adds a DEBUG option that checks
  the lock is properly held.

• xive: Workaround HW issue with scrub facility

  Without this, we sometimes don't observe from a CPU the values
  written to the ENDs or NVTs via the cache watch.

• xive: Add exerciser for cache watch/scrub facility in DEBUG builds

• xive: Make assertion in xive_eq_for_target() more informative

• xive: Add debug code to check initial cache updates

• xive: Ensure pressure relief interrupts are disabled

  We don't use them and we hijack the VP field with their
  configuration to store the EQ reference, so make sure the kernel or
  guest can't turn them back on by doing MMIO writes to ACK#

• xive: Don't try setting the reserved ACK# field in VPs

  That doesn't work, the HW doesn't implement it in the cache watch
  facility anyway.

• xive: Remove useless memory barriers in VP/EQ inits

  We no longer update "live" memory structures, we use a temporary
  copy on the stack and update the actual memory structure using the
  cache watch, so those barriers are pointless.

PHB4

Since skiboot-5.9-rc4:

• phb4: Escalate freeze to fence to avoid checkstop

  Freeze events such as MMIO loads can cause the PHB to lose it's
  limited powerbus credits. If all credits are used and a further MMIO
  will cause a checkstop.

  To work around this, we escalate the troublesome freeze events to a
  fence. The fence will cause a full PHB reset which resets the
  powerbus credits and avoids the checkstop.

• phb4: Update some init registers

  New inits based on next PHB4 workbook. Increases some timeouts to
  avoid some spurious error conditions.

• phb4: Enable PHB MMIO in phb4_root_port_init()

  Linux EEH flow is somewhat broken. It saves the PCIe config space of
  the PHB on boot, which it then uses to restore on EEH recovery. It
  does this to restore MMIO bars and some other pieces.

  Unfortunately this save is done before any drivers are bound to
  devices under the PHB. A number of other things are configured in
  the PHB after drivers start, hence some configuration space settings
  aren't saved correctly. These include bus master and MMIO bits in
  the command register.

  Linux tried to hack around this in this linux commit bf898ec5cb
  powerpc/eeh: Enable PCI_COMMAND_MASTER for PCI bridges This sets
  the bus master bit but ignores the MMIO bit.

  Hence we lose MMIO after a full PHB reset. This causes the next MMIO
  access to the device to fail and for us to perform a PE freeze
  recovery, which still doesn't set the MMIO bit and hence we still
  fail.

  This works around this by forcing MMIO on during
  phb4_root_port_init().

  With this we can recovery from a PHB fence event on POWER9.

• phb4: Reduce link degraded message log level to debug

  If we hit this message we'll retry and fix the problem. If we run
  out of retries and can't fix the problem, we'll still print a log
  message at error level indicating a problem.

• phb4: Fix GEN3 for DD2.00

  In this fix: 62ac7631ae phb4: Fix PCIe GEN4 on DD2.1 and above We
  fixed DD2.1 GEN4 but broke DD2.00 as GEN3.

  This fixes DD2.00 back to GEN3. This time for sure!

Since skiboot-5.9-rc3: - phb4: Fix PCIe GEN4 on DD2.1 and above

In this change:

: eef0e19 PHB4: Default to PCIe GEN3 on POWER9 DD2.00

We clamped DD2.00 parts to GEN3 but unfortunately this change also
applies to DD2.1 and above.

This fixes this to only apply to DD2.00.

Since skiboot-5.8:

• phb4: Mask RXE_ARB: DEC Stage Valid Error

  Change the inits to mask out the RXE ARB: DEC Stage Valid Error (bit
  370. This has been a fatal error but should be informational only.

  This update will be in the next version of the phb4 workbook.

• phb4: Add additional adapter to retrain whitelist

  The single port version of the ConnectX-5 has a different device ID
  0x1017. Updated descriptions to match pciutils database.

• PHB4: Default to PCIe GEN3 on POWER9 DD2.00

  You can use the NVRAM override for DD2.00 screened parts.

• phb4: Retrain link if degraded

  On P9 Scale Out (Nimbus) DD2.0 and Scale in (Cumulus) DD1.0 (and
  below) the PCIe PHY can lockup causing training issues. This can
  cause a degradation in speed or width in ~5% of training cases
  (depending on the card). This is fixed in later chip revisions. This
  issue can also cause PCIe links to not train at all, but this case
  is already handled.

  This patch checks if the PCIe link has trained optimally and if not,
  does a full PHB reset (to fix the PHY lockup) and retrain.

  One complication is some devices are known to train degraded unless
  device specific configuration is performed. Because of this, we only
  retrain when the device is in a whitelist. All devices in the
  current whitelist have been testing on a P9DSU/Boston, ZZ and
  Witherspoon.

  We always gather information on the link and print it in the logs
  even if the card is not in the whitelist.

  For testing purposes, there's an nvram to retry all PCIe cards and
  all P9 chips when a degraded link is detected. The new option is
  'pci-retry-all=true' which can be set using:
  nvram -p ibm,skiboot --update-config pci-retry-all=true. This option
  may increase the boot time if used on a badly behaving card.

IBM FSP platforms

Since skiboot-5.9-rc5: - FSP/CONSOLE: Disable notification on
unresponsive consoles

Commit fd6b71f fixed the situation where ipmi console was open (hvc0)
but got data on different console (hvc1).

During FSP Reset/Reload OPAL closes all consoles. After Reset/Reload
complete FSP requests to open hvc1 and sends data on this. If hvc1
registration failed or not opened in host kernel then it will not read
data and results in RCU stalls.

Note that this is workaround for older kernel where we don't have
separate irq for each console. Latest kernel works fine without this
patch.

Since skiboot-5.9-rc1:

• FSP/CONSOLE: Limit number of error logging

  Commit c8a7535 (FSP/CONSOLE: Workaround for unresponsive ipmi
  daemon) added error logging when buffer is full. In some corner
  cases kernel may call this function multiple time and we may endup
  logging error again and again.

  This patch fixes it by generating error log only once.

• FSP/CONSOLE: Fix fsp_console_write_buffer_space() call

  Kernel calls fsp_console_write_buffer_space() to check console
  buffer space availability. If there is enough buffer space to write
  data, then kernel will call fsp_console_write() to write actual
  data.

  In some extreme corner cases (like one explained in commit c8a7535)
  console becomes full and this function returns 0 to kernel (or space
  available in console buffer < next incoming data size). Kernel
  will continue retrying until it gets enough space. So we will start
  seeing RCU stalls.

  This patch keeps track of previous available space. If previous
  space is same as current means not enough space in console buffer to
  write incoming data. It may be due to very high console write
  operation and slow response from FSP -OR- FSP has stopped processing
  data (ex: because of ipmi daemon died). At this point we will start
  timer with timeout of SER_BUFFER_OUT_TIMEOUT (10 secs). If
  situation is not improved within 10 seconds means something went
  bad. Lets return OPAL_RESOURCE so that kernel can drop console
  write and continue.

• FSP/CONSOLE: Close SOL session during R/R

  Presently we are not closing SOL and FW console sessions during R/R.
  Host will continue to write to SOL buffer during FSP R/R. If there
  is heavy console write operation happening during FSP R/R (like
  running top command inside console), then at some point console
  buffer becomes full. fsp_console_write_buffer_space() returns 0
  (or less than required space to write data) to host. While one
  thread is busy writing to console, if some other threads tries to
  write data to console we may see RCU stalls (like below) in kernel.
  :

  [ 2082.828363] INFO: rcu_sched detected stalls on CPUs/tasks: { 32} (detected by 16, t=6002 jiffies, g=23154, c=23153, q=254769)
  [ 2082.828365] Task dump for CPU 32:
  [ 2082.828368] kworker/32:3    R  running task        0  4637      2 0x00000884
  [ 2082.828375] Workqueue: events dump_work_fn
  [ 2082.828376] Call Trace:
  [ 2082.828382] [c000000f1633fa00] [c00000000013b6b0] console_unlock+0x570/0x600 (unreliable)
  [ 2082.828384] [c000000f1633fae0] [c00000000013ba34] vprintk_emit+0x2f4/0x5c0
  [ 2082.828389] [c000000f1633fb60] [c00000000099e644] printk+0x84/0x98
  [ 2082.828391] [c000000f1633fb90] [c0000000000851a8] dump_work_fn+0x238/0x250
  [ 2082.828394] [c000000f1633fc60] [c0000000000ecb98] process_one_work+0x198/0x4b0
  [ 2082.828396] [c000000f1633fcf0] [c0000000000ed3dc] worker_thread+0x18c/0x5a0
  [ 2082.828399] [c000000f1633fd80] [c0000000000f4650] kthread+0x110/0x130
  [ 2082.828403] [c000000f1633fe30] [c000000000009674] ret_from_kernel_thread+0x5c/0x68
  

  Hence lets close SOL (and FW console) during FSP R/R.

• FSP/CONSOLE: Do not associate unavailable console

  Presently OPAL sends associate/unassociate MBOX command for all FSP
  serial console (like below OPAL message). We have to check console
  is available or not before sending this message. :

  [ 5013.227994012,7] FSP: Reassociating HVSI console 1
  [ 5013.227997540,7] FSP: Reassociating HVSI console 2
  

• FSP: Disable PSI link whenever FSP tells OPAL about impending R/R

  Commit 42d5d04 fixed scenario where DPO has been initiated, but FSP
  went into reset before the CEC power down came in. But this is
  generic issue that can happen in normal shutdown path as well.

  Hence disable PSI link as soon as we detect FSP impending R/R.

• fsp: return OPAL_BUSY_EVENT on failure sending
  FSP_CMD_POWERDOWN_NORM Also, return OPAL_BUSY_EVENT on failure
  sending FSP_CMD_REBOOT / DEEP_REBOOT.

  We had a race condition between FSP Reset/Reload and powering down
  the system from the host:

  Roughly:

  # FSP Host

  ---

  1 Power on
  2 Power on
  3 (inject EPOW)
  4 (trigger FSP R/R)
  5 Processes EPOW event, starts shutting down
  6 calls OPAL_CEC_POWER_DOWN
  7 (is still in R/R)
  8 gets OPAL_INTERNAL_ERROR, spins in opal_poll_events
  9 (FSP comes back)
  10 spinning in opal_poll_events
  11 (thinks host is running)

  The call to OPAL_CEC_POWER_DOWN is only made once as the
  reset/reload error path for fsp_sync_msg() is to return -1, which
  means we give the OS OPAL_INTERNAL_ERROR, which is fine, except
  that our own API docs give us the opportunity to return OPAL_BUSY
  when trying again later may be successful, and we're ambiguous as to
  if you should retry on OPAL_INTERNAL_ERROR.

  For reference, the linux code looks like this: :

  static void __noreturn pnv_power_off(void)
  {
          long rc = OPAL_BUSY;
  
          pnv_prepare_going_down();
  
          while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                  rc = opal_cec_power_down(0);
                  if (rc == OPAL_BUSY_EVENT)
                          opal_poll_events(NULL);
                  else
                          mdelay(10);
          }
          for (;;)
                  opal_poll_events(NULL);
  }
  

  Which means that practically our only option is to return
  OPAL_BUSY or OPAL_BUSY_EVENT.

  We choose OPAL_BUSY_EVENT for FSP systems as we do want to ensure
  we're running pollers to communicate with the FSP and do the final
  bits of Reset/Reload handling before we power off the system.

Since skiboot-5.8:

• FSP/NVRAM: Handle "get vNVRAM statistics" command

  FSP sends MBOX command (cmd : 0xEB, subcmd : 0x05, mod : 0x00) to
  get vNVRAM statistics. OPAL doesn't maintain any such statistics.
  Hence return FSP_STATUS_INVALID_SUBCMD.

  Fixes these messages appearing in the OPAL log: :

  [16944.384670488,3] FSP: Unhandled message eb0500
  [16944.474110465,3] FSP: Unhandled message eb0500
  [16945.111280784,3] FSP: Unhandled message eb0500
  [16945.293393485,3] FSP: Unhandled message eb0500
  

• fsp: Move common prints to trace

  These two prints just end up filling the skiboot logs on any machine
  that's been booted for more than a few hours.

  They have never been useful, so make them trace level. They were: ::

  : SURV: Received heartbeat acknowledge from FSP SURV: Sending the
  heartbeat command to FSP

BMC based systems

• hw/lpc-uart: read from RBR to clear character timeout interrupts

  When using the aspeed SUART, we see a condition where the UART sends
  continuous character timeout interrupts. This change adds a (heavily
  commented) dummy read from the RBR to clear the interrupt condition
  on init.

  This was observed on p9dsu systems, but likely applies to other
  systems using the SUART.

• astbmc: Add methods for handing Device Tree based slots e.g. ones
  from HDAT on POWER9.

General

Since skiboot-5.9-rc5:

• p8-i2c: Further timeout reworks

  This patch reworks the way timeouts are set so that rather than
  imposing a hard deadline based on the transaction length it uses a
  kick-the-can-down-the-road approach where the timeout will be reset
  each time data is written to or received from the master. This fits
  better with the actual failure modes that timeouts are designed to
  handle, such as unusually slow or broken devices.

  Additionally this patch moves all the special case detection out of
  the timeout handler. This is help to improve the robustness of the
  driver and prepare for a more substantial rework of the driver as a
  whole later on.

• npu: Fix broken fast reset

  0679f61 "fast-reset: by default (if possible)" broke NPU - now
  the NV links does not get enabled after reboot.

  This disables fast reboot for NPU machines till a better solution is
  found.

Since skiboot-5.9-rc2:

• Improvements to vpd device tree entries

  Previously we would miss some properties

Since skiboot-5.9-rc1:

• hw/p8-i2c: Fix deadlock in p9_i2c_bus_owner_change

  When debugging a system where Linux was taking soft lockup errors
  with two CPUs stuck in OPAL:

  CPU0 CPU1

  ---

  lock
  p8_i2c_recover
  opal_handle_interrupt
  sync_timer
  cancel_timer
  p9_i2c_bus_o wner_change
  occ_p9_inter rupt
  xive_source interrupt
  opal_handle interrupt

  p8_i2c_recover() is a timer, and is stuck trying to take
  master->lock. p9_i2c_bus_owner_change() has taken
  master->lock, but then is stuck waiting for all timers to
  complete. We deadlock.

  Fix this by using cancel_timer_async().

• opal/cpu: Mark the core as bad while disabling threads of the core.

  If any of the core fails to sync its TB during chipTOD
  initialization, all the threads of that core are disabled. But this
  does not make linux kernel to ignore the core/cpus. It crashes while
  bringing them up with below backtrace: :

  [   38.883898] kexec_core: Starting new kernel
  cpu 0x0: Vector: 300 (Data Access) at [c0000003f277b730]
      pc: c0000000001b9890: internal_create_group+0x30/0x304
      lr: c0000000001b9880: internal_create_group+0x20/0x304
      sp: c0000003f277b9b0
     msr: 900000000280b033
     dar: 40
   dsisr: 40000000
    current = 0xc0000003f9f41000
    paca    = 0xc00000000fe00000   softe: 0        irq_happened: 0x01
      pid   = 2572, comm = kexec
  Linux version 4.13.2-openpower1 (jenkins@p89) (gcc version 6.4.0 (Buildroot 2017.08-00006-g319c6e1)) #1 SMP Wed Sep 20 05:42:11 UTC 2017
  enter ? for help
  [c0000003f277b9b0] c0000000008a8780 (unreliable)
  [c0000003f277ba50] c00000000041c3ac topology_add_dev+0x2c/0x40
  [c0000003f277ba70] c00000000006b078 cpuhp_invoke_callback+0x88/0x170
  [c0000003f277bac0] c00000000006b22c cpuhp_up_callbacks+0x54/0xb8
  [c0000003f277bb10] c00000000006bc68 cpu_up+0x11c/0x168
  [c0000003f277bbc0] c00000000002f0e0 default_machine_kexec+0x1fc/0x274
  [c0000003f277bc50] c00000000002e2d8 machine_kexec+0x50/0x58
  [c0000003f277bc70] c0000000000de4e8 kernel_kexec+0x98/0xb4
  [c0000003f277bce0] c00000000008b0f0 SyS_reboot+0x1c8/0x1f4
  [c0000003f277be30] c00000000000b118 system_call+0x58/0x6c
  

Since skiboot-5.8:

• ipmi: Convert common debug prints to trace

  OPAL logs messages for every IPMI request from host. Sometime OPAL
  console is filled with only these messages. This path is pretty
  stable now and we have enough logs to cover bad path. Hence lets
  convert these debug message to trace/info message. Examples are: :

  [ 1356.423958816,7] opal_ipmi_recv(cmd: 0xf0 netfn: 0x3b resp_size: 0x02)
  [ 1356.430774496,7] opal_ipmi_send(cmd: 0xf0 netfn: 0x3a len: 0x3b)
  [ 1356.430797392,7] BT: seq 0x20 netfn 0x3a cmd 0xf0: Message sent to host
  [ 1356.431668496,7] BT: seq 0x20 netfn 0x3a cmd 0xf0: IPMI MSG done
  

• libflash/file: Handle short read()s and write()s correctly

  Currently we don't move the buffer along for a short read() or
  write() and nor do we request only the remaining amount.

• hw/p8-i2c: Rework timeout handling

  Currently we treat a timeout as a hard failure and will
  automatically fail any transations that hit their timeout. This
  results in unnecessarily failing I2C requests if interrupts are
  dropped, etc. Although these are bad things that we should log we
  can handle them better by checking the actual hardware status and
  completing the transation if there are no real errors. This patch
  reworks the timeout handling to check the status and continue the
  transaction if it can. if it can while logging an error if it
  detects a timeout due to a dropped interrupt.

• core/flash: Only expect ELF header for BOOTKERNEL partition flash
  resource

  When loading a flash resource which isn't signed (secure and trusted
  boot) and which doesn't have a subpartition, we assume it's the
  BOOTKERNEL since previously this was the only such resource. Thus we
  also assumed it had an ELF header which we parsed to get the size of
  the partition rather than trusting the actual_size field in the FFS
  header. A previous commit (9727fe3 DT: Add ibm,firmware-versions
  node) added the version resource which isn't signed and also doesn't
  have a subpartition, thus we expect it to have an ELF header. It
  doesn't so we print the error message "FLASH: Invalid ELF header
  part VERSION".

  It is a fluke that this works currently since we load the secure
  boot header unconditionally and this happen to be the same size as
  the version partition. We also don't update the return code on error
  so happen to return OPAL_SUCCESS.

  To make this explicitly correct; only check for an ELF header if we
  are loading the BOOTKERNEL resource, otherwise use the partition
  size from the FFS header. Also set the return code on error so we
  don't erroneously return OPAL_SUCCESS. Add a check that the
  resource will fit in the supplied buffer to prevent buffer overrun.

• flash: Support adding the no-erase property to flash

  The mbox protocol explicitly states that an erase is not required
  before a write. This means that issuing an erase from userspace,
  through the mtd device, and back returns a successful operation that
  does nothing. Unfortunately, this makes userspace tools unhappy.
  Linux MTD devices support the MTD_NO_ERASE flag which conveys that
  writes do not require erases on the underlying flash devices. We
  should set this property on all of our devices which do not require
  erases to be performed.

  NOTE: This still requires a linux kernel component to set the
  MTD_NO_ERASE flag from the device tree property.

Utilities

Since skiboot-5.9-rc1: - opal-prd: Fix memory leak

Since skiboot-5.8:

• external/gard: Clear entire guard partition instead of entry by
  entry

  When using the current implementation of the gard tool to ecc clear
  the entire GUARD partition it is done one gard record at a time.
  While this may be ok when accessing the actual flash this is very
  slow when done from the host over the mbox protocol (on the order of
  4 minutes) because the bmc side is required to do many read, erase,
  writes under the hood.

  Fix this by rewriting the gard tool reset_partition() function. Now
  we allocate all the erased guard entries and (if required) apply ecc
  to the entire buffer. Then we can do one big erase and write of the
  entire partition. This reduces the time to clear the guard partition
  to on the order of 4 seconds.

• opal-prd: Fix opal-prd command line options

  HBRT OCC reset interface depends on service processor type.

  • FSP: reset_pm_complex()
  • BMC: process_occ_reset()

  We have both occ and pm-complex command line interfaces. This patch
  adds support to dispaly appropriate message depending on system
  type.

  SP Command Action

  ---

  FSP opal-prd occ display error message
  FSP opal-prd pm-complex Call pm_complex_reset()
  BMC opal-prd occ Call process_occ_reset()
  BMC opal-prd pm-complex display error message

• opal-prd: detect service processor type and then make appropriate
  occ reset call.

• pflash: Fix erase command for unaligned start address

  The erase_range() function handles erasing the flash for a given
  start address and length, and can handle an unaligned start address
  and length. However in the unaligned start address case we are
  incorrectly calculating the remaining size which can lead to
  incomplete erases.

  If we're going to update the remaining size based on what the start
  address was then we probably want to do that before we overide the
  origin start address. So rearrange the code so that this is indeed
  the case.

• external/gard: Print an error if run on an FSP system

Simulators

• mambo: Add mambo socket program

  This adds a program that can be run inside a mambo simulator in
  linux userspace which enables TCP sockets to be proxied in and out
  of the simulator to the host.

  Unlike mambo bogusnet, it's requires no linux or skiboot specific
  drivers/infrastructure to run.

  Run inside the simulator:

  • to forward host ssh connections to sim ssh server:
    ./mambo-socket-proxy -h 10022 -s 22, then connect to port
    10022 on your host with ssh -p 10022 localhost
  • to allow http proxy access from inside the sim to local http
    proxy: ./mambo-socket-proxy -b proxy.mynetwork -h 3128 -s 3128

  Multiple connections are supported.

• idle: disable stop*_lite POWER9 idle states for Mambo platform

  Mambo prior to Mambo.7.8.21 had a bug where the stop idle
  instruction with PSSCR[ESL]=PSSCR[EC]=0 would resume with MSR
  set as though it had taken a system reset interrupt.

  Linux currently executes this instruction with MSR already set that
  way, so the problem went unnoticed. A proposed patch to Linux
  changes that, and causes the idle code to crash. Work around this by
  disabling lite stop states for the mambo platform for now.