powerpc: fix typos in comments

Various spelling mistakes in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220430185654.5855-1-Julia.Lawall@inria.fr

powerpc/eeh: Fix build with STACKTRACE=n

The build breaks when STACKTRACE=n, eg. skiroot_defconfig:

arch/powerpc/kernel/eeh_event.c:124:23: error: implicit declaration of function 'stack_trace_save'

Fix it with some ifdefs for now.

Fixes: 25baf3d81614 ("powerpc/eeh: Defer printing stack trace")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/eeh: Defer printing stack trace

Currently we print a stack trace in the event handler to help with
debugging EEH issues. In the case of suprise hot-unplug this is unneeded,
so we want to prevent printing the stack trace unless we know it's due to
an actual device error. To accomplish this, we can save a stack trace at
the point of detection and only print it once the EEH recovery handler has
determined the freeze was due to an actual error.

Since the whole point of this is to prevent spurious EEH output we also
move a few prints out of the detection thread, or mark them as pr_debug
so anyone interested can get output from the eeh_check_dev_failure()
if they want.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-6-oohall@gmail.com

powerpc/eeh: Clean up EEH PEs after recovery finishes

When the last device in an eeh_pe is removed the eeh_pe structure itself
(and any empty parents) are freed since they are no longer needed. This
results in a crash when a hotplug driver is involved since the following
may occur:

1. Device is suprise removed.
2. Driver performs an MMIO, which fails and queues and eeh_event.
3. Hotplug driver receives a hotplug interrupt and removes any
pci_devs that were under the slot.
4. pci_dev is torn down and the eeh_pe is freed.
5. The EEH event handler thread processes the eeh_event and crashes
since the eeh_pe pointer in the eeh_event structure is no
longer valid.

Crashing is generally considered poor form. Instead of doing that use
the fact PEs are marked as EEH_PE_INVALID to keep them around until the
end of the recovery cycle, at which point we can safely prune any empty
PEs.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-2-oohall@gmail.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/eeh: Add eeh_force_recover to debugfs

This patch adds a debugfs interface to force scheduling a recovery event.
This can be used to recover a specific PE or schedule a "special" recovery
even that checks for errors at the PHB level.
To force a recovery of a normal PE, use:

echo '<#pe>:<#phb>' > /sys/kernel/debug/powerpc/eeh_force_recover

To force a scan for broken PHBs:

echo 'hwcheck' > /sys/kernel/debug/powerpc/eeh_force_recover

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/eeh: Allow disabling recovery

Currently when we detect an error we automatically invoke the EEH recovery
handler. This can be annoying when debugging EEH problems, or when working
on EEH itself so this patch adds a debugfs knob that will prevent a
recovery event from being queued up when an issue is detected.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: eeh_event: convert semaphore to completion

For this use case, completions and semaphores are equivalent,
but semaphores are an awkward interface that should generally
be avoided, so use the completion instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/eeh: Manage EEH_PE_RECOVERING inside eeh_handle_normal_event()

Currently the EEH_PE_RECOVERING flag for a PE is managed by both the
caller and callee of eeh_handle_normal_event() (among other places not
considered here). This is complicated by the fact that the PE may
or may not have been invalidated by the call.

So move the callee's handling into eeh_handle_normal_event(), which
clarifies it and allows the return type to be changed to void (because
it no longer needs to indicate at the PE has been invalidated).

This should not change behaviour except in eeh_event_handler() where
it was previously possible to cause eeh_pe_state_clear() to be called
on an invalid PE, which is now avoided.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/eeh: Remove eeh_handle_event()

The function eeh_handle_event(pe) does nothing other than switching
between calling eeh_handle_normal_event(pe) and
eeh_handle_special_event(). However it is only called in two places,
one where pe can't be NULL and the other where it must be NULL (see
eeh_event_handler()) so it does nothing but obscure the flow of
control.

So, remove it.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pci: Always print PHB and PE numbers as hexadecimal

PHB, PE (and by association MVE) numbers are printed as a mix of decimal
and hexadecimal throughout the kernel. This can be misleading, so make
them all hexadecimal.

Standardising on hex instead of dec because:

- PHB numbers are presented in hex in sysfs/debugfs (and lspci, etc)
- PE numbers are presented as hex in sysfs and parsed in hex in debugfs

The only place I think this could cause confusing are the messages during
boot, i.e.

pci 000a:01 : [PE# 000] Secondary bus 1 associated with PE#0

which can be a quick way to check PE numbers. pe_level_printk() will
only print two characters instead of three, so the above would be

pci 000a:01 : [PE# 00] Secondary bus 1 associated with PE#0

which gives a hint it's in hex.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: sparse: static-ify some things

As sparse suggests, these should be made static.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: Fix killed EEH event

On PowerNV platform, EEH errors are reported by IO accessors or poller
driven by interrupt. After the PE is isolated, we won't produce EEH
event for the PE. The current implementation has possibility of EEH
event lost in this way:

The interrupt handler queues one "special" event, which drives the poller.
EEH thread doesn't pick the special event yet. IO accessors kicks in, the
frozen PE is marked as "isolated" and EEH event is queued to the list.
EEH thread runs because of special event and purge all existing EEH events.
However, we never produce an other EEH event for the frozen PE. Eventually,
the PE is marked as "isolated" and we don't have EEH event to recover it.

The patch fixes the issue to keep EEH events for PEs that have been
marked as "isolated" with the help of additional "force" help to
eeh_remove_event().

Reported-by: Rolf Brudeseth <rolfb@us.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/eeh: More accurate log

This clarifies in the log whether the error is a global PHB error
or an individual PE being frozen.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/eeh: Use interruptible sleep in keehd

To replace down() with down_interrutible() to avoid following
warning:

[c00000007ba7b710] [c000000000014410] .__switch_to+0x1b0/0x380
[c00000007ba7b7c0] [c0000000007b408c] .__schedule+0x3ec/0x970
[c00000007ba7ba50] [c0000000007b1f24] .schedule_timeout+0x1a4/0x2b0
[c00000007ba7bb30] [c0000000007b34a4] .__down+0xa4/0x104
[c00000007ba7bbf0] [c0000000000b9230] .down+0x60/0x70
[c00000007ba7bc80] [c0000000000336d0] .eeh_event_handler+0x70/0x190
[c00000007ba7bd30] [c0000000000b1a58] .kthread+0xe8/0xf0
[c00000007ba7be30] [c00000000000a05c] .ret_from_kernel_thread+0x5c/0x8

This also avoids keeping the load average up while doing nothing.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/eeh: Allow to purge EEH events

On PowerNV platform, we might run into the situation where subsequent
events are duplicated events of former one, which is being processed.
For the case, we need the function implemented by the patch to purge
EEH events accordingly.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/eeh: Single kthread to handle events

We possiblly have multiple kthreads running for multiple EEH errors
(events) and use one spinlock to make the process of handling those
EEH events serialized. That's unnecessary and the patch creates only
one kthread, which is started during EEH core initialization time in
eeh_init(). A new semaphore introduced to count the number of existing
EEH events in the queue and the kthread waiting on the semaphore.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/eeh: Move common part to kernel directory

The patch moves the common part of EEH core into arch/powerpc/kernel
directory so that we needn't PPC_PSERIES while compiling POWERNV
platform:

* Move the EEH common part into arch/powerpc/kernel
* Move the functions for PCI hotplug from pSeries platform to
arch/powerpc/kernel/pci-hotplug.c
* Move CONFIG_EEH from arch/powerpc/platforms/pseries/Kconfig to
arch/powerpc/platforms/Kconfig
* Adjust makefile accordingly

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>