powerpc/pseries: Honour current SMT state when DLPAR onlining CPUs

Integrate with the generic SMT support, so that when a CPU is DLPAR
onlined it is brought up with the correct SMT mode.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230705145143.40545-11-ldufour@linux.ibm.com

powerpc/pseries: Initialise CPU hotplug callbacks earlier

As part of the generic HOTPLUG_SMT code, there is support for disabling
secondary SMT threads at boot time, by passing "nosmt" on the kernel
command line.

The way that is implemented is the secondary threads are brought partly
online, and then taken back offline again. That is done to support x86
CPUs needing certain initialisation done on all threads. However powerpc
has similar needs, see commit d70a54e2d085 ("powerpc/powernv: Ignore
smt-enabled on Power8 and later").

For that to work the powerpc CPU hotplug callbacks need to be registered
before secondary CPUs are brought online, otherwise __cpu_disable()
fails due to smp_ops->cpu_disable being NULL.

So split the basic initialisation into pseries_cpu_hotplug_init() which
can be called early from setup_arch(). The DLPAR related initialisation
can still be done later, because it needs to do allocations.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230705145143.40545-9-ldufour@linux.ibm.com

powerpc: Use of_property_present() for testing DT property presence

It is preferred to use typed property access functions (i.e.
of_property_read_<type> functions) rather than low-level
of_get_property/of_find_property functions for reading properties. As
part of this, convert of_get_property/of_find_property calls to the
recently added of_property_present() helper when we just want to test
for presence of a property and nothing more.

Signed-off-by: Rob Herring <robh@kernel.org>
[mpe: Drop change in ppc4xx_probe_pci_bridge(), formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230310144657.1541039-1-robh@kernel.org

powerpc/rtas: arch-wide function token lookup conversions

With the tokens for all implemented RTAS functions now available via
rtas_function_token(), which is optimal and safe for arbitrary
contexts, there is no need to use rtas_token() or cache its result.

Most conversions are trivial, but a few are worth describing in more
detail:

* Error injection token comparisons for lockdown purposes are
consolidated into a simple predicate: token_is_restricted_errinjct().

* A couple of special cases in block_rtas_call() do not use
rtas_token() but perform string comparisons against names in the
function table. These are converted to compare against token values
instead, which is logically equivalent but less expensive.

* The lookup for the ibm,os-term token can be deferred until needed,
instead of caching it at boot to avoid device tree traversal during
panic.

* Since rtas_function_token() accesses a read-only data structure
without taking any locks, xmon's lookup of set-indicator can be
performed as needed instead of cached at startup.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230125-b4-powerpc-rtas-queue-v3-20-26929c8cce78@linux.ibm.com

powerpc/pseries: unregister VPA when hot unplugging a CPU

The VPA should unregister when offlining a CPU. Otherwise there could be
a short window where 2 CPUs could share the same VPA.

This happens because the hypervisor is still keeping the VPA attached to
the vCPU even if it became offline.

Here is a potential situation:
1. remove proc A,
2. add proc B. If proc B gets proc A's place in cpu_present_mask, then
it registers proc A's VPAs.
3. If proc B is then re-added to the LP, its threads are sharing VPAs
with proc A briefly as they come online.

As the hypervisor may check for the VPA's yield_count field oddity, it
may detect an unexpected value and kill the LPAR.

Suggested-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
[mpe: s/cpu_present_map/cpu_present_mask/ in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114160150.13554-1-ldufour@linux.ibm.com

powerpc/pseries: Add missing of_node_put()s in hotplug-cpu.c

In pseries_cpuhp_cache_use_count() and pseries_cpuhp_detach_nodes(),
we need carefully hold the reference returned by
of_find_next_cache_node() and use it to call of_node_put() to keep
refcount balance.

Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220621111701.4082889-1-windhl@126.com

powerpc/numa: Associate numa node to its cpu earlier

powerpc is the only platform that do not rely on
cpu_up()->try_online_node() to bring up a numa node,
and special cases it, instead, deep in its own machinery:

dlpar_online_cpu
find_and_online_cpu_nid
try_online_node

This should not be needed, but the thing is that the try_online_node()
from cpu_up() will not apply on the right node, because cpu_to_node()
will return the old mapping numa<->cpu that gets set on boot stage
for all possible cpus.

That can be seen easily if we try to print out the numa node passed
to try_online_node() in cpu_up().

The thing is that the numa<->cpu mapping does not get updated till a much
later stage in start_secondary:

start_secondary:
set_numa_node(numa_cpu_lookup_table[cpu])

But we do not really care, as we already now the
CPU <-> NUMA associativity back in find_and_online_cpu_nid(),
so let us make use of that and set the proper numa<->cpu mapping,
so cpu_to_node() in cpu_up() returns the right node and
try_online_node() can do its work.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220411074934.4632-1-osalvador@suse.de

powerpc/pseries: use slab context cpumask allocation in CPU hotplug init

Slab is up at this point, using the bootmem allocator triggers a
warning. Switch to using the regular cpumask allocator.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211105132923.1582514-1-npiggin@gmail.com

powerpc/pseries/cpuhp: remove obsolete comment from pseries_cpu_die

This comment likely refers to the obsolete DLPAR workflow where some
resource state transitions were driven more directly from user space
utilities, but it also seems to contradict itself: "Change isolate state to
Isolate [...]" is at odds with the preceding sentences, and it does not
relate at all to the code that follows.

Remove it to prevent confusion.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210927201933.76786-5-nathanl@linux.ibm.com

powerpc/pseries/cpuhp: delete add/remove_by_count code

The core DLPAR code supports two actions (add and remove) and three
subtypes of action:

* By DRC index: the action is attempted on a single specified resource.
This is the usual case for processors.
* By indexed count: the action is attempted on a range of resources
beginning at the specified index. This is implemented only by the memory
DLPAR code.
* By count: the lower layer (CPU or memory) is responsible for locating the
specified number of resources to which the action can be applied.

I cannot find any evidence of the "by count" subtype being used by drmgr or
qemu for processors. And when I try to exercise this code, the add case
does not work:

$ ppc64_cpu --smt ; nproc
SMT=8
24
$ printf "cpu remove count 2" > /sys/kernel/dlpar
$ nproc
8
$ printf "cpu add count 2" > /sys/kernel/dlpar
-bash: printf: write error: Invalid argument
$ dmesg | tail -2
pseries-hotplug-cpu: Failed to find enough CPUs (1 of 2) to add
dlpar: Could not handle DLPAR request "cpu add count 2"
$ nproc
8
$ drmgr -c cpu -a -q 2 # this uses the by-index method
Validating CPU DLPAR capability...yes.
CPU 1
CPU 17
$ nproc
24

This is because find_drc_info_cpus_to_add() does not increment drc_index
appropriately during its search.

This is not hard to fix. But the _by_count() functions also have the
property that they attempt to roll back all prior operations if the entire
request cannot be satisfied, even though the rollback itself can encounter
errors. It's not possible to provide transaction-like behavior at this
level, and it's undesirable to have code that can only pretend to do that.
Any users of these functions cannot know what the state of the system is in
the error case. And the error paths are, to my knowledge, impossible to
test without adding custom error injection code.

Summary:

* This code has not worked reliably since its introduction.
* There is no evidence that it is used.
* It contains questionable rollback behaviors in error paths which are
difficult to test.

So let's remove it.

Fixes: ac71380071d1 ("powerpc/pseries: Add CPU dlpar remove functionality")
Fixes: 90edf184b9b7 ("powerpc/pseries: Add CPU dlpar add functionality")
Fixes: b015f6bc9547 ("powerpc/pseries: Add cpu DLPAR support for drc-info property")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210927201933.76786-4-nathanl@linux.ibm.com

powerpc/pseries/cpuhp: cache node corrections

On pseries, cache nodes in the device tree can be added and removed by the
CPU DLPAR code as well as the partition migration (mobility) code. PowerVM
partitions in dedicated processor mode typically have L2 and L3 cache
nodes.

The CPU DLPAR code has the following shortcomings:

* Cache nodes returned as siblings of a new CPU node by
ibm,configure-connector are silently discarded; only the CPU node is
added to the device tree.

* Cache nodes which become unreferenced in the processor removal path are
not removed from the device tree. This can lead to duplicate nodes when
the post-migration device tree update code replaces cache nodes.

This is long-standing behavior. Presumably it has gone mostly unnoticed
because the two bugs have the property of obscuring each other in common
simple scenarios (e.g. remove a CPU and add it back). Likely you'd notice
only if you cared to inspect the device tree or the sysfs cacheinfo
information.

Booted with two processors:

$ pwd
/sys/firmware/devicetree/base/cpus
$ ls -1d */
l2-cache@2010/
l2-cache@2011/
l3-cache@3110/
l3-cache@3111/
PowerPC,POWER9@0/
PowerPC,POWER9@8/
$ lsprop */l2-cache
l2-cache@2010/l2-cache
00003110 (12560)
l2-cache@2011/l2-cache
00003111 (12561)
PowerPC,POWER9@0/l2-cache
00002010 (8208)
PowerPC,POWER9@8/l2-cache
00002011 (8209)
$ ls /sys/devices/system/cpu/cpu0/cache/
index0 index1 index2 index3

After DLPAR-adding PowerPC,POWER9@10, we see that its associated cache
nodes are absent, its threads' L2+L3 cacheinfo is unpopulated, and it is
missing a cache level in its sched domain hierarchy:

$ ls -1d */
l2-cache@2010/
l2-cache@2011/
l3-cache@3110/
l3-cache@3111/
PowerPC,POWER9@0/
PowerPC,POWER9@10/
PowerPC,POWER9@8/
$ lsprop PowerPC\,POWER9@10/l2-cache
PowerPC,POWER9@10/l2-cache
00002012 (8210)
$ ls /sys/devices/system/cpu/cpu16/cache/
index0 index1
$ grep . /sys/kernel/debug/sched/domains/cpu{0,8,16}/domain*/name
/sys/kernel/debug/sched/domains/cpu0/domain0/name:SMT
/sys/kernel/debug/sched/domains/cpu0/domain1/name:CACHE
/sys/kernel/debug/sched/domains/cpu0/domain2/name:DIE
/sys/kernel/debug/sched/domains/cpu8/domain0/name:SMT
/sys/kernel/debug/sched/domains/cpu8/domain1/name:CACHE
/sys/kernel/debug/sched/domains/cpu8/domain2/name:DIE
/sys/kernel/debug/sched/domains/cpu16/domain0/name:SMT
/sys/kernel/debug/sched/domains/cpu16/domain1/name:DIE

When removing PowerPC,POWER9@8, we see that its cache nodes are left
behind:

$ ls -1d */
l2-cache@2010/
l2-cache@2011/
l3-cache@3110/
l3-cache@3111/
PowerPC,POWER9@0/

When DLPAR is combined with VM migration, we can get duplicate nodes. E.g.
removing one processor, then migrating, adding a processor, and then
migrating again can result in warnings from the OF core during
post-migration device tree updates:

Duplicate name in cpus, renamed to "l2-cache@2011#1"
Duplicate name in cpus, renamed to "l3-cache@3111#1"

and nodes with duplicated phandles in the tree, making lookup behavior
unpredictable:

$ lsprop l[23]-cache@*/ibm,phandle
l2-cache@2010/ibm,phandle
00002010 (8208)
l2-cache@2011#1/ibm,phandle
00002011 (8209)
l2-cache@2011/ibm,phandle
00002011 (8209)
l3-cache@3110/ibm,phandle
00003110 (12560)
l3-cache@3111#1/ibm,phandle
00003111 (12561)
l3-cache@3111/ibm,phandle
00003111 (12561)

Address these issues by:

* Correctly processing siblings of the node returned from
dlpar_configure_connector().
* Removing cache nodes in the CPU remove path when it can be determined
that they are not associated with other CPUs or caches.

Use the of_changeset API in both cases, which allows us to keep the error
handling in this code from becoming more complex while ensuring that the
device tree cannot become inconsistent.

Fixes: ac71380071d1 ("powerpc/pseries: Add CPU dlpar remove functionality")
Fixes: 90edf184b9b7 ("powerpc/pseries: Add CPU dlpar add functionality")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210927201933.76786-2-nathanl@linux.ibm.com

powerpc/pseries: Fix build error when NUMA=n

As reported by lkp, if NUMA=n we see a build error:

arch/powerpc/platforms/pseries/hotplug-cpu.c: In function 'pseries_cpu_hotplug_init':
arch/powerpc/platforms/pseries/hotplug-cpu.c:1022:8: error: 'node_to_cpumask_map' undeclared
1022 | node_to_cpumask_map[node]);

Use cpumask_of_node() which has an empty stub for NUMA=n, and when
NUMA=y does a lookup from node_to_cpumask_map[].

Fixes: bd1dd4c5f528 ("powerpc/pseries: Prevent free CPU ids being reused on another node")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210816041032.2839343-1-mpe@ellerman.id.au

powerpc/pseries: Consolidate different NUMA distance update code paths

The associativity details of the newly added resourced are collected from
the hypervisor via "ibm,configure-connector" rtas call. Update the numa
distance details of the newly added numa node after the above call.

Instead of updating NUMA distance every time we lookup a node id
from the associativity property, add helpers that can be used
during boot which does this only once. Also remove the distance
update from node id lookup helpers.

Currently, we duplicate parsing code for ibm,associativity and
ibm,associativity-lookup-arrays in the kernel. The associativity array provided
by these device tree properties are very similar and hence can use
a helper to parse the node id and numa distance details.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210812132223.225214-4-aneesh.kumar@linux.ibm.com

powerpc/pseries: Prevent free CPU ids being reused on another node

When a CPU is hot added, the CPU ids are taken from the available mask
from the lower possible set. If that set of values was previously used
for a CPU attached to a different node, it appears to an application as
if these CPUs have migrated from one node to another node which is not
expected.

To prevent this, it is needed to record the CPU ids used for each node
and to not reuse them on another node. However, to prevent CPU hot plug
to fail, in the case the CPU ids is starved on a node, the capability to
reuse other nodes’ free CPU ids is kept. A warning is displayed in such
a case to warn the user.

A new CPU bit mask (node_recorded_ids_map) is introduced for each
possible node. It is populated with the CPU onlined at boot time, and
then when a CPU is hot plugged to a node. The bits in that mask remain
when the CPU is hot unplugged, to remind this CPU ids have been used for
this node.

If no id set was found, a retry is made without removing the ids used on
the other nodes to try reusing them. This is the way ids have been
allocated prior to this patch.

The effect of this patch can be seen by removing and adding CPUs using
the Qemu monitor. In the following case, the first CPU from the node 2
is removed, then the first one from the node 1 is removed too. Later,
the first CPU of the node 2 is added back. Without that patch, the
kernel will number these CPUs using the first CPU ids available which
are the ones freed when removing the second CPU of the node 0. This
leads to the CPU ids 16-23 to move from the node 1 to the node 2. With
the patch applied, the CPU ids 32-39 are used since they are the lowest
free ones which have not been used on another node.

At boot time:
[root@vm40 ~]# numactl -H | grep cpus
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
node 1 cpus: 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
node 2 cpus: 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Vanilla kernel, after the CPU hot unplug/plug operations:
[root@vm40 ~]# numactl -H | grep cpus
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
node 1 cpus: 24 25 26 27 28 29 30 31
node 2 cpus: 16 17 18 19 20 21 22 23 40 41 42 43 44 45 46 47

Patched kernel, after the CPU hot unplug/plug operations:
[root@vm40 ~]# numactl -H | grep cpus
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
node 1 cpus: 24 25 26 27 28 29 30 31
node 2 cpus: 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210429174908.16613-1-ldufour@linux.ibm.com

powerpc/pseries: Stop calling printk in rtas_stop_self()

RCU complains about us calling printk() from an offline CPU:

=============================
WARNING: suspicious RCU usage
5.12.0-rc7-02874-g7cf90e481cb8 #1 Not tainted
-----------------------------
kernel/locking/lockdep.c:3568 RCU-list traversed in non-reader section!!

other info that might help us debug this:

RCU used illegally from offline CPU!
rcu_scheduler_active = 2, debug_locks = 1
no locks held by swapper/0/0.

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc7-02874-g7cf90e481cb8 #1
Call Trace:
dump_stack+0xec/0x144 (unreliable)
lockdep_rcu_suspicious+0x124/0x144
__lock_acquire+0x1098/0x28b0
lock_acquire+0x128/0x600
_raw_spin_lock_irqsave+0x6c/0xc0
down_trylock+0x2c/0x70
__down_trylock_console_sem+0x60/0x140
vprintk_emit+0x1a8/0x4b0
vprintk_func+0xcc/0x200
printk+0x40/0x54
pseries_cpu_offline_self+0xc0/0x120
arch_cpu_idle_dead+0x54/0x70
do_idle+0x174/0x4a0
cpu_startup_entry+0x38/0x40
rest_init+0x268/0x388
start_kernel+0x748/0x790
start_here_common+0x1c/0x614

Which happens because by the time we get to rtas_stop_self() we are
already offline. In addition the message can be spammy, and is not that
helpful for users, so remove it.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210418135413.1204031-1-mpe@ellerman.id.au

powerpc/pseries: Set UNISOLATE on dlpar_cpu_remove() failure

The RTAS set-indicator call, when attempting to UNISOLATE a DRC that is
already UNISOLATED or CONFIGURED, returns RTAS_OK and does nothing else
for both QEMU and phyp. This gives us an opportunity to use this
behavior to signal the hypervisor layer when an error during device
removal happens, allowing it to do a proper error handling, while not
breaking QEMU/phyp implementations that don't have this support.

This patch introduces this idea by unisolating all CPU DRCs that failed
to be removed by dlpar_cpu_remove_by_index(), when handling the
PSERIES_HP_ELOG_ID_DRC_INDEX event. This is being done for this event
only because its the only CPU removal event QEMU uses, and there's no
need at this moment to add this mechanism for phyp only code.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210416210216.380291-3-danielhb413@gmail.com

powerpc/pseries/hotplug-cpu: Show 'last online CPU' error in dlpar_cpu_offline()

One of the reasons that dlpar_cpu_offline can fail is when attempting to
offline the last online CPU of the kernel. This can be observed in a
pseries QEMU guest that has hotplugged CPUs. If the user offlines all
other CPUs of the guest, and a hotplugged CPU is now the last online
CPU, trying to reclaim it will fail.

The current error message in this situation returns rc with -EBUSY and a
generic explanation, e.g.:

pseries-hotplug-cpu: Failed to offline CPU PowerPC,POWER9, rc: -16

EBUSY can be caused by other conditions, such as cpu_hotplug_disable
being true. Throwing a more specific error message for this case,
instead of just "Failed to offline CPU", makes it clearer that the error
is in fact a known error situation instead of other generic/unknown
cause.

This patch adds a 'last online' check in dlpar_cpu_offline() to catch
the 'last online CPU' offline error, eturning a more informative error
message:

pseries-hotplug-cpu: Unable to remove last online CPU PowerPC,POWER9

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210323205056.52768-2-danielhb413@gmail.com

powerpc/64s: Trim offlined CPUs from mm_cpumasks

When offlining a CPU, powerpc/64s does not flush TLBs, rather it just
leaves the CPU set in mm_cpumasks, so it continues to receive TLBIEs
to manage its TLBs.

However the exit_flush_lazy_tlbs() function expects that after
returning, all CPUs (except self) have flushed TLBs for that mm, in
which case TLBIEL can be used for this flush. This breaks for offline
CPUs because they don't get the IPI to flush their TLB. This can lead
to stale translations.

Fix this by clearing the CPU from mm_cpumasks, then flushing all TLBs
before going offline.

These offlined CPU bits stuck in the cpumask also prevents the cpumask
from being trimmed back to local mode, which means continual broadcast
IPIs or TLBIEs are needed for TLB flushing. This patch prevents that
situation too.

A cast of many were involved in working this out, but in particular
Milton, Aneesh, Paul made key discoveries.

Fixes: 0cef77c7798a7 ("powerpc/64s/radix: flush remote CPUs out of single-threaded mm_cpumask")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Debugged-by: Milton Miller <miltonm@us.ibm.com>
Debugged-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Debugged-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201126102530.691335-5-npiggin@gmail.com

Revert "powerpc/pseries/hotplug-cpu: Remove double free in error path"

This reverts commit a0ff72f9f5a780341e7ff5e9ba50a0dad5fa1980.

Since the commit b015f6bc9547 ("powerpc/pseries: Add cpu DLPAR
support for drc-info property"), the 'cpu_drcs' wouldn't be double
freed when the 'cpus' node not found.

So we needn't apply this patch, otherwise, the memory will be leaked.

Fixes: a0ff72f9f5a7 ("powerpc/pseries/hotplug-cpu: Remove double free in error path")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
[mpe: Caused by me applying a patch to a function that had changed in the interim]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201111020752.1686139-1-zhangxiaoxu5@huawei.com

powerpc/smp: Move ppc_md.cpu_die() to smp_ops.cpu_offline_self()

We have smp_ops->cpu_die() and ppc_md.cpu_die(). One of them offlines
the current CPU and one offlines another CPU, can you guess which is
which? Also one is in smp_ops and one is in ppc_md?

So rename ppc_md.cpu_die(), to cpu_offline_self(), because that's what
it does. And move it into smp_ops where it belongs.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015634.1974478-3-mpe@ellerman.id.au

powerpc/pseries/hotplug-cpu: wait indefinitely for vCPU death

For a power9 KVM guest with XIVE enabled, running a test loop
where we hotplug 384 vcpus and then unplug them, the following traces
can be seen (generally within a few loops) either from the unplugged
vcpu:

cpu 65 (hwid 65) Ready to die...
Querying DEAD? cpu 66 (66) shows 2
list_del corruption. next->prev should be c00a000002470208, but was c00a000002470048
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:56!
Oops: Exception in kernel mode, sig: 5 [#1]
LE SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: fuse nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 ...
CPU: 66 PID: 0 Comm: swapper/66 Kdump: loaded Not tainted 4.18.0-221.el8.ppc64le #1
NIP: c0000000007ab50c LR: c0000000007ab508 CTR: 00000000000003ac
REGS: c0000009e5a17840 TRAP: 0700 Not tainted (4.18.0-221.el8.ppc64le)
MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28000842 XER: 20040000
...
NIP __list_del_entry_valid+0xac/0x100
LR __list_del_entry_valid+0xa8/0x100
Call Trace:
__list_del_entry_valid+0xa8/0x100 (unreliable)
free_pcppages_bulk+0x1f8/0x940
free_unref_page+0xd0/0x100
xive_spapr_cleanup_queue+0x148/0x1b0
xive_teardown_cpu+0x1bc/0x240
pseries_mach_cpu_die+0x78/0x2f0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x2f4/0x4c0
cpu_startup_entry+0x38/0x40
start_secondary+0x7bc/0x8f0
start_secondary_prolog+0x10/0x14

or on the worker thread handling the unplug:

pseries-hotplug-cpu: Attempting to remove CPU <NULL>, drc index: 1000013a
Querying DEAD? cpu 314 (314) shows 2
BUG: Bad page state in process kworker/u768:3 pfn:95de1
cpu 314 (hwid 314) Ready to die...
page:c00a000002577840 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0
flags: 0x5ffffc00000000()
raw: 005ffffc00000000 5deadbeef0000100 5deadbeef0000200 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffff7f 0000000000000000
page dumped because: nonzero mapcount
Modules linked in: kvm xt_CHECKSUM ipt_MASQUERADE xt_conntrack ...
CPU: 0 PID: 548 Comm: kworker/u768:3 Kdump: loaded Not tainted 4.18.0-224.el8.bz1856588.ppc64le #1
Workqueue: pseries hotplug workque pseries_hp_work_fn
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
bad_page+0x12c/0x1b0
free_pcppages_bulk+0x5bc/0x940
page_alloc_cpu_dead+0x118/0x120
cpuhp_invoke_callback.constprop.5+0xb8/0x760
_cpu_down+0x188/0x340
cpu_down+0x5c/0xa0
cpu_subsys_offline+0x24/0x40
device_offline+0xf0/0x130
dlpar_offline_cpu+0x1c4/0x2a0
dlpar_cpu_remove+0xb8/0x190
dlpar_cpu_remove_by_index+0x12c/0x150
dlpar_cpu+0x94/0x800
pseries_hp_work_fn+0x128/0x1e0
process_one_work+0x304/0x5d0
worker_thread+0xcc/0x7a0
kthread+0x1ac/0x1c0
ret_from_kernel_thread+0x5c/0x80

The latter trace is due to the following sequence:

page_alloc_cpu_dead
drain_pages
drain_pages_zone
free_pcppages_bulk

where drain_pages() in this case is called under the assumption that
the unplugged cpu is no longer executing. To ensure that is the case,
and early call is made to __cpu_die()->pseries_cpu_die(), which runs a
loop that waits for the cpu to reach a halted state by polling its
status via query-cpu-stopped-state RTAS calls. It only polls for 25
iterations before giving up, however, and in the trace above this
results in the following being printed only .1 seconds after the
hotplug worker thread begins processing the unplug request:

pseries-hotplug-cpu: Attempting to remove CPU <NULL>, drc index: 1000013a
Querying DEAD? cpu 314 (314) shows 2

At that point the worker thread assumes the unplugged CPU is in some
unknown/dead state and procedes with the cleanup, causing the race
with the XIVE cleanup code executed by the unplugged CPU.

Fix this by waiting indefinitely, but also making an effort to avoid
spurious lockup messages by allowing for rescheduling after polling
the CPU status and printing a warning if we wait for longer than 120s.

Fixes: eac1e731b59ee ("powerpc/xive: guest exploitation of the XIVE interrupt controller")
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Tested-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
[mpe: Trim oopses in change log slightly for readability]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200811161544.10513-1-mdroth@linux.vnet.ibm.com

powerpc/pseries/hotplug-cpu: Remove double free in error path

In the unlikely event that the device tree lacks a /cpus node,
find_dlpar_cpus_to_add() oddly frees the cpu_drcs buffer it has been
passed before returning an error. Its only caller also frees the
buffer on error.

Remove the less conventional kfree() of a caller-supplied buffer from
find_dlpar_cpus_to_add().

Fixes: 90edf184b9b7 ("powerpc/pseries: Add CPU dlpar add functionality")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190919231633.1344-1-nathanl@linux.ibm.com

powerpc/pseries: remove dlpar_cpu_readd()

dlpar_cpu_readd() is unused now.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-18-nathanl@linux.ibm.com

powerpc/numa: remove timed_topology_update()

timed_topology_update is a no-op now, so remove it and all call sites.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-11-nathanl@linux.ibm.com

powerpc/pseries: remove cede offline state for CPUs

This effectively reverts commit 3aa565f53c39 ("powerpc/pseries: Add
hooks to put the CPU into an appropriate offline state"), which added
an offline mode for CPUs which uses the H_CEDE hcall instead of the
architected stop-self RTAS function in order to facilitate "folding"
of dedicated mode processors on PowerVM platforms to achieve energy
savings. This has been the default offline mode since its
introduction.

There's nothing about stop-self that would prevent the hypervisor from
achieving the energy savings available via H_CEDE, so the original
premise of this change appears to be flawed.

I also have encountered the claim that the transition to and from
ceded state is much faster than stop-self/start-cpu. Certainly we
would not want to use stop-self as an *idle* mode. That is what H_CEDE
is for. However, this difference is insignificant in the context of
Linux CPU hotplug, where the latency of an offline or online operation
on current systems is on the order of 100ms, mainly attributable to
all the various subsystems' cpuhp callbacks.

The cede offline mode also prevents accurate accounting, as discussed
before:
https://lore.kernel.org/linuxppc-dev/1571740391-3251-1-git-send-email-ego@linux.vnet.ibm.com/

Unconditionally use stop-self to offline processor threads. This is
the architected method for offlining CPUs on PAPR systems.

The "cede_offline" boot parameter is rendered obsolete.

Removing this code enables the removal of the partition suspend code
which temporarily onlines all present CPUs.

Fixes: 3aa565f53c39 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-2-nathanl@linux.ibm.com

powerpc/pseries: Add cpu DLPAR support for drc-info property

Older firmwares provided information about Dynamic Reconfig
Connectors (DRC) through several device tree properties, namely
ibm,drc-types, ibm,drc-indexes, ibm,drc-names, and
ibm,drc-power-domains. New firmwares have the ability to present this
same information in a much condensed format through a device tree
property called ibm,drc-info.

The existing cpu DLPAR hotplug code only understands the older DRC
property format when validating the drc-index of a cpu during a
hotplug add. This updates those code paths to use the ibm,drc-info
property, when present, instead for validation.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1573449697-5448-4-git-send-email-tyreld@linux.ibm.com

powerpc/pseries: safely roll back failed DLPAR cpu add

dlpar_online_cpu() attempts to online all threads of a core that has
been added to an LPAR. If onlining a non-primary thread
fails (e.g. due to an allocation failure), the core is left with at
least one thread online. dlpar_cpu_add() attempts to roll back the
whole operation, releasing the core back to the platform. However,
since some threads of the core being removed are still online, the
BUG_ON(cpu_online(cpu)) in pseries_remove_processor() strikes:

LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 3 PID: 8587 Comm: drmgr Not tainted 5.3.0-rc2-00190-g9b123d1ea237-dirty #46
NIP: c0000000000eeb2c LR: c0000000000eeac4 CTR: c0000000000ee9e0
REGS: c0000001f745b6c0 TRAP: 0700 Not tainted (5.3.0-rc2-00190-g9b123d1ea237-dirty)
MSR: 800000010282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 44002448 XER: 00000000
CFAR: c00000000195d718 IRQMASK: 0
GPR00: c0000000000eeac4 c0000001f745b950 c0000000032f6200 0000000000000008
GPR04: 0000000000000008 c000000003349c78 0000000000000040 00000000000001ff
GPR08: 0000000000000008 0000000000000000 0000000000000001 0007ffffffffffff
GPR12: 0000000084002844 c00000001ecacb80 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000008
GPR24: c000000003349ee0 c00000000334a2e4 c0000000fca4d7a8 c000000001d20048
GPR28: 0000000000000001 ffffffffffffffff ffffffffffffffff c0000000fca4d7c4
NIP [c0000000000eeb2c] pseries_smp_notifier+0x14c/0x2e0
LR [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0
Call Trace:
[c0000001f745b950] [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0 (unreliable)
[c0000001f745ba10] [c0000000001ac774] notifier_call_chain+0xb4/0x190
[c0000001f745bab0] [c0000000001ad62c] blocking_notifier_call_chain+0x7c/0xb0
[c0000001f745baf0] [c00000000167bda0] of_detach_node+0xc0/0x110
[c0000001f745bb50] [c0000000000e7ae4] dlpar_detach_node+0x64/0xa0
[c0000001f745bb80] [c0000000000edefc] dlpar_cpu_add+0x31c/0x360
[c0000001f745bc10] [c0000000000ee980] dlpar_cpu_probe+0x50/0xb0
[c0000001f745bc50] [c00000000002cf70] arch_cpu_probe+0x40/0x70
[c0000001f745bc70] [c000000000ccd808] cpu_probe_store+0x48/0x80
[c0000001f745bcb0] [c000000000cbcef8] dev_attr_store+0x38/0x60
[c0000001f745bcd0] [c00000000059c980] sysfs_kf_write+0x70/0xb0
[c0000001f745bd10] [c00000000059afb8] kernfs_fop_write+0xf8/0x280
[c0000001f745bd60] [c0000000004b437c] __vfs_write+0x3c/0x70
[c0000001f745bd80] [c0000000004b8710] vfs_write+0xd0/0x220
[c0000001f745bdd0] [c0000000004b8acc] ksys_write+0x7c/0x140
[c0000001f745be20] [c00000000000bbd8] system_call+0x5c/0x68

Move dlpar_offline_cpu() up in the file so that dlpar_online_cpu() can
use it to re-offline any threads that have been onlined when an error
is encountered.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: e666ae0b10aa ("powerpc/pseries: Update CPU hotplug error recovery")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191016183611.10867-3-nathanl@linux.ibm.com

powerpc/pseries: address checkpatch warnings in dlpar_offline_cpu

Remove some stray blank lines, convert a printk to pr_warn, and
address a line length violation.

One functional change: use WARN_ON instead of BUG_ON in case H_PROD of
a ceded thread yields an unexpected result from the platform. We can
expect this code path to get uninterruptibly stuck in __cpu_die() if
this happens, but that's more desirable than crashing.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: b6db63d1a7f0 ("pseries/pseries: Add code to online/offline CPUs of a DLPAR node")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191016183611.10867-2-nathanl@linux.ibm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

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

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/pseries: Perform full re-add of CPU for topology update post-migration

On pseries systems, performing a partition migration can result in
altering the nodes a CPU is assigned to on the destination system. For
exampl, pre-migration on the source system CPUs are in node 1 and 3,
post-migration on the destination system CPUs are in nodes 2 and 3.

Handling the node change for a CPU can cause corruption in the slab
cache if we hit a timing where a CPUs node is changed while cache_reap()
is invoked. The corruption occurs because the slab cache code appears
to rely on the CPU and slab cache pages being on the same node.

The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c
does not prevent us from hitting this scenario.

Changing the device tree property update notification handler that
recognizes an affinity change for a CPU to do a full DLPAR remove and
add of the CPU instead of dynamically changing its node resolves this
issue.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>
Tested-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Convert to using %pOFn instead of device_node.name

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64: Use array of paca pointers and allocate pacas individually

Change the paca array into an array of pointers to pacas. Allocate
pacas individually.

This allows flexibility in where the PACAs are allocated. Future work
will allocate them node-local. Platforms that don't have address limits
on PACAs would be able to defer PACA allocations until later in boot
rather than allocate all possible ones up-front then freeing unused.

This is slightly more overhead (one additional indirection) for cross
CPU paca references, but those aren't too common.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Fix build break for SPLPAR=n and CPU hotplug

Commit e67e02a544e9 ("powerpc/pseries: Fix cpu hotplug crash with
memoryless nodes") adds an unconditional call to
find_and_online_cpu_nid(), which is only declared if CONFIG_PPC_SPLPAR
is enabled. This results in the following build error if this is not
the case.

arch/powerpc/platforms/pseries/hotplug-cpu.o: In function `dlpar_online_cpu':
arch/powerpc/platforms/pseries/hotplug-cpu.c:369:
undefined reference to `.find_and_online_cpu_nid'

Follow the guideline provided by similar functions and provide a dummy
function if CONFIG_PPC_SPLPAR is not enabled. This also moves the
external function declaration into an include file where it should be.

Fixes: e67e02a544e9 ("powerpc/pseries: Fix cpu hotplug crash with memoryless nodes")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[mpe: Change subject to emphasise the build fix]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/numa: Invalidate numa_cpu_lookup_table on cpu remove

When DLPAR removing a CPU, the unmapping of the cpu from a node in
unmap_cpu_from_node() should also invalidate the CPUs entry in the
numa_cpu_lookup_table. There is not a guarantee that on a subsequent
DLPAR add of the CPU the associativity will be the same and thus
could be in a different node. Invalidating the entry in the
numa_cpu_lookup_table causes the associativity to be read from the
device tree at the time of the add.

The current behavior of not invalidating the CPUs entry in the
numa_cpu_lookup_table can result in scenarios where the the topology
layout of CPUs in the partition does not match the device tree
or the topology reported by the HMC.

This bug looks like it was introduced in 2004 in the commit titled
"ppc64: cpu hotplug notifier for numa", which is 6b15e4e87e32 in the
linux-fullhist tree. Hence tag it for all stable releases.

Cc: stable@vger.kernel.org
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Fix cpu hotplug crash with memoryless nodes

On powerpc systems with shared configurations of CPUs and memory and
memoryless nodes at boot, an event ordering problem was observed on a
SLES12 build platforms with the hot-add of CPUs to the memoryless
nodes.

* The most common error occurred when the memory SLAB driver attempted
to reference the memoryless node to which a CPU was being added
before the kernel had finished initializing all of the data
structures for the CPU and exited 'device_online' under
DLPAR/hot-add.

Normally the memoryless node would be initialized through the call
path device_online ... arch_update_cpu_topology ... find_cpu_nid ...
try_online_node. This patch ensures that the powerpc node will be
initialized as early as possible, even if it was memoryless and
CPU-less at the point when we are trying to hot-add a new CPU to it.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/hotplug: Improve responsiveness of hotplug change

powerpc/hotplug: On Power systems with shared configurations of CPUs
and memory, there are some issues with the association of additional
CPUs and memory to nodes when hot-adding resources. During hotplug
CPU operations, this patch resets the timer on topology update work
function to a small value to better ensure that the CPU topology is
detected and configured sooner.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Fix "OF: ERROR: Bad of_node_put() on /cpus" during DLPAR

Commit 215ee763f8cb ("powerpc: pseries: remove dlpar_attach_node
dependency on full path") reworked dlpar_attach_node() to no longer
look up the parent node "/cpus", but instead to have the parent node
passed by the caller in the function parameter list.

As a result dlpar_attach_node() is no longer responsible for freeing
the reference to the parent node. However, commit 215ee763f8cb failed
to remove the of_node_put(parent) call in dlpar_attach_node(), or to
take into account that the reference to the parent in the caller
dlpar_cpu_add() needs to be held until after dlpar_attach_node()
returns.

As a result doing repeated cpu add/remove dlpar operations will
eventually result in the following error:

OF: ERROR: Bad of_node_put() on /cpus
CPU: 0 PID: 10896 Comm: drmgr Not tainted 4.13.0-autotest #1
Call Trace:
dump_stack+0x15c/0x1f8 (unreliable)
of_node_release+0x1a4/0x1c0
kobject_put+0x1a8/0x310
kobject_del+0xbc/0xf0
__of_detach_node_sysfs+0x144/0x210
of_detach_node+0xf0/0x180
dlpar_detach_node+0xc4/0x120
dlpar_cpu_remove+0x280/0x560
dlpar_cpu_release+0xbc/0x1b0
arch_cpu_release+0x6c/0xb0
cpu_release_store+0xa0/0x100
dev_attr_store+0x68/0xa0
sysfs_kf_write+0xa8/0xf0
kernfs_fop_write+0x2cc/0x400
__vfs_write+0x5c/0x340
vfs_write+0x1a8/0x3d0
SyS_write+0xa8/0x1a0
system_call+0x58/0x6c

Fix the issue by removing the of_node_put(parent) call from
dlpar_attach_node(), and ensuring that the reference to the parent
node is properly held and released by the caller dlpar_cpu_add().

Fixes: 215ee763f8cb ("powerpc: pseries: remove dlpar_attach_node dependency on full path")
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
[mpe: Add a comment in the code and frob the change log slightly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/xive: guest exploitation of the XIVE interrupt controller

This is the framework for using XIVE in a PowerVM guest. The support
is very similar to the native one in a much simpler form.

Each source is associated with an Event State Buffer (ESB). This is a
two bit state machine which is used to trigger events. The bits are
named "P" (pending) and "Q" (queued) and can be controlled by MMIO.
The Guest OS registers event (or notifications) queues on which the HW
will post event data for a target to notify.

Instead of OPAL calls, a set of Hypervisors call are used to configure
the interrupt sources and the event/notification queues of the guest:

- H_INT_GET_SOURCE_INFO

used to obtain the address of the MMIO page of the Event State
Buffer (PQ bits) entry associated with the source.

- H_INT_SET_SOURCE_CONFIG

assigns a source to a "target".

- H_INT_GET_SOURCE_CONFIG

determines to which "target" and "priority" is assigned to a source

- H_INT_GET_QUEUE_INFO

returns the address of the notification management page associated
with the specified "target" and "priority".

- H_INT_SET_QUEUE_CONFIG

sets or resets the event queue for a given "target" and "priority".
It is also used to set the notification config associated with the
queue, only unconditional notification for the moment. Reset is
performed with a queue size of 0 and queueing is disabled in that
case.

- H_INT_GET_QUEUE_CONFIG

returns the queue settings for a given "target" and "priority".

- H_INT_RESET

resets all of the partition's interrupt exploitation structures to
their initial state, losing all configuration set via the hcalls
H_INT_SET_SOURCE_CONFIG and H_INT_SET_QUEUE_CONFIG.

- H_INT_SYNC

issue a synchronisation on a source to make sure sure all
notifications have reached their queue.

As for XICS, the XIVE interface for the guest is described in the
device tree under the "interrupt-controller" node. A couple of new
properties are specific to XIVE :

- "reg"

contains the base address and size of the thread interrupt
managnement areas (TIMA), also called rings, for the User level and
for the Guest OS level. Only the Guest OS level is taken into
account today.

- "ibm,xive-eq-sizes"

the size of the event queues. One cell per size supported, contains
log2 of size, in ascending order.

- "ibm,xive-lisn-ranges"

the interrupt numbers ranges assigned to the guest. These are
allocated using a simple bitmap.

and also :

- "/ibm,plat-res-int-priorities"

contains a list of priorities that the hypervisor has reserved for
its own use.

Tested with a QEMU XIVE model for pseries and with the Power hypervisor.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: pseries: remove dlpar_attach_node dependency on full path

In preparation to stop storing the full node path in full_name, remove the
dependency on full_name from dlpar_attach_node(). Callers of
dlpar_attach_node() already have the parent device_node, so just pass the
parent node into dlpar_attach_node instead of the path. This avoids doing
a lookup of the parent node by the path.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Convert to using %pOF instead of full_name

Now that we have a custom printf format specifier, convert users of
full_name to use %pOF instead. This is preparation to remove storing
of the full path string for each node.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Scott Wood <oss@buserror.net>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@lists.ozlabs.org
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Fix some spelling mistakes

Collation of some spelling fixes from Colin.

Attemping -> Attempting
intialized -> initialized
missmanaged -> mismanaged

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/hotplug.h>

We are going to split <linux/sched/hotplug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/hotplug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

powerpc/pseries: Remove MPIC from pseries cpu hotplug

MPIC was only used by Power3 which is now unsupported, so remove MPIC
code.

Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

param: convert some "on"/"off" users to strtobool

This changes several users of manual "on"/"off" parsing to use
strtobool.

Some side-effects:
- these uses will now parse y/n/1/0 meaningfully too
- the early_param uses will now bubble up parse errors

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Amitkumar Karwar <akarwar@marvell.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Joe Perches <joe@perches.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nishant Sarmukadam <nishants@marvell.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Steve French <sfrench@samba.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

powerpc/pseries: Add CPU dlpar add functionality

Add the ability to hotplug add cpus via rtas hotplug events by either
specifying the drc index of the CPU to add, or providing a count of the
number of CPUs to add.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Add CPU dlpar remove functionality

Add the ability to dlpar remove CPUs via hotplug rtas events, either by
specifying the drc-index of the CPU to remove or providing a count of cpus
to remove.

To remove multiple cpus in a single request we create a list of possible
DR (Dynamic Reconfiguration) cpus and their drc indexes that can be
removed. We can then traverse the list remove each cpu and easily clean
up in any cases of failure.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Update CPU hotplug error recovery

Update the cpu dlpar add/remove paths to do better error recovery when
a failure occurs during the add/remove operation.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Factor out common cpu hotplug code

Re-factor the cpu hotplug code to support doing cpu hotplug completely in
the kernel and using the existing sysfs probe/release interfaces. This
patch pulls out pieces of existing cpu hotplug code into common routines,
dlpar_cpu_add() and dlpar_cpu_remove(), to be used by both interfaces.
There are no functional changes introduced.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Consolidate CPU hotplug code to hotplug-cpu.c

No functional changes, this patch is simply a move of the cpu hotplug
code from pseries/dlpar.c to pseries/hotplug-cpu.c. This is in an effort
to consolidate all of the cpu hotplug code in a common place.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Use rtas_call_unlocked() in pseries hotplug

Avoid open coding the logic by using rtas_call_unlocked().

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Replace cpumask_weight(cpu_possible_mask) with num_possible_cpus()

num_possible_cpus() is just a shorthand for it.

Signed-off-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

of/reconfig: Always use the same structure for notifiers

The OF_RECONFIG notifier callback uses a different structure depending
on whether it is a node change or a property change. This is silly, and
not very safe. Rework the code to use the same data structure regardless
of the type of notifier.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Cc: <linuxppc-dev@lists.ozlabs.org>

powerpc/pseries: Make CPU hotplug path endian safe

- ibm,rtas-configure-connector should treat the RTAS data as big endian.
- Treat ibm,ppc-interrupt-server#s as big-endian when setting
smp_processor_id during hotplug.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Acked-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

pseries: Fix endian issues in cpu hot-removal

When removing a cpu, this patch makes sure that values
gotten from or passed to firmware are in the correct
endian format.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Fix Oops in rtas_stop_self()

commit 41dd03a9 may cause Oops in rtas_stop_self().

The reason is that the rtas_args was moved into stack space. For a box
with more that 4GB RAM, the stack could easily be outside 32bit range,
but RTAS is 32bit.

So the patch moves rtas_args away from stack by adding static before
it.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Don't try to register pseries cpu hotplug on non-pseries

This results in oddball messages at boot on other platforms telling us
that CPU hotplug isn't supported even when it is.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/le: Ensure that the 'stop-self' RTAS token is handled correctly

Currently we're storing a host endian RTAS token in
rtas_stop_self_args.token. We then pass that directly to rtas. This is
fine on big endian however on little endian the token is not what we
expect.

This will typically result in hitting:
panic("Alas, I survived.\n");

To fix this we always use the stop-self token in host order and always
convert it to be32 before passing this to rtas.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

pseries: Move plpar_wrapper.h to powerpc common include/asm location.

As a part of pseries_idle backend driver cleanup to make
the code common to both pseries and powernv platforms, it
is necessary to move the backend-driver code to drivers/cpuidle.

As a pre-requisite for that, it is essential to move plpar_wrapper.h
to include/asm.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Stop using non-architected shared_proc field in lppaca

Although the shared_proc field in the lppaca works today, it is
not architected. A shared processor partition will always have a non
zero yield_count so use that instead. Create a wrapper so users
don't have to know about the details.

In order for older kernels to continue to work on KVM we need
to set the shared_proc bit. While here, remove the ugly bitfield.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Fix a lazy irq related WARING in arch_local_irq_restore()

The pseries CPU hotplug code uses cede_processor without properly
synchronizing the SW and HW interrupt enable state. This fixes
it using the same helpers that were written for the idle code.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>

=======================
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc+of: Add of node/property notification chain for adds and removes

This patch moves the notification chain for updates to the device tree
from the powerpc/pseries code to the base OF code. This makes this
functionality available to all architectures.

Additionally the notification chain is updated to allow notifications
for property add/remove/update. To make this work a pointer to a new
struct (of_prop_reconfig) is passed to the routines in the notification chain.
The of_prop_reconfig property contains a pointer to the node containing the
property and a pointer to the property itself. In the case of property
updates, the property pointer refers to the new property.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Disintegrate asm/system.h for PowerPC

Disintegrate asm/system.h for PowerPC.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
cc: linuxppc-dev@lists.ozlabs.org

powerpc: Fix up implicit sched.h users

They are getting it through device.h --> module.h path, but we want
to clean that up. This is a sample of what will happen if we don't:

pseries/iommu.c: In function 'tce_build_pSeriesLP':
pseries/iommu.c:136: error: implicit declaration of function 'show_stack'

pseries/eeh.c: In function 'eeh_token_to_phys':
pseries/eeh.c:359: error: 'init_mm' undeclared (first use in this function)

pseries/eeh_event.c: In function 'eeh_event_handler':
pseries/eeh_event.c:63: error: implicit declaration of function 'daemonize'
pseries/eeh_event.c:64: error: implicit declaration of function 'set_current_state'
pseries/eeh_event.c:64: error: 'TASK_INTERRUPTIBLE' undeclared (first use in this function)
pseries/eeh_event.c:64: error: (Each undeclared identifier is reported only once
pseries/eeh_event.c:64: error: for each function it appears in.)
pseries/eeh_event.c: In function 'eeh_thread_launcher':
pseries/eeh_event.c:109: error: 'CLONE_KERNEL' undeclared (first use in this function)

hotplug-cpu.c: In function 'pseries_mach_cpu_die':
hotplug-cpu.c:115: error: implicit declaration of function 'idle_task_exit'

kernel/swsusp_64.c: In function 'do_after_copyback':
kernel/swsusp_64.c:17: error: implicit declaration of function 'touch_softlockup_watchdog'

cell/spufs/context.c: In function 'alloc_spu_context':
cell/spufs/context.c:60: error: implicit declaration of function 'get_task_mm'
cell/spufs/context.c:60: warning: assignment makes pointer from integer without a cast
cell/spufs/context.c: In function 'spu_forget':
cell/spufs/context.c:127: error: implicit declaration of function 'mmput'

pasemi/dma_lib.c: In function 'pasemi_dma_stop_chan':
pasemi/dma_lib.c:332: error: implicit declaration of function 'cond_resched'

sysdev/fsl_lbc.c: In function 'fsl_lbc_ctrl_irq':
sysdev/fsl_lbc.c:247: error: 'TASK_NORMAL' undeclared (first use in this function)

Add in sched.h so these get the definitions they are looking for.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

powerpc/pseries: Simplify vpa deregistration functions

The VPA, SLB shadow and DTL degistration functions do not need an
address, so simplify things and remove it.

Also cleanup pseries_kexec_cpu_down a bit by storing the cpu IDs
in local variables.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Improve error code on reconfiguration notifier failure

Reconfiguration notifier call for device node may fail by several reasons,
but it always assumes kmalloc failures.

This enables reconfiguration notifier call chain to get the actual error
code rather than -ENOMEM by converting all reconfiguration notifier calls
to return encapsulate error code with notifier_from_errno().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Convert old cpumask API into new one

Adapt new API.

Almost change is trivial. Most important change is the below line
because we plan to change task->cpus_allowed implementation.

- ctx->cpus_allowed = current->cpus_allowed;

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/xics: Rewrite XICS driver

This is a significant rework of the XICS driver, too significant to
conveniently break it up into a series of smaller patches to be honest.

The driver is moved to a more generic location to allow new platforms
to use it, and is broken up into separate ICP and ICS "backends". For
now we have the native and "hypervisor" ICP backends and one common
RTAS ICS backend.

The driver supports one ICP backend instanciation, and many ICS ones,
in order to accomodate future platforms with multiple possibly different
interrupt "sources" mechanisms.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

powerpc/pseries: Increase cpu die timeout

In testing SMT disable, we have been regularly seeing the following
message:

Querying DEAD? cpu %i (%i) shows %i

This indicates the current delay in pseries_cpu_die where we wait
for the specified CPU to die, is insufficient. Usually, this does
not cause a problem, but we've seen this result in BUG_ON's going
off in the timer code when we try to migrate the timers off the
dead cpu while a timer is still running. Increasing this delay,
as is done in this patch, seems to resolve this issue.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Partition hibernation support

Enables support for HMC initiated partition hibernation. This is
a firmware assisted hibernation, since the firmware handles writing
the memory out to disk, along with other partition information,
so we just mimic suspend to ram.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/cpumask: Update some comments

Since the *_map cpumask variants are deprecated, change the comments to
instead refer to *_mask.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/cpumask: Convert hotplug-cpu code to new cpumask API

Convert hotplug-cpu code to new cpumask API.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Make query_cpu_stopped callable outside hotplug cpu

This moves query_cpu_stopped() out of the hotplug cpu code and into
smp.c so it can called in other places and renames it to
smp_query_cpu_stopped().

It also cleans up the return values by adding some #defines

Cc: <stable@kernel.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Reduce printk from pseries_mach_cpu_die()

Remove debug printks in pseries_mach_cpu_die(). These are
noisy at runtime. Traceevents can be added to instrument this
section of code.

The following KERN_INFO printks are removed:

cpu 62 (hwid 62) returned from cede.
Decrementer value = b2802fff Timebase value = 2fa8f95035f4a
cpu 62 (hwid 62) got prodded to go online
cpu 58 (hwid 58) ceding for offline with hint 2

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Move checks in pseries_mach_cpu_die()

Rearrange condition checks for better code readability and
prevention of possible race conditions when
preferred_offline_state can potentially change during the
execution of pseries_mach_cpu_die(). The patch will make
pseries_mach_cpu_die() put cpu in one of the consistent states
and not hit the run over BUG()

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc: Reset kernel stack on cpu online from cede state

Cpu hotplug (offline) without dlpar operation will place cpu
in cede state and the extended_cede_processor() function will
return when resumed.

Kernel stack pointer needs to be reset before
start_secondary() is called to continue the online operation.

Added new function start_secondary_resume() to do the above
steps.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Quieten cede latency printk

The cede latency stuff is relatively new and we don't need to complain about
it not working on older firmware.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc: Fix continuation line formats

String constants that are continued on subsequent lines with \
are not good.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Add hooks to put the CPU into an appropriate offline state

When a CPU is offlined on POWER currently, we call rtas_stop_self() and hand
the CPU back to the resource pool. This path is used for DLPAR which will
cause a change in the LPAR configuration which will be visible outside.

This patch changes the default state a CPU is put into when it is offlined.
On platforms which support ceding the processor to the hypervisor with
latency hint specifier value, during a cpu offline operation,
instead of calling rtas_stop_self(), we cede the vCPU to the hypervisor
while passing a latency hint specifier value. The Hypervisor can use this hint
to provide better energy savings. Also, during the offline
operation, the control of the vCPU remains with the LPAR as oppposed to
returning it to the resource pool.

The patch achieves this by creating an infrastructure to set the
preferred_offline_state() which can be either
- CPU_STATE_OFFLINE: which is the current behaviour of calling
rtas_stop_self()

- CPU_STATE_INACTIVE: which cedes the vCPU to the hypervisor with the latency
hint specifier.

The codepath which wants to perform a DLPAR operation can set the
preferred_offline_state() of a CPU to CPU_STATE_OFFLINE before invoking
cpu_down().

The patch also provides a boot-time command line argument to disable/enable
CPU_STATE_INACTIVE.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

cpumask: Use accessors for cpu_*_mask: powerpc

Use the accessors rather than frobbing bits directly (the new versions
are const).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>

powerpc/pseries: Fix cpu hotplug

Currently, pseries_cpu_die() calls msleep() while polling RTAS for
the status of the dying cpu.

However, if the cpu that is going down also happens to be the one
doing the tick then we're hosed as the tick_do_timer_cpu 'baton' is
only passed later on in tick_shutdown() when _cpu_down() does the
CPU_DEAD notification. Therefore jiffies won't be updated anymore.

This replaces that msleep() with a cpu_relax() to make sure we're not
going to schedule at that point.

With this patch my test box survives a 100k iterations hotplug stress
test on _all_ cpus, whereas without it, it quickly dies after ~50
iterations.

Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Split xics_teardown_cpu()

This splits off the kexec path bits of the xics_teardown_cpu() routine
into its own xics_kexec_teardown_cpu() routine. With the previous
combined routine the CPPR for a cpu that is being removed may have its
CPPR reset in the plpar_eoi() call (which explicitly sets the CPPR to
a non-zero value). Splitting of the kexec bits of the code prevents
this from happening in the cpu remove path.

Once again, this does not cause the cpu remove from the kernel to
fail, but it does cause cpu dlpar operations to not be able to return
the cpu to the hypervisor.

Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[POWERPC] Fix CPU hotplug when using the SLB shadow buffer

Before we register the SLB shadow buffer, we need to invalidate the
entries in the buffer, otherwise we can end up stale entries from when
we previously offlined the CPU.

This does this invalidate as well as unregistering the buffer with
PHYP before we offline the cpu. Tested and fixes crashes seen on
970MP (thanks to tonyb) and POWER5.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Don't enable cpu hotplug on pSeries machines with MPIC

Don't allow cpu hotplug on systems lacking XICS interrupt controller
(i.e. with an MPIC interrupt controller), since the current pSeries
platform code is hardcoded for XICS.

This works around the bug reported by Paul Mackerras where the
disable_nonboot_cpus() call recently added to the shutdown path will
cause an oops on older pSeries machines.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Rename get_property to of_get_property: arch/powerpc

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Cleanup pass over platforms/pseries/hotplug-cpu.c

Purely cosmetic. Change pSeries to pseries inline with other parts of the
kernel, and fix an overly long line.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Only enable cpu hotplug via RTAS if the required firmware support is found

To support cpu hotplug on pseries we require two RTAS tokens. The cpu
hotplug machinery should only be wired up if these tokens are found in
the device tree.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Move the rest of the hotplug cpu code into platforms/pseries/hotplug-cpu.c

Move the rest of the hotplug cpu code from platforms/pseries/smp.c into
platforms/pseries/hotplug-cpu.c.

Wire up the smp_ops callbacks and the notifier in the hotplug cpu initcall,
rather than in smp_init_pseries(). No change in behaviour.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Move pSeries_mach_cpu_die() into platforms/pseries/hotplug-cpu.c

Move pSeries_mach_cpu_die() into platforms/pseries/hotplug-cpu.c,
this allows rtas_stop_self() to be static so remove the prototype.

Wire up pSeries_mach_cpu_die() in the initcall, rather than statically
in setup.c, the initcall will still run prior to the cpu hotplug code
being callable, so there should be no change in behaviour.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

[POWERPC] Move rtas_stop_self() into platforms/pseries/hotplug-cpu.c

As the first step in consolidating the pseries hotplug cpu code,
create platforms/pseries/hotplug-cpu.c and move rtas_stop_self()
into it. Do the rtas token initialisation in a new initcall, rather
than rtas_initialize().

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>