Bring in yet another series that touches KVM code, and might need to
be merged into the kvm-ppc branch to resolve conflicts.
This required some changes in pnv_power9_force_smt4_catch/release()
due to the paca array becomming an array of pointers.
Move this into the early setup code, and don't iterate over CPU masks.
We don't want to call into sysfs so early from setup, and a future patch
won't initialize CPU masks by the time this is called.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in incremental fix from Nick for DSCR handling]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
The TSCR can only be accessed in hypervisor mode.
Fixes: 88b5e12eeb11 ("powerpc: Expose TSCR via sysfs")
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The thread switch control register (TSCR) is a per core register
that configures how the CPU shares resources between SMT threads.
Exposing it via sysfs allows us to tune it at run time.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Take the DSCR value set by firmware as the dscr_default value,
rather than zero.
POWER9 recommends DSCR default to a non-zero value.
Signed-off-by: From: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make record_spr_defaults() __init]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The entire body of unregister_cpu_online() is inside an #ifdef
CONFIG_HOTPLUG_CPU block. This is ugly and means we create an empty function
when hotplug is disabled for no reason.
Instead move the #ifdef out of the function body and define the function to be
NULL in the else case. This means we'll pass NULL to cpuhp_setup_state(), but
that's fine because it accepts NULL to mean there is no teardown callback, which
is exactly what we want.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
For CPUs present at boot each logical CPU acquires a reference to the
associated device node of the core. This happens in register_cpu() which
is called by topology_init(). The result of this is that we end up with
a reference held by each thread of the core. However, these references
are never freed if the CPU core is DLPAR removed.
This patch fixes the reference leaks by acquiring and releasing the references
in the CPU hotplug callbacks un/register_cpu_online(). With this patch symmetric
reference counting is observed with both CPUs present at boot, and those DLPAR
added after boot.
Fixes: f86e4718f2 ("driver/core: cpu: initialize of_node in cpu's device struture")
Cc: stable@vger.kernel.org # v3.12+
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This is just a smattering of things picked up by sparse that should
be made static.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch adds some in-code documentation to the DSCR related code to
make it more readable without having any functional change to it.
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This still has not been merged and now powerpc is the only arch that does
not have this change. Sorry about missing linuxppc-dev before.
V2->V2
- Fix up to work against 3.18-rc1
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
[mpe: Fix build errors caused by set/or_softirq_pending(), and rework
assignment in __set_breakpoint() to use memcpy().]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)"
it is no longer possible to set the DSCR on a per-CPU basis.
The old behaviour was to minipulate the DSCR SPR directly but this is no
longer sufficient: the value is quickly overwritten by context switching.
This patch stores the per-CPU DSCR value in a kernel variable rather than
directly in the SPR and it is used whenever a process has not set the DSCR
itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged.
Writes to the old global default (/sys/devices/system/cpu/dscr_default)
now set all of the per-CPU values and reads return the last written value.
The new per-CPU default is added to the paca_struct and is used everywhere
outside of sysfs.c instead of the old global default.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Split the __SYSFS_SPRSETUP macro into two parts so that registers requiring
custom read and write functions can use common code for their show and store
functions.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
register_cpu_notifier(&foobar_cpu_notifier);
put_online_cpus();
This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).
Instead, the correct and race-free way of performing the callback
registration is:
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
init_cpu(cpu);
/* Note the use of the double underscored version of the API */
__register_cpu_notifier(&foobar_cpu_notifier);
cpu_notifier_register_done();
Fix the sysfs code in powerpc by using this latter form of callback
registration.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Olof Johansson <olof@lixom.net>
Cc: Wang Dongsheng <dongsheng.wang@freescale.com>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
smt-snooze-delay was designed to disable NAP state or delay the entry
to the NAP state prior to adoption of cpuidle framework. This
is per-cpu variable. With the coming of CPUIDLE framework,
states can be disabled on per-cpu basis using the cpuidle/enable
sysfs entry.
Also, with the coming of cpuidle driver each state's target residency
is per-driver unlike earlier which was per-device. Therefore,
the per-cpu sysfs smt-snooze-delay which decides the target residency
of the idle state on a particular cpu causes more confusion to the user
as we cannot have different smt-snooze-delay (target residency)
values for each cpu.
In the current code, smt-snooze-delay functionality is completely broken.
It makes sense to remove smt-snooze-delay from idle driver with the
coming of cpuidle framework.
However, sysfs files are retained as ppc64_util currently
utilises it. Once we fix ppc64_util, propose to clean
up the kernel code.
Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a sys interface to enable/diable pw20 state or altivec idle, and
control the wait entry time.
Enable/Disable interface:
0, disable. 1, enable.
/sys/devices/system/cpu/cpuX/pw20_state
/sys/devices/system/cpu/cpuX/altivec_idle
Set wait time interface:(Nanosecond)
/sys/devices/system/cpu/cpuX/pw20_wait_time
/sys/devices/system/cpu/cpuX/altivec_idle_wait_time
Example: Base on TBfreq is 41MHZ.
1~48(ns): TB[63]
49~97(ns): TB[62]
98~195(ns): TB[61]
196~390(ns): TB[60]
391~780(ns): TB[59]
781~1560(ns): TB[58]
...
Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
[scottwood@freescale.com: change ifdef]
Signed-off-by: Scott Wood <scottwood@freescale.com>
Currently PMC (Performance Monitor Counter) setup macros are used
for other SPRs. Since not all SPRs are PMC related, this patch
modifies the exisiting macro and uses it to setup both PMC and
non PMC SPRs accordingly.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/kernel/sysfs.c exports PURR with write permission.
This may be valid for kernel in phyp mode. But writing to
the file in guest mode causes crash due to a priviledge violation
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the powerpc uses of the __cpuinit macros. There
are no __CPUINIT users in assembly files in powerpc.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We are registering the attribute with permission 0600 but it
doesn't have a store callback, which causes WARN_ON's during
boot. Fix the permission.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
smt_snooze_delay was designed to delay idle loop's nap entry
in the native idle code before it got ported over to use as part of
the cpuidle framework.
A -ve value assigned to smt_snooze_delay should result in
busy looping, in other words disabling the entry to nap state.
- https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html
This particular functionality can be achieved currently by
echo 1 > /sys/devices/system/cpu/cpu*/state1/disable
but it is broken when one assigns -ve value to the smt_snooze_delay
variable either via sysfs entry or ppc64_cpu util.
This patch aims to fix this, by disabling nap state when smt_snooze_delay
variable is set to -ve value.
Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When we update the DSCR either via emulation of mtspr(DSCR) or via
a change to dscr_default in sysfs we don't update thread.dscr.
We will eventually update it at context switch time but there is
a period where thread.dscr is incorrect.
If we fork at this point we will copy the old value of thread.dscr
into the child. To avoid this, always keep thread.dscr in sync with
reality.
This issue was found with the following testcase:
http://ozlabs.org/~anton/junkcode/dscr_inherit_test.c
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org> # 3.0+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Writing to dscr_default in sysfs doesn't actually change the DSCR -
we rely on a context switch on each CPU to do the work. There is no
guarantee we will get a context switch in a reasonable amount of time
so fire off an IPI to force an immediate change.
This issue was found with the following test case:
http://ozlabs.org/~anton/junkcode/dscr_explicit_test.c
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org> # 3.0+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Michael Ellerman
Nicholas Piggin
Cyril Bur
Anton Blanchard
Tyrel Datwyler
Sebastian Andrzej Siewior
Daniel Axtens
Anshuman Khandual
Christoph Lameter
Sam bobroff
Srivatsa S. Bhat
Deepthi Dharwar
Wang Dongsheng
Madhavan Srinivasan
Paul Gortmaker
Benjamin Herrenschmidt
Wen Congyang