linux.git/drivers/base/cpu.c, branch v4.14.49

x86/bugs: Expose /sys/../spec_store_bypass

2018-05-22T16:54:02+00:00

commit c456442cd3a59eeb1d60293c26cbe2ff2c4e42cf upstream

Add the sysfs file for the new vulerability. It does not do much except
show the words 'Vulnerable' for recent x86 cores.

Intel cores prior to family 6 are known not to be vulnerable, and so are
some Atoms and some Xeon Phi.

It assumes that older Cyrix, Centaur, etc. cores are immune.

Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Reviewed-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sysfs/cpu: Add vulnerability folder

2018-01-17T08:45:27+00:00

commit 87590ce6e373d1a5401f6539f0c59ef92dd924a9 upstream.

As the meltdown/spectre problem affects several CPU architectures, it makes
sense to have common way to express whether a system is affected by a
particular vulnerability or not. If affected the way to express the
mitigation should be common as well.

Create /sys/devices/system/cpu/vulnerabilities folder and files for
meltdown, spectre_v1 and spectre_v2.

Allow architectures to override the show function.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Konrad Rzeszutek Wilk 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Dave Hansen 
Cc: Linus Torvalds 
Cc: Borislav Petkov 
Cc: David Woodhouse 
Link: https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Revert "PM / QoS: Fix device resume latency PM QoS"

2017-10-31T17:35:40+00:00

This reverts commit 0cc2b4e5a020 (PM / QoS: Fix device resume latency PM
QoS) as it introduced regressions on multiple systems and the fix-up
in commit 2a9a86d5c813 (PM / QoS: Fix default runtime_pm device resume
latency) does not address all of them.

The original problem that commit 0cc2b4e5a020 was attempting to fix
will be addressed later.

Fixes: 0cc2b4e5a020 (PM / QoS: Fix device resume latency PM QoS)
Reported-by: Geert Uytterhoeven 
Signed-off-by: Rafael J. Wysocki

PM / QoS: Fix device resume latency PM QoS

2017-10-24T13:20:45+00:00

The special value of 0 for device resume latency PM QoS means
"no restriction", but there are two problems with that.

First, device resume latency PM QoS requests with 0 as the
value are always put in front of requests with positive
values in the priority lists used internally by the PM QoS
framework, causing 0 to be chosen as an effective constraint
value.  However, that 0 is then interpreted as "no restriction"
effectively overriding the other requests with specific
restrictions which is incorrect.

Second, the users of device resume latency PM QoS have no
way to specify that *any* resume latency at all should be
avoided, which is an artificial limitation in general.

To address these issues, modify device resume latency PM QoS to
use S32_MAX as the "no constraint" value and 0 as the "no
latency at all" one and rework its users (the cpuidle menu
governor, the genpd QoS governor and the runtime PM framework)
to follow these changes.

Also add a special "n/a" value to the corresponding user space I/F
to allow user space to indicate that it cannot accept any resume
latencies at all for the given device.

Fixes: 85dc0b8a4019 (PM / QoS: Make it possible to expose PM QoS latency constraints)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=197323
Reported-by: Reinette Chatre 
Tested-by: Reinette Chatre 
Signed-off-by: Rafael J. Wysocki 
Acked-by: Alex Shi 
Cc: All applicable

treewide: make "nr_cpu_ids" unsigned

2017-09-09T01:26:48+00:00

First, number of CPUs can't be negative number.

Second, different signnnedness leads to suboptimal code in the following
cases:

1)
	kmalloc(nr_cpu_ids * sizeof(X));

"int" has to be sign extended to size_t.

2)
	while (loff_t *pos < nr_cpu_ids)

MOVSXD is 1 byte longed than the same MOV.

Other cases exist as well. Basically compiler is told that nr_cpu_ids
can't be negative which can't be deduced if it is "int".

Code savings on allyesconfig kernel: -3KB

	add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370)
	function                                     old     new   delta
	coretemp_cpu_online                          450     512     +62
	rcu_init_one                                1234    1272     +38
	pci_device_probe                             374     399     +25

				...

	pgdat_reclaimable_pages                      628     556     -72
	select_fallback_rq                           446     369     -77
	task_numa_find_cpu                          1923    1807    -116

Link: http://lkml.kernel.org/r/20170819114959.GA30580@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

CPU / PM: expose pm_qos_resume_latency for CPUs

2017-01-30T10:05:29+00:00

The cpu-dma PM QoS constraint impacts all the cpus in the system. There
is no way to let the user to choose a PM QoS constraint per cpu.

The following patch exposes to the userspace a per cpu based sysfs file
in order to let the userspace to change the value of the PM QoS latency
constraint.

This change is inoperative in its form and the cpuidle governors have to
take into account the per cpu latency constraint in addition to the
global cpu-dma latency constraint in order to operate properly.

BTW
The pm_qos_resume_latency usage defined in
Documentation/ABI/testing/sysfs-devices-power
The /sys/devices/.../power/pm_qos_resume_latency_us attribute
contains the PM QoS resume latency limit for the given device,
which is the maximum allowed time it can take to resume the
device, after it has been suspended at run time, from a resume
request to the moment the device will be ready to process I/O,
in microseconds.  If it is equal to 0, however, this means that
the PM QoS resume latency may be arbitrary.

Signed-off-by: Alex Shi 
Signed-off-by: Rafael J. Wysocki

cpu: clean up register_cpu func

2016-08-31T13:19:55+00:00

This patch could reduce one branch in this function. Also
make the code more readble.

Signed-off-by: Alex Shi 
Acked-by: Daniel Lezcano 
To: linux-kernel@vger.kernel.org
To: Greg Kroah-Hartman 
Cc: linux-pm@vger.kernel.org
Cc: Ulf Hansson 
Cc: Daniel Lezcano 
Signed-off-by: Greg Kroah-Hartman

drivers/base/cpu.c: use __cpu_*_mask directly

2016-01-21T01:09:18+00:00

The only user of the lvalue-ness of the cpu_*_mask variables is in
drivers/base/cpu.c, and that is mostly a work-around for the fact that not
even const variables can be used in static initialization.  Now that the
underlying struct cpumasks are exposed we can take their address.

Signed-off-by: Rasmus Villemoes 
Acked-by: Rusty Russell 
Acked-by: Greg Kroah-Hartman 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpu: Remove bogus __ref annotation of cpu_subsys_online()

2015-08-05T22:18:26+00:00

In commit 0db0628d9012 ("kernel: delete __cpuinit usage from all core
kernel files") cpu_up() lost its __cpuinit annotation, vanishing the
need for cpu_subsys_online() to have a __ref annotation. Just drop it
to be able to catch real section mismatches in the future.

Signed-off-by: Mathias Krause 
Cc: Paul Gortmaker 
Signed-off-by: Greg Kroah-Hartman

show nohz_full cpus in sysfs

2015-05-20T07:15:09+00:00

Currently there is no way to query which CPUs are in nohz_full
mode from userspace.

Export the CPU list running in nohz_full mode in sysfs,
specifically in the file /sys/devices/system/cpu/nohz_full

This can be used by system management tools like libvirt,
openstack, and others to ensure proper task placement.

Signed-off-by: Rik van Riel 
Acked-by: Mike Galbraith 
Acked-by: Chris Metcalf 
Signed-off-by: Greg Kroah-Hartman