The intel_pstate CPU frequency scaling driver does not
use policy->cur and it is 0.
When the CPU frequency is outdated arch_freq_get_on_cpu()
will default to the nominal clock frequency when its call to
cpufreq_quick_getpolicy_cur returns the never updated 0.
Thus, the listed frequency might be outside of currently
set limits. Some users are complaining about the high
reported frequency, albeit stale, when their system is
idle and/or it is above the reduced maximum they have set.

This patch will maintain policy_cur for the intel_pstate
driver at the current minimum CPU frequency.

Reported-by: Yang Jie <yang.jie@linux.intel.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217597
Signed-off-by: Doug Smythies <dsmythies@telus.net>
[ rjw: White space damage fixes and comment adjustment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Some system BIOS configuration may provide option to disable E-cores.
As part of this change, CPUID feature for hybrid (Leaf 7 sub leaf 0,
EDX[15] = 0) may not be set. But HWP performance limits will still be
using a scaling factor like any other hybrid enabled system.

The current check for applying scaling factor will fail when hybrid
CPUID feature is not set and the only way to make sure that scaling
should be applied by checking CPPC nominal frequency and nominal
performance.

First, or systems predating Alder Lake, the CPPC nominal frequency and
nominal performance are 0, which can be used to distinguish those
systems from hybrid systems with disabled E-cores.

Second, if the CPPC nominal frequency and nominal performance are
defined, which indicates the need to use a special scaling factor, and
the nominal performance value multiplied by 100 is not equal to the
nominal frequency one, use hybrid scaling factor.

This can be done for all HWP systems without additional CPU model check.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject and changelog edits, removal of unneeded parens, comment
  edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If the intel_pstate driver is set to passive mode, then writing the
same value to the energy_performance_preference sysfs twice will fail.
This is caused by the wrong return value used (index of the matched
energy_perf_string), instead of the length of the passed in parameter.
Fix by forcing the internal return value to zero when the same
preference is passed in by user. This same issue is not present when
active mode is used for the driver.

Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled")
Reported-by: Niklas Neronin <niklas.neronin@intel.com>
Signed-off-by: Tero Kristo <tero.kristo@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull driver core updates from Greg KH:
 "Here is the large set of driver core changes for 6.4-rc1.

  Once again, a busy development cycle, with lots of changes happening
  in the driver core in the quest to be able to move "struct bus" and
  "struct class" into read-only memory, a task now complete with these
  changes.

  This will make the future rust interactions with the driver core more
  "provably correct" as well as providing more obvious lifetime rules
  for all busses and classes in the kernel.

  The changes required for this did touch many individual classes and
  busses as many callbacks were changed to take const * parameters
  instead. All of these changes have been submitted to the various
  subsystem maintainers, giving them plenty of time to review, and most
  of them actually did so.

  Other than those changes, included in here are a small set of other
  things:

   - kobject logging improvements

   - cacheinfo improvements and updates

   - obligatory fw_devlink updates and fixes

   - documentation updates

   - device property cleanups and const * changes

   - firwmare loader dependency fixes.

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (120 commits)
  device property: make device_property functions take const device *
  driver core: update comments in device_rename()
  driver core: Don't require dynamic_debug for initcall_debug probe timing
  firmware_loader: rework crypto dependencies
  firmware_loader: Strip off \n from customized path
  zram: fix up permission for the hot_add sysfs file
  cacheinfo: Add use_arch[|_cache]_info field/function
  arch_topology: Remove early cacheinfo error message if -ENOENT
  cacheinfo: Check cache properties are present in DT
  cacheinfo: Check sib_leaf in cache_leaves_are_shared()
  cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
  cacheinfo: Add arm64 early level initializer implementation
  cacheinfo: Add arch specific early level initializer
  tty: make tty_class a static const structure
  driver core: class: remove struct class_interface * from callbacks
  driver core: class: mark the struct class in struct class_interface constant
  driver core: class: make class_register() take a const *
  driver core: class: mark class_release() as taking a const *
  driver core: remove incorrect comment for device_create*
  MIPS: vpe-cmp: remove module owner pointer from struct class usage.
  ...

The HWP IO boost results in slight improvements for IO performance on
both Ice Lake and Sapphire Rapid servers.

Currently there is a CPU model check for Skylake desktop and server along
with the ACPI PM profile for performance and enterprise servers to enable
IO boost.

Remove the CPU model check, so that all current server models enable HWP
IO boost by default.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20230313182918.1312597-3-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull more power management updates from Rafael Wysocki:
 "These update power capping (new hardware support and cleanup) and
  cpufreq (bug fixes, cleanups and intel_pstate adjustment for a new
  platform).

  Specifics:

   - Fix error handling in the apple-soc cpufreq driver (Dan Carpenter)

   - Change the log level of a message in the amd-pstate cpufreq driver
     so it is more visible to users (Kai-Heng Feng)

   - Adjust the balance_performance EPP value for Sapphire Rapids in the
     intel_pstate cpufreq driver (Srinivas Pandruvada)

   - Remove MODULE_LICENSE from 3 pieces of non-modular code (Nick
     Alcock)

   - Make a read-only kobj_type structure in the schedutil cpufreq
     governor constant (Thomas Weißschuh)

   - Add Add Power Limit4 support for Meteor Lake SoC to the Intel RAPL
     power capping driver (Sumeet Pawnikar)"

* tag 'pm-6.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: apple-soc: Fix an IS_ERR() vs NULL check
  powercap: remove MODULE_LICENSE in non-modules
  cpufreq: intel_pstate: remove MODULE_LICENSE in non-modules
  powercap: RAPL: Add Power Limit4 support for Meteor Lake SoC
  cpufreq: amd-pstate: remove MODULE_LICENSE in non-modules
  cpufreq: schedutil: make kobj_type structure constant
  cpufreq: amd-pstate: Let user know amd-pstate is disabled
  cpufreq: intel_pstate: Adjust balance_performance EPP for Sapphire Rapids

Since commit 8b41fc4454e ("kbuild: create modules.builtin without
Makefile.modbuiltin or tristate.conf"), MODULE_LICENSE declarations
are used to identify modules. As a consequence, uses of the macro
in non-modules will cause modprobe to misidentify their containing
object file as a module when it is not (false positives), and modprobe
might succeed rather than failing with a suitable error message.

So remove it in the files in this commit, none of which can be built as
modules.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Suggested-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

While the majority of server OS distributions are deployed with the
"performance" governor as the default, some distributions like Ubuntu use
the "powersave" governor by default.

While using the "powersave" governor in its default configuration on
Sapphire Rapids systems leads to much lower power, the performance is
lower by more than 25% for several workloads relative to the
"performance" governor.

A 37% difference has been reported by www.Phoronix.com [1].

This is a consequence of using a relatively high EPP value in the
default configuration of the "powersave" governor and the performance
can be made much closer to the "performance" governor's level by
adjusting the default EPP value. Based on experiments, with EPP of 0x00,
0x10, 0x20, the performance delta between the "powersave" governor and
the "performance" one is around 12%. However, the EPP of 0x20 reduces
average power by 18% with respect to the lower EPP values.

[Note that raising min_perf_pct in sysfs as high as 50% in addition to
 adjusting EPP does not improve the performance any further.]

For this reason, change the EPP value corresponding to the the default
balance_performance setting for Sapphire Rapids to 0x20, which is
straightforward, because analogous default EPP adjustment has been
applied to Alder Lake and there is a way to set the balance_performance
EPP value in intel_pstate based on the processor model already.

The goal here is to limit the mean performance delta between the
"powersave" governor in the default configuration and the "performance"
governor for a wide variety of server workloadsto to around 10-12%. For
some bursty workloads, this delta can be still large, as the frequency
ramp-up will still lag when the "powersave" governor is in use
irrespective of the EPP setting, because the performance governor always
requests the maximum possible frequency.

Link: https://www.phoronix.com/review/centos-clear-spr/6 # [1]
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

After making acpi_processor_get_platform_limit() use the "no limit"
value for its frequency QoS request when _PPC returns 0, it is not
necessary to replace the frequency corresponding to the first _PSS
return package entry with the maximum turbo frequency of the given
CPU in intel_pstate_init_acpi_perf_limits() any more, so drop the
code doing that along with the comment explaining it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>