linux.git/drivers/cpufreq/intel_pstate.c, branch v6.0 Linux kernel source tree cpufreq: intel_pstate: Support Sapphire Rapids OOB mode 2022-05-11T17:17:43+00:00 Srinivas Pandruvada srinivas.pandruvada@linux.intel.com 2022-05-02T20:50:52+00:00 bbd67f1b5a9449b090560ca5288aef0cfe623275 Prevent intel_pstate to load when OOB (Out Of Band) P-states mode is enabled in Sapphire Rapids. The OOB identifying bits are same as the prior generation CPUs like Ice Lake servers. So, also add Sapphire Rapids to intel_pstate_cpu_oob_ids list. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Prevent intel_pstate to load when OOB (Out Of Band) P-states mode is
enabled in Sapphire Rapids. The OOB identifying bits are same as the
prior generation CPUs like Ice Lake servers. So, also add Sapphire
Rapids to intel_pstate_cpu_oob_ids list.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Handle no_turbo in frequency invariance 2022-04-13T15:38:04+00:00 Chen Yu yu.c.chen@intel.com 2022-04-07T23:42:58+00:00 addca285120b0edf2fef795f7809c83774cf74b7 Problem statement: Once the user has disabled turbo frequency by # echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo the cfs_rq's util_avg becomes quite small when compared with CPU capacity. Step to reproduce: # echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo # ./x86_cpuload --count 1 --start 3 --timeout 100 --busy 99 would launch 1 thread and bind it to CPU3, lasting for 100 seconds, with a CPU utilization of 99%. [1] top result: %Cpu3 : 98.4 us, 0.0 sy, 0.0 ni, 1.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st check util_avg: cat /sys/kernel/debug/sched/debug | grep "cfs_rq\[3\]" -A 20 | grep util_avg .util_avg : 611 So the util_avg/cpu capacity is 611/1024, which is much smaller than 98.4% shown in the top result. This might impact some logic in the scheduler. For example, group_is_overloaded() would compare the group_capacity and group_util in the sched group, to check if this sched group is overloaded or not. With this gap, even when there is a nearly 100% workload, the sched group will not be regarded as overloaded. Besides group_is_overloaded(), there are also other victims. There is a ongoing work that aims to optimize the task wakeup in a LLC domain. The main idea is to stop searching idle CPUs if the sched domain is overloaded[2]. This proposal also relies on the util_avg/CPU capacity to decide whether the LLC domain is overloaded. Analysis: CPU frequency invariance has caused this difference. In summary, the util_sum of cfs rq would decay quite fast when the CPU is in idle, when the CPU frequency invariance is enabled. The detail is as followed: As depicted in update_rq_clock_pelt(), when the frequency invariance is enabled, there would be two clock variables on each rq, clock_task and clock_pelt: The clock_pelt scales the time to reflect the effective amount of computation done during the running delta time but then syncs back to clock_task when rq is idle. absolute time | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15|16 @ max frequency ------******---------------******--------------- @ half frequency ------************---------************--------- clock pelt | 1| 2| 3| 4| 7| 8| 9| 10| 11|14|15|16 The fast decay of util_sum during idle is due to: 1. rq->clock_pelt is always behind rq->clock_task 2. rq->last_update is updated to rq->clock_pelt' after invoking ___update_load_sum() 3. Then the CPU becomes idle, the rq->clock_pelt' would be suddenly increased a lot to rq->clock_task 4. Enters ___update_load_sum() again, the idle period is calculated by rq->clock_task - rq->last_update, AKA, rq->clock_task - rq->clock_pelt'. The lower the CPU frequency is, the larger the delta = rq->clock_task - rq->clock_pelt' will be. Since the idle period will be used to decay the util_sum only, the util_sum drops significantly during idle period. Proposal: This symptom is not only caused by disabling turbo frequency, but it would also appear if the user limits the max frequency at runtime. Because, if the frequency is always lower than the max frequency, CPU frequency invariance would decay the util_sum quite fast during idle. As some end users would disable turbo after boot up, this patch aims to present this symptom and deals with turbo scenarios for now. It might be ideal if CPU frequency invariance is aware of the max CPU frequency (user specified) at runtime in the future. Link: https://github.com/yu-chen-surf/x86_cpuload.git #1 Link: https://lore.kernel.org/lkml/20220310005228.11737-1-yu.c.chen@intel.com/ #2 Signed-off-by: Chen Yu <yu.c.chen@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Giovanni Gherdovich <ggherdovich@suse.cz> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Problem statement:

Once the user has disabled turbo frequency by

# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo

the cfs_rq's util_avg becomes quite small when compared with
CPU capacity.

Step to reproduce:

# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo

# ./x86_cpuload --count 1 --start 3 --timeout 100 --busy 99

would launch 1 thread and bind it to CPU3, lasting for 100 seconds,
with a CPU utilization of 99%. [1]

top result:
%Cpu3  : 98.4 us,  0.0 sy,  0.0 ni,  1.6 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st

check util_avg:
cat /sys/kernel/debug/sched/debug | grep "cfs_rq\[3\]" -A 20 | grep util_avg
  .util_avg                      : 611

So the util_avg/cpu capacity is 611/1024, which is much smaller than
98.4% shown in the top result.

This might impact some logic in the scheduler. For example,
group_is_overloaded() would compare the group_capacity and group_util
in the sched group, to check if this sched group is overloaded or not.
With this gap, even when there is a nearly 100% workload, the sched
group will not be regarded as overloaded. Besides group_is_overloaded(),
there are also other victims. There is a ongoing work that aims to
optimize the task wakeup in a LLC domain. The main idea is to stop
searching idle CPUs if the sched domain is overloaded[2]. This proposal
also relies on the util_avg/CPU capacity to decide whether the LLC
domain is overloaded.

Analysis:

CPU frequency invariance has caused this difference. In summary,
the util_sum of cfs rq would decay quite fast when the CPU is in
idle, when the CPU frequency invariance is enabled.

The detail is as followed:

As depicted in update_rq_clock_pelt(), when the frequency invariance
is enabled, there would be two clock variables on each rq, clock_task
and clock_pelt:

   The clock_pelt scales the time to reflect the effective amount of
   computation done during the running delta time but then syncs back to
   clock_task when rq is idle.

   absolute time    | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15|16
   @ max frequency  ------******---------------******---------------
   @ half frequency ------************---------************---------
   clock pelt       | 1| 2|    3|    4| 7| 8| 9|   10|   11|14|15|16

The fast decay of util_sum during idle is due to:

 1. rq->clock_pelt is always behind rq->clock_task
 2. rq->last_update is updated to rq->clock_pelt' after invoking
    ___update_load_sum()
 3. Then the CPU becomes idle, the rq->clock_pelt' would be suddenly
    increased a lot to rq->clock_task
 4. Enters ___update_load_sum() again, the idle period is calculated by
    rq->clock_task - rq->last_update, AKA, rq->clock_task - rq->clock_pelt'.
    The lower the CPU frequency is, the larger the delta =
    rq->clock_task - rq->clock_pelt' will be. Since the idle period will be
    used to decay the util_sum only, the util_sum drops significantly during
    idle period.

Proposal:

This symptom is not only caused by disabling turbo frequency, but it
would also appear if the user limits the max frequency at runtime.

Because, if the frequency is always lower than the max frequency,
CPU frequency invariance would decay the util_sum quite fast during
idle.

As some end users would disable turbo after boot up, this patch aims to
present this symptom and deals with turbo scenarios for now.

It might be ideal if CPU frequency invariance is aware of the max CPU
frequency (user specified) at runtime in the future.

Link: https://github.com/yu-chen-surf/x86_cpuload.git #1
Link: https://lore.kernel.org/lkml/20220310005228.11737-1-yu.c.chen@intel.com/ #2
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Use firmware default EPP 2022-03-16T18:14:55+00:00 Srinivas Pandruvada srinivas.pandruvada@linux.intel.com 2022-03-10T22:42:23+00:00 3d13058ed2a6d0ddb55a45a979acc49a845be874 For some specific platforms (E.g. AlderLake) the balance performance EPP is updated from the hard coded value in the driver. This acts as the default and balance_performance EPP. The purpose of this EPP update is to reach maximum 1 core turbo frequency (when possible) out of the box. Although we can achieve the objective by using hard coded value in the driver, there can be other EPP which can be better in terms of power. But that will be very subjective based on platform and use cases. This is not practical to have a per platform specific default hard coded in the driver. If a platform wants to specify default EPP, it can be set in the firmware. If this EPP is not the chipset default of 0x80 (balance_perf_epp unless driver changed it) and more performance oriented but not 0, the driver can use this as the default and balanced_perf EPP. In this case no driver update is required every time there is some new platform and default EPP. If the firmware didn't update the EPP from the chipset default then the hard coded value is used as per existing implementation. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
For some specific platforms (E.g. AlderLake) the balance performance
EPP is updated from the hard coded value in the driver. This acts as
the default and balance_performance EPP. The purpose of this EPP
update is to reach maximum 1 core turbo frequency (when possible) out
of the box.

Although we can achieve the objective by using hard coded value in the
driver, there can be other EPP which can be better in terms of power.
But that will be very subjective based on platform and use cases.
This is not practical to have a per platform specific default hard coded
in the driver.

If a platform wants to specify default EPP, it can be set in the firmware.
If this EPP is not the chipset default of 0x80 (balance_perf_epp unless
driver changed it) and more performance oriented but not 0, the driver
can use this as the default and balanced_perf EPP. In this case no driver
update is required every time there is some new platform and default EPP.

If the firmware didn't update the EPP from the chipset default then
the hard coded value is used as per existing implementation.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Update cpuinfo.max_freq on HWP_CAP changes 2021-12-22T17:36:07+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2021-12-17T19:06:08+00:00 dfeeedc1bf5772226bddf51ed3f853e5a6707bf1 With HWP enabled, when the turbo range of performance levels is disabled by the platform firmware, the CPU capacity is given by the "guaranteed performance" field in MSR_HWP_CAPABILITIES which is generally dynamic. When it changes, the kernel receives an HWP notification interrupt handled by notify_hwp_interrupt(). When the "guaranteed performance" value changes in the above configuration, the CPU performance scaling needs to be adjusted so as to use the new CPU capacity in computations, which means that the cpuinfo.max_freq value needs to be updated for that CPU. Accordingly, modify intel_pstate_notify_work() to read MSR_HWP_CAPABILITIES and update cpuinfo.max_freq to reflect the new configuration (this update can be carried out even if the configuration doesn't actually change, because it simply doesn't matter then and it takes less time to update it than to do extra checks to decide whether or not a change has really occurred). Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
With HWP enabled, when the turbo range of performance levels is
disabled by the platform firmware, the CPU capacity is given by
the "guaranteed performance" field in MSR_HWP_CAPABILITIES which
is generally dynamic.  When it changes, the kernel receives an HWP
notification interrupt handled by notify_hwp_interrupt().

When the "guaranteed performance" value changes in the above
configuration, the CPU performance scaling needs to be adjusted so
as to use the new CPU capacity in computations, which means that
the cpuinfo.max_freq value needs to be updated for that CPU.

Accordingly, modify intel_pstate_notify_work() to read
MSR_HWP_CAPABILITIES and update cpuinfo.max_freq to reflect the
new configuration (this update can be carried out even if the
configuration doesn't actually change, because it simply doesn't
matter then and it takes less time to update it than to do extra
checks to decide whether or not a change has really occurred).

Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Update EPP for AlderLake mobile 2021-12-17T15:44:15+00:00 Srinivas Pandruvada srinivas.pandruvada@linux.intel.com 2021-12-16T18:33:05+00:00 b6e6f8beec98ba7541213c506fe908517fdc52b8 There is an expectation from users that they can get frequency specified by cpufreq/cpuinfo_max_freq when conditions permit. But with AlderLake mobile it may not be possible. This is possible that frequency is clipped based on the system power-up EPP value. In this case users can update cpufreq/energy_performance_preference to some performance oriented EPP to limit clipping of frequencies. To get out of box behavior as the prior generations of CPUs, update EPP for AlderLake mobile CPUs on boot. On prior generations of CPUs EPP = 128 was enough to get maximum frequency, but with AlderLake mobile the equivalent EPP is 102. Since EPP is model specific, this is possible that they have different meaning on each generation of CPU. The current EPP string "balance_performance" corresponds to EPP = 128. Change the EPP corresponding to "balance_performance" to 102 for only AlderLake mobile CPUs and update this on each CPU during boot. To implement reuse epp_values[] array and update the modified EPP at the index for BALANCE_PERFORMANCE. Add a dummy EPP_INDEX_DEFAULT to epp_values[] to match indexes in the energy_perf_strings[]. After HWP PM is enabled also update EPP when "balance_performance" is redefined for the very first time after the boot on each CPU. On subsequent suspend/resume or offline/online the old EPP is restored, so no specific action is needed. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
There is an expectation from users that they can get frequency specified
by cpufreq/cpuinfo_max_freq when conditions permit. But with AlderLake
mobile it may not be possible. This is possible that frequency is clipped
based on the system power-up EPP value. In this case users can update
cpufreq/energy_performance_preference to some performance oriented EPP to
limit clipping of frequencies.

To get out of box behavior as the prior generations of CPUs, update EPP
for AlderLake mobile CPUs on boot. On prior generations of CPUs EPP = 128
was enough to get maximum frequency, but with AlderLake mobile the
equivalent EPP is 102. Since EPP is model specific, this is possible that
they have different meaning on each generation of CPU.

The current EPP string "balance_performance" corresponds to EPP = 128.
Change the EPP corresponding to "balance_performance" to 102 for only
AlderLake mobile CPUs and update this on each CPU during boot.

To implement reuse epp_values[] array and update the modified EPP at the
index for BALANCE_PERFORMANCE. Add a dummy EPP_INDEX_DEFAULT to
epp_values[] to match indexes in the energy_perf_strings[].

After HWP PM is enabled also update EPP when "balance_performance" is
redefined for the very first time after the boot on each CPU. On
subsequent suspend/resume or offline/online the old EPP is restored,
so no specific action is needed.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Drop redundant intel_pstate_get_hwp_cap() call 2021-12-17T15:26:50+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2021-12-10T16:12:18+00:00 458b03f81afbb27143c45d47c2d8f418b2ba2407 It is not necessary to call intel_pstate_get_hwp_cap() from intel_pstate_update_perf_limits(), because it gets called from intel_pstate_verify_cpu_policy() which is either invoked directly right before intel_pstate_update_perf_limits(), in intel_cpufreq_verify_policy() in the passive mode, or called from driver callbacks in a sequence that causes it to be followed by an immediate intel_pstate_update_perf_limits(). Namely, in the active mode intel_cpufreq_verify_policy() is called by intel_pstate_verify_policy() which is the ->verify() callback routine of intel_pstate and gets called by the cpufreq core right before intel_pstate_set_policy(), which is the driver's ->setoplicy() callback routine, where intel_pstate_update_perf_limits() is called. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
It is not necessary to call intel_pstate_get_hwp_cap() from
intel_pstate_update_perf_limits(), because it gets called from
intel_pstate_verify_cpu_policy() which is either invoked directly
right before intel_pstate_update_perf_limits(), in
intel_cpufreq_verify_policy() in the passive mode, or called
from driver callbacks in a sequence that causes it to be followed
by an immediate intel_pstate_update_perf_limits().

Namely, in the active mode intel_cpufreq_verify_policy() is called
by intel_pstate_verify_policy() which is the ->verify() callback
routine of intel_pstate and gets called by the cpufreq core right
before intel_pstate_set_policy(), which is the driver's ->setoplicy()
callback routine, where intel_pstate_update_perf_limits() is called.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: ITMT support for overclocked system 2021-11-23T13:11:18+00:00 Srinivas Pandruvada srinivas.pandruvada@linux.intel.com 2021-11-19T05:18:01+00:00 03c83982a0278207709143ba78c5a470179febee On systems with overclocking enabled, CPPC Highest Performance can be hard coded to 0xff. In this case even if we have cores with different highest performance, ITMT can't be enabled as the current implementation depends on CPPC Highest Performance. On such systems we can use MSR_HWP_CAPABILITIES maximum performance field when CPPC.Highest Performance is 0xff. Due to legacy reasons, we can't solely depend on MSR_HWP_CAPABILITIES as in some older systems CPPC Highest Performance is the only way to identify different performing cores. Reported-by: Michael Larabel <Michael@MichaelLarabel.com> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Tested-by: Michael Larabel <Michael@MichaelLarabel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
On systems with overclocking enabled, CPPC Highest Performance can be
hard coded to 0xff. In this case even if we have cores with different
highest performance, ITMT can't be enabled as the current implementation
depends on CPPC Highest Performance.

On such systems we can use MSR_HWP_CAPABILITIES maximum performance field
when CPPC.Highest Performance is 0xff.

Due to legacy reasons, we can't solely depend on MSR_HWP_CAPABILITIES as
in some older systems CPPC Highest Performance is the only way to identify
different performing cores.

Reported-by: Michael Larabel <Michael@MichaelLarabel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Tested-by: Michael Larabel <Michael@MichaelLarabel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Fix active mode offline/online EPP handling 2021-11-23T13:02:11+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2021-11-17T13:57:31+00:00 ed38eb49d101e829ae0f8c0a0d3bf5cb6bcbc6b2 After commit 4adcf2e5829f ("cpufreq: intel_pstate: Add ->offline and ->online callbacks") the EPP value set by the "performance" scaling algorithm in the active mode is not restored after an offline/online cycle which replaces it with the saved EPP value coming from user space. Address this issue by forcing intel_pstate_hwp_set() to set a new EPP value when it runs first time after online. Fixes: 4adcf2e5829f ("cpufreq: intel_pstate: Add ->offline and ->online callbacks") Link: https://lore.kernel.org/linux-pm/adc7132c8655bd4d1c8b6129578e931a14fe1db2.camel@linux.intel.com/ Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Cc: 5.9+ <stable@vger.kernel.org> # 5.9+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
After commit 4adcf2e5829f ("cpufreq: intel_pstate: Add ->offline and
->online callbacks") the EPP value set by the "performance" scaling
algorithm in the active mode is not restored after an offline/online
cycle which replaces it with the saved EPP value coming from user
space.

Address this issue by forcing intel_pstate_hwp_set() to set a new
EPP value when it runs first time after online.

Fixes: 4adcf2e5829f ("cpufreq: intel_pstate: Add ->offline and ->online callbacks")
Link: https://lore.kernel.org/linux-pm/adc7132c8655bd4d1c8b6129578e931a14fe1db2.camel@linux.intel.com/
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 5.9+ <stable@vger.kernel.org> # 5.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Add Ice Lake server to out-of-band IDs 2021-11-23T13:02:10+00:00 Adamos Ttofari attofari@amazon.de 2021-11-12T09:16:57+00:00 cd23f02f166892603eb9f2d488152b975872b682 Commit fbdc21e9b038 ("cpufreq: intel_pstate: Add Icelake servers support in no-HWP mode") enabled the use of Intel P-State driver for Ice Lake servers. But it doesn't cover the case when OS can't control P-States. Therefore, for Ice Lake server, if MSR_MISC_PWR_MGMT bits 8 or 18 are enabled, then the Intel P-State driver should exit as OS can't control P-States. Fixes: fbdc21e9b038 ("cpufreq: intel_pstate: Add Icelake servers support in no-HWP mode") Signed-off-by: Adamos Ttofari <attofari@amazon.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Commit fbdc21e9b038 ("cpufreq: intel_pstate: Add Icelake servers
support in no-HWP mode") enabled the use of Intel P-State driver
for Ice Lake servers.

But it doesn't cover the case when OS can't control P-States.

Therefore, for Ice Lake server, if MSR_MISC_PWR_MGMT bits 8 or 18
are enabled, then the Intel P-State driver should exit as OS can't
control P-States.

Fixes: fbdc21e9b038 ("cpufreq: intel_pstate: Add Icelake servers support in no-HWP mode")
Signed-off-by: Adamos Ttofari <attofari@amazon.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Clear HWP Status during HWP Interrupt enable 2021-11-04T18:48:47+00:00 Srinivas Pandruvada srinivas.pandruvada@linux.intel.com 2021-11-04T10:22:30+00:00 074d0cdfbb2f5985c5748fe80f6f8a2a7db8b63f It is possible that some performance excursions happened before OS boot or enable HWP interrupts. So clear MSR_HWP_STATUS bits when we enable HWP interrupt. In this way a next excursion will results in a HWP interrupt. The status bits of MSR_HWP_STATUS must be cleared (0) by software so that a new status condition change will cause the hardware to set the bit again and issue the notification. Fixes: 57577c996d73 ("cpufreq: intel_pstate: Process HWP Guaranteed change notification") Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
It is possible that some performance excursions happened before OS boot
or enable HWP interrupts. So clear MSR_HWP_STATUS bits when we enable
HWP interrupt. In this way a next excursion will results in a HWP
interrupt.

The status bits of MSR_HWP_STATUS must be cleared (0) by software so
that a new status condition change will cause the hardware to set the
bit again and issue the notification.

Fixes: 57577c996d73 ("cpufreq: intel_pstate: Process HWP Guaranteed change notification")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>