linux-stable.git/drivers/cpufreq, branch v6.12.96 Linux kernel stable tree cpufreq: pcc: fix use-after-free and double free in _OSC evaluation 2026-07-18T14:52:06+00:00 Yuho Choi dbgh9129@gmail.com 2026-04-16T14:46:21+00:00 a36ca93a8ba57464e521d70a337d37f069064111 commit 266d3dd8b757b48a576e90f018b51f7b7563cc32 upstream. pcc_cpufreq_do_osc() calls acpi_evaluate_object() twice for the two-phase _OSC negotiation. Between the two calls it freed output.pointer but left output.length unchanged. Since acpi_evaluate_object() treats a non-zero length with a non-NULL pointer as an existing buffer to write into, the second call wrote into freed memory (use-after-free). The subsequent kfree(output.pointer) at out_free then freed the same pointer a second time (double free). Reset output.pointer to NULL and output.length to ACPI_ALLOCATE_BUFFER after freeing the first result, so ACPICA allocates a fresh buffer for each phase independently. Fixes: 0f1d683fb35d ("[CPUFREQ] Processor Clocking Control interface driver") Signed-off-by: Yuho Choi <dbgh9129@gmail.com> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Cc: All applicable <stable@vger.kernel.org> Link: https://patch.msgid.link/20260416144621.93964-1-dbgh9129@gmail.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 266d3dd8b757b48a576e90f018b51f7b7563cc32 upstream.

pcc_cpufreq_do_osc() calls acpi_evaluate_object() twice for the
two-phase _OSC negotiation. Between the two calls it freed
output.pointer but left output.length unchanged. Since
acpi_evaluate_object() treats a non-zero length with a non-NULL
pointer as an existing buffer to write into, the second call wrote
into freed memory (use-after-free). The subsequent kfree(output.pointer)
at out_free then freed the same pointer a second time (double free).

Reset output.pointer to NULL and output.length to ACPI_ALLOCATE_BUFFER
after freeing the first result, so ACPICA allocates a fresh buffer for
each phase independently.

Fixes: 0f1d683fb35d ("[CPUFREQ] Processor Clocking Control interface driver")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260416144621.93964-1-dbgh9129@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: Fix hotplug-suspend race during reboot 2026-07-18T14:52:06+00:00 Tianxiang Chen nanmu@xiaomi.com 2026-04-08T14:19:14+00:00 a0ef2fc89d28ca62923376c4b8ffaa57136a36be commit a9029dd55696c651ee46912afa2a166fa456bb3e upstream. During system reboot, cpufreq_suspend() is called via the kernel_restart() -> device_shutdown() path. Unlike the normal system suspend path, the reboot path does not call freeze_processes(), so userspace processes and kernel threads remain active. This allows CPU hotplug operations to run concurrently with cpufreq_suspend(). The original code has no synchronization with CPU hotplug, leading to a race condition where governor_data can be freed by the hotplug path while cpufreq_suspend() is still accessing it, resulting in a null pointer dereference: Unable to handle kernel NULL pointer dereference Call Trace: do_kernel_fault+0x28/0x3c cpufreq_suspend+0xdc/0x160 device_shutdown+0x18/0x200 kernel_restart+0x40/0x80 arm64_sys_reboot+0x1b0/0x200 Fix this by adding cpus_read_lock()/cpus_read_unlock() to cpufreq_suspend() to block CPU hotplug operations while suspend is in progress. Fixes: 65650b35133f ("cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown") Signed-off-by: Tianxiang Chen <nanmu@xiaomi.com> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Cc: All applicable <stable@vger.kernel.org> [ rjw: Changelog edits ] Link: https://patch.msgid.link/20260408141914.35281-1-nanmu@xiaomi.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a9029dd55696c651ee46912afa2a166fa456bb3e upstream.

During system reboot, cpufreq_suspend() is called via the
kernel_restart() -> device_shutdown() path. Unlike the normal system
suspend path, the reboot path does not call freeze_processes(), so
userspace processes and kernel threads remain active.

This allows CPU hotplug operations to run concurrently with
cpufreq_suspend(). The original code has no synchronization with CPU
hotplug, leading to a race condition where governor_data can be freed
by the hotplug path while cpufreq_suspend() is still accessing it,
resulting in a null pointer dereference:

  Unable to handle kernel NULL pointer dereference
  Call Trace:
   do_kernel_fault+0x28/0x3c
   cpufreq_suspend+0xdc/0x160
   device_shutdown+0x18/0x200
   kernel_restart+0x40/0x80
   arm64_sys_reboot+0x1b0/0x200

Fix this by adding cpus_read_lock()/cpus_read_unlock() to
cpufreq_suspend() to block CPU hotplug operations while suspend is in
progress.

Fixes: 65650b35133f ("cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown")
Signed-off-by: Tianxiang Chen <nanmu@xiaomi.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
[ rjw: Changelog edits ]
Link: https://patch.msgid.link/20260408141914.35281-1-nanmu@xiaomi.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: intel_pstate: Sync policy->cur during CPU offline 2026-07-18T14:52:06+00:00 Fushuai Wang wangfushuai@baidu.com 2026-05-20T03:21:19+00:00 89899b16992d2015cd8ce052ac3298a302c87be1 commit bcbdaa1086c25a8a5d48e04e1b82fdfb0682b681 upstream. When a CPU goes offline with HWP disabled, intel_pstate_set_min_pstate() sets the MSR_IA32_PERF_CTL to minimum frequency to prevent SMT siblings from being restricted. However, the policy->cur value was not updated, leaving it at the previous value. When the CPU comes back online, governor->limits() checks if target_freq equals policy->cur and skips the frequency adjustment if they match. Since policy->cur still holds the previous value, the governor does not call cpufreq_driver->target to update MSR_IA32_PERF_CTL. Fix this by synchronizing policy->cur with the hardware state when setting minimum pstate during CPU offline. Fixes: bb18008f8086 ("intel_pstate: Set core to min P state during core offline") Cc: stable@vger.kernel.org # 3.15+ Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Fushuai Wang <wangfushuai@baidu.com> [ rjw: Subject refinement ] Link: https://patch.msgid.link/20260520032119.30615-1-fushuai.wang@linux.dev Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bcbdaa1086c25a8a5d48e04e1b82fdfb0682b681 upstream.

When a CPU goes offline with HWP disabled, intel_pstate_set_min_pstate()
sets the MSR_IA32_PERF_CTL to minimum frequency to prevent SMT siblings
from being restricted. However, the policy->cur value was not updated,
leaving it at the previous value.

When the CPU comes back online, governor->limits() checks if target_freq
equals policy->cur and skips the frequency adjustment if they match. Since
policy->cur still holds the previous value, the governor does not call
cpufreq_driver->target to update MSR_IA32_PERF_CTL.

Fix this by synchronizing policy->cur with the hardware state when setting
minimum pstate during CPU offline.

Fixes: bb18008f8086 ("intel_pstate: Set core to min P state during core offline")
Cc: stable@vger.kernel.org # 3.15+
Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
[ rjw: Subject refinement ]
Link: https://patch.msgid.link/20260520032119.30615-1-fushuai.wang@linux.dev
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: qcom-cpufreq-hw: Fix possible double free 2026-07-18T14:52:06+00:00 Guangshuo Li lgs201920130244@gmail.com 2026-05-01T19:00:05+00:00 28a03a3f6e6cda0b0da3b43761d175dec5d14d13 commit bcb8889c4981fdde42d4fd2c29a77d510fe21da2 upstream. qcom_cpufreq.data is allocated with devm_kzalloc() in probe() as an array of per-domain data. qcom_cpufreq_hw_cpu_init() stores a pointer to one element of this array in policy->driver_data. qcom_cpufreq_hw_cpu_exit() currently calls kfree() on policy->driver_data. This is not valid because the memory is devm-managed. For the first domain, this can free the devm-managed allocation while the devres entry is still active, leading to a possible double free when the platform device is later detached. For other domains, the pointer may refer to an element inside the array rather than the allocation base. Remove the kfree(data) call and let devres release qcom_cpufreq.data. This issue was found by a static analysis tool I am developing. Fixes: 054a3ef683a1 ("cpufreq: qcom-hw: Allocate qcom_cpufreq_data during probe") Cc: stable@vger.kernel.org Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bcb8889c4981fdde42d4fd2c29a77d510fe21da2 upstream.

qcom_cpufreq.data is allocated with devm_kzalloc() in probe() as an
array of per-domain data. qcom_cpufreq_hw_cpu_init() stores a pointer to
one element of this array in policy->driver_data.

qcom_cpufreq_hw_cpu_exit() currently calls kfree() on policy->driver_data.
This is not valid because the memory is devm-managed. For the first
domain, this can free the devm-managed allocation while the devres entry
is still active, leading to a possible double free when the platform
device is later detached. For other domains, the pointer may refer to an
element inside the array rather than the allocation base.

Remove the kfree(data) call and let devres release qcom_cpufreq.data.

This issue was found by a static analysis tool I am developing.

Fixes: 054a3ef683a1 ("cpufreq: qcom-hw: Allocate qcom_cpufreq_data during probe")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: governor: fix double free in cpufreq_dbs_governor_init() error path 2026-04-11T12:24:49+00:00 Guangshuo Li lgs201920130244@gmail.com 2026-04-01T02:45:35+00:00 427d048e4f6acbfa01b5a8062449fe0ee8987c0d commit 6dcf9d0064ce2f3e3dfe5755f98b93abe6a98e1e upstream. When kobject_init_and_add() fails, cpufreq_dbs_governor_init() calls kobject_put(&dbs_data->attr_set.kobj). The kobject release callback cpufreq_dbs_data_release() calls gov->exit(dbs_data) and kfree(dbs_data), but the current error path then calls gov->exit(dbs_data) and kfree(dbs_data) again, causing a double free. Keep the direct kfree(dbs_data) for the gov->init() failure path, but after kobject_init_and_add() has been called, let kobject_put() handle the cleanup through cpufreq_dbs_data_release(). Fixes: 4ebe36c94aed ("cpufreq: Fix kobject memleak") Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: All applicable <stable@vger.kernel.org> Link: https://patch.msgid.link/20260401024535.1395801-1-lgs201920130244@gmail.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6dcf9d0064ce2f3e3dfe5755f98b93abe6a98e1e upstream.

When kobject_init_and_add() fails, cpufreq_dbs_governor_init() calls
kobject_put(&dbs_data->attr_set.kobj).

The kobject release callback cpufreq_dbs_data_release() calls
gov->exit(dbs_data) and kfree(dbs_data), but the current error path
then calls gov->exit(dbs_data) and kfree(dbs_data) again, causing a
double free.

Keep the direct kfree(dbs_data) for the gov->init() failure path, but
after kobject_init_and_add() has been called, let kobject_put() handle
the cleanup through cpufreq_dbs_data_release().

Fixes: 4ebe36c94aed ("cpufreq: Fix kobject memleak")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260401024535.1395801-1-lgs201920130244@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: conservative: Reset requested_freq on limits change 2026-04-02T11:09:42+00:00 Viresh Kumar viresh.kumar@linaro.org 2026-03-20T09:38:14+00:00 72d35b92d329aa40458f0088262aaae5c3c0483d commit 6a28fb8cb28b9eb39a392e531d938a889eacafc5 upstream. A recently reported issue highlighted that the cached requested_freq is not guaranteed to stay in sync with policy->cur. If the platform changes the actual CPU frequency after the governor sets one (e.g. due to platform-specific frequency scaling) and a re-sync occurs later, policy->cur may diverge from requested_freq. This can lead to incorrect behavior in the conservative governor. For example, the governor may assume the CPU is already running at the maximum frequency and skip further increases even though there is still headroom. Avoid this by resetting the cached requested_freq to policy->cur on detecting a change in policy limits. Reported-by: Lifeng Zheng <zhenglifeng1@huawei.com> Tested-by: Lifeng Zheng <zhenglifeng1@huawei.com> Link: https://lore.kernel.org/all/20260210115458.3493646-1-zhenglifeng1@huawei.com/ Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Cc: All applicable <stable@vger.kernel.org> Link: https://patch.msgid.link/d846a141a98ac0482f20560fcd7525c0f0ec2f30.1773999467.git.viresh.kumar@linaro.org Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6a28fb8cb28b9eb39a392e531d938a889eacafc5 upstream.

A recently reported issue highlighted that the cached requested_freq
is not guaranteed to stay in sync with policy->cur. If the platform
changes the actual CPU frequency after the governor sets one (e.g.
due to platform-specific frequency scaling) and a re-sync occurs
later, policy->cur may diverge from requested_freq.

This can lead to incorrect behavior in the conservative governor.
For example, the governor may assume the CPU is already running at
the maximum frequency and skip further increases even though there
is still headroom.

Avoid this by resetting the cached requested_freq to policy->cur on
detecting a change in policy limits.

Reported-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Tested-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Link: https://lore.kernel.org/all/20260210115458.3493646-1-zhenglifeng1@huawei.com/
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/d846a141a98ac0482f20560fcd7525c0f0ec2f30.1773999467.git.viresh.kumar@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpufreq: dt-platdev: Block the driver from probing on more QC platforms 2026-03-04T12:20:55+00:00 Konrad Dybcio konrad.dybcio@oss.qualcomm.com 2026-01-13T15:25:35+00:00 e35db916e8039f0db5ed616026fc89914eaaac44 [ Upstream commit 7b781899072c5701ef9538c365757ee9ab9c00bd ] Add a number of QC platforms to the blocklist, they all use either the qcom-cpufreq-hw driver. Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7b781899072c5701ef9538c365757ee9ab9c00bd ]

Add a number of QC platforms to the blocklist, they all use either the
qcom-cpufreq-hw driver.

Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
cpufreq: intel_pstate: Enable asym capacity only when CPU SMT is not possible 2026-03-04T12:19:31+00:00 Yaxiong Tian tianyaxiong@kylinos.cn 2026-02-03T02:48:52+00:00 73caf86fe92ef53518a341e0925b7fb2a40f4986 [ Upstream commit 1fedbb589448bee9f20bb2ed9c850d1d2cf9963c ] According to the description in the intel_pstate.rst documentation, Capacity-Aware Scheduling and Energy-Aware Scheduling are only supported on a hybrid processor without SMT. Previously, the system used sched_smt_active() for judgment, which is not a strict condition because users can switch it on or off via /sys at any time. This could lead to incorrect driver settings in certain scenarios. For example, on a CPU that supports SMT, a user can disable SMT via the nosmt parameter to enable asym capacity, and then re-enable SMT via /sys. In such cases, some settings in the driver would no longer be correct. To address this issue, replace sched_smt_active() with cpu_smt_possible(), and only enable asym capacity when CPU SMT is not possible. Fixes: 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU capacity on hybrid systems") Signed-off-by: Yaxiong Tian <tianyaxiong@kylinos.cn> [ rjw: Subject and changelog edits ] Link: https://patch.msgid.link/20260203024852.301066-1-tianyaxiong@kylinos.cn Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1fedbb589448bee9f20bb2ed9c850d1d2cf9963c ]

According to the description in the intel_pstate.rst documentation,
Capacity-Aware Scheduling and Energy-Aware Scheduling are only
supported on a hybrid processor without SMT. Previously, the system
used sched_smt_active() for judgment, which is not a strict condition
because users can switch it on or off via /sys at any time.

This could lead to incorrect driver settings in certain scenarios.
For example, on a CPU that supports SMT, a user can disable SMT
via the nosmt parameter to enable asym capacity, and then re-enable
SMT via /sys. In such cases, some settings in the driver would no
longer be correct.

To address this issue, replace sched_smt_active() with cpu_smt_possible(),
and only enable asym capacity when CPU SMT is not possible.

Fixes: 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU capacity on hybrid systems")
Signed-off-by: Yaxiong Tian <tianyaxiong@kylinos.cn>
[ rjw: Subject and changelog edits ]
Link: https://patch.msgid.link/20260203024852.301066-1-tianyaxiong@kylinos.cn
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
cpufreq: scmi: Fix device_node reference leak in scmi_cpu_domain_id() 2026-03-04T12:19:29+00:00 Felix Gu ustc.gu@gmail.com 2026-01-21T15:32:06+00:00 10bb2f5d365de512062c59bd03bb7eca1e47bba8 [ Upstream commit 0b7fbf9333fa4699a53145bad8ce74ea986caa13 ] When calling of_parse_phandle_with_args(), the caller is responsible to call of_node_put() to release the reference of device node. In scmi_cpu_domain_id(), it does not release the reference. Fixes: e336baa4193e ("cpufreq: scmi: Prepare to move OF parsing of domain-id to cpufreq") Signed-off-by: Felix Gu <ustc.gu@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0b7fbf9333fa4699a53145bad8ce74ea986caa13 ]

When calling of_parse_phandle_with_args(), the caller is responsible
to call of_node_put() to release the reference of device node.
In scmi_cpu_domain_id(), it does not release the reference.

Fixes: e336baa4193e ("cpufreq: scmi: Prepare to move OF parsing of domain-id to cpufreq")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
cpufreq: intel_pstate: Check IDA only before MSR_IA32_PERF_CTL writes 2026-01-11T14:25:21+00:00 Richa Bharti richa.bharti@siemens.com 2026-01-07T11:49:38+00:00 b03136582acb583fc5d4bf5bff3808f63fcec7d4 [ Upstream commit 4b747cc628d8f500d56cf1338280eacc66362ff3 ] Commit ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in legacy mode") introduced a check for feature X86_FEATURE_IDA to verify turbo mode support. Although this is the correct way to check for turbo mode support, it causes issues on some platforms that disable turbo during OS boot, but enable it later [1]. Before adding this feature check, users were able to get turbo mode frequencies by writing 0 to /sys/devices/system/cpu/intel_pstate/no_turbo post-boot. To restore the old behavior on the affected systems while still addressing the unchecked MSR issue on some Skylake-X systems, check X86_FEATURE_IDA only immediately before updates of MSR_IA32_PERF_CTL that may involve setting the Turbo Engage Bit (bit 32). Fixes: ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in legacy mode") Reported-by: Aaron Rainbolt <arainbolt@kfocus.org> Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2122531 [1] Tested-by: Aaron Rainbolt <arainbolt@kfocus.org> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> [ rjw: Subject adjustment, changelog edits ] Link: https://patch.msgid.link/20251111010840.141490-1-srinivas.pandruvada@linux.intel.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [ richa: Backport to 6.12.y with context adjustments ] Signed-off-by: Richa Bharti <richa.bharti@siemens.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 4b747cc628d8f500d56cf1338280eacc66362ff3 ]

Commit ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in
legacy mode") introduced a check for feature X86_FEATURE_IDA to verify
turbo mode support. Although this is the correct way to check for turbo
mode support, it causes issues on some platforms that disable turbo
during OS boot, but enable it later [1]. Before adding this feature
check, users were able to get turbo mode frequencies by writing 0 to
/sys/devices/system/cpu/intel_pstate/no_turbo post-boot.

To restore the old behavior on the affected systems while still
addressing the unchecked MSR issue on some Skylake-X systems, check
X86_FEATURE_IDA only immediately before updates of MSR_IA32_PERF_CTL
that may involve setting the Turbo Engage Bit (bit 32).

Fixes: ac4e04d9e378 ("cpufreq: intel_pstate: Unchecked MSR aceess in legacy mode")
Reported-by: Aaron Rainbolt <arainbolt@kfocus.org>
Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2122531 [1]
Tested-by: Aaron Rainbolt <arainbolt@kfocus.org>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject adjustment, changelog edits ]
Link: https://patch.msgid.link/20251111010840.141490-1-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[ richa: Backport to 6.12.y with context adjustments ]
Signed-off-by: Richa Bharti <richa.bharti@siemens.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>