kernel/drivers/cpufreq/intel_pstate.c, branch master

cpufreq: intel_pstate: Fix crash during turbo disable

2026-02-25T13:39:19Z

When the system is booted with kernel command line argument "nosmt" or "maxcpus" to limit the number of CPUs, disabling turbo via: echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo results in a crash: PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI ... RIP: 0010:store_no_turbo+0x100/0x1f0 ... This occurs because for_each_possible_cpu() returns CPUs even if they are not online. For those CPUs, all_cpu_data[] will be NULL. Since commit 973207ae3d7c ("cpufreq: intel_pstate: Rearrange max frequency updates handling code"), all_cpu_data[] is dereferenced even for CPUs which are not online, causing the NULL pointer dereference. To fix that, pass CPU number to intel_pstate_update_max_freq() and use all_cpu_data[] for those CPUs for which there is a valid cpufreq policy. Fixes: 973207ae3d7c ("cpufreq: intel_pstate: Rearrange max frequency updates handling code") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221068 Signed-off-by: Srinivas Pandruvada Cc: 6.16+ # 6.16+ Link: https://patch.msgid.link/20260225001752.890164-1-srinivas.pandruvada@linux.intel.com Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Fix NULL pointer dereference in update_cpu_qos_request()

2026-02-24T14:38:16Z

The update_cpu_qos_request() function attempts to initialize the 'freq' variable by dereferencing 'cpudata' before verifying if the 'policy' is valid. This issue occurs on systems booted with the "nosmt" parameter, where all_cpu_data[cpu] is NULL for the SMT sibling threads. As a result, any call to update_qos_requests() will result in a NULL pointer dereference as the code will attempt to access pstate.turbo_freq using the NULL cpudata pointer. Also, pstate.turbo_freq may be updated by intel_pstate_get_hwp_cap() after initializing the 'freq' variable, so it is better to defer the 'freq' until intel_pstate_get_hwp_cap() has been called. Fix this by deferring the 'freq' assignment until after the policy and driver_data have been validated. Fixes: ae1bdd23b99f ("cpufreq: intel_pstate: Adjust frequency percentage computations") Reported-by: Jirka Hladky Closes: https://lore.kernel.org/all/CAE4VaGDfiPvz3AzrwrwM4kWB3SCkMci25nPO8W1JmTBd=xHzZg@mail.gmail.com/ Signed-off-by: David Arcari Cc: 6.18+ # 6.18+ [ rjw: Added one paragraph to the changelog ] Link: https://patch.msgid.link/20260224122106.228116-1-darcari@redhat.com Signed-off-by: Rafael J. Wysocki

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51Z

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

cpufreq: intel_pstate: Enable asym capacity only when CPU SMT is not possible

2026-02-03T21:15:46Z

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 [ rjw: Subject and changelog edits ] Link: https://patch.msgid.link/20260203024852.301066-1-tianyaxiong@kylinos.cn Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Eliminate some code duplication

2025-11-18T14:51:31Z

To eliminate some code duplication from the intel_pstate driver, move the core_get_val() function body to a new function called get_perf_ctl_val() and make both core_get_val() and atom_get_val() invoke it to carry out the same computation. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Acked-by: Srinivas Pandruvada Link: https://patch.msgid.link/2829273.mvXUDI8C0e@rafael.j.wysocki

cpufreq: intel_pstate: Use mutex guard for driver locking

2025-11-12T19:54:57Z

Use guard(mutex)(&intel_pstate_driver_lock), or the scoped variant of it, wherever intel_pstate_driver_lock needs to be held. This allows some local variables and goto statements to be dropped as they are not necessary any more. Signed-off-by: Rafael J. Wysocki Reviewed-by: Muhammad Usama Anjum Link: https://patch.msgid.link/2807232.mvXUDI8C0e@rafael.j.wysocki

Merge back cpufreq material for 6.19

2025-11-12T19:50:58Z

cpufreq: intel_pstate: Check IDA only before MSR_IA32_PERF_CTL writes

2025-11-12T16:59:37Z

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 Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2122531 [1] Tested-by: Aaron Rainbolt Signed-off-by: Srinivas Pandruvada [ rjw: Subject adjustment, changelog edits ] Link: https://patch.msgid.link/20251111010840.141490-1-srinivas.pandruvada@linux.intel.com Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Add Diamond Rapids OOB mode support

2025-10-30T19:13:14Z

Prevent intel_pstate from loading when Out-of-Band (OOB) P-states mode is enabled. The OOB identification mechanism for Diamond Rapids servers is the same as for prior generation CPUs such as Granite Rapids. Add the Diamond Rapids CPU model to intel_pstate_cpu_oob_ids[] to ensure correct OOB handling. Signed-off-by: Kuppuswamy Sathyanarayanan Link: https://patch.msgid.link/20251022215425.3566218-1-sathyanarayanan.kuppuswamy@linux.intel.com Signed-off-by: Rafael J. Wysocki