linux-toradex.git/drivers/powercap/intel_rapl_msr.c, branch v7.0-rc2

powercap: intel_rapl: Remove incorrect CPU check in PMU context

2026-02-11T20:03:39+00:00

The RAPL MSR read path incorrectly validates CPU context when called
from the PMU subsystem:

    if (atomic) {
        if (unlikely(smp_processor_id() != cpu))
            return -EIO;
        rdmsrq(ra->reg.msr, ra->value);
    }

This check fails for package-scoped MSRs like RAPL energy counters,
which are readable from any CPU within the package.

The perf tool avoids hitting this check by validating against
/sys/bus/event_source/devices/power/cpumask before opening events.
However, turbostat does not perform this validation and may attempt
reads from non-lead CPUs, causing the check to fail and return zero
power values.

Since package-scoped MSRs are architecturally accessible from any CPU
in the package, remove the CPU matching check.

Also rename 'atomic' to 'pmu_ctx' to clarify this indicates PMU context
where rdmsrq() can be used directly instead of rdmsrl_safe_on_cpu().

Fixes: 748d6ba43afd ("powercap: intel_rapl: Enable MSR-based RAPL PMU support")
Signed-off-by: Kuppuswamy Sathyanarayanan 
Tested-by: Furquim Ulisses 
Reviewed-by: Srinivas Pandruvada 
Link: https://patch.msgid.link/20260209234310.1440722-2-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Add PL4 support for Ice Lake

2026-01-15T20:14:54+00:00

Microsoft Surface Pro 7 firmware throttles the processor upon
boot/resume. Userspace needs to be able to restore the correct value.

Link: https://github.com/linux-surface/linux-surface/issues/706
Signed-off-by: Daniel Tang 
Link: https://patch.msgid.link/6088605.ChMirdbgyp@daniel-desktop3
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Fix possible recursive lock warning

2025-12-17T16:24:28+00:00

With the RAPL PMU addition, there is a recursive locking when CPU online
callback function calls rapl_package_add_pmu(). Here cpu_hotplug_lock
is already acquired by cpuhp_thread_fun() and rapl_package_add_pmu()
tries to acquire again.

<4>[ 8.197433] ============================================
<4>[ 8.197437] WARNING: possible recursive locking detected
<4>[ 8.197440] 6.19.0-rc1-lgci-xe-xe-4242-05b7c58b3367dca84+ #1 Not tainted
<4>[ 8.197444] --------------------------------------------
<4>[ 8.197447] cpuhp/0/20 is trying to acquire lock:
<4>[ 8.197450] ffffffff83487870 (cpu_hotplug_lock){++++}-{0:0}, at:
rapl_package_add_pmu+0x37/0x370 [intel_rapl_common]
<4>[ 8.197463]
but task is already holding lock:
<4>[ 8.197466] ffffffff83487870 (cpu_hotplug_lock){++++}-{0:0}, at:
cpuhp_thread_fun+0x6d/0x290
<4>[ 8.197477]
other info that might help us debug this:
<4>[ 8.197480] Possible unsafe locking scenario:

<4>[ 8.197483] CPU0
<4>[ 8.197485] ----
<4>[ 8.197487] lock(cpu_hotplug_lock);
<4>[ 8.197490] lock(cpu_hotplug_lock);
<4>[ 8.197493]
*** DEADLOCK ***
..
..
<4>[ 8.197542] __lock_acquire+0x146e/0x2790
<4>[ 8.197548] lock_acquire+0xc4/0x2c0
<4>[ 8.197550] ? rapl_package_add_pmu+0x37/0x370 [intel_rapl_common]
<4>[ 8.197556] cpus_read_lock+0x41/0x110
<4>[ 8.197558] ? rapl_package_add_pmu+0x37/0x370 [intel_rapl_common]
<4>[ 8.197561] rapl_package_add_pmu+0x37/0x370 [intel_rapl_common]
<4>[ 8.197565] rapl_cpu_online+0x85/0x87 [intel_rapl_msr]
<4>[ 8.197568] ? __pfx_rapl_cpu_online+0x10/0x10 [intel_rapl_msr]
<4>[ 8.197570] cpuhp_invoke_callback+0x41f/0x6c0
<4>[ 8.197573] ? cpuhp_thread_fun+0x6d/0x290
<4>[ 8.197575] cpuhp_thread_fun+0x1e2/0x290
<4>[ 8.197578] ? smpboot_thread_fn+0x26/0x290
<4>[ 8.197581] smpboot_thread_fn+0x12f/0x290
<4>[ 8.197584] ? __pfx_smpboot_thread_fn+0x10/0x10
<4>[ 8.197586] kthread+0x11f/0x250
<4>[ 8.197589] ? __pfx_kthread+0x10/0x10
<4>[ 8.197592] ret_from_fork+0x344/0x3a0
<4>[ 8.197595] ? __pfx_kthread+0x10/0x10
<4>[ 8.197597] ret_from_fork_asm+0x1a/0x30
<4>[ 8.197604] 

Fix this issue in the same way as rapl powercap package domain is added
from the same CPU online callback by introducing another interface which
doesn't call cpus_read_lock(). Add rapl_package_add_pmu_locked() and
rapl_package_remove_pmu_locked() which don't call cpus_read_lock().

Fixes: 748d6ba43afd ("powercap: intel_rapl: Enable MSR-based RAPL PMU support")
Reported-by: Borah, Chaitanya Kumar 
Closes: https://lore.kernel.org/linux-pm/5427ede1-57a0-43d1-99f3-8ca4b0643e82@intel.com/T/#u
Tested-by: Kuppuswamy Sathyanarayanan 
Tested-by: RavitejaX Veesam 
Signed-off-by: Srinivas Pandruvada 
Link: https://patch.msgid.link/20251217153455.3560176-1-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Enable MSR-based RAPL PMU support

2025-11-21T20:47:08+00:00

Currently, RAPL PMU support requires adding CPU model entries to
arch/x86/events/rapl.c for each new generation. However, RAPL MSRs are
not architectural and require platform-specific customization, making
arch/x86 an inappropriate location for this functionality.

The powercap subsystem already handles RAPL functionality and is the
natural place to consolidate all RAPL features. The powercap RAPL
driver already includes PMU support for TPMI-based RAPL interfaces,
making it straightforward to extend this support to MSR-based RAPL
interfaces as well.

This consolidation eliminates the need to maintain RAPL support in
multiple subsystems and provides a unified approach for both TPMI and
MSR-based RAPL implementations.

The MSR-based PMU support includes the following updates:

1. Register MSR-based PMU support for the supported platforms
and unregister it when no online CPUs remain in the package.

2. Remove existing checks that restrict RAPL PMU support to TPMI-based
interfaces and extend the logic to allow MSR-based RAPL interfaces.

3. Define a CPU model list to determine which processors should
register RAPL PMU interface through the powercap driver for
MSR-based RAPL, excluding those that support TPMI interface.
This list prevents conflicts with existing arch/x86 PMU code
that already registers RAPL PMU for some processors. Add
Panther Lake & Wildcat Lake to the CPU models list.

Signed-off-by: Kuppuswamy Sathyanarayanan
Reviewed-by: Srinivas Pandruvada
[ rjw: Changelog edits ]
Link: https://patch.msgid.link/20251121000539.386069-3-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Prepare read_raw() interface for atomic-context callers

2025-11-21T20:47:08+00:00

The current read_raw() implementation of the TPMI, MMIO and MSR
interfaces does not distinguish between atomic and non-atomic callers.

rapl_msr_read_raw() uses rdmsrq_safe_on_cpu(), which can sleep and
issue cross CPU calls. When MSR-based RAPL PMU support is enabled, PMU
event handlers can invoke this function from atomic context where
sleeping or rescheduling is not allowed. In atomic context, the caller
is already executing on the target CPU, so a direct rdmsrq() is
sufficient.

To support such usage, introduce an atomic flag to the read_raw()
interface to allow callers pass the context information. Modify the
common RAPL code to propagate this flag, and set the flag to reflect
the calling contexts.

Utilize the atomic flag in rapl_msr_read_raw() to perform direct MSR
read with rdmsrq() when running in atomic context, and a sanity check
to ensure target CPU matches the current CPU for such use cases.

The TPMI and MMIO implementations do not require special atomic
handling, so the flag is ignored in those paths.

This is a preparatory patch for adding MSR-based RAPL PMU support.

Signed-off-by: Kuppuswamy Sathyanarayanan 
Reviewed-by: Srinivas Pandruvada 
[ rjw: Subject tweak ]
Link: https://patch.msgid.link/20251121000539.386069-2-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Add support for Nova Lake processors

2025-11-18T14:39:29+00:00

Add RAPL support for Intel Nova Lake and Nova Lake L processors using
the core defaults configuration.

Signed-off-by: Kaushlendra Kumar 
[ rjw: Subject and changelog edits, rebase ]
Link: https://patch.msgid.link/20251028101814.3482508-1-kaushlendra.kumar@intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl: Add support for Wildcat Lake platform

2025-10-30T19:15:02+00:00

Add Wildcat Lake to the list of supported processors for RAPL.

Signed-off-by: Srinivas Pandruvada 
Link: https://patch.msgid.link/20251023174532.1882008-1-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki

powercap: intel_rapl_msr: Add PL4 support for Panther Lake

2025-06-30T18:34:57+00:00

Add Panther Lake to the list of processors where PL4 is supported.

Signed-off-by: Zhang Rui 
Link: https://patch.msgid.link/20250625020522.253548-1-rui.zhang@intel.com
Signed-off-by: Rafael J. Wysocki

x86/msr: Add explicit includes of

2025-05-02T08:23:47+00:00

For historic reasons there are some TSC-related functions in the
 header, even though there's an  header.

To facilitate the relocation of rdtsc{,_ordered}() from 
to  and to eventually eliminate the inclusion of
 in , add an explicit  dependency
to the source files that reference definitions from .

[ mingo: Clarified the changelog. ]

Signed-off-by: Xin Li (Intel) 
Signed-off-by: Ingo Molnar 
Acked-by: Dave Hansen 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Ilpo Järvinen 
Cc: Andy Lutomirski 
Cc: Brian Gerst 
Cc: Juergen Gross 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Kees Cook 
Cc: Peter Zijlstra 
Cc: Borislav Petkov 
Cc: Thomas Gleixner 
Cc: Josh Poimboeuf 
Cc: Uros Bizjak 
Link: https://lore.kernel.org/r/20250501054241.1245648-1-xin@zytor.com

x86/msr: Rename 'rdmsrl_safe_on_cpu()' to 'rdmsrq_safe_on_cpu()'

2025-04-10T09:58:49+00:00

Suggested-by: "H. Peter Anvin" 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra (Intel) 
Cc: Juergen Gross 
Cc: Dave Hansen 
Cc: Xin Li 
Cc: Linus Torvalds