diff options
| author | Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> | 2026-02-09 15:43:09 -0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2026-02-11 21:03:39 +0100 |
| commit | 7537bae8b6eb635583e0e6260f61d13ddbd52087 (patch) | |
| tree | d9cae43a7abcb2d90b436375a256ea73f37b482f /drivers/powercap | |
| parent | 9b1b3dcd28c271fc8c4a87e81860f3a34b6d29b7 (diff) | |
powercap: intel_rapl: Remove incorrect CPU check in PMU context
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 <sathyanarayanan.kuppuswamy@linux.intel.com>
Tested-by: Furquim Ulisses <ulisses.furquim@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260209234310.1440722-2-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/powercap')
| -rw-r--r-- | drivers/powercap/intel_rapl_common.c | 6 | ||||
| -rw-r--r-- | drivers/powercap/intel_rapl_msr.c | 12 |
2 files changed, 8 insertions, 10 deletions
diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c index 3ff6da3bf4e6..3705d0608a0f 100644 --- a/drivers/powercap/intel_rapl_common.c +++ b/drivers/powercap/intel_rapl_common.c @@ -254,7 +254,7 @@ static void rapl_init_domains(struct rapl_package *rp); static int rapl_read_data_raw(struct rapl_domain *rd, enum rapl_primitives prim, bool xlate, u64 *data, - bool atomic); + bool pmu_ctx); static int rapl_write_data_raw(struct rapl_domain *rd, enum rapl_primitives prim, unsigned long long value); @@ -832,7 +832,7 @@ prim_fixups(struct rapl_domain *rd, enum rapl_primitives prim) */ static int rapl_read_data_raw(struct rapl_domain *rd, enum rapl_primitives prim, bool xlate, u64 *data, - bool atomic) + bool pmu_ctx) { u64 value; enum rapl_primitives prim_fixed = prim_fixups(rd, prim); @@ -854,7 +854,7 @@ static int rapl_read_data_raw(struct rapl_domain *rd, ra.mask = rpi->mask; - if (rd->rp->priv->read_raw(get_rid(rd->rp), &ra, atomic)) { + if (rd->rp->priv->read_raw(get_rid(rd->rp), &ra, pmu_ctx)) { pr_debug("failed to read reg 0x%llx for %s:%s\n", ra.reg.val, rd->rp->name, rd->name); return -EIO; } diff --git a/drivers/powercap/intel_rapl_msr.c b/drivers/powercap/intel_rapl_msr.c index a2bc0a9c1e10..3d5e7f56d68a 100644 --- a/drivers/powercap/intel_rapl_msr.c +++ b/drivers/powercap/intel_rapl_msr.c @@ -110,16 +110,14 @@ static int rapl_cpu_down_prep(unsigned int cpu) return 0; } -static int rapl_msr_read_raw(int cpu, struct reg_action *ra, bool atomic) +static int rapl_msr_read_raw(int cpu, struct reg_action *ra, bool pmu_ctx) { /* - * When called from atomic-context (eg PMU event handler) - * perform MSR read directly using rdmsrq(). + * When called from PMU context, perform MSR read directly using + * rdmsrq() without IPI overhead. Package-scoped MSRs are readable + * from any CPU in the package. */ - if (atomic) { - if (unlikely(smp_processor_id() != cpu)) - return -EIO; - + if (pmu_ctx) { rdmsrq(ra->reg.msr, ra->value); goto out; } |