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>
---
 drivers/cpufreq/intel_pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index ec4abe374573..1625ec2d0d06 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1161,7 +1161,7 @@ static void hybrid_init_cpu_capacity_scaling(bool refresh)
 	 * the capacity of SMT threads is not deterministic even approximately,
 	 * do not do that when SMT is in use.
 	 */
-	if (hwp_is_hybrid && !sched_smt_active() && arch_enable_hybrid_capacity_scale()) {
+	if (hwp_is_hybrid && !cpu_smt_possible() && arch_enable_hybrid_capacity_scale()) {
 		hybrid_refresh_cpu_capacity_scaling();
 		/*
 		 * Disabling ITMT causes sched domains to be rebuilt to disable asym
-- 
2.25.1

On Tue, Feb 3, 2026 at 3:49 AM Yaxiong Tian <tianyaxiong@kylinos.cn> wrote:
>
> 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>
> ---
>  drivers/cpufreq/intel_pstate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index ec4abe374573..1625ec2d0d06 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -1161,7 +1161,7 @@ static void hybrid_init_cpu_capacity_scaling(bool refresh)
>          * the capacity of SMT threads is not deterministic even approximately,
>          * do not do that when SMT is in use.
>          */
> -       if (hwp_is_hybrid && !sched_smt_active() && arch_enable_hybrid_capacity_scale()) {
> +       if (hwp_is_hybrid && !cpu_smt_possible() && arch_enable_hybrid_capacity_scale()) {
>                 hybrid_refresh_cpu_capacity_scaling();
>                 /*
>                  * Disabling ITMT causes sched domains to be rebuilt to disable asym
> --

Applied as 6.20/7.0 material, thanks!