Re: [PATCH v9 1/7] arm64/acpi: Add acpi_get_cpu_uid() and switch arm_cspmu to use it

[fengchengwen <fengchengwen@xxxxxxxxxx>]

On 3/19/2026 11:46 PM, Punit Agrawal wrote:
> Chengwen Feng <fengchengwen@xxxxxxxxxx> writes:
> 
>> Add arch-specific acpi_get_cpu_uid() for arm64, and update dependent
>> code:
>> - Declare acpi_get_cpu_uid() in arch/arm64/include/asm/acpi.h
>> - Implement acpi_get_cpu_uid() with input parameter validation
>> - Replace get_acpi_id_for_cpu() with acpi_get_cpu_uid() in
>>   drivers/perf/arm_cspmu/arm_cspmu.c
>> - Reimplement get_cpu_for_acpi_id() based on acpi_get_cpu_uid() (to
>>   align with new interface) and move its implementation next to
>>   acpi_get_cpu_uid()
> 
> There is no benefit in describing the code changes like this in the
> commit log. It makes it hard to follow the intent of the patch.
> 
>> This is the first step towards unifying ACPI CPU UID retrieval interface
>> across architectures, while adding input validation for robustness.
> 
> I would simplify the commit log to something along the lines of -
> 
>     As a step towards unifying the interface for retrieving ACPI CPU uid
>     across architectures, introduce a new function
>     acpi_get_cpu_uid(). While at it, also add input validation to make
>     the code more robust.

Thank you for your advice.
I've reviewed all the commit logs and made some optimizations, and done in v10

> 
> Just my 2c.
> 
> The code changes looks fine.
> 
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Chengwen Feng <fengchengwen@xxxxxxxxxx>
>> Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
>> ---
>>  arch/arm64/include/asm/acpi.h      | 14 ++------------
>>  arch/arm64/kernel/acpi.c           | 30 ++++++++++++++++++++++++++++++
>>  drivers/perf/arm_cspmu/arm_cspmu.c |  6 ++++--
>>  3 files changed, 36 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
>> index c07a58b96329..2219a3301e72 100644
>> --- a/arch/arm64/include/asm/acpi.h
>> +++ b/arch/arm64/include/asm/acpi.h
>> @@ -118,18 +118,8 @@ static inline u32 get_acpi_id_for_cpu(unsigned int cpu)
>>  {
>>      return  acpi_cpu_get_madt_gicc(cpu)->uid;
>>  }
>> -
>> -static inline int get_cpu_for_acpi_id(u32 uid)
>> -{
>> -    int cpu;
>> -
>> -    for (cpu = 0; cpu < nr_cpu_ids; cpu++)
>> -            if (acpi_cpu_get_madt_gicc(cpu) &&
>> -                uid == get_acpi_id_for_cpu(cpu))
>> -                    return cpu;
>> -
>> -    return -EINVAL;
>> -}
>> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid);
>> +int get_cpu_for_acpi_id(u32 uid);
>>  
>>  static inline void arch_fix_phys_package_id(int num, u32 slot) { }
>>  void __init acpi_init_cpus(void);
>> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
>> index af90128cfed5..24b9d934be54 100644
>> --- a/arch/arm64/kernel/acpi.c
>> +++ b/arch/arm64/kernel/acpi.c
>> @@ -458,3 +458,33 @@ int acpi_unmap_cpu(int cpu)
>>  }
>>  EXPORT_SYMBOL(acpi_unmap_cpu);
>>  #endif /* CONFIG_ACPI_HOTPLUG_CPU */
>> +
>> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
>> +{
>> +    struct acpi_madt_generic_interrupt *gicc;
>> +
>> +    if (cpu >= nr_cpu_ids)
>> +            return -EINVAL;
>> +
>> +    gicc = acpi_cpu_get_madt_gicc(cpu);
>> +    if (!gicc)
>> +            return -ENODEV;
>> +
>> +    *uid = gicc->uid;
>> +    return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
>> +
>> +int get_cpu_for_acpi_id(u32 uid)
>> +{
>> +    u32 cpu_uid;
>> +    int ret;
>> +
>> +    for (int cpu = 0; cpu < nr_cpu_ids; cpu++) {
>> +            ret = acpi_get_cpu_uid(cpu, &cpu_uid);
>> +            if (ret == 0 && uid == cpu_uid)
>> +                    return cpu;
>> +    }
>> +
>> +    return -EINVAL;
>> +}
>> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c 
>> b/drivers/perf/arm_cspmu/arm_cspmu.c
>> index 34430b68f602..ed72c3d1f796 100644
>> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
>> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
>> @@ -1107,15 +1107,17 @@ static int arm_cspmu_acpi_get_cpus(struct arm_cspmu 
>> *cspmu)
>>  {
>>      struct acpi_apmt_node *apmt_node;
>>      int affinity_flag;
>> +    u32 cpu_uid;
>>      int cpu;
>> +    int ret;
>>  
>>      apmt_node = arm_cspmu_apmt_node(cspmu->dev);
>>      affinity_flag = apmt_node->flags & ACPI_APMT_FLAGS_AFFINITY;
>>  
>>      if (affinity_flag == ACPI_APMT_FLAGS_AFFINITY_PROC) {
>>              for_each_possible_cpu(cpu) {
>> -                    if (apmt_node->proc_affinity ==
>> -                        get_acpi_id_for_cpu(cpu)) {
>> +                    ret = acpi_get_cpu_uid(cpu, &cpu_uid);
>> +                    if (ret == 0 && apmt_node->proc_affinity == cpu_uid) {
>>                              cpumask_set_cpu(cpu, &cspmu->associated_cpus);
>>                              break;
>>                      }
> 
> I think cspmu changes go via a separate pull request. You might have to
> split this change into a separate commit.

done in v10

Thanks