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

[Punit Agrawal <punit.agrawal@xxxxxxxxxxxxxxxx>]

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.

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.