On Thu, 12 Mar 2026 15:23:14 +0800
Chengwen Feng <[email protected]> wrote:

> To unify the CPU ACPI ID retrieval interface across architectures,
> rename the existing get_acpi_id_for_cpu() function to
> acpi_get_cpu_uid() on arm64/riscv/loongarch platforms.
> 
> This is a pure rename with no functional change, preparing for a

It's not just a rename.  This should mention that the addition of error
checks and hence the resulting signature change.

> consistent ACPI Processor UID retrieval interface across all ACPI-enabled
> platforms.
> 
> Note: Move the ARM64-specific get_cpu_for_acpi_id() implementation to
>       arch/arm64/kernel/acpi_numa.c to fix compilation errors from
>       circular header dependencies introduced by the rename.
> 
> Cc: [email protected]
> Signed-off-by: Chengwen Feng <[email protected]>
> Reviewed-by: Jonathan Cameron <[email protected]>
From a reread, a few minor style consistency things inline.

> ---
>  arch/arm64/include/asm/acpi.h      | 16 +---------
>  arch/arm64/kernel/acpi.c           | 16 ++++++++++
>  arch/arm64/kernel/acpi_numa.c      | 15 ++++++++++
>  arch/loongarch/include/asm/acpi.h  |  5 ----
>  arch/loongarch/kernel/acpi.c       |  9 ++++++
>  arch/riscv/include/asm/acpi.h      |  4 ---
>  arch/riscv/kernel/acpi.c           | 16 ++++++++++
>  arch/riscv/kernel/acpi_numa.c      |  8 +++--
>  drivers/acpi/pptt.c                | 47 +++++++++++++++++++++---------
>  drivers/acpi/riscv/rhct.c          |  7 ++++-
>  drivers/perf/arm_cspmu/arm_cspmu.c |  6 ++--
>  include/linux/acpi.h               | 13 +++++++++
>  12 files changed, 120 insertions(+), 42 deletions(-)

> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index af90128cfed5..984a11788265 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -458,3 +458,19 @@ 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 == NULL)

Seems local style for null pointer checks is
        if (!gicc)
Just for consistency we should follow that.

> +             return -ENODEV;
> +
> +     *uid = gicc->uid;
> +     return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
> diff --git a/arch/arm64/kernel/acpi_numa.c b/arch/arm64/kernel/acpi_numa.c
> index 2465f291c7e1..56e2e486e49b 100644
> --- a/arch/arm64/kernel/acpi_numa.c
> +++ b/arch/arm64/kernel/acpi_numa.c
> @@ -34,6 +34,21 @@ int __init acpi_numa_get_nid(unsigned int cpu)
>       return acpi_early_node_map[cpu];
>  }
>  
> +int get_cpu_for_acpi_id(u32 uid)
> +{
> +     u32 cpu_uid;
> +     int cpu;
> +     int ret;
> +
> +     for (cpu = 0; cpu < nr_cpu_ids; cpu++) {

Given more recent acceptance of the following perhaps it is neater here.

        for (int cpu = 0; cpu < nr_cpu_ids; cpu++) {

Amazingly there aren't any for loops in this file so we can do what we
like from a consistency point of view.


> +             ret = acpi_get_cpu_uid(cpu, &cpu_uid);
> +             if (ret == 0 && uid == cpu_uid)
> +                     return cpu;
> +     }
> +
> +     return -EINVAL;
> +}
> +
>  static int __init acpi_parse_gicc_pxm(union acpi_subtable_headers *header,
>                                     const unsigned long end)
>  {


> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index 71698ee11621..bde810d02c4f 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -337,3 +337,19 @@ int raw_pci_write(unsigned int domain, unsigned int bus,
>  }
>  
>  #endif       /* CONFIG_PCI */
> +
> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
> +{
> +     struct acpi_madt_rintc *rintc;
> +
> +     if (cpu >= nr_cpu_ids)
> +             return -EINVAL;
> +
> +     rintc = acpi_cpu_get_madt_rintc(cpu);
> +     if (rintc == NULL)

Similar to above. Local style for NULL checks is
        if (!rintc)
so this should follow that.
> +             return -ENODEV;
> +
> +     *uid = rintc->uid;
> +     return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
> diff --git a/arch/riscv/kernel/acpi_numa.c b/arch/riscv/kernel/acpi_numa.c
> index 130769e3a99c..cd8adc9857e3 100644
> --- a/arch/riscv/kernel/acpi_numa.c
> +++ b/arch/riscv/kernel/acpi_numa.c
> @@ -37,11 +37,15 @@ static int __init acpi_numa_get_nid(unsigned int cpu)
>  
>  static inline int get_cpu_for_acpi_id(u32 uid)
>  {
> +     u32 cpu_uid;
>       int cpu;
> +     int ret;
>  
> -     for (cpu = 0; cpu < nr_cpu_ids; cpu++)
> -             if (uid == get_acpi_id_for_cpu(cpu))
> +     for (cpu = 0; cpu < nr_cpu_ids; cpu++) {

Can pull the int into the loop her as well.

> +             ret = acpi_get_cpu_uid(cpu, &cpu_uid);
> +             if (ret == 0 && uid == cpu_uid)
>                       return cpu;
> +     }
>  
>       return -EINVAL;
>  }
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index de5f8c018333..d034a217e85b 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c

>  static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag)
>  {
>       struct acpi_table_header *table;
> -     u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> +     u32 acpi_cpu_id;
>       struct acpi_pptt_processor *cpu_node = NULL;
>       int ret = -ENOENT;
>  
> +     if (acpi_get_cpu_uid(cpu, &acpi_cpu_id) != 0)
> +             return -ENOENT;
> +
>       table = acpi_get_pptt();
>       if (!table)
>               return -ENOENT;
> @@ -651,7 +661,8 @@ static int check_acpi_cpu_flag(unsigned int cpu, int rev, 
> u32 flag)
>   * in the PPTT. Errors caused by lack of a PPTT table, or otherwise, return 0
>   * indicating we didn't find any cache levels.
>   *
> - * Return: -ENOENT if no PPTT table or no PPTT processor struct found.
> + * Return: -ENOENT if no PPTT table, can't get CPU's ACPI Process UID or no 
> PPTT
> + *      processor struct found.
>   *      0 on success.
>   */
>  int acpi_get_cache_info(unsigned int cpu, unsigned int *levels,
> @@ -671,7 +682,8 @@ int acpi_get_cache_info(unsigned int cpu, unsigned int 
> *levels,
>  
>       pr_debug("Cache Setup: find cache levels for CPU=%d\n", cpu);
>  
> -     acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> +     if (acpi_get_cpu_uid(cpu, &acpi_cpu_id))
> +             return -ENOENT;
I'd put a blank line here (similar to the code you added just above).
>       cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
>       if (!cpu_node)
>               return -ENOENT;
> @@ -780,8 +792,9 @@ int find_acpi_cpu_topology_package(unsigned int cpu)
>   * It may not exist in single CPU systems. In simple multi-CPU systems,
>   * it may be equal to the package topology level.
>   *
> - * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found
> - * or there is no toplogy level above the CPU..
> + * Return: -ENOENT if the PPTT doesn't exist, can't get CPU's ACPI
> + * Processor UID, the CPU cannot be found or there is no toplogy level
> + * above the CPU.
>   * Otherwise returns a value which represents the package for this CPU.
>   */
>  
> @@ -797,7 +810,8 @@ int find_acpi_cpu_topology_cluster(unsigned int cpu)
>       if (!table)
>               return -ENOENT;
>  
> -     acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> +     if (acpi_get_cpu_uid(cpu, &acpi_cpu_id) != 0)
> +             return -ENOENT;
Again, I'd put a blank line here.

>       cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
>       if (!cpu_node || !cpu_node->parent)
>               return -ENOENT;
> @@ -872,7 +886,8 @@ static void acpi_pptt_get_child_cpus(struct 
> acpi_table_header *table_hdr,
>       cpumask_clear(cpus);
>  
>       for_each_possible_cpu(cpu) {
> -             acpi_id = get_acpi_id_for_cpu(cpu);
> +             if (acpi_get_cpu_uid(cpu, &acpi_id) != 0)
> +                     continue;
and here.
>               cpu_node = acpi_find_processor_node(table_hdr, acpi_id);
>  
>               while (cpu_node) {



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