Re: [PATCH 2/3] RISC-V: Move cpuid to hartid mapping to SMP.

[Anup Patel <anup@brainfault.org>]

On Thu, Dec 27, 2018 at 4:39 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> Currently, logical CPU id to physical hartid mapping is
> defined for both smp and non-smp configurations. This
> is not required as we need this only for smp configuration.
> The mapping function can define directly boot_cpu_hartid
> for non-smp usecase.
>
> The reverse mapping function i.e. hartid to cpuid can be called
> for any valid but not booted harts. So it should return default
> cpu 0 only if it is a boot hartid
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  arch/riscv/include/asm/smp.h | 13 +++++++++++--
>  arch/riscv/kernel/setup.c    |  2 ++
>  2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
> index 41aa73b4..8f30300f 100644
> --- a/arch/riscv/include/asm/smp.h
> +++ b/arch/riscv/include/asm/smp.h
> @@ -22,12 +22,13 @@
>  /*
>   * Mapping between linux logical cpu index and hartid.
>   */
> -extern unsigned long __cpuid_to_hartid_map[NR_CPUS];
> -#define cpuid_to_hartid_map(cpu)    __cpuid_to_hartid_map[cpu]
>
> +extern unsigned long boot_cpu_hartid;
>  struct seq_file;
>
>  #ifdef CONFIG_SMP
> +extern unsigned long __cpuid_to_hartid_map[NR_CPUS];
> +#define cpuid_to_hartid_map(cpu)    __cpuid_to_hartid_map[cpu]
>
>  /* print IPI stats */
>  void show_ipi_stats(struct seq_file *p, int prec);
> @@ -58,7 +59,15 @@ static inline void show_ipi_stats(struct seq_file *p, int prec)
>
>  static inline int riscv_hartid_to_cpuid(int hartid)
>  {
> +       if (hartid == boot_cpu_hartid)
>                 return 0;
> +       else
> +               return -1;
> +}
> +static inline unsigned long cpuid_to_hartid_map(int cpu)
> +{
> +
> +       return boot_cpu_hartid;
>  }
>
>  static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in,
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 2c290e6a..bd4d7b85 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -83,6 +83,7 @@ EXPORT_SYMBOL(empty_zero_page);
>  atomic_t hart_lottery;
>  unsigned long boot_cpu_hartid;
>
> +#ifdef CONFIG_SMP
>  unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
>         [0 ... NR_CPUS-1] = INVALID_HARTID
>  };
> @@ -91,6 +92,7 @@ void __init smp_setup_processor_id(void)
>  {
>         cpuid_to_hartid_map(0) = boot_cpu_hartid;
>  }
> +#endif

Please move __cpuid_to_hartid_map[] and smp_setup_processor_id()
to arch/riscv/kernel/smp.c

Otherwise, looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>