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

[Atish Patra]

On 12/26/18 7:38 PM, Anup Patel wrote:

On Thu, Dec 27, 2018 at 4:39 AM Atish Patra <atish.pa...@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.pa...@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

Will do. Thanks for the review.

Otherwise, looks good to me.

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

Regards,
Atish