RISC-V: Implement nosmp commandline option.

nosmp command line option sets max_cpus to zero. No secondary harts
will boot if this is enabled. But present cpu mask will still point to
all possible masks.

Fix present cpu mask for nosmp usecase.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index eb533b5c2c8c04d6552664439602fcd204748b0c..a8ad200581aa1b2a7ee58eed7dc94e053ba8e059 100644 (file)
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -47,6 +47,17 @@ void __init smp_prepare_boot_cpu(void)
 
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+       int cpuid;
+
+       /* This covers non-smp usecase mandated by "nosmp" option */
+       if (max_cpus == 0)
+               return;
+
+       for_each_possible_cpu(cpuid) {
+               if (cpuid == smp_processor_id())
+                       continue;
+               set_cpu_present(cpuid, true);
+       }
 }
 
 void __init setup_smp(void)
@@ -74,7 +85,6 @@ void __init setup_smp(void)
 
                cpuid_to_hartid_map(cpuid) = hart;
                set_cpu_possible(cpuid, true);
-               set_cpu_present(cpuid, true);
                cpuid++;
        }