• Conor Dooley's avatar
    riscv: topology: fix default topology reporting · fbd92809
    Conor Dooley authored
    RISC-V has no sane defaults to fall back on where there is no cpu-map
    in the devicetree.
    Without sane defaults, the package, core and thread IDs are all set to
    -1. This causes user-visible inaccuracies for tools like hwloc/lstopo
    which rely on the sysfs cpu topology files to detect a system's
    topology.
    
    On a PolarFire SoC, which should have 4 harts with a thread each,
    lstopo currently reports:
    
    Machine (793MB total)
      Package L#0
        NUMANode L#0 (P#0 793MB)
        Core L#0
          L1d L#0 (32KB) + L1i L#0 (32KB) + PU L#0 (P#0)
          L1d L#1 (32KB) + L1i L#1 (32KB) + PU L#1 (P#1)
          L1d L#2 (32KB) + L1i L#2 (32KB) + PU L#2 (P#2)
          L1d L#3 (32KB) + L1i L#3 (32KB) + PU L#3 (P#3)
    
    Adding calls to store_cpu_topology() in {boot,smp} hart bringup code
    results in the correct topolgy being reported:
    
    Machine (793MB total)
      Package L#0
        NUMANode L#0 (P#0 793MB)
        L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0 + PU L#0 (P#0)
        L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1 + PU L#1 (P#1)
        L1d L#2 (32KB) + L1i L#2 (32KB) + Core L#2 + PU L#2 (P#2)
        L1d L#3 (32KB) + L1i L#3 (32KB) + Core L#3 + PU L#3 (P#3)
    
    CC: stable@vger.kernel.org # 456797da: arm64: topology: move store_cpu_topology() to shared code
    Fixes: 03f11f03 ("RISC-V: Parse cpu topology during boot.")
    Reported-by: default avatarBrice Goglin <Brice.Goglin@inria.fr>
    Link: https://github.com/open-mpi/hwloc/issues/536Reviewed-by: default avatarSudeep Holla <sudeep.holla@arm.com>
    Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
    Signed-off-by: default avatarConor Dooley <conor.dooley@microchip.com>
    fbd92809
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