riscv: topology: fix default topology reporting

commit 9bed98dfd4993a352db91246d621c9194909940e upstream.

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 # f925e1848b58: arm64: topology: move store_cpu_topology() to shared code
Fixes: 83d57b1d0686 ("RISC-V: Parse cpu topology during boot.")
Reported-by: Brice Goglin <Brice.Goglin@inria.fr>
Link: https://github.com/open-mpi/hwloc/issues/536
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index b21549a34447c2427924f53d87a8a70116da2b08..e0a77af5c130c493b50644f3c21c53dde63f7608 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -51,7 +51,7 @@ config RISCV
        select PCI_MSI if PCI
        select RISCV_TIMER
        select GENERIC_IRQ_MULTI_HANDLER
-       select GENERIC_ARCH_TOPOLOGY if SMP
+       select GENERIC_ARCH_TOPOLOGY
        select ARCH_HAS_PTE_SPECIAL
        select ARCH_HAS_MMIOWB
        select HAVE_EBPF_JIT if 64BIT

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 261f4087cc39e177fbc063b003dfafc57488cc18..0576a6b2bcc562ae46e130d1214013746c6a783b 100644 (file)
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -46,6 +46,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 {
        int cpuid;
 
+       store_cpu_topology(smp_processor_id());
+
        /* This covers non-smp usecase mandated by "nosmp" option */
        if (max_cpus == 0)
                return;
@@ -142,8 +144,8 @@ asmlinkage __visible void __init smp_callin(void)
        current->active_mm = mm;
 
        trap_init();
+       store_cpu_topology(smp_processor_id());
        notify_cpu_starting(smp_processor_id());
-       update_siblings_masks(smp_processor_id());
        set_cpu_online(smp_processor_id(), 1);
        /*
         * Remote TLB flushes are ignored while the CPU is offline, so emit