iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

riscv: topology: fix default topology reporting

Browse Source 
commit fbd92809997a391f28075f1c8b5ee314c225557c 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 # 456797da792f: arm64: topology: move store_cpu_topology() to shared code
Fixes: 03f11f03dbfe ("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>
This commit is contained in:
Conor Dooley 2022-10-19 13:52:10 +01:00 committed by Greg Kroah-Hartman
parent 60dd3dc2ac
commit 8ad8fc82ee
2 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/riscv/Kconfig
View File

@ -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

4
arch/riscv/kernel/smpboot.c
View File

@ -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