[PATCH 5.19 050/717] riscv: topology: fix default topology reporting

Greg Kroah-Hartman
2022-10-22T07:39:53Z

From: Conor Dooley <conor.dooley@microchip.com>

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>
---
arch/riscv/Kconfig | 2 +-
arch/riscv/kernel/smpboot.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)

--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -52,7 +52,7 @@ config RISCV
select COMMON_CLK
select CPU_PM if CPU_IDLE
select EDAC_SUPPORT
- select GENERIC_ARCH_TOPOLOGY if SMP
+ select GENERIC_ARCH_TOPOLOGY
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_EARLY_IOREMAP
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -49,6 +49,7 @@ void __init smp_prepare_cpus(unsigned in
unsigned int curr_cpuid;

curr_cpuid = smp_processor_id();
+ store_cpu_topology(curr_cpuid);
numa_store_cpu_info(curr_cpuid);
numa_add_cpu(curr_cpuid);

@@ -161,9 +162,9 @@ asmlinkage __visible void smp_callin(voi
mmgrab(mm);
current->active_mm = mm;

+ store_cpu_topology(curr_cpuid);
notify_cpu_starting(curr_cpuid);
numa_add_cpu(curr_cpuid);
- update_siblings_masks(curr_cpuid);
set_cpu_online(curr_cpuid, 1);

/*