Messages in this thread Patch in this message | | | From | Conor Dooley <> | Subject | [RFC 1/4] riscv: arch-topology: fix default topology reporting | Date | Thu, 7 Jul 2022 23:04:34 +0100 |
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From: Conor Dooley <conor.dooley@microchip.com>
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.
Add sane defaults in ~the exact same way as ARM64.
CC: stable@vger.kernel.org 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 Signed-off-by: Conor Dooley <conor.dooley@microchip.com> --- Sudeep suggested that this be backported rather than the changes to the devicetrees adding cpu-map since that property is optional. That patchset is still valid in it's own right.
Changes since v1: - removed the GENERIC_ARCH_TOPOLOGY dependancy on SMP - removed a duplicate call to update_siblings_masks() --- arch/riscv/Kconfig | 2 +- arch/riscv/include/asm/topology.h | 13 +++++++++++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/smpboot.c | 5 ++++- arch/riscv/kernel/topology.c | 32 +++++++++++++++++++++++++++++++ 5 files changed, 51 insertions(+), 2 deletions(-) create mode 100644 arch/riscv/include/asm/topology.h create mode 100644 arch/riscv/kernel/topology.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 2af0701b7518..4b6c2fdbb57c 100644 --- 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 diff --git a/arch/riscv/include/asm/topology.h b/arch/riscv/include/asm/topology.h new file mode 100644 index 000000000000..36bc6ecda898 --- /dev/null +++ b/arch/riscv/include/asm/topology.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries + */ + +#ifndef _ASM_RISCV_TOPOLOGY_H +#define _ASM_RISCV_TOPOLOGY_H + +#include <asm-generic/topology.h> + +void store_cpu_topology(unsigned int cpuid); + +#endif /* _ASM_RISCV_TOPOLOGY_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index c71d6591d539..9518882ba6f9 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -50,6 +50,7 @@ obj-y += riscv_ksyms.o obj-y += stacktrace.o obj-y += cacheinfo.o obj-y += patch.o +obj-y += topology.o obj-y += probes/ obj-$(CONFIG_MMU) += vdso.o vdso/ diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index f1e4948a4b52..a8239b4b61f3 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -32,6 +32,7 @@ #include <asm/sections.h> #include <asm/sbi.h> #include <asm/smp.h> +#include <asm/topology.h> #include "head.h" @@ -40,6 +41,8 @@ static DECLARE_COMPLETION(cpu_running); void __init smp_prepare_boot_cpu(void) { init_cpu_topology(); + + store_cpu_topology(smp_processor_id()); } void __init smp_prepare_cpus(unsigned int max_cpus) @@ -161,9 +164,9 @@ asmlinkage __visible void smp_callin(void) 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); /* diff --git a/arch/riscv/kernel/topology.c b/arch/riscv/kernel/topology.c new file mode 100644 index 000000000000..db72862bd5b5 --- /dev/null +++ b/arch/riscv/kernel/topology.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries + * + * Based on the arm64 version, which was in turn based on arm32, which was + * ultimately based on sh's. + * The arm64 version was listed as: + * Copyright (C) 2011,2013,2014 Linaro Limited. + */ + +#include <linux/arch_topology.h> +#include <linux/topology.h> +#include <asm/topology.h> + +void store_cpu_topology(unsigned int cpuid) +{ + struct cpu_topology *cpuid_topo = &cpu_topology[cpuid]; + + if (cpuid_topo->package_id != -1) + goto topology_populated; + + cpuid_topo->thread_id = -1; + cpuid_topo->core_id = cpuid; + cpuid_topo->package_id = cpu_to_node(cpuid); + + pr_debug("CPU%u: package %d core %d thread %d\n", + cpuid, cpuid_topo->package_id, cpuid_topo->core_id, + cpuid_topo->thread_id); + +topology_populated: + update_siblings_masks(cpuid); +} -- 2.37.0
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