| Message ID | 20230913163823.7880-4-james.morse@arm.com (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpuhotplug | expand |
On Wed, Sep 13, 2023 at 04:37:51PM +0000, James Morse wrote: > Architectures often have extra per-cpu work that needs doing > before a CPU is registered, often to determine if a CPU is > hotpluggable. > > To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move > the cpu_register() call into arch_register_cpu(), which is made __weak > so architectures with extra work can override it. > This aligns with the way x86, ia64 and loongarch register hotplug CPUs > when they become present. > > Signed-off-by: James Morse <james.morse@arm.com> LGTM. Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
On Wed, 13 Sep 2023 16:37:51 +0000 James Morse <james.morse@arm.com> wrote: > Architectures often have extra per-cpu work that needs doing > before a CPU is registered, often to determine if a CPU is > hotpluggable. > > To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move > the cpu_register() call into arch_register_cpu(), which is made __weak > so architectures with extra work can override it. > This aligns with the way x86, ia64 and loongarch register hotplug CPUs > when they become present. > > Signed-off-by: James Morse <james.morse@arm.com> > --- > Changes since RFC: > * Dropped __init from x86/ia64 arch_register_cpu() Confused... > diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c > index 94a848b06f15..741863a187a6 100644 > --- a/arch/ia64/kernel/topology.c > +++ b/arch/ia64/kernel/topology.c > @@ -59,7 +59,7 @@ void __ref arch_unregister_cpu(int num) > } > EXPORT_SYMBOL(arch_unregister_cpu); > #else > -static int __init arch_register_cpu(int num) > +int __init arch_register_cpu(int num) Still seems to be here... > { > return register_cpu(&sysfs_cpus[num].cpu, num); > } Even more confused because the block wasn't in the RFC at all. Maybe dropped static?
On Wed, 13 Sep 2023 16:37:51 +0000 James Morse <james.morse@arm.com> wrote: > Architectures often have extra per-cpu work that needs doing > before a CPU is registered, often to determine if a CPU is > hotpluggable. > > To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move > the cpu_register() call into arch_register_cpu(), which is made __weak > so architectures with extra work can override it. > This aligns with the way x86, ia64 and loongarch register hotplug CPUs > when they become present. Perhaps call out that you are also making cpu_devices visible outside of base/cpu.c Note it isn't obvious to me why you do that in this patch. I assume it will be needed later... Otherwise seems sensible to me. > > Signed-off-by: James Morse <james.morse@arm.com> > --- > Changes since RFC: > * Dropped __init from x86/ia64 arch_register_cpu() > --- > arch/ia64/include/asm/cpu.h | 1 - > arch/ia64/kernel/topology.c | 2 +- > arch/loongarch/include/asm/cpu.h | 1 - > arch/x86/include/asm/cpu.h | 1 - > arch/x86/kernel/topology.c | 2 +- > drivers/base/cpu.c | 14 ++++++++++---- > include/linux/cpu.h | 5 +++++ > 7 files changed, 17 insertions(+), 9 deletions(-) > > diff --git a/arch/ia64/include/asm/cpu.h b/arch/ia64/include/asm/cpu.h > index db125df9e088..a3e690e685e5 100644 > --- a/arch/ia64/include/asm/cpu.h > +++ b/arch/ia64/include/asm/cpu.h > @@ -16,7 +16,6 @@ DECLARE_PER_CPU(struct ia64_cpu, cpu_devices); > DECLARE_PER_CPU(int, cpu_state); > > #ifdef CONFIG_HOTPLUG_CPU > -extern int arch_register_cpu(int num); > extern void arch_unregister_cpu(int); > #endif > > diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c > index 94a848b06f15..741863a187a6 100644 > --- a/arch/ia64/kernel/topology.c > +++ b/arch/ia64/kernel/topology.c > @@ -59,7 +59,7 @@ void __ref arch_unregister_cpu(int num) > } > EXPORT_SYMBOL(arch_unregister_cpu); > #else > -static int __init arch_register_cpu(int num) > +int __init arch_register_cpu(int num) > { > return register_cpu(&sysfs_cpus[num].cpu, num); > } > diff --git a/arch/loongarch/include/asm/cpu.h b/arch/loongarch/include/asm/cpu.h > index 7afe8cbb844e..b8568e637420 100644 > --- a/arch/loongarch/include/asm/cpu.h > +++ b/arch/loongarch/include/asm/cpu.h > @@ -130,7 +130,6 @@ enum cpu_type_enum { > > #if !defined(__ASSEMBLY__) > #ifdef CONFIG_HOTPLUG_CPU > -int arch_register_cpu(int num); > void arch_unregister_cpu(int cpu); > #endif > #endif /* ! __ASSEMBLY__ */ > diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h > index 3a233ebff712..96dc4665e87d 100644 > --- a/arch/x86/include/asm/cpu.h > +++ b/arch/x86/include/asm/cpu.h > @@ -28,7 +28,6 @@ struct x86_cpu { > }; > > #ifdef CONFIG_HOTPLUG_CPU > -extern int arch_register_cpu(int num); > extern void arch_unregister_cpu(int); > extern void soft_restart_cpu(void); > #endif > diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c > index ca004e2e4469..0bab03130033 100644 > --- a/arch/x86/kernel/topology.c > +++ b/arch/x86/kernel/topology.c > @@ -54,7 +54,7 @@ void arch_unregister_cpu(int num) > EXPORT_SYMBOL(arch_unregister_cpu); > #else /* CONFIG_HOTPLUG_CPU */ > > -static int __init arch_register_cpu(int num) > +int __init arch_register_cpu(int num) > { > return register_cpu(&per_cpu(cpu_devices, num).cpu, num); > } > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index 34b48f660b6b..579064fda97b 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -525,19 +525,25 @@ bool cpu_is_hotpluggable(unsigned int cpu) > EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); > > #ifdef CONFIG_GENERIC_CPU_DEVICES > -static DEFINE_PER_CPU(struct cpu, cpu_devices); > +DEFINE_PER_CPU(struct cpu, cpu_devices); > + > +int __weak arch_register_cpu(int cpu) > +{ > + return register_cpu(&per_cpu(cpu_devices, cpu), cpu); > +} > #endif > > static void __init cpu_dev_register_generic(void) > { > -#ifdef CONFIG_GENERIC_CPU_DEVICES > int i; > > + if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES)) > + return; > + > for_each_present_cpu(i) { > - if (register_cpu(&per_cpu(cpu_devices, i), i)) > + if (arch_register_cpu(i)) > panic("Failed to register CPU device"); > } > -#endif > } > > #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index 0abd60a7987b..a71691d7c2ca 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -80,12 +80,17 @@ extern __printf(4, 5) > struct device *cpu_device_create(struct device *parent, void *drvdata, > const struct attribute_group **groups, > const char *fmt, ...); > +extern int arch_register_cpu(int cpu); > #ifdef CONFIG_HOTPLUG_CPU > extern void unregister_cpu(struct cpu *cpu); > extern ssize_t arch_cpu_probe(const char *, size_t); > extern ssize_t arch_cpu_release(const char *, size_t); > #endif > > +#ifdef CONFIG_GENERIC_CPU_DEVICES > +DECLARE_PER_CPU(struct cpu, cpu_devices); > +#endif > + > /* > * These states are not related to the core CPU hotplug mechanism. They are > * used by various (sub)architectures to track internal state
diff --git a/arch/ia64/include/asm/cpu.h b/arch/ia64/include/asm/cpu.h index db125df9e088..a3e690e685e5 100644 --- a/arch/ia64/include/asm/cpu.h +++ b/arch/ia64/include/asm/cpu.h @@ -16,7 +16,6 @@ DECLARE_PER_CPU(struct ia64_cpu, cpu_devices); DECLARE_PER_CPU(int, cpu_state); #ifdef CONFIG_HOTPLUG_CPU -extern int arch_register_cpu(int num); extern void arch_unregister_cpu(int); #endif diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c index 94a848b06f15..741863a187a6 100644 --- a/arch/ia64/kernel/topology.c +++ b/arch/ia64/kernel/topology.c @@ -59,7 +59,7 @@ void __ref arch_unregister_cpu(int num) } EXPORT_SYMBOL(arch_unregister_cpu); #else -static int __init arch_register_cpu(int num) +int __init arch_register_cpu(int num) { return register_cpu(&sysfs_cpus[num].cpu, num); } diff --git a/arch/loongarch/include/asm/cpu.h b/arch/loongarch/include/asm/cpu.h index 7afe8cbb844e..b8568e637420 100644 --- a/arch/loongarch/include/asm/cpu.h +++ b/arch/loongarch/include/asm/cpu.h @@ -130,7 +130,6 @@ enum cpu_type_enum { #if !defined(__ASSEMBLY__) #ifdef CONFIG_HOTPLUG_CPU -int arch_register_cpu(int num); void arch_unregister_cpu(int cpu); #endif #endif /* ! __ASSEMBLY__ */ diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h index 3a233ebff712..96dc4665e87d 100644 --- a/arch/x86/include/asm/cpu.h +++ b/arch/x86/include/asm/cpu.h @@ -28,7 +28,6 @@ struct x86_cpu { }; #ifdef CONFIG_HOTPLUG_CPU -extern int arch_register_cpu(int num); extern void arch_unregister_cpu(int); extern void soft_restart_cpu(void); #endif diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index ca004e2e4469..0bab03130033 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -54,7 +54,7 @@ void arch_unregister_cpu(int num) EXPORT_SYMBOL(arch_unregister_cpu); #else /* CONFIG_HOTPLUG_CPU */ -static int __init arch_register_cpu(int num) +int __init arch_register_cpu(int num) { return register_cpu(&per_cpu(cpu_devices, num).cpu, num); } diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 34b48f660b6b..579064fda97b 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -525,19 +525,25 @@ bool cpu_is_hotpluggable(unsigned int cpu) EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); #ifdef CONFIG_GENERIC_CPU_DEVICES -static DEFINE_PER_CPU(struct cpu, cpu_devices); +DEFINE_PER_CPU(struct cpu, cpu_devices); + +int __weak arch_register_cpu(int cpu) +{ + return register_cpu(&per_cpu(cpu_devices, cpu), cpu); +} #endif static void __init cpu_dev_register_generic(void) { -#ifdef CONFIG_GENERIC_CPU_DEVICES int i; + if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES)) + return; + for_each_present_cpu(i) { - if (register_cpu(&per_cpu(cpu_devices, i), i)) + if (arch_register_cpu(i)) panic("Failed to register CPU device"); } -#endif } #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 0abd60a7987b..a71691d7c2ca 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -80,12 +80,17 @@ extern __printf(4, 5) struct device *cpu_device_create(struct device *parent, void *drvdata, const struct attribute_group **groups, const char *fmt, ...); +extern int arch_register_cpu(int cpu); #ifdef CONFIG_HOTPLUG_CPU extern void unregister_cpu(struct cpu *cpu); extern ssize_t arch_cpu_probe(const char *, size_t); extern ssize_t arch_cpu_release(const char *, size_t); #endif +#ifdef CONFIG_GENERIC_CPU_DEVICES +DECLARE_PER_CPU(struct cpu, cpu_devices); +#endif + /* * These states are not related to the core CPU hotplug mechanism. They are * used by various (sub)architectures to track internal state
Architectures often have extra per-cpu work that needs doing before a CPU is registered, often to determine if a CPU is hotpluggable. To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move the cpu_register() call into arch_register_cpu(), which is made __weak so architectures with extra work can override it. This aligns with the way x86, ia64 and loongarch register hotplug CPUs when they become present. Signed-off-by: James Morse <james.morse@arm.com> --- Changes since RFC: * Dropped __init from x86/ia64 arch_register_cpu() --- arch/ia64/include/asm/cpu.h | 1 - arch/ia64/kernel/topology.c | 2 +- arch/loongarch/include/asm/cpu.h | 1 - arch/x86/include/asm/cpu.h | 1 - arch/x86/kernel/topology.c | 2 +- drivers/base/cpu.c | 14 ++++++++++---- include/linux/cpu.h | 5 +++++ 7 files changed, 17 insertions(+), 9 deletions(-)