[PATCH 14/39] x86/topology: Switch over to GENERIC_CPU_DEVICES

Russell King
2023-10-24T15:19:19Z

Now that GENERIC_CPU_DEVICES calls arch_register_cpu(), which can be
overridden by the arch code, switch over to this to allow common code
to choose when the register_cpu() call is made.

x86's struct cpus come from struct x86_cpu, which has no other members
or users. Remove this and use the version defined by common code.

This is an intermediate step to the logic being moved to drivers/acpi,
where GENERIC_CPU_DEVICES will do the work when booting with acpi=off.

This patch also has the effect of moving the registration of CPUs from
subsys to driver core initialisation, prior to any initcalls running.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
----
Changes since RFC:
* Fixed the second copy of arch_register_cpu() used for non-hotplug
Changes since RFC v2:
* Remove duplicate of the weak generic arch_register_cpu(), spotted
by Jonathan Cameron. Add note about initialisation order change.
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/cpu.h | 4 ----
arch/x86/kernel/topology.c | 27 ++++-----------------------
3 files changed, 5 insertions(+), 27 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 18729edc879d..a11c0aea5176 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -148,6 +148,7 @@ config X86
select GENERIC_CLOCKEVENTS_MIN_ADJUST
select GENERIC_CMOS_UPDATE
select GENERIC_CPU_AUTOPROBE
+ select GENERIC_CPU_DEVICES
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
select GENERIC_ENTRY
diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 25050d953eee..91867a6a9f8e 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -23,10 +23,6 @@ static inline void prefill_possible_map(void) {}

#endif /* CONFIG_SMP */

-struct x86_cpu {
- struct cpu cpu;
-};
-
#ifdef CONFIG_HOTPLUG_CPU
extern void soft_restart_cpu(void);
#endif
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index 0bab03130033..027897054424 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -35,38 +35,19 @@
#include <asm/io_apic.h>
#include <asm/cpu.h>

-static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
-
#ifdef CONFIG_HOTPLUG_CPU
int arch_register_cpu(int cpu)
{
- struct x86_cpu *xc = per_cpu_ptr(&cpu_devices, cpu);
+ struct cpu *c = per_cpu_ptr(&cpu_devices, cpu);

- xc->cpu.hotpluggable = cpu > 0;
- return register_cpu(&xc->cpu, cpu);
+ c->hotpluggable = cpu > 0;
+ return register_cpu(c, cpu);
}
EXPORT_SYMBOL(arch_register_cpu);

void arch_unregister_cpu(int num)
{
- unregister_cpu(&per_cpu(cpu_devices, num).cpu);
+ unregister_cpu(&per_cpu(cpu_devices, num));
}
EXPORT_SYMBOL(arch_unregister_cpu);
-#else /* CONFIG_HOTPLUG_CPU */
-
-int __init arch_register_cpu(int num)
-{
- return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
-}
#endif /* CONFIG_HOTPLUG_CPU */
-
-static int __init topology_init(void)
-{
- int i;
-
- for_each_present_cpu(i)
- arch_register_cpu(i);
-
- return 0;
-}
-subsys_initcall(topology_init);
--
2.30.2