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x86/smpboot: Get rid of cpu_init_secondary() 

The synchronization of the AP with the control CPU is a SMP boot problem
and has nothing to do with cpu_init().

Open code cpu_init_secondary() in start_secondary() and move
wait_for_master_cpu() into the SMP boot code.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.981999763@linutronix.de
This commit is contained in:
Thomas Gleixner 2023-05-12 23:07:12 +02:00 committed by Peter Zijlstra
parent 2b3be65d2e
commit e94cd1503b
3 changed files with 19 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/processor.h
View File

@ -551,7 +551,6 @@ extern void switch_gdt_and_percpu_base(int);
extern void load_direct_gdt(int);
extern void load_fixmap_gdt(int);
extern void cpu_init(void);
extern void cpu_init_secondary(void);
extern void cpu_init_exception_handling(void);
extern void cr4_init(void);

27
arch/x86/kernel/cpu/common.c
View File

@ -2123,19 +2123,6 @@ static void dbg_restore_debug_regs(void)
#define dbg_restore_debug_regs()
#endif /* ! CONFIG_KGDB */
static void wait_for_master_cpu(int cpu)
{
#ifdef CONFIG_SMP
/*
* wait for ACK from master CPU before continuing
* with AP initialization
*/
WARN_ON(cpumask_test_and_set_cpu(cpu, cpu_initialized_mask));
while (!cpumask_test_cpu(cpu, cpu_callout_mask))
cpu_relax();
#endif
}
static inline void setup_getcpu(int cpu)
{
unsigned long cpudata = vdso_encode_cpunode(cpu, early_cpu_to_node(cpu));
@ -2239,8 +2226,6 @@ void cpu_init(void)
struct task_struct *cur = current;
int cpu = raw_smp_processor_id();
wait_for_master_cpu(cpu);
ucode_cpu_init(cpu);
#ifdef CONFIG_NUMA
@ -2293,18 +2278,6 @@ void cpu_init(void)
load_fixmap_gdt(cpu);
}
#ifdef CONFIG_SMP
void cpu_init_secondary(void)
{
/*
* Relies on the BP having set-up the IDT tables, which are loaded
* on this CPU in cpu_init_exception_handling().
*/
cpu_init_exception_handling();
cpu_init();
}
#endif
#ifdef CONFIG_MICROCODE_LATE_LOADING
/**
* store_cpu_caps() - Store a snapshot of CPU capabilities

24
arch/x86/kernel/smpboot.c
View File

@ -220,6 +220,17 @@ static void ap_calibrate_delay(void)
cpu_data(smp_processor_id()).loops_per_jiffy = loops_per_jiffy;
}
static void wait_for_master_cpu(int cpu)
{
/*
* Wait for release by control CPU before continuing with AP
* initialization.
*/
WARN_ON(cpumask_test_and_set_cpu(cpu, cpu_initialized_mask));
while (!cpumask_test_cpu(cpu, cpu_callout_mask))
cpu_relax();
}
/*
* Activate a secondary processor.
*/
@ -237,13 +248,16 @@ static void notrace start_secondary(void *unused)
load_cr3(swapper_pg_dir);
__flush_tlb_all();
#endif
cpu_init_exception_handling();
/*
* Sync point with wait_cpu_initialized(). Before proceeding through
* cpu_init(), the AP will call wait_for_master_cpu() which sets its
* own bit in cpu_initialized_mask and then waits for the BSP to set
* its bit in cpu_callout_mask to release it.
* Sync point with wait_cpu_initialized(). Sets AP in
* cpu_initialized_mask and then waits for the control CPU
* to release it.
*/
cpu_init_secondary();
wait_for_master_cpu(raw_smp_processor_id());
cpu_init();
rcu_cpu_starting(raw_smp_processor_id());
x86_cpuinit.early_percpu_clock_init();