Commit e94cd150 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Tested-by: default avatarOleksandr 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
parent 2b3be65d

arch/x86/include/asm/processor.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/cpu/common.c

+0 −27
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/smpboot.c

+19 −5
Original line number Diff line number Diff line
@@ -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();