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x86/smpboot: Enable split CPU startup 

The x86 CPU bringup state currently does AP wake-up, wait for AP to
respond and then release it for full bringup.

It is safe to be split into a wake-up and and a separate wait+release
state.

Provide the required functions and enable the split CPU bringup, which
prepares for parallel bringup, where the bringup of the non-boot CPUs takes
two iterations: One to prepare and wake all APs and the second to wait and
release them. Depending on timing this can eliminate the wait time
completely.

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/20230512205257.133453992@linutronix.de
This commit is contained in:
Thomas Gleixner 2023-05-12 23:07:46 +02:00 committed by Peter Zijlstra
parent a631be92b9
commit 8b5a0f957c
5 changed files with 10 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/Kconfig
View File

@ -274,8 +274,8 @@ config X86
select HAVE_UNSTABLE_SCHED_CLOCK
select HAVE_USER_RETURN_NOTIFIER
select HAVE_GENERIC_VDSO
select HOTPLUG_CORE_SYNC_FULL if SMP
select HOTPLUG_SMT if SMP
select HOTPLUG_SPLIT_STARTUP if SMP
select IRQ_FORCED_THREADING
select NEED_PER_CPU_EMBED_FIRST_CHUNK
select NEED_PER_CPU_PAGE_FIRST_CHUNK

9
arch/x86/include/asm/smp.h
View File

@ -40,7 +40,7 @@ struct smp_ops {
void (*cleanup_dead_cpu)(unsigned cpu);
void (*poll_sync_state)(void);
int (*cpu_up)(unsigned cpu, struct task_struct *tidle);
int (*kick_ap_alive)(unsigned cpu, struct task_struct *tidle);
int (*cpu_disable)(void);
void (*cpu_die)(unsigned int cpu);
void (*play_dead)(void);
@ -80,11 +80,6 @@ static inline void smp_cpus_done(unsigned int max_cpus)
smp_ops.smp_cpus_done(max_cpus);
}
static inline int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
return smp_ops.cpu_up(cpu, tidle);
}
static inline int __cpu_disable(void)
{
return smp_ops.cpu_disable();
@ -124,7 +119,7 @@ void native_smp_prepare_cpus(unsigned int max_cpus);
void calculate_max_logical_packages(void);
void native_smp_cpus_done(unsigned int max_cpus);
int common_cpu_up(unsigned int cpunum, struct task_struct *tidle);
int native_cpu_up(unsigned int cpunum, struct task_struct *tidle);
int native_kick_ap(unsigned int cpu, struct task_struct *tidle);
int native_cpu_disable(void);
void __noreturn hlt_play_dead(void);
void native_play_dead(void);

2
arch/x86/kernel/smp.c
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@ -268,7 +268,7 @@ struct smp_ops smp_ops = {
#endif
.smp_send_reschedule = native_smp_send_reschedule,
.cpu_up = native_cpu_up,
.kick_ap_alive = native_kick_ap,
.cpu_disable = native_cpu_disable,
.play_dead = native_play_dead,

8
arch/x86/kernel/smpboot.c
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@ -1052,7 +1052,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
return ret;
}
static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
{
int apicid = apic->cpu_present_to_apicid(cpu);
int err;
@ -1088,15 +1088,15 @@ static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
return err;
}
int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
int arch_cpuhp_kick_ap_alive(unsigned int cpu, struct task_struct *tidle)
{
return native_kick_ap(cpu, tidle);
return smp_ops.kick_ap_alive(cpu, tidle);
}
void arch_cpuhp_cleanup_kick_cpu(unsigned int cpu)
{
/* Cleanup possible dangling ends... */
if (smp_ops.cpu_up == native_cpu_up && x86_platform.legacy.warm_reset)
if (smp_ops.kick_ap_alive == native_kick_ap && x86_platform.legacy.warm_reset)
smpboot_restore_warm_reset_vector();
}

4
arch/x86/xen/smp_pv.c
View File

@ -314,7 +314,7 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
return 0;
}
static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
static int xen_pv_kick_ap(unsigned int cpu, struct task_struct *idle)
{
int rc;
@ -438,7 +438,7 @@ static const struct smp_ops xen_smp_ops __initconst = {
.smp_prepare_cpus = xen_pv_smp_prepare_cpus,
.smp_cpus_done = xen_smp_cpus_done,
.cpu_up = xen_pv_cpu_up,
.kick_ap_alive = xen_pv_kick_ap,
.cpu_die = xen_pv_cpu_die,
.cleanup_dead_cpu = xen_pv_cleanup_dead_cpu,
.poll_sync_state = xen_pv_poll_sync_state,