If the helper is defined, it is called instead of halt() to stop the CPU
at the end of stop_this_cpu() and on crash CPU shutdown.
ACPI MADT will use it to hand over the CPU to BIOS in order to be able
to wake it up again after kexec.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
v5.1:
- Fix build for !SMP;
---
arch/x86/include/asm/smp.h | 1 +
arch/x86/kernel/process.c | 7 +++++++
arch/x86/kernel/reboot.c | 12 ++++++++----
3 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 4fab2ed454f3..390d53fd34f9 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -38,6 +38,7 @@ struct smp_ops {
int (*cpu_disable)(void);
void (*cpu_die)(unsigned int cpu);
void (*play_dead)(void);
+ void (*stop_this_cpu)(void);
void (*send_call_func_ipi)(const struct cpumask *mask);
void (*send_call_func_single_ipi)(int cpu);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b6f4e8399fca..ea4c812c7bf3 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -835,6 +835,13 @@ void __noreturn stop_this_cpu(void *dummy)
*/
cpumask_clear_cpu(cpu, &cpus_stop_mask);
+#ifdef CONFIG_SMP
+ if (smp_ops.stop_this_cpu) {
+ smp_ops.stop_this_cpu();
+ unreachable();
+ }
+#endif
+
for (;;) {
/*
* Use native_halt() so that memory contents don't change
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 16dde83df49a..738b3e810196 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -881,10 +881,14 @@ static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
cpu_emergency_disable_virtualization();
atomic_dec(&waiting_for_crash_ipi);
- /* Assume hlt works */
- halt();
- for (;;)
- cpu_relax();
+
+ if (smp_ops.stop_this_cpu) {
+ smp_ops.stop_this_cpu();
+ } else {
+ halt();
+ for (;;)
+ cpu_relax();
+ }
return NMI_HANDLED;
}
--
2.41.0
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