Re: [PATCHv6 14/16] x86/smp: Add smp_ops.stop_this_cpu() callback
From: Huang, Kai <hidden>
Date: 2024-01-26 14:08:39
Also in:
kexec, lkml
On Wed, 2024-01-24 at 14:55 +0200, Kirill A. Shutemov wrote:
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 <redacted>
Acked-by: Kai Huang <redacted>
quoted hunk ↗ jump to hunk
--- arch/x86/include/asm/smp.h | 1 + arch/x86/kernel/process.c | 7 +++++++ arch/x86/kernel/reboot.c | 6 ++++++ 3 files changed, 14 insertions(+)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 ab49ade31b0d..00c1b957476d 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 changediff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 0574d4ad6b41..0a75efe579c0 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c@@ -880,6 +880,12 @@ static int crash_nmi_callback(unsigned int val, struct pt_regs *regs) cpu_emergency_disable_virtualization(); atomic_dec(&waiting_for_crash_ipi); + + if (smp_ops.stop_this_cpu) { + smp_ops.stop_this_cpu(); + unreachable(); + } + /* Assume hlt works */ halt(); for (;;)