diff mbox series

[PATCHv7,14/16] x86/smp: Add smp_ops.stop_this_cpu() callback

Message ID 20240212104448.2589568-15-kirill.shutemov@linux.intel.com
State New
Headers
Series x86/tdx: Add kexec support |

Commit Message

Kirill A. Shutemov Feb. 12, 2024, 10:44 a.m. UTC 
  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@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
---
 arch/x86/include/asm/smp.h | 1 +
 arch/x86/kernel/process.c  | 7 +++++++
 arch/x86/kernel/reboot.c   | 6 ++++++
 3 files changed, 14 insertions(+)

Comments

Thomas Gleixner Feb. 23, 2024, 10:26 a.m. UTC | #1 
On Mon, Feb 12 2024 at 12:44, 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 <kirill.shutemov@linux.intel.com>
> Acked-by: Kai Huang <kai.huang@intel.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff mbox series

Patch

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 change
diff --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 (;;)