[PATCH] riscv: smp: Invoke cpu_ops->cpu_stop() in ipi_stop() for hotplug

[Guo Ren]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren at kernel.org>

When a CPU receives an IPI stop during hotplug teardown, the
platform-specific cpu_stop() callback should be called before
spinning in wait_for_interrupt(), so that firmware (e.g. SBI HSM)
is notified that the hart has stopped.

This aligns ipi_stop() with the existing behavior of
ipi_cpu_crash_stop(), which already calls cpu_ops[cpu]->cpu_stop()
under CONFIG_HOTPLUG_CPU.

Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren at kernel.org>
---
 arch/riscv/kernel/smp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index fa66f9c97d74..95aa11a0e590 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -82,6 +82,12 @@ int riscv_hartid_to_cpuid(unsigned long hartid)
 static void ipi_stop(void)
 {
 	set_cpu_online(smp_processor_id(), false);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	if (cpu_has_hotplug(cpu))
+		cpu_ops->cpu_stop();
+#endif
+
 	while (1)
 		wait_for_interrupt();
 }
-- 
2.43.0