1 files changed, 23 insertions, 0 deletions

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 6ab16ac64d29..e4572601e91e 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -97,6 +97,29 @@ static inline int cpu_stopped(int cpu)
         return raw_cpu_stopped(cpu_logical_map(cpu));
 }
 
+/*
+ * Ensure that PSW restart is done on an online CPU
+ */
+void smp_restart_with_online_cpu(void)
+{
+        int cpu;
+
+        for_each_online_cpu(cpu) {
+                if (stap() == __cpu_logical_map[cpu]) {
+                        /* We are online: Enable DAT again and return */
+                        __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
+                        return;
+                }
+        }
+        /* We are not online: Do PSW restart on an online CPU */
+        while (sigp(cpu, sigp_restart) == sigp_busy)
+                cpu_relax();
+        /* And stop ourself */
+        while (raw_sigp(stap(), sigp_stop) == sigp_busy)
+                cpu_relax();
+        for (;;);
+}
+
 void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
 {
         struct _lowcore *lc, *current_lc;