[S390] Force PSW restart on online CPU
PSW restart can be triggered on offline CPUs. If this happens, currently
the PSW restart code fails, because functions like smp_processor_id()
do not work on offline CPUs. This patch fixes this as follows:
If PSW restart is triggered on an offline CPU, the PSW restart (sigp restart)
is done a second time on another CPU that is online and the old CPU is
stopped afterwards.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/smp.h b/arch/s390/include/asm/smp.h
index 045e009f..ab47a69 100644
--- a/arch/s390/include/asm/smp.h
+++ b/arch/s390/include/asm/smp.h
@@ -33,6 +33,7 @@
extern void smp_switch_to_ipl_cpu(void (*func)(void *), void *);
extern void smp_switch_to_cpu(void (*)(void *), void *, unsigned long sp,
int from, int to);
+extern void smp_restart_with_online_cpu(void);
extern void smp_restart_cpu(void);
/*
@@ -64,6 +65,10 @@
func(data);
}
+static inline void smp_restart_with_online_cpu(void)
+{
+}
+
#define smp_vcpu_scheduled (1)
#endif /* CONFIG_SMP */
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 48c7102..90769b4 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1738,6 +1738,7 @@
void do_restart(void)
{
+ smp_restart_with_online_cpu();
smp_send_stop();
on_restart_trigger.action->fn(&on_restart_trigger);
stop_run(&on_restart_trigger);
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 6ab16ac..e457260 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -97,6 +97,29 @@
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;