[S390] Standby cpu activation/deactivation.

Add a new interface so that cpus can be put into standby state and
configured state.
Only offline cpus can be put into standby state or configured state.
For that the new percpu sysfs attribute "configure" must be used.
To put a cpu in standby state a "0" must be written to the attribute.
In order to switch it into configured state a "1" must be written to
the attribute.
Only cpus in configured state can be brought online.
In addition this patch introduces a static mapping of physical to
logical cpus. As a result only the sysfs directories of present cpus
will be created. To scan for new cpus the new sysfs attribute "rescan"
must be used.
Writing to /sys/devices/system/cpu/rescan will trigger a rescan of
cpus and will create directories for new cpus.

On IPL only configured cpus will be used. And on reboot/shutdown all
cpus will remain in their current state (configured/standby).

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 330 insertions, 71 deletions

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 264ea906db4c..66fe28930d82 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -42,6 +42,7 @@
 #include <asm/tlbflush.h>
 #include <asm/timer.h>
 #include <asm/lowcore.h>
+#include <asm/sclp.h>
 #include <asm/cpu.h>
 
 /*
@@ -58,6 +59,22 @@ EXPORT_SYMBOL(cpu_possible_map);
 
 static struct task_struct *current_set[NR_CPUS];
 
+static u8 smp_cpu_type;
+static int smp_use_sigp_detection;
+
+enum s390_cpu_state {
+	CPU_STATE_STANDBY,
+	CPU_STATE_CONFIGURED,
+};
+
+#ifdef CONFIG_HOTPLUG_CPU
+static DEFINE_MUTEX(smp_cpu_state_mutex);
+#endif
+static int smp_cpu_state[NR_CPUS];
+
+static DEFINE_PER_CPU(struct cpu, cpu_devices);
+DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
+
 static void smp_ext_bitcall(int, ec_bit_sig);
 
 /*
@@ -355,6 +372,13 @@ void smp_ctl_clear_bit(int cr, int bit)
 }
 EXPORT_SYMBOL(smp_ctl_clear_bit);
 
+/*
+ * In early ipl state a temp. logically cpu number is needed, so the sigp
+ * functions can be used to sense other cpus. Since NR_CPUS is >= 2 on
+ * CONFIG_SMP and the ipl cpu is logical cpu 0, it must be 1.
+ */
+#define CPU_INIT_NO	1
+
 #if defined(CONFIG_ZFCPDUMP) || defined(CONFIG_ZFCPDUMP_MODULE)
 
 /*
@@ -376,8 +400,9 @@ static void __init smp_get_save_area(unsigned int cpu, unsigned int phy_cpu)
 		return;
 	}
 	zfcpdump_save_areas[cpu] = alloc_bootmem(sizeof(union save_area));
-	__cpu_logical_map[1] = (__u16) phy_cpu;
-	while (signal_processor(1, sigp_stop_and_store_status) == sigp_busy)
+	__cpu_logical_map[CPU_INIT_NO] = (__u16) phy_cpu;
+	while (signal_processor(CPU_INIT_NO, sigp_stop_and_store_status) ==
+	       sigp_busy)
 		cpu_relax();
 	memcpy(zfcpdump_save_areas[cpu],
 	       (void *)(unsigned long) store_prefix() + SAVE_AREA_BASE,
@@ -397,32 +422,166 @@ static inline void smp_get_save_area(unsigned int cpu, unsigned int phy_cpu) { }
 
 #endif /* CONFIG_ZFCPDUMP || CONFIG_ZFCPDUMP_MODULE */
 
+static int cpu_stopped(int cpu)
+{
+	__u32 status;
+
+	/* Check for stopped state */
+	if (signal_processor_ps(&status, 0, cpu, sigp_sense) ==
+	    sigp_status_stored) {
+		if (status & 0x40)
+			return 1;
+	}
+	return 0;
+}
+
 /*
  * Lets check how many CPUs we have.
  */
-static unsigned int __init smp_count_cpus(void)
+static void __init smp_count_cpus(unsigned int *configured_cpus,
+				  unsigned int *standby_cpus)
 {
-	unsigned int cpu, num_cpus;
-	__u16 boot_cpu_addr;
+	unsigned int cpu;
+	struct sclp_cpu_info *info;
+	u16 boot_cpu_addr, cpu_addr;
 
-	/*
-	 * cpu 0 is the boot cpu. See smp_prepare_boot_cpu.
-	 */
 	boot_cpu_addr = S390_lowcore.cpu_data.cpu_addr;
 	current_thread_info()->cpu = 0;
-	num_cpus = 1;
-	for (cpu = 0; cpu <= 65535; cpu++) {
-		if ((__u16) cpu == boot_cpu_addr)
+	*configured_cpus = 1;
+	*standby_cpus = 0;
+
+	info = alloc_bootmem_pages(sizeof(*info));
+	if (!info)
+		disabled_wait((unsigned long) __builtin_return_address(0));
+
+	/* Use sigp detection algorithm if sclp doesn't work. */
+	if (sclp_get_cpu_info(info)) {
+		smp_use_sigp_detection = 1;
+		for (cpu = 0; cpu <= 65535; cpu++) {
+			if (cpu == boot_cpu_addr)
+				continue;
+			__cpu_logical_map[CPU_INIT_NO] = cpu;
+			if (cpu_stopped(CPU_INIT_NO))
+				(*configured_cpus)++;
+		}
+		goto out;
+	}
+
+	if (info->has_cpu_type) {
+		for (cpu = 0; cpu < info->combined; cpu++) {
+			if (info->cpu[cpu].address == boot_cpu_addr) {
+				smp_cpu_type = info->cpu[cpu].type;
+				break;
+			}
+		}
+	}
+	/* Count cpus. */
+	for (cpu = 0; cpu < info->combined; cpu++) {
+		if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
+			continue;
+		cpu_addr = info->cpu[cpu].address;
+		if (cpu_addr == boot_cpu_addr)
 			continue;
-		__cpu_logical_map[1] = (__u16) cpu;
-		if (signal_processor(1, sigp_sense) == sigp_not_operational)
+		__cpu_logical_map[CPU_INIT_NO] = cpu_addr;
+		if (!cpu_stopped(CPU_INIT_NO)) {
+			(*standby_cpus)++;
 			continue;
-		smp_get_save_area(num_cpus, cpu);
-		num_cpus++;
+		}
+		smp_get_save_area(*configured_cpus, cpu_addr);
+		(*configured_cpus)++;
 	}
-	printk("Detected %d CPU's\n", (int) num_cpus);
-	printk("Boot cpu address %2X\n", boot_cpu_addr);
-	return num_cpus;
+out:
+	printk(KERN_INFO "CPUs: %d configured, %d standby\n",
+	       *configured_cpus, *standby_cpus);
+	free_bootmem((unsigned long) info, sizeof(*info));
+}
+
+static int cpu_known(int cpu_id)
+{
+	int cpu;
+
+	for_each_present_cpu(cpu) {
+		if (__cpu_logical_map[cpu] == cpu_id)
+			return 1;
+	}
+	return 0;
+}
+
+static int smp_rescan_cpus_sigp(cpumask_t avail)
+{
+	int cpu_id, logical_cpu;
+
+	logical_cpu = first_cpu(avail);
+	if (logical_cpu == NR_CPUS)
+		return 0;
+	for (cpu_id = 0; cpu_id <= 65535; cpu_id++) {
+		if (cpu_known(cpu_id))
+			continue;
+		__cpu_logical_map[logical_cpu] = cpu_id;
+		if (!cpu_stopped(logical_cpu))
+			continue;
+		cpu_set(logical_cpu, cpu_present_map);
+		smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
+		logical_cpu = next_cpu(logical_cpu, avail);
+		if (logical_cpu == NR_CPUS)
+			break;
+	}
+	return 0;
+}
+
+static int __init_refok smp_rescan_cpus_sclp(cpumask_t avail)
+{
+	struct sclp_cpu_info *info;
+	int cpu_id, logical_cpu, cpu;
+	int rc;
+
+	logical_cpu = first_cpu(avail);
+	if (logical_cpu == NR_CPUS)
+		return 0;
+	if (slab_is_available())
+		info = kmalloc(sizeof(*info), GFP_KERNEL);
+	else
+		info = alloc_bootmem(sizeof(*info));
+	if (!info)
+		return -ENOMEM;
+	rc = sclp_get_cpu_info(info);
+	if (rc)
+		goto out;
+	for (cpu = 0; cpu < info->combined; cpu++) {
+		if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
+			continue;
+		cpu_id = info->cpu[cpu].address;
+		if (cpu_known(cpu_id))
+			continue;
+		__cpu_logical_map[logical_cpu] = cpu_id;
+		cpu_set(logical_cpu, cpu_present_map);
+		if (cpu >= info->configured)
+			smp_cpu_state[logical_cpu] = CPU_STATE_STANDBY;
+		else
+			smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
+		logical_cpu = next_cpu(logical_cpu, avail);
+		if (logical_cpu == NR_CPUS)
+			break;
+	}
+out:
+	if (slab_is_available())
+		kfree(info);
+	else
+		free_bootmem((unsigned long) info, sizeof(*info));
+	return rc;
+}
+
+static int smp_rescan_cpus(void)
+{
+	cpumask_t avail;
+
+	cpus_setall(avail);
+	cpus_and(avail, avail, cpu_possible_map);
+	cpus_andnot(avail, avail, cpu_present_map);
+	if (smp_use_sigp_detection)
+		return smp_rescan_cpus_sigp(avail);
+	else
+		return smp_rescan_cpus_sclp(avail);
 }
 
 /*
@@ -453,8 +612,6 @@ int __cpuinit start_secondary(void *cpuvoid)
 	return 0;
 }
 
-DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
-
 static void __init smp_create_idle(unsigned int cpu)
 {
 	struct task_struct *p;
@@ -470,37 +627,16 @@ static void __init smp_create_idle(unsigned int cpu)
 	spin_lock_init(&(&per_cpu(s390_idle, cpu))->lock);
 }
 
-static int cpu_stopped(int cpu)
-{
-	__u32 status;
-
-	/* Check for stopped state */
-	if (signal_processor_ps(&status, 0, cpu, sigp_sense) ==
-	    sigp_status_stored) {
-		if (status & 0x40)
-			return 1;
-	}
-	return 0;
-}
-
 /* Upping and downing of CPUs */
-
 int __cpu_up(unsigned int cpu)
 {
 	struct task_struct *idle;
 	struct _lowcore *cpu_lowcore;
 	struct stack_frame *sf;
 	sigp_ccode ccode;
-	int curr_cpu;
-
-	for (curr_cpu = 0; curr_cpu <= 65535; curr_cpu++) {
-		__cpu_logical_map[cpu] = (__u16) curr_cpu;
-		if (cpu_stopped(cpu))
-			break;
-	}
 
-	if (!cpu_stopped(cpu))
-		return -ENODEV;
+	if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED)
+		return -EIO;
 
 	ccode = signal_processor_p((__u32)(unsigned long)(lowcore_ptr[cpu]),
 				   cpu, sigp_set_prefix);
@@ -543,21 +679,18 @@ static unsigned int __initdata possible_cpus;
 
 void __init smp_setup_cpu_possible_map(void)
 {
-	unsigned int phy_cpus, pos_cpus, cpu;
-
-	phy_cpus = smp_count_cpus();
-	pos_cpus = min(phy_cpus + additional_cpus, (unsigned int) NR_CPUS);
+	unsigned int pos_cpus, cpu;
+	unsigned int configured_cpus, standby_cpus;
 
+	smp_count_cpus(&configured_cpus, &standby_cpus);
+	pos_cpus = min(configured_cpus + standby_cpus + additional_cpus,
+		       (unsigned int) NR_CPUS);
 	if (possible_cpus)
 		pos_cpus = min(possible_cpus, (unsigned int) NR_CPUS);
-
 	for (cpu = 0; cpu < pos_cpus; cpu++)
 		cpu_set(cpu, cpu_possible_map);
-
-	phy_cpus = min(phy_cpus, pos_cpus);
-
-	for (cpu = 0; cpu < phy_cpus; cpu++)
-		cpu_set(cpu, cpu_present_map);
+	cpu_present_map = cpumask_of_cpu(0);
+	smp_rescan_cpus();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -612,7 +745,7 @@ void __cpu_die(unsigned int cpu)
 	/* Wait until target cpu is down */
 	while (!smp_cpu_not_running(cpu))
 		cpu_relax();
-	printk("Processor %d spun down\n", cpu);
+	printk(KERN_INFO "Processor %d spun down\n", cpu);
 }
 
 void cpu_die(void)
@@ -686,12 +819,12 @@ void __init smp_prepare_boot_cpu(void)
 	cpu_set(0, cpu_online_map);
 	S390_lowcore.percpu_offset = __per_cpu_offset[0];
 	current_set[0] = current;
+	smp_cpu_state[0] = CPU_STATE_CONFIGURED;
 	spin_lock_init(&(&__get_cpu_var(s390_idle))->lock);
 }
 
 void __init smp_cpus_done(unsigned int max_cpus)
 {
-	cpu_present_map = cpu_possible_map;
 }
 
 /*
@@ -705,7 +838,79 @@ int setup_profiling_timer(unsigned int multiplier)
 	return 0;
 }
 
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
+#ifdef CONFIG_HOTPLUG_CPU
+static ssize_t cpu_configure_show(struct sys_device *dev, char *buf)
+{
+	ssize_t count;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	count = sprintf(buf, "%d\n", smp_cpu_state[dev->id]);
+	mutex_unlock(&smp_cpu_state_mutex);
+	return count;
+}
+
+static ssize_t cpu_configure_store(struct sys_device *dev, const char *buf,
+				   size_t count)
+{
+	int cpu = dev->id;
+	int val, rc;
+	char delim;
+
+	if (sscanf(buf, "%d %c", &val, &delim) != 1)
+		return -EINVAL;
+	if (val != 0 && val != 1)
+		return -EINVAL;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	lock_cpu_hotplug();
+	rc = -EBUSY;
+	if (cpu_online(cpu))
+		goto out;
+	rc = 0;
+	switch (val) {
+	case 0:
+		if (smp_cpu_state[cpu] == CPU_STATE_CONFIGURED) {
+			rc = sclp_cpu_deconfigure(__cpu_logical_map[cpu]);
+			if (!rc)
+				smp_cpu_state[cpu] = CPU_STATE_STANDBY;
+		}
+		break;
+	case 1:
+		if (smp_cpu_state[cpu] == CPU_STATE_STANDBY) {
+			rc = sclp_cpu_configure(__cpu_logical_map[cpu]);
+			if (!rc)
+				smp_cpu_state[cpu] = CPU_STATE_CONFIGURED;
+		}
+		break;
+	default:
+		break;
+	}
+out:
+	unlock_cpu_hotplug();
+	mutex_unlock(&smp_cpu_state_mutex);
+	return rc ? rc : count;
+}
+static SYSDEV_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static ssize_t show_cpu_address(struct sys_device *dev, char *buf)
+{
+	return sprintf(buf, "%d\n", __cpu_logical_map[dev->id]);
+}
+static SYSDEV_ATTR(address, 0444, show_cpu_address, NULL);
+
+
+static struct attribute *cpu_common_attrs[] = {
+#ifdef CONFIG_HOTPLUG_CPU
+	&attr_configure.attr,
+#endif
+	&attr_address.attr,
+	NULL,
+};
+
+static struct attribute_group cpu_common_attr_group = {
+	.attrs = cpu_common_attrs,
+};
 
 static ssize_t show_capability(struct sys_device *dev, char *buf)
 {
@@ -750,15 +955,15 @@ static ssize_t show_idle_time(struct sys_device *dev, char *buf)
 }
 static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 
-static struct attribute *cpu_attrs[] = {
+static struct attribute *cpu_online_attrs[] = {
 	&attr_capability.attr,
 	&attr_idle_count.attr,
 	&attr_idle_time_us.attr,
 	NULL,
 };
 
-static struct attribute_group cpu_attr_group = {
-	.attrs = cpu_attrs,
+static struct attribute_group cpu_online_attr_group = {
+	.attrs = cpu_online_attrs,
 };
 
 static int __cpuinit smp_cpu_notify(struct notifier_block *self,
@@ -778,12 +983,12 @@ static int __cpuinit smp_cpu_notify(struct notifier_block *self,
 		idle->idle_time = 0;
 		idle->idle_count = 0;
 		spin_unlock_irq(&idle->lock);
-		if (sysfs_create_group(&s->kobj, &cpu_attr_group))
+		if (sysfs_create_group(&s->kobj, &cpu_online_attr_group))
 			return NOTIFY_BAD;
 		break;
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		sysfs_remove_group(&s->kobj, &cpu_attr_group);
+		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
 		break;
 	}
 	return NOTIFY_OK;
@@ -793,6 +998,62 @@ static struct notifier_block __cpuinitdata smp_cpu_nb = {
 	.notifier_call = smp_cpu_notify,
 };
 
+static int smp_add_present_cpu(int cpu)
+{
+	struct cpu *c = &per_cpu(cpu_devices, cpu);
+	struct sys_device *s = &c->sysdev;
+	int rc;
+
+	c->hotpluggable = 1;
+	rc = register_cpu(c, cpu);
+	if (rc)
+		goto out;
+	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
+	if (rc)
+		goto out_cpu;
+	if (!cpu_online(cpu))
+		goto out;
+	rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
+	if (!rc)
+		return 0;
+	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
+out_cpu:
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_cpu(c);
+#endif
+out:
+	return rc;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static ssize_t rescan_store(struct sys_device *dev, const char *buf,
+			    size_t count)
+{
+	cpumask_t newcpus;
+	int cpu;
+	int rc;
+
+	mutex_lock(&smp_cpu_state_mutex);
+	lock_cpu_hotplug();
+	newcpus = cpu_present_map;
+	rc = smp_rescan_cpus();
+	if (rc)
+		goto out;
+	cpus_andnot(newcpus, cpu_present_map, newcpus);
+	for_each_cpu_mask(cpu, newcpus) {
+		rc = smp_add_present_cpu(cpu);
+		if (rc)
+			cpu_clear(cpu, cpu_present_map);
+	}
+	rc = 0;
+out:
+	unlock_cpu_hotplug();
+	mutex_unlock(&smp_cpu_state_mutex);
+	return rc ? rc : count;
+}
+static SYSDEV_ATTR(rescan, 0200, NULL, rescan_store);
+#endif /* CONFIG_HOTPLUG_CPU */
+
 static int __init topology_init(void)
 {
 	int cpu;
@@ -800,16 +1061,14 @@ static int __init topology_init(void)
 
 	register_cpu_notifier(&smp_cpu_nb);
 
-	for_each_possible_cpu(cpu) {
-		struct cpu *c = &per_cpu(cpu_devices, cpu);
-		struct sys_device *s = &c->sysdev;
-
-		c->hotpluggable = 1;
-		register_cpu(c, cpu);
-		if (!cpu_online(cpu))
-			continue;
-		s = &c->sysdev;
-		rc = sysfs_create_group(&s->kobj, &cpu_attr_group);
+#ifdef CONFIG_HOTPLUG_CPU
+	rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+			       &attr_rescan.attr);
+	if (rc)
+		return rc;
+#endif
+	for_each_present_cpu(cpu) {
+		rc = smp_add_present_cpu(cpu);
 		if (rc)
 			return rc;
 	}