[PATCH] ppc64: Add support for hotplug cpus

From: Joel Schopp <jschopp@austin.ibm.com>

Add support for hotplug cpus

arch/ppc64/Kconfig

@@ -248,6 +248,14 @@ source "fs/Kconfig.binfmt"
 
 source "drivers/pci/Kconfig"
 
+config HOTPLUG_CPU
+	bool "Support for hot-pluggable CPUs"
+	depends on SMP && HOTPLUG && EXPERIMENTAL
+	---help---
+	  Say Y here to be able to turn CPUs off and on.
+
+	  Say N if you are unsure.
+
 source "drivers/pcmcia/Kconfig"
 
 source "drivers/pci/hotplug/Kconfig"

arch/ppc64/kernel/idle.c

@@ -26,6 +26,7 @@
 #include <linux/unistd.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
+#include <linux/cpu.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -150,12 +151,18 @@ int default_idle(void)
 		}
 
 		schedule();
+		if (cpu_is_offline(smp_processor_id()) &&
+				system_state == SYSTEM_RUNNING)
+			cpu_die();
 	}
 
 	return 0;
 }
 
 #ifdef CONFIG_PPC_PSERIES
+
+DECLARE_PER_CPU(smt_snooze_delay);
+
 int dedicated_idle(void)
 {
 	long oldval;
@@ -236,6 +243,9 @@ int dedicated_idle(void)
 		HMT_medium();
 		lpaca->xLpPaca.xIdle = 0;
 		schedule();
+		if (cpu_is_offline(smp_processor_id()) &&
+				system_state == SYSTEM_RUNNING)
+			cpu_die();
 	}
 	return 0;
 }
@@ -245,6 +255,10 @@ int shared_idle(void)
 	struct paca_struct *lpaca = get_paca();
 
 	while (1) {
+		if (cpu_is_offline(smp_processor_id()) &&
+				system_state == SYSTEM_RUNNING)
+			cpu_die();
+
 		/* Indicate to the HV that we are idle.  Now would be
 		 * a good time to find other work to dispatch. */
 		lpaca->xLpPaca.xIdle = 1;

arch/ppc64/kernel/irq.c

@@ -683,6 +683,7 @@ static struct proc_dir_entry * root_irq_dir;
 static struct proc_dir_entry * irq_dir [NR_IRQS];
 static struct proc_dir_entry * smp_affinity_entry [NR_IRQS];
 
+/* Protected by irq descriptor spinlock */
 #ifdef CONFIG_IRQ_ALL_CPUS
 cpumask_t irq_affinity [NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };
 #else  /* CONFIG_IRQ_ALL_CPUS */
@@ -702,16 +703,17 @@ static int irq_affinity_read_proc (char *page, char **start, off_t off,
 static int irq_affinity_write_proc (struct file *file, const char *buffer,
 					unsigned long count, void *data)
 {
-	int irq = (long)data, full_count = count, err;
+	int irq = (long)data;
+	int ret;
 	cpumask_t new_value, tmp;
 	cpumask_t allcpus = CPU_MASK_ALL;
 
 	if (!irq_desc[irq].handler->set_affinity)
 		return -EIO;
 
-	err = cpumask_parse(buffer, count, new_value);
-	if (err)
-		return err;
+	ret = cpumask_parse(buffer, count, new_value);
+	if (ret != 0)
+		return ret;
 
 	/*
 	 * We check for CPU_MASK_ALL in xics to send irqs to all cpus.
@@ -721,19 +723,30 @@ static int irq_affinity_write_proc (struct file *file, const char *buffer,
 	 */
 	cpus_and(new_value, new_value, allcpus);
 
+	/*
+	 * Grab lock here so cpu_online_map can't change, and also
+	 * protect irq_affinity[].
+	 */
+	spin_lock(&irq_desc[irq].lock);
+
 	/*
 	 * Do not allow disabling IRQs completely - it's a too easy
 	 * way to make the system unusable accidentally :-) At least
 	 * one online CPU still has to be targeted.
 	 */
 	cpus_and(tmp, new_value, cpu_online_map);
-	if (cpus_empty(tmp))
-		return -EINVAL;
+	if (cpus_empty(tmp)) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	irq_affinity[irq] = new_value;
 	irq_desc[irq].handler->set_affinity(irq, new_value);
+	ret = count;
 
-	return full_count;
+out:
+	spin_unlock(&irq_desc[irq].lock);
+	return ret;
 }
 
 static int prof_cpu_mask_read_proc (char *page, char **start, off_t off,
@@ -946,5 +959,4 @@ unsigned int real_irq_to_virt_slowpath(unsigned int real_irq)
 
 }
 
-
 #endif

arch/ppc64/kernel/rtas.c

@@ -494,6 +494,25 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 	return 0;
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/* This version can't take the spinlock. */
+
+void rtas_stop_self(void)
+{
+	struct rtas_args *rtas_args = &(get_paca()->xRtas);
+
+	rtas_args->token = rtas_token("stop-self");
+	BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
+	rtas_args->nargs = 0;
+	rtas_args->nret  = 1;
+	rtas_args->rets  = &(rtas_args->args[0]);
+
+	printk("%u %u Ready to die...\n",
+	       smp_processor_id(), hard_smp_processor_id());
+	enter_rtas((void *)__pa(rtas_args));
+	panic("Alas, I survived.\n");
+}
+#endif /* CONFIG_HOTPLUG_CPU */
 
 EXPORT_SYMBOL(rtas_firmware_flash_list);
 EXPORT_SYMBOL(rtas_token);

arch/ppc64/kernel/setup.c

@@ -25,6 +25,7 @@
 #include <linux/version.h>
 #include <linux/tty.h>
 #include <linux/root_dev.h>
+#include <linux/cpu.h>
 #include <asm/io.h>
 #include <asm/prom.h>
 #include <asm/processor.h>
@@ -338,8 +339,13 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		return 0;
 	}
 
-	if (!cpu_online(cpu_id))
+	/* We only show online cpus: disable preempt (overzealous, I
+	 * knew) to prevent cpu going down. */
+	preempt_disable();
+	if (!cpu_online(cpu_id)) {
+		preempt_enable();
 		return 0;
+	}
 
 #ifdef CONFIG_SMP
 	pvr = per_cpu(pvr, cpu_id);
@@ -373,6 +379,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 
 	seq_printf(m, "revision\t: %hd.%hd\n\n", maj, min);
 
+	preempt_enable();
 	return 0;
 }
 

arch/ppc64/kernel/smp.c

@@ -230,10 +230,237 @@ static void __devinit smp_openpic_setup_cpu(int cpu)
 	do_openpic_setup_cpu();
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/* Get state of physical CPU.
+ * Return codes:
+ *	0	- The processor is in the RTAS stopped state
+ *	1	- stop-self is in progress
+ *	2	- The processor is not in the RTAS stopped state
+ *	-1	- Hardware Error
+ *	-2	- Hardware Busy, Try again later.
+ */
+static int query_cpu_stopped(unsigned int pcpu)
+{
+	long cpu_status;
+	int status, qcss_tok;
+
+	qcss_tok = rtas_token("query-cpu-stopped-state");
+	BUG_ON(qcss_tok == RTAS_UNKNOWN_SERVICE);
+	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
+	if (status != 0) {
+		printk(KERN_ERR
+		       "RTAS query-cpu-stopped-state failed: %i\n", status);
+		return status;
+	}
+
+	return cpu_status;
+}
+
+int __cpu_disable(void)
+{
+	/* FIXME: go put this in a header somewhere */
+	extern void xics_migrate_irqs_away(void);
+
+	systemcfg->processorCount--;
+
+	/*fix boot_cpuid here*/
+	if (smp_processor_id() == boot_cpuid)
+		boot_cpuid = any_online_cpu(cpu_online_map);
+
+	/* FIXME: abstract this to not be platform specific later on */
+	xics_migrate_irqs_away();
+	return 0;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+	int tries;
+	int cpu_status;
+	unsigned int pcpu = get_hard_smp_processor_id(cpu);
+
+	for (tries = 0; tries < 5; tries++) {
+		cpu_status = query_cpu_stopped(pcpu);
+
+		if (cpu_status == 0)
+			break;
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(HZ);
+	}
+	if (cpu_status != 0) {
+		printk("Querying DEAD? cpu %i (%i) shows %i\n",
+		       cpu, pcpu, cpu_status);
+	}
+
+	/* Isolation and deallocation are definatly done by
+	 * drslot_chrp_cpu.  If they were not they would be
+	 * done here.  Change isolate state to Isolate and
+	 * change allocation-state to Unusable.
+	 */
+	paca[cpu].xProcStart = 0;
+
+	/* So we can recognize if it fails to come up next time. */
+	cpu_callin_map[cpu] = 0;
+}
+
+/* Kill this cpu */
+void cpu_die(void)
+{
+	local_irq_disable();
+	rtas_stop_self();
+	/* Should never get here... */
+	BUG();
+	for(;;);
+}
+
+/* Search all cpu device nodes for an offline logical cpu.  If a
+ * device node has a "ibm,my-drc-index" property (meaning this is an
+ * LPAR), paranoid-check whether we own the cpu.  For each "thread"
+ * of a cpu, if it is offline and has the same hw index as before,
+ * grab that in preference.
+ */
+static unsigned int find_physical_cpu_to_start(unsigned int old_hwindex)
+{
+	struct device_node *np = NULL;
+	unsigned int best = -1U;
+
+	while ((np = of_find_node_by_type(np, "cpu"))) {
+		int nr_threads, len;
+		u32 *index = (u32 *)get_property(np, "ibm,my-drc-index", NULL);
+		u32 *tid = (u32 *)
+			get_property(np, "ibm,ppc-interrupt-server#s", &len);
+
+		if (!tid)
+			tid = (u32 *)get_property(np, "reg", &len);
+
+		if (!tid)
+			continue;
+
+		/* If there is a drc-index, make sure that we own
+		 * the cpu.
+		 */
+		if (index) {
+			int state;
+			int rc = rtas_get_sensor(9003, *index, &state);
+			if (rc != 0 || state != 1)
+				continue;
+		}
+
+		nr_threads = len / sizeof(u32);
+
+		while (nr_threads--) {
+			if (0 == query_cpu_stopped(tid[nr_threads])) {
+				best = tid[nr_threads];
+				if (best == old_hwindex)
+					goto out;
+			}
+		}
+	}
+out:
+	of_node_put(np);
+	return best;
+}
+
+/**
+ * smp_startup_cpu() - start the given cpu
+ *
+ * At boot time, there is nothing to do.  At run-time, call RTAS with
+ * the appropriate start location, if the cpu is in the RTAS stopped
+ * state.
+ *
+ * Returns:
+ *	0	- failure
+ *	1	- success
+ */
+static inline int __devinit smp_startup_cpu(unsigned int lcpu)
+{
+	int status;
+	extern void (*pseries_secondary_smp_init)(unsigned int cpu);
+	unsigned long start_here = __pa(pseries_secondary_smp_init);
+	unsigned int pcpu;
+
+	/* At boot time the cpus are already spinning in hold
+	 * loops, so nothing to do. */
+ 	if (system_state == SYSTEM_BOOTING)
+		return 1;
+
+	pcpu = find_physical_cpu_to_start(get_hard_smp_processor_id(lcpu));
+	if (pcpu == -1U) {
+		printk(KERN_INFO "No more cpus available, failing\n");
+		return 0;
+	}
+
+	/* Fixup atomic count: it exited inside IRQ handler. */
+	((struct task_struct *)paca[lcpu].xCurrent)->thread_info->preempt_count
+		= 0;
+	/* Fixup SLB round-robin so next segment (kernel) goes in segment 0 */
+	paca[lcpu].xStab_data.next_round_robin = 0;
+
+	/* At boot this is done in prom.c. */
+	paca[lcpu].xHwProcNum = pcpu;
+
+	status = rtas_call(rtas_token("start-cpu"), 3, 1, NULL,
+			   pcpu, start_here, lcpu);
+	if (status != 0) {
+		printk(KERN_ERR "start-cpu failed: %i\n", status);
+		return 0;
+	}
+	return 1;
+}
+
+static inline void look_for_more_cpus(void)
+{
+	int num_addr_cell, num_size_cell, len, i, maxcpus;
+	struct device_node *np;
+	unsigned int *ireg;
+
+	/* Find the property which will tell us about how many CPUs
+	 * we're allowed to have. */
+	if ((np = find_path_device("/rtas")) == NULL) {
+		printk(KERN_ERR "Could not find /rtas in device tree!");
+		return;
+	}
+	num_addr_cell = prom_n_addr_cells(np);
+	num_size_cell = prom_n_size_cells(np);
+
+	ireg = (unsigned int *)get_property(np, "ibm,lrdr-capacity", &len);
+	if (ireg == NULL) {
+		/* FIXME: make sure not marked as lrdr_capable() */
+		return;
+	}
+
+	maxcpus = ireg[num_addr_cell + num_size_cell];
+	/* DRENG need to account for threads here too */
+
+	if (maxcpus > NR_CPUS) {
+		printk(KERN_WARNING
+		       "Partition configured for %d cpus, "
+		       "operating system maximum is %d.\n", maxcpus, NR_CPUS);
+		maxcpus = NR_CPUS;
+	} else
+		printk(KERN_INFO "Partition configured for %d cpus.\n",
+		       maxcpus);
+
+	/* Make those cpus (which might appear later) possible too. */
+	for (i = 0; i < maxcpus; i++)
+		cpu_set(i, cpu_possible_map);
+}
+#else /* ... CONFIG_HOTPLUG_CPU */
+static inline int __devinit smp_startup_cpu(unsigned int lcpu)
+{
+	return 1;
+}
+static inline void look_for_more_cpus(void)
+{
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 static void smp_pSeries_kick_cpu(int nr)
 {
 	BUG_ON(nr < 0 || nr >= NR_CPUS);
 
+	if (!smp_startup_cpu(nr))
+		return;
+
 	/* The processor is currently spinning, waiting
 	 * for the xProcStart field to become non-zero
 	 * After we set xProcStart, the processor will
@@ -241,7 +468,7 @@ static void smp_pSeries_kick_cpu(int nr)
 	 */
 	paca[nr].xProcStart = 1;
 }
-#endif
+#endif /* CONFIG_PPC_PSERIES */
 
 static void __init smp_space_timers(unsigned int max_cpus)
 {
@@ -462,12 +689,9 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 		       int wait)
 { 
 	struct call_data_struct data;
-	int ret = -1, cpus = num_online_cpus()-1;
+	int ret = -1, cpus;
 	unsigned long timeout;
 
-	if (!cpus)
-		return 0;
-
 	data.func = func;
 	data.info = info;
 	atomic_set(&data.started, 0);
@@ -476,6 +700,14 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 		atomic_set(&data.finished, 0);
 
 	spin_lock(&call_lock);
+	/* Must grab online cpu count with preempt disabled, otherwise
+	 * it can change. */
+	cpus = num_online_cpus() - 1;
+	if (!cpus) {
+		ret = 0;
+		goto out;
+	}
+
 	call_data = &data;
 	wmb();
 	/* Send a message to all other CPUs and wait for them to respond */
@@ -565,8 +797,31 @@ static void __devinit smp_store_cpu_info(int id)
 	per_cpu(pvr, id) = _get_PVR();
 }
 
+static void __init smp_create_idle(unsigned int cpu)
+{
+	struct pt_regs regs;
+	struct task_struct *p;
+
+	/* create a process for the processor */
+	/* only regs.msr is actually used, and 0 is OK for it */
+	memset(&regs, 0, sizeof(struct pt_regs));
+	p = copy_process(CLONE_VM | CLONE_IDLETASK,
+			 0, &regs, 0, NULL, NULL);
+	if (IS_ERR(p))
+		panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
+
+	wake_up_forked_process(p);
+	init_idle(p, cpu);
+	unhash_process(p);
+
+	paca[cpu].xCurrent = (u64)p;
+	current_set[cpu] = p->thread_info;
+}
+
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+	unsigned int cpu;
+
 	/* 
 	 * setup_cpu may need to be called on the boot cpu. We havent
 	 * spun any cpus up but lets be paranoid.
@@ -593,6 +848,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	 * number of msecs off until someone does a settimeofday()
 	 */
 	do_gtod.tb_orig_stamp = tb_last_stamp;
+
+	look_for_more_cpus();
 #endif
 
 	max_cpus = smp_ops->probe();
@@ -601,20 +858,31 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	__save_cpu_setup();
 
 	smp_space_timers(max_cpus);
+
+	for_each_cpu(cpu)
+		if (cpu != boot_cpuid)
+			smp_create_idle(cpu);
 }
 
 void __devinit smp_prepare_boot_cpu(void)
 {
-	cpu_set(smp_processor_id(), cpu_online_map);
-	/* FIXME: what about cpu_possible()? */
+	BUG_ON(smp_processor_id() != boot_cpuid);
+
+	/* cpu_possible is set up in prom.c */
+	cpu_set(boot_cpuid, cpu_online_map);
+
+	paca[boot_cpuid].xCurrent = (u64)current;
+	current_set[boot_cpuid] = current->thread_info;
 }
 
 int __devinit __cpu_up(unsigned int cpu)
 {
-	struct pt_regs regs;
-	struct task_struct *p;
 	int c;
 
+	/* At boot, don't bother with non-present cpus -JSCHOPP */
+	if (system_state == SYSTEM_BOOTING && !cpu_present_at_boot(cpu))
+		return -ENOENT;
+
 	paca[cpu].prof_counter = 1;
 	paca[cpu].prof_multiplier = 1;
 	paca[cpu].default_decr = tb_ticks_per_jiffy / decr_overclock;
@@ -632,19 +900,9 @@ int __devinit __cpu_up(unsigned int cpu)
 		paca[cpu].xStab_data.real = virt_to_abs(tmp);
 	}
 
-	/* create a process for the processor */
-	/* only regs.msr is actually used, and 0 is OK for it */
-	memset(&regs, 0, sizeof(struct pt_regs));
-	p = copy_process(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL, NULL);
-	if (IS_ERR(p))
-		panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
-
-	wake_up_forked_process(p);
-	init_idle(p, cpu);
-	unhash_process(p);
-
-	paca[cpu].xCurrent = (u64)p;
-	current_set[cpu] = p->thread_info;
+	/* The information for processor bringup must be written out
+	 * to main store before we release the processor. */
+	mb();
 
 	/* The information for processor bringup must
 	 * be written out to main store before we release

arch/ppc64/kernel/xics.c

@@ -19,6 +19,7 @@
 #include <linux/init.h>
 #include <linux/gfp.h>
 #include <linux/radix-tree.h>
+#include <linux/cpu.h>
 #include <asm/prom.h>
 #include <asm/io.h>
 #include <asm/pgtable.h>
@@ -372,6 +373,9 @@ irqreturn_t xics_ipi_action(int irq, void *dev_id, struct pt_regs *regs)
 	int cpu = smp_processor_id();
 
 	ops->qirr_info(cpu, 0xff);
+
+	WARN_ON(cpu_is_offline(cpu));
+
 	while (xics_ipi_message[cpu].value) {
 		if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION,
 				       &xics_ipi_message[cpu].value)) {
@@ -514,6 +518,9 @@ void xics_init_IRQ(void)
 	if (systemcfg->platform == PLATFORM_PSERIES) {
 #ifdef CONFIG_SMP
 		for_each_cpu(i) {
+			/* FIXME: Do this dynamically! --RR */
+			if (!cpu_present_at_boot(i))
+				continue;
 			xics_per_cpu[i] = __ioremap((ulong)inodes[get_hard_smp_processor_id(i)].addr, 
 						    (ulong)inodes[get_hard_smp_processor_id(i)].size,
 						    _PAGE_NO_CACHE);
@@ -575,9 +582,7 @@ void xics_request_IPIs(void)
 
 static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
 {
-        irq_desc_t *desc = irq_desc + virq;
 	unsigned int irq;
-	unsigned long flags;
 	long status;
 	unsigned long xics_status[2];
 	unsigned long newmask;
@@ -589,14 +594,12 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
 	if (irq == XICS_IPI)
 		return;
 
-        spin_lock_irqsave(&desc->lock, flags);
-
 	status = rtas_call(ibm_get_xive, 1, 3, (void *)&xics_status, irq);
 
 	if (status) {
 		printk(KERN_ERR "xics_set_affinity: irq=%d ibm,get-xive "
 		       "returns %ld\n", irq, status);
-		goto out;
+		return;
 	}
 
 	/* For the moment only implement delivery to all cpus or one cpu */
@@ -605,7 +608,7 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
 	} else {
 		cpus_and(tmp, cpu_online_map, cpumask);
 		if (cpus_empty(tmp))
-			goto out;
+			return;
 		newmask = get_hard_smp_processor_id(first_cpu(cpumask));
 	}
 
@@ -615,9 +618,86 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
 	if (status) {
 		printk(KERN_ERR "xics_set_affinity irq=%d ibm,set-xive "
 		       "returns %ld\n", irq, status);
-		goto out;
+		return;
+	}
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* Interrupts are disabled. */
+void xics_migrate_irqs_away(void)
+{
+	int set_indicator = rtas_token("set-indicator");
+	const unsigned long giqs = 9005UL; /* Global Interrupt Queue Server */
+	unsigned long status = 0;
+	unsigned int irq, cpu = smp_processor_id();
+	unsigned long xics_status[2];
+	unsigned long flags;
+
+	BUG_ON(set_indicator == RTAS_UNKNOWN_SERVICE);
+
+	/* Reject any interrupt that was queued to us... */
+	ops->cppr_info(cpu, 0);
+	iosync();
+
+	/* Refuse any new interrupts... */
+	rtas_call(set_indicator, 3, 1, &status, giqs,
+		  hard_smp_processor_id(), 0UL);
+	WARN_ON(status != 0);
+
+	/* Allow IPIs again... */
+	ops->cppr_info(cpu, DEFAULT_PRIORITY);
+	iosync();
+
+	printk(KERN_WARNING "HOTPLUG: Migrating IRQs away\n");
+	for_each_irq(irq) {
+		irq_desc_t *desc = get_irq_desc(irq);
+
+		/* We need to get IPIs still. */
+		if (irq_offset_down(irq) == XICS_IPI)
+			continue;
+
+		/* We only need to migrate enabled IRQS */
+		if (desc == NULL || desc->handler == NULL
+		    || desc->action == NULL
+		    || desc->handler->set_affinity == NULL)
+			continue;
+
+		spin_lock_irqsave(&desc->lock, flags);
+
+		status = rtas_call(ibm_get_xive, 1, 3, (void *)&xics_status,
+				   irq);
+		if (status) {
+			printk(KERN_ERR "migrate_irqs_away: irq=%d "
+					"ibm,get-xive returns %ld\n",
+					irq, status);
+			goto unlock;
 		}
 
-out:
+		/*
+		 * We only support delivery to all cpus or to one cpu.
+		 * The irq has to be migrated only in the single cpu
+		 * case.
+		 */
+		if (xics_status[0] != get_hard_smp_processor_id(cpu))
+			goto unlock;
+
+		printk(KERN_WARNING "IRQ %d affinity broken off cpu %u\n",
+		       irq, cpu);
+
+		/* Reset affinity to all cpus */
+		xics_status[0] = default_distrib_server;
+
+		status = rtas_call(ibm_set_xive, 3, 1, NULL,
+				irq, xics_status[0], xics_status[1]);
+		if (status)
+			printk(KERN_ERR "migrate_irqs_away irq=%d "
+					"ibm,set-xive returns %ld\n",
+					irq, status);
+
+unlock:
 		spin_unlock_irqrestore(&desc->lock, flags);
+	}
+
 }
+#endif

include/asm-ppc64/rtas.h

@@ -219,6 +219,8 @@ extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
 extern spinlock_t rtas_data_buf_lock;
 extern char rtas_data_buf[RTAS_DATA_BUF_SIZE];
 
+extern void rtas_stop_self(void);
+
 /* RMO buffer reserved for user-space RTAS use */
 extern unsigned long rtas_rmo_buf;
 

include/asm-ppc64/smp.h

@@ -70,6 +70,9 @@ extern cpumask_t cpu_available_map;
 void smp_init_iSeries(void);
 void smp_init_pSeries(void);
 
+extern int __cpu_disable(void);
+extern void __cpu_die(unsigned int cpu);
+extern void cpu_die(void) __attribute__((noreturn));
 #endif /* !(CONFIG_SMP) */
 
 #define get_hard_smp_processor_id(CPU) (paca[(CPU)].xHwProcNum)