---

yaml
---
r: 175795
b: refs/heads/master
c: 3aa565f
h: refs/heads/master
i:
  175793: 50cbe72
  175791: a0b48be
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 69ddb57cbea0b3dd851ea5f1edd1e609ad4da04e
+refs/heads/master: 3aa565f53c396914a9406388efaa238e9c937fc6

trunk/Documentation/cpu-hotplug.txt

@@ -49,6 +49,12 @@ maxcpus=n    Restrict boot time cpus to n. Say if you have 4 cpus, using
 additional_cpus=n (*)	Use this to limit hotpluggable cpus. This option sets
   			cpu_possible_map = cpu_present_map + additional_cpus
 
+cede_offline={"off","on"}  Use this option to disable/enable putting offlined
+		            processors to an extended H_CEDE state on
+			    supported pseries platforms.
+			    If nothing is specified,
+			    cede_offline is set to "on".
+
 (*) Option valid only for following architectures
 - ia64
 

trunk/arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -30,6 +30,7 @@
 #include <asm/pSeries_reconfig.h>
 #include "xics.h"
 #include "plpar_wrappers.h"
+#include "offline_states.h"
 
 /* This version can't take the spinlock, because it never returns */
 static struct rtas_args rtas_stop_self_args = {
@@ -39,6 +40,55 @@ static struct rtas_args rtas_stop_self_args = {
 	.rets = &rtas_stop_self_args.args[0],
 };
 
+static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
+							CPU_STATE_OFFLINE;
+static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;
+
+static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;
+
+static int cede_offline_enabled __read_mostly = 1;
+
+/*
+ * Enable/disable cede_offline when available.
+ */
+static int __init setup_cede_offline(char *str)
+{
+	if (!strcmp(str, "off"))
+		cede_offline_enabled = 0;
+	else if (!strcmp(str, "on"))
+		cede_offline_enabled = 1;
+	else
+		return 0;
+	return 1;
+}
+
+__setup("cede_offline=", setup_cede_offline);
+
+enum cpu_state_vals get_cpu_current_state(int cpu)
+{
+	return per_cpu(current_state, cpu);
+}
+
+void set_cpu_current_state(int cpu, enum cpu_state_vals state)
+{
+	per_cpu(current_state, cpu) = state;
+}
+
+enum cpu_state_vals get_preferred_offline_state(int cpu)
+{
+	return per_cpu(preferred_offline_state, cpu);
+}
+
+void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
+{
+	per_cpu(preferred_offline_state, cpu) = state;
+}
+
+void set_default_offline_state(int cpu)
+{
+	per_cpu(preferred_offline_state, cpu) = default_offline_state;
+}
+
 static void rtas_stop_self(void)
 {
 	struct rtas_args *args = &rtas_stop_self_args;
@@ -56,11 +106,61 @@ static void rtas_stop_self(void)
 
 static void pseries_mach_cpu_die(void)
 {
+	unsigned int cpu = smp_processor_id();
+	unsigned int hwcpu = hard_smp_processor_id();
+	u8 cede_latency_hint = 0;
+
 	local_irq_disable();
 	idle_task_exit();
 	xics_teardown_cpu();
-	unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
-	rtas_stop_self();
+
+	if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
+		set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
+		cede_latency_hint = 2;
+
+		get_lppaca()->idle = 1;
+		if (!get_lppaca()->shared_proc)
+			get_lppaca()->donate_dedicated_cpu = 1;
+
+		printk(KERN_INFO
+			"cpu %u (hwid %u) ceding for offline with hint %d\n",
+			cpu, hwcpu, cede_latency_hint);
+		while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
+			extended_cede_processor(cede_latency_hint);
+			printk(KERN_INFO "cpu %u (hwid %u) returned from cede.\n",
+				cpu, hwcpu);
+			printk(KERN_INFO
+			"Decrementer value = %x Timebase value = %llx\n",
+			get_dec(), get_tb());
+		}
+
+		printk(KERN_INFO "cpu %u (hwid %u) got prodded to go online\n",
+			cpu, hwcpu);
+
+		if (!get_lppaca()->shared_proc)
+			get_lppaca()->donate_dedicated_cpu = 0;
+		get_lppaca()->idle = 0;
+	}
+
+	if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
+		unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
+
+		/*
+		 * NOTE: Calling start_secondary() here for now to
+		 * start new context.
+		 * However, need to do it cleanly by resetting the
+		 * stack pointer.
+		 */
+		start_secondary();
+
+	} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
+
+		set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
+		unregister_slb_shadow(hard_smp_processor_id(),
+					__pa(get_slb_shadow()));
+		rtas_stop_self();
+	}
+
 	/* Should never get here... */
 	BUG();
 	for(;;);
@@ -106,18 +206,43 @@ static int pseries_cpu_disable(void)
 	return 0;
 }
 
+/*
+ * pseries_cpu_die: Wait for the cpu to die.
+ * @cpu: logical processor id of the CPU whose death we're awaiting.
+ *
+ * This function is called from the context of the thread which is performing
+ * the cpu-offline. Here we wait for long enough to allow the cpu in question
+ * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
+ * notifications.
+ *
+ * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
+ * self-destruct.
+ */
 static void pseries_cpu_die(unsigned int cpu)
 {
 	int tries;
-	int cpu_status;
+	int cpu_status = 1;
 	unsigned int pcpu = get_hard_smp_processor_id(cpu);
 
-	for (tries = 0; tries < 25; tries++) {
-		cpu_status = query_cpu_stopped(pcpu);
-		if (cpu_status == 0 || cpu_status == -1)
-			break;
-		cpu_relax();
+	if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
+		cpu_status = 1;
+		for (tries = 0; tries < 1000; tries++) {
+			if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
+				cpu_status = 0;
+				break;
+			}
+			cpu_relax();
+		}
+	} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
+
+		for (tries = 0; tries < 25; tries++) {
+			cpu_status = query_cpu_stopped(pcpu);
+			if (cpu_status == 0 || cpu_status == -1)
+				break;
+			cpu_relax();
+		}
 	}
+
 	if (cpu_status != 0) {
 		printk("Querying DEAD? cpu %i (%i) shows %i\n",
 		       cpu, pcpu, cpu_status);
@@ -252,10 +377,41 @@ static struct notifier_block pseries_smp_nb = {
 	.notifier_call = pseries_smp_notifier,
 };
 
+#define MAX_CEDE_LATENCY_LEVELS		4
+#define	CEDE_LATENCY_PARAM_LENGTH	10
+#define CEDE_LATENCY_PARAM_MAX_LENGTH	\
+	(MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
+#define CEDE_LATENCY_TOKEN		45
+
+static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
+
+static int parse_cede_parameters(void)
+{
+	int call_status;
+
+	memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
+	call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
+				NULL,
+				CEDE_LATENCY_TOKEN,
+				__pa(cede_parameters),
+				CEDE_LATENCY_PARAM_MAX_LENGTH);
+
+	if (call_status != 0)
+		printk(KERN_INFO "CEDE_LATENCY: \
+			%s %s Error calling get-system-parameter(0x%x)\n",
+			__FILE__, __func__, call_status);
+	else
+		printk(KERN_INFO "CEDE_LATENCY: \
+			get-system-parameter successful.\n");
+
+	return call_status;
+}
+
 static int __init pseries_cpu_hotplug_init(void)
 {
 	struct device_node *np;
 	const char *typep;
+	int cpu;
 
 	for_each_node_by_name(np, "interrupt-controller") {
 		typep = of_get_property(np, "compatible", NULL);
@@ -283,8 +439,16 @@ static int __init pseries_cpu_hotplug_init(void)
 	smp_ops->cpu_die = pseries_cpu_die;
 
 	/* Processors can be added/removed only on LPAR */
-	if (firmware_has_feature(FW_FEATURE_LPAR))
+	if (firmware_has_feature(FW_FEATURE_LPAR)) {
 		pSeries_reconfig_notifier_register(&pseries_smp_nb);
+		cpu_maps_update_begin();
+		if (cede_offline_enabled && parse_cede_parameters() == 0) {
+			default_offline_state = CPU_STATE_INACTIVE;
+			for_each_online_cpu(cpu)
+				set_default_offline_state(cpu);
+		}
+		cpu_maps_update_done();
+	}
 
 	return 0;
 }

trunk/arch/powerpc/platforms/pseries/offline_states.h

@@ -0,0 +1,18 @@
+#ifndef _OFFLINE_STATES_H_
+#define _OFFLINE_STATES_H_
+
+/* Cpu offline states go here */
+enum cpu_state_vals {
+	CPU_STATE_OFFLINE,
+	CPU_STATE_INACTIVE,
+	CPU_STATE_ONLINE,
+	CPU_MAX_OFFLINE_STATES
+};
+
+extern enum cpu_state_vals get_cpu_current_state(int cpu);
+extern void set_cpu_current_state(int cpu, enum cpu_state_vals state);
+extern enum cpu_state_vals get_preferred_offline_state(int cpu);
+extern void set_preferred_offline_state(int cpu, enum cpu_state_vals state);
+extern void set_default_offline_state(int cpu);
+extern int start_secondary(void);
+#endif

trunk/arch/powerpc/platforms/pseries/smp.c

@@ -48,6 +48,7 @@
 #include "plpar_wrappers.h"
 #include "pseries.h"
 #include "xics.h"
+#include "offline_states.h"
 
 
 /*
@@ -84,6 +85,9 @@ static inline int __devinit smp_startup_cpu(unsigned int lcpu)
 	/* Fixup atomic count: it exited inside IRQ handler. */
 	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
 
+	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
+		goto out;
+
 	/* 
 	 * If the RTAS start-cpu token does not exist then presume the
 	 * cpu is already spinning.
@@ -98,6 +102,7 @@ static inline int __devinit smp_startup_cpu(unsigned int lcpu)
 		return 0;
 	}
 
+out:
 	return 1;
 }
 
@@ -111,12 +116,16 @@ static void __devinit smp_xics_setup_cpu(int cpu)
 		vpa_init(cpu);
 
 	cpu_clear(cpu, of_spin_map);
+	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
+	set_default_offline_state(cpu);
 
 }
 #endif /* CONFIG_XICS */
 
 static void __devinit smp_pSeries_kick_cpu(int nr)
 {
+	long rc;
+	unsigned long hcpuid;
 	BUG_ON(nr < 0 || nr >= NR_CPUS);
 
 	if (!smp_startup_cpu(nr))
@@ -128,6 +137,16 @@ static void __devinit smp_pSeries_kick_cpu(int nr)
 	 * the processor will continue on to secondary_start
 	 */
 	paca[nr].cpu_start = 1;
+
+	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
+
+	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
+		hcpuid = get_hard_smp_processor_id(nr);
+		rc = plpar_hcall_norets(H_PROD, hcpuid);
+		if (rc != H_SUCCESS)
+			panic("Error: Prod to wake up processor %d Ret= %ld\n",
+				nr, rc);
+	}
 }
 
 static int smp_pSeries_cpu_bootable(unsigned int nr)