[PATCH 0/6 v5] Kernel handling of Dynamic Logical Partitioning

@@ -0,0 +1,414 @@
+/*
+ * dlpar.c - support for dynamic reconfiguration (including PCI
+ * Hotplug and Dynamic Logical Partitioning on RPA platforms).
+ *
+ * Copyright (C) 2009 Nathan Fontenot
+ * Copyright (C) 2009 IBM Corporation
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/notifier.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/uaccess.h>
+#include <asm/rtas.h>
+#include <asm/pSeries_reconfig.h>
+
+#define CFG_CONN_WORK_SIZE	4096
+static char workarea[CFG_CONN_WORK_SIZE];
+static DEFINE_SPINLOCK(workarea_lock);
+
+struct cc_workarea {
+	u32	drc_index;
+	u32	zero;
+	u32	name_offset;
+	u32	prop_length;
+	u32	prop_offset;
+};
+
+static struct property *parse_cc_property(char *workarea)
+{
+	struct property *prop;
+	struct cc_workarea *ccwa;
+	char *name;
+	char *value;
+
+	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+	if (!prop)
+		return NULL;
+
+	ccwa = (struct cc_workarea *)workarea;
+	name = workarea + ccwa->name_offset;
+	prop->name = kzalloc(strlen(name) + 1, GFP_KERNEL);
+	if (!prop->name) {
+		kfree(prop);
+		return NULL;
+	}
+
+	strcpy(prop->name, name);
+
+	prop->length = ccwa->prop_length;
+	value = workarea + ccwa->prop_offset;
+	prop->value = kzalloc(prop->length, GFP_KERNEL);
+	if (!prop->value) {
+		kfree(prop->name);
+		kfree(prop);
+		return NULL;
+	}
+
+	memcpy(prop->value, value, prop->length);
+	return prop;
+}
+
+static void free_property(struct property *prop)
+{
+	kfree(prop->name);
+	kfree(prop->value);
+	kfree(prop);
+}
+
+static struct device_node *parse_cc_node(char *work_area)
+{
+	struct device_node *dn;
+	struct cc_workarea *ccwa;
+	char *name;
+
+	dn = kzalloc(sizeof(*dn), GFP_KERNEL);
+	if (!dn)
+		return NULL;
+
+	ccwa = (struct cc_workarea *)work_area;
+	name = work_area + ccwa->name_offset;
+	dn->full_name = kzalloc(strlen(name) + 1, GFP_KERNEL);
+	if (!dn->full_name) {
+		kfree(dn);
+		return NULL;
+	}
+
+	strcpy(dn->full_name, name);
+	return dn;
+}
+
+static void free_one_cc_node(struct device_node *dn)
+{
+	struct property *prop;
+
+	while (dn->properties) {
+		prop = dn->properties;
+		dn->properties = prop->next;
+		free_property(prop);
+	}
+
+	kfree(dn->full_name);
+	kfree(dn);
+}
+
+static void free_cc_nodes(struct device_node *dn)
+{
+	if (dn->child)
+		free_cc_nodes(dn->child);
+
+	if (dn->sibling)
+		free_cc_nodes(dn->sibling);
+
+	free_one_cc_node(dn);
+}
+
+#define NEXT_SIBLING    1
+#define NEXT_CHILD      2
+#define NEXT_PROPERTY   3
+#define PREV_PARENT     4
+#define MORE_MEMORY     5
+#define CALL_AGAIN	-2
+#define ERR_CFG_USE     -9003
+
+struct device_node *configure_connector(u32 drc_index)
+{
+	struct device_node *dn;
+	struct device_node *first_dn = NULL;
+	struct device_node *last_dn = NULL;
+	struct property *property;
+	struct property *last_property = NULL;
+	struct cc_workarea *ccwa;
+	int cc_token;
+	int rc;
+
+	cc_token = rtas_token("ibm,configure-connector");
+	if (cc_token == RTAS_UNKNOWN_SERVICE)
+		return NULL;
+
+	spin_lock(&workarea_lock);
+
+	ccwa = (struct cc_workarea *)&workarea[0];
+	ccwa->drc_index = drc_index;
+	ccwa->zero = 0;
+
+	rc = rtas_call(cc_token, 2, 1, NULL, workarea, NULL);
+	while (rc) {
+		switch (rc) {
+		case NEXT_SIBLING:
+			dn = parse_cc_node(workarea);
+			if (!dn)
+				goto cc_error;
+
+			dn->parent = last_dn->parent;
+			last_dn->sibling = dn;
+			last_dn = dn;
+			break;
+
+		case NEXT_CHILD:
+			dn = parse_cc_node(workarea);
+			if (!dn)
+				goto cc_error;
+
+			if (!first_dn)
+				first_dn = dn;
+			else {
+				dn->parent = last_dn;
+				if (last_dn)
+					last_dn->child = dn;
+			}
+
+			last_dn = dn;
+			break;
+
+		case NEXT_PROPERTY:
+			property = parse_cc_property(workarea);
+			if (!property)
+				goto cc_error;
+
+			if (!last_dn->properties)
+				last_dn->properties = property;
+			else
+				last_property->next = property;
+
+			last_property = property;
+			break;
+
+		case PREV_PARENT:
+			last_dn = last_dn->parent;
+			break;
+
+		case CALL_AGAIN:
+			break;
+
+		case MORE_MEMORY:
+		case ERR_CFG_USE:
+		default:
+			printk(KERN_ERR "Unexpected Error (%d) "
+			       "returned from configure-connector\n", rc);
+			goto cc_error;
+		}
+
+		rc = rtas_call(cc_token, 2, 1, NULL, workarea, NULL);
+	}
+
+	spin_unlock(&workarea_lock);
+	return first_dn;
+
+cc_error:
+	spin_unlock(&workarea_lock);
+
+	if (first_dn)
+		free_cc_nodes(first_dn);
+
+	return NULL;
+}
+
+static struct device_node *derive_parent(const char *path)
+{
+	struct device_node *parent;
+	char parent_path[128];
+	int parent_path_len;
+
+	parent_path_len = strrchr(path, '/') - path + 1;
+	strlcpy(parent_path, path, parent_path_len);
+
+	parent = of_find_node_by_path(parent_path);
+
+	return parent;
+}
+
+static int add_one_node(struct device_node *dn)
+{
+	struct proc_dir_entry *ent;
+	int rc;
+
+	of_node_set_flag(dn, OF_DYNAMIC);
+	kref_init(&dn->kref);
+	dn->parent = derive_parent(dn->full_name);
+
+	rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
+					  PSERIES_RECONFIG_ADD, dn);
+	if (rc == NOTIFY_BAD) {
+		printk(KERN_ERR "Failed to add device node %s\n",
+		       dn->full_name);
+		return -ENOMEM; /* For now, safe to assume kmalloc failure */
+	}
+
+	of_attach_node(dn);
+
+#ifdef CONFIG_PROC_DEVICETREE
+	ent = proc_mkdir(strrchr(dn->full_name, '/') + 1, dn->parent->pde);
+	if (ent)
+		proc_device_tree_add_node(dn, ent);
+#endif
+
+	of_node_put(dn->parent);
+	return 0;
+}
+
+int add_device_tree_nodes(struct device_node *dn)
+{
+	struct device_node *child = dn->child;
+	struct device_node *sibling = dn->sibling;
+	int rc;
+
+	dn->child = NULL;
+	dn->sibling = NULL;
+	dn->parent = NULL;
+
+	rc = add_one_node(dn);
+	if (rc)
+		return rc;
+
+	if (child) {
+		rc = add_device_tree_nodes(child);
+		if (rc)
+			return rc;
+	}
+
+	if (sibling)
+		rc = add_device_tree_nodes(sibling);
+
+	return rc;
+}
+
+static int remove_one_node(struct device_node *dn)
+{
+	struct device_node *parent = dn->parent;
+	struct property *prop = dn->properties;
+
+#ifdef CONFIG_PROC_DEVICETREE
+	while (prop) {
+		remove_proc_entry(prop->name, dn->pde);
+		prop = prop->next;
+	}
+
+	if (dn->pde)
+		remove_proc_entry(dn->pde->name, parent->pde);
+#endif
+
+	blocking_notifier_call_chain(&pSeries_reconfig_chain,
+			    PSERIES_RECONFIG_REMOVE, dn);
+	of_detach_node(dn);
+	of_node_put(dn); /* Must decrement the refcount */
+
+	return 0;
+}
+
+static int _remove_device_tree_nodes(struct device_node *dn)
+{
+	int rc;
+
+	if (dn->child) {
+		rc = _remove_device_tree_nodes(dn->child);
+		if (rc)
+			return rc;
+	}
+
+	if (dn->sibling) {
+		rc = _remove_device_tree_nodes(dn->sibling);
+		if (rc)
+			return rc;
+	}
+
+	rc = remove_one_node(dn);
+	return rc;
+}
+
+int remove_device_tree_nodes(struct device_node *dn)
+{
+	int rc;
+
+	if (dn->child) {
+		rc = _remove_device_tree_nodes(dn->child);
+		if (rc)
+			return rc;
+	}
+
+	rc = remove_one_node(dn);
+	return rc;
+}
+
+#define DR_ENTITY_SENSE		9003
+#define DR_ENTITY_PRESENT	1
+#define DR_ENTITY_UNUSABLE	2
+#define ALLOCATION_STATE	9003
+#define ALLOC_UNUSABLE		0
+#define ALLOC_USABLE		1
+#define ISOLATION_STATE		9001
+#define ISOLATE			0
+#define UNISOLATE		1
+
+int acquire_drc(u32 drc_index)
+{
+	int dr_status, rc;
+
+	rc = rtas_call(rtas_token("get-sensor-state"), 2, 2, &dr_status,
+		       DR_ENTITY_SENSE, drc_index);
+	if (rc || dr_status != DR_ENTITY_UNUSABLE)
+		return -1;
+
+	rc = rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_USABLE);
+	if (rc)
+		return rc;
+
+	rc = rtas_set_indicator(ISOLATION_STATE, drc_index, UNISOLATE);
+	if (rc) {
+		rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_UNUSABLE);
+		return rc;
+	}
+
+	return 0;
+}
+
+int release_drc(u32 drc_index)
+{
+	int dr_status, rc;
+
+	rc = rtas_call(rtas_token("get-sensor-state"), 2, 2, &dr_status,
+		       DR_ENTITY_SENSE, drc_index);
+	if (rc || dr_status != DR_ENTITY_PRESENT)
+		return -1;
+
+	rc = rtas_set_indicator(ISOLATION_STATE, drc_index, ISOLATE);
+	if (rc)
+		return rc;
+
+	rc = rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_UNUSABLE);
+	if (rc) {
+		rtas_set_indicator(ISOLATION_STATE, drc_index, UNISOLATE);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int pseries_dlpar_init(void)
+{
+	if (!machine_is(pseries))
+		return 0;
+
+	return 0;
+}
+device_initcall(pseries_dlpar_init);

@@ -8,7 +8,7 @@
 
 obj-y			:= lpar.o hvCall.o nvram.o reconfig.o \
 			   setup.o iommu.o ras.o rtasd.o \
-			   firmware.o power.o
+			   firmware.o power.o dlpar.o
 obj-$(CONFIG_SMP)	+= smp.o
 obj-$(CONFIG_XICS)	+= xics.o
 obj-$(CONFIG_SCANLOG)	+= scanlog.o

@@ -17,6 +17,7 @@
 #ifdef CONFIG_PPC_PSERIES
 extern int pSeries_reconfig_notifier_register(struct notifier_block *);
 extern void pSeries_reconfig_notifier_unregister(struct notifier_block *);
+extern struct blocking_notifier_head pSeries_reconfig_chain;
 #else /* !CONFIG_PPC_PSERIES */
 static inline int pSeries_reconfig_notifier_register(struct notifier_block *nb)
 {

@@ -96,7 +96,7 @@
 	return parent;
 }
 
-static BLOCKING_NOTIFIER_HEAD(pSeries_reconfig_chain);
+BLOCKING_NOTIFIER_HEAD(pSeries_reconfig_chain);
 
 int pSeries_reconfig_notifier_register(struct notifier_block *nb)
 {

@@ -349,6 +349,18 @@
  */
 extern void __iomem *of_iomap(struct device_node *device, int index);
 
+struct of_drconf_cell {
+	u64	base_addr;
+	u32	drc_index;
+	u32	reserved;
+	u32	aa_index;
+	u32	flags;
+};
+
+#define DRCONF_MEM_ASSIGNED	0x00000008
+#define DRCONF_MEM_AI_INVALID	0x00000040
+#define DRCONF_MEM_RESERVED	0x00000080
+
 /*
  * NB:  This is here while we transition from using asm/prom.h
  * to linux/of.h

@@ -296,18 +296,6 @@
 	return result;
 }
 
-struct of_drconf_cell {
-	u64	base_addr;
-	u32	drc_index;
-	u32	reserved;
-	u32	aa_index;
-	u32	flags;
-};
-
-#define DRCONF_MEM_ASSIGNED	0x00000008
-#define DRCONF_MEM_AI_INVALID	0x00000040
-#define DRCONF_MEM_RESERVED	0x00000080
-
 /*
  * Read the next lmb list entry from the ibm,dynamic-memory property
  * and return the information in the provided of_drconf_cell structure.

@@ -110,6 +110,26 @@
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+int arch_memory_release(const char *buf, size_t count)
+{
+	if (ppc_md.memory_release)
+		return ppc_md.memory_release(buf, count);
+
+	return -EINVAL;
+}
+#endif
+
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+int arch_memory_probe(u64 phys_addr)
+{
+	if (ppc_md.memory_probe)
+		return ppc_md.memory_probe(phys_addr);
+
+	return -EINVAL;
+}
+#endif
+
 #ifdef CONFIG_NUMA
 int memory_add_physaddr_to_nid(u64 start)
 {

@@ -319,6 +319,10 @@
 
 	phys_addr = simple_strtoull(buf, NULL, 0);
 
+	ret = arch_memory_probe(phys_addr);
+	if (ret)
+		return ret;
+
 	nid = memory_add_physaddr_to_nid(phys_addr);
 	ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
 

@@ -328,19 +332,35 @@
 	return count;
 }
 static CLASS_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
+#endif
 
-static int memory_probe_init(void)
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+static ssize_t
+memory_release_store(struct class *class, const char *buf, size_t count)
 {
-	return sysfs_create_file(&memory_sysdev_class.kset.kobj,
-				&class_attr_probe.attr);
+	return arch_memory_release(buf, count);
 }
-#else
-static inline int memory_probe_init(void)
+static CLASS_ATTR(release, S_IWUSR, NULL, memory_release_store);
+#endif
+
+static int memory_probe_release_init(void)
 {
-	return 0;
-}
+	int rc = 0;
+
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+	rc = sysfs_create_file(&memory_sysdev_class.kset.kobj,
+			       &class_attr_probe.attr);
+#endif
+
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+	if (!rc)
+		rc = sysfs_create_file(&memory_sysdev_class.kset.kobj,
+				       &class_attr_release.attr);
 #endif
 
+	return rc;
+}
+
 /*
  * Note that phys_device is optional.  It is here to allow for
  * differentiation between which *physical* devices each

@@ -470,7 +490,7 @@
 			ret = err;
 	}
 
-	err = memory_probe_init();
+	err = memory_probe_release_init();
 	if (!ret)
 		ret = err;
 	err = block_size_init();

@@ -266,6 +266,14 @@
 	void (*suspend_disable_irqs)(void);
 	void (*suspend_enable_irqs)(void);
 #endif
+
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+	int (*memory_release)(const char *, size_t);
+#endif
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+	int (*memory_probe)(u64);
+#endif
+
 };
 
 extern void e500_idle(void);

@@ -414,6 +414,10 @@
 	def_bool y
 	depends on MEMORY_HOTPLUG
 
+config ARCH_MEMORY_RELEASE
+	def_bool y
+	depends on MEMORY_HOTPLUG
+
 # Some NUMA nodes have memory ranges that span
 # other nodes.  Even though a pfn is valid and
 # between a node's start and end pfns, it may not

@@ -86,6 +86,14 @@
 }
 #endif
 
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+extern int arch_memory_release(const char *, size_t);
+#endif
+
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+extern int arch_memory_probe(u64);
+#endif
+
 #ifdef CONFIG_HAVE_ARCH_NODEDATA_EXTENSION
 /*
  * For supporting node-hotadd, we have to allocate a new pgdat.

@@ -16,6 +16,10 @@
 #include <linux/notifier.h>
 #include <linux/proc_fs.h>
 #include <linux/spinlock.h>
+#include <linux/memory_hotplug.h>
+#include <linux/sysdev.h>
+#include <linux/sysfs.h>
+
 
 #include <asm/prom.h>
 #include <asm/machdep.h>

@@ -404,11 +408,189 @@
 	return 0;
 }
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+
+static struct property *clone_property(struct property *old_prop)
+{
+	struct property *new_prop;
+
+	new_prop = kzalloc((sizeof *new_prop), GFP_KERNEL);
+	if (!new_prop)
+		return NULL;
+
+	new_prop->name = kstrdup(old_prop->name, GFP_KERNEL);
+	new_prop->value = kzalloc(old_prop->length + 1, GFP_KERNEL);
+	if (!new_prop->name || !new_prop->value) {
+		free_property(new_prop);
+		return NULL;
+	}
+
+	memcpy(new_prop->value, old_prop->value, old_prop->length);
+	new_prop->length = old_prop->length;
+
+	return new_prop;
+}
+
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+
+int memory_probe(u64 phys_addr)
+{
+	struct device_node *dn = NULL;
+	struct property *new_prop;
+	struct property *old_prop;
+	struct of_drconf_cell *drmem;
+	const u64 *lmb_size;
+	int num_entries, i;
+	int rc = -EINVAL;
+
+	if (!phys_addr)
+		goto memory_probe_exit;
+
+	dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (!dn)
+		goto memory_probe_exit;
+
+	lmb_size = of_get_property(dn, "ibm,lmb-size", NULL);
+	if (!lmb_size)
+		goto memory_probe_exit;
+
+	old_prop = of_find_property(dn, "ibm,dynamic-memory", NULL);
+	if (!old_prop)
+		goto memory_probe_exit;
+
+	num_entries = *(u32 *)old_prop->value;
+	drmem = (struct of_drconf_cell *)
+				((char *)old_prop->value + sizeof(u32));
+
+	for (i = 0; i < num_entries; i++) {
+		u64 lmb_end_addr = drmem[i].base_addr + *lmb_size;
+		if (phys_addr >= drmem[i].base_addr
+		    && phys_addr < lmb_end_addr)
+			break;
+	}
+
+	if (i >= num_entries)
+		goto memory_probe_exit;
+
+	if (drmem[i].flags & DRCONF_MEM_ASSIGNED) {
+		/* This lmb is already adssigned to the system, nothing to do */
+		rc = 0;
+		goto memory_probe_exit;
+	}
+
+	rc = acquire_drc(drmem[i].drc_index);
+	if (rc) {
+		rc = -EINVAL;
+		goto memory_probe_exit;
+	}
+
+	new_prop = clone_property(old_prop);
+	drmem = (struct of_drconf_cell *)
+				((char *)new_prop->value + sizeof(u32));
+
+	drmem[i].flags |= DRCONF_MEM_ASSIGNED;
+	rc = prom_update_property(dn, new_prop, old_prop);
+	if (rc) {
+		free_property(new_prop);
+		rc = -EINVAL;
+		goto memory_probe_exit;
+	}
+
+	rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
+					  PSERIES_DRCONF_MEM_ADD,
+					  &drmem[i].base_addr);
+	if (rc == NOTIFY_BAD) {
+		prom_update_property(dn, old_prop, new_prop);
+		release_drc(drmem[i].drc_index);
+		rc = -EINVAL;
+	} else
+		rc = 0;
+
+memory_probe_exit:
+	of_node_put(dn);
+	return rc;
+}
+
+#endif /* CONFIG_ARCH_MEMORY_PROBE */
+
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+
+static int memory_release(const char *buf, size_t count)
+{
+	unsigned long drc_index;
+	struct device_node *dn;
+	struct property *new_prop, *old_prop;
+	struct of_drconf_cell *drmem;
+	int num_entries;
+	int i;
+	int rc = -EINVAL;
+
+	rc = strict_strtoul(buf, 0, &drc_index);
+	if (rc)
+		return rc;
+
+	dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (!dn)
+		return rc;
+
+	old_prop = of_find_property(dn, "ibm,dynamic-memory", NULL);
+	if (!old_prop)
+		goto memory_release_exit;
+
+	num_entries = *(u32 *)old_prop->value;
+	drmem = (struct of_drconf_cell *)
+				((char *)old_prop->value + sizeof(u32));
+
+	for (i = 0; i < num_entries; i++) {
+		if (drmem[i].drc_index == drc_index)
+			break;
+	}
+
+	if (i >= num_entries)
+		goto memory_release_exit;
+
+	new_prop = clone_property(old_prop);
+	drmem = (struct of_drconf_cell *)
+				((char *)new_prop->value + sizeof(u32));
+
+	drmem[i].flags &= ~DRCONF_MEM_ASSIGNED;
+	rc = prom_update_property(dn, new_prop, old_prop);
+	if (rc) {
+		free_property(new_prop);
+		rc = -EINVAL;
+		goto memory_release_exit;
+	}
+
+	rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
+					  PSERIES_DRCONF_MEM_REMOVE,
+					  &drmem[i].base_addr);
+	if (rc != NOTIFY_BAD)
+		rc = release_drc(drc_index);
+
+	if (rc) {
+		prom_update_property(dn, old_prop, new_prop);
+		rc = -EINVAL;
+	}
+
+memory_release_exit:
+	of_node_put(dn);
+	return rc ? rc : count;
+}
+#endif /* CONFIG_ARCH_MEMORY_RELEASE */
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
 static int pseries_dlpar_init(void)
 {
 	if (!machine_is(pseries))
 		return 0;
 
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+	ppc_md.memory_release = memory_release;
+#endif
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+	ppc_md.memory_probe = memory_probe;
+#endif
+
 	return 0;
 }
 device_initcall(pseries_dlpar_init);

@@ -54,6 +54,7 @@
 		ret = count;
 	return ret;
 }
+
 static SYSDEV_ATTR(online, 0644, show_online, store_online);
 
 static void __cpuinit register_cpu_control(struct cpu *cpu)

@@ -72,6 +73,38 @@
 	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
 	return;
 }
+
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+static ssize_t cpu_probe_store(struct class *class, const char *buf,
+			       size_t count)
+{
+	return arch_cpu_probe(buf, count);
+}
+
+static ssize_t cpu_release_store(struct class *class, const char *buf,
+				 size_t count)
+{
+	return arch_cpu_release(buf, count);
+}
+
+static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
+static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
+
+int __init cpu_probe_release_init(void)
+{
+	int rc;
+
+	rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+			       &class_attr_probe.attr);
+	if (!rc)
+		rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+				       &class_attr_release.attr);
+
+	return rc;
+}
+device_initcall(cpu_probe_release_init);
+#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
+
 #else /* ... !CONFIG_HOTPLUG_CPU */
 static inline void register_cpu_control(struct cpu *cpu)
 {

@@ -274,6 +274,11 @@
 	int (*memory_probe)(u64);
 #endif
 
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+	ssize_t (*cpu_probe)(const char *, size_t);
+	ssize_t (*cpu_release)(const char *, size_t);
+#endif
+
 };
 
 extern void e500_idle(void);

@@ -461,6 +461,25 @@
 
 	cacheinfo_cpu_offline(cpu);
 }
+
+#ifdef CONFIG_ARCH_PROBE_RELEASE
+ssize_t arch_cpu_probe(const char *buf, size_t count)
+{
+	if (ppc_md.cpu_probe)
+		return ppc_md.cpu_probe(buf, count);
+
+	return -EINVAL;
+}
+
+ssize_t arch_cpu_release(const char *buf, size_t count)
+{
+	if (ppc_md.cpu_release)
+		return ppc_md.cpu_release(buf, count);
+
+	return -EINVAL;
+}
+#endif /* CONFIG_ARCH_PROBE_RELEASE */
+
 #endif /* CONFIG_HOTPLUG_CPU */
 
 static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,

@@ -320,6 +320,10 @@
 
 	  Say N if you are unsure.
 
+config ARCH_CPU_PROBE_RELEASE
+	def_bool y
+	depends on HOTPLUG_CPU
+
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 

@@ -43,6 +43,10 @@
 
 #ifdef CONFIG_HOTPLUG_CPU
 extern void unregister_cpu(struct cpu *cpu);
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+extern ssize_t arch_cpu_probe(const char *, size_t);
+extern ssize_t arch_cpu_release(const char *, size_t);
+#endif
 #endif
 
 struct notifier_block;

@@ -364,7 +364,24 @@
 	set_cpu_online(cpu, true);
 	local_irq_enable();
 }
+
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+ssize_t arch_cpu_probe(const char *buf, size_t count)
+{
+	if (ppc_md.cpu_probe)
+		return ppc_md.cpu_probe(buf, count);
+
+	return -EINVAL;
+}
+ssize_t arch_cpu_release(const char *buf, size_t count)
+{
+	if (ppc_md.cpu_release)
+		return ppc_md.cpu_release(buf, count);
+
+	return -EINVAL;
+}
 #endif
+#endif /* CONFIG_HOTPLUG_CPU */
 
 static int __devinit cpu_enable(unsigned int cpu)
 {

@@ -1,11 +1,10 @@
 /*
- * dlpar.c - support for dynamic reconfiguration (including PCI
- * Hotplug and Dynamic Logical Partitioning on RPA platforms).
+ * Support for dynamic reconfiguration (including PCI, Memory, and CPU
+ * Hotplug and Dynamic Logical Partitioning on PAPR platforms).
  *
  * Copyright (C) 2009 Nathan Fontenot
  * Copyright (C) 2009 IBM Corporation
  *
- *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version
  * 2 as published by the Free Software Foundation.

@@ -19,7 +18,7 @@
 #include <linux/memory_hotplug.h>
 #include <linux/sysdev.h>
 #include <linux/sysfs.h>
-
+#include <linux/cpu.h>
 
 #include <asm/prom.h>
 #include <asm/machdep.h>

@@ -408,6 +407,80 @@
 	return 0;
 }
 
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+static ssize_t cpu_probe(const char *buf, size_t count)
+{
+	struct device_node *dn;
+	unsigned long drc_index;
+	char *cpu_name;
+	int rc;
+
+	rc = strict_strtoul(buf, 0, &drc_index);
+	if (rc)
+		return -EINVAL;
+
+	rc = acquire_drc(drc_index);
+	if (rc)
+		return -EINVAL;
+
+	dn = configure_connector(drc_index);
+	if (!dn) {
+		release_drc(drc_index);
+		return -EINVAL;
+	}
+
+	/* fixup dn name */
+	cpu_name = kzalloc(strlen(dn->full_name) + strlen("/cpus/") + 1,
+			   GFP_KERNEL);
+	if (!cpu_name) {
+		free_cc_nodes(dn);
+		release_drc(drc_index);
+		return -ENOMEM;
+	}
+
+	sprintf(cpu_name, "/cpus/%s", dn->full_name);
+	kfree(dn->full_name);
+	dn->full_name = cpu_name;
+
+	rc = add_device_tree_nodes(dn);
+	if (rc)
+		release_drc(drc_index);
+
+	return rc ? -EINVAL : count;
+}
+
+static ssize_t cpu_release(const char *buf, size_t count)
+{
+	struct device_node *dn;
+	const u32 *drc_index;
+	int rc;
+
+	dn = of_find_node_by_path(buf);
+	if (!dn)
+		return -EINVAL;
+
+	drc_index = of_get_property(dn, "ibm,my-drc-index", NULL);
+	if (!drc_index) {
+		of_node_put(dn);
+		return -EINVAL;
+	}
+
+	rc = release_drc(*drc_index);
+	if (rc) {
+		of_node_put(dn);
+		return -EINVAL;
+	}
+
+	rc = remove_device_tree_nodes(dn);
+	if (rc)
+		acquire_drc(*drc_index);
+
+	of_node_put(dn);
+	return rc ? -EINVAL : count;
+}
+
+#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 
 static struct property *clone_property(struct property *old_prop)

@@ -591,6 +664,11 @@
 	ppc_md.memory_probe = memory_probe;
 #endif
 
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+	ppc_md.cpu_release = cpu_release;
+	ppc_md.cpu_probe = cpu_probe;
+#endif
+
 	return 0;
 }
 device_initcall(pseries_dlpar_init);