Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 834 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
new file mode 100644
index 000000000..634fac5db
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -0,0 +1,834 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Support for Partition Mobility/Migration
+ *
+ * Copyright (C) 2010 Nathan Fontenot
+ * Copyright (C) 2010 IBM Corporation
+ */
+
+
+#define pr_fmt(fmt) "mobility: " fmt
+
+#include <linux/cpu.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/nmi.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/stat.h>
+#include <linux/stop_machine.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/stringify.h>
+
+#include <asm/machdep.h>
+#include <asm/rtas.h>
+#include "pseries.h"
+#include "vas.h"	/* vas_migration_handler() */
+#include "../../kernel/cacheinfo.h"
+
+static struct kobject *mobility_kobj;
+
+struct update_props_workarea {
+	__be32 phandle;
+	__be32 state;
+	__be64 reserved;
+	__be32 nprops;
+} __packed;
+
+#define NODE_ACTION_MASK	0xff000000
+#define NODE_COUNT_MASK		0x00ffffff
+
+#define DELETE_DT_NODE	0x01000000
+#define UPDATE_DT_NODE	0x02000000
+#define ADD_DT_NODE	0x03000000
+
+#define MIGRATION_SCOPE	(1)
+#define PRRN_SCOPE -2
+
+#ifdef CONFIG_PPC_WATCHDOG
+static unsigned int nmi_wd_lpm_factor = 200;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table nmi_wd_lpm_factor_ctl_table[] = {
+	{
+		.procname	= "nmi_wd_lpm_factor",
+		.data		= &nmi_wd_lpm_factor,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_douintvec_minmax,
+	},
+	{}
+};
+static struct ctl_table nmi_wd_lpm_factor_sysctl_root[] = {
+	{
+		.procname       = "kernel",
+		.mode           = 0555,
+		.child          = nmi_wd_lpm_factor_ctl_table,
+	},
+	{}
+};
+
+static int __init register_nmi_wd_lpm_factor_sysctl(void)
+{
+	register_sysctl_table(nmi_wd_lpm_factor_sysctl_root);
+
+	return 0;
+}
+device_initcall(register_nmi_wd_lpm_factor_sysctl);
+#endif /* CONFIG_SYSCTL */
+#endif /* CONFIG_PPC_WATCHDOG */
+
+static int mobility_rtas_call(int token, char *buf, s32 scope)
+{
+	int rc;
+
+	spin_lock(&rtas_data_buf_lock);
+
+	memcpy(rtas_data_buf, buf, RTAS_DATA_BUF_SIZE);
+	rc = rtas_call(token, 2, 1, NULL, rtas_data_buf, scope);
+	memcpy(buf, rtas_data_buf, RTAS_DATA_BUF_SIZE);
+
+	spin_unlock(&rtas_data_buf_lock);
+	return rc;
+}
+
+static int delete_dt_node(struct device_node *dn)
+{
+	struct device_node *pdn;
+	bool is_platfac;
+
+	pdn = of_get_parent(dn);
+	is_platfac = of_node_is_type(dn, "ibm,platform-facilities") ||
+		     of_node_is_type(pdn, "ibm,platform-facilities");
+	of_node_put(pdn);
+
+	/*
+	 * The drivers that bind to nodes in the platform-facilities
+	 * hierarchy don't support node removal, and the removal directive
+	 * from firmware is always followed by an add of an equivalent
+	 * node. The capability (e.g. RNG, encryption, compression)
+	 * represented by the node is never interrupted by the migration.
+	 * So ignore changes to this part of the tree.
+	 */
+	if (is_platfac) {
+		pr_notice("ignoring remove operation for %pOFfp\n", dn);
+		return 0;
+	}
+
+	pr_debug("removing node %pOFfp\n", dn);
+	dlpar_detach_node(dn);
+	return 0;
+}
+
+static int update_dt_property(struct device_node *dn, struct property **prop,
+			      const char *name, u32 vd, char *value)
+{
+	struct property *new_prop = *prop;
+	int more = 0;
+
+	/* A negative 'vd' value indicates that only part of the new property
+	 * value is contained in the buffer and we need to call
+	 * ibm,update-properties again to get the rest of the value.
+	 *
+	 * A negative value is also the two's compliment of the actual value.
+	 */
+	if (vd & 0x80000000) {
+		vd = ~vd + 1;
+		more = 1;
+	}
+
+	if (new_prop) {
+		/* partial property fixup */
+		char *new_data = kzalloc(new_prop->length + vd, GFP_KERNEL);
+		if (!new_data)
+			return -ENOMEM;
+
+		memcpy(new_data, new_prop->value, new_prop->length);
+		memcpy(new_data + new_prop->length, value, vd);
+
+		kfree(new_prop->value);
+		new_prop->value = new_data;
+		new_prop->length += vd;
+	} else {
+		new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
+		if (!new_prop)
+			return -ENOMEM;
+
+		new_prop->name = kstrdup(name, GFP_KERNEL);
+		if (!new_prop->name) {
+			kfree(new_prop);
+			return -ENOMEM;
+		}
+
+		new_prop->length = vd;
+		new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
+		if (!new_prop->value) {
+			kfree(new_prop->name);
+			kfree(new_prop);
+			return -ENOMEM;
+		}
+
+		memcpy(new_prop->value, value, vd);
+		*prop = new_prop;
+	}
+
+	if (!more) {
+		pr_debug("updating node %pOF property %s\n", dn, name);
+		of_update_property(dn, new_prop);
+		*prop = NULL;
+	}
+
+	return 0;
+}
+
+static int update_dt_node(struct device_node *dn, s32 scope)
+{
+	struct update_props_workarea *upwa;
+	struct property *prop = NULL;
+	int i, rc, rtas_rc;
+	char *prop_data;
+	char *rtas_buf;
+	int update_properties_token;
+	u32 nprops;
+	u32 vd;
+
+	update_properties_token = rtas_token("ibm,update-properties");
+	if (update_properties_token == RTAS_UNKNOWN_SERVICE)
+		return -EINVAL;
+
+	rtas_buf = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
+	if (!rtas_buf)
+		return -ENOMEM;
+
+	upwa = (struct update_props_workarea *)&rtas_buf[0];
+	upwa->phandle = cpu_to_be32(dn->phandle);
+
+	do {
+		rtas_rc = mobility_rtas_call(update_properties_token, rtas_buf,
+					scope);
+		if (rtas_rc < 0)
+			break;
+
+		prop_data = rtas_buf + sizeof(*upwa);
+		nprops = be32_to_cpu(upwa->nprops);
+
+		/* On the first call to ibm,update-properties for a node the
+		 * first property value descriptor contains an empty
+		 * property name, the property value length encoded as u32,
+		 * and the property value is the node path being updated.
+		 */
+		if (*prop_data == 0) {
+			prop_data++;
+			vd = be32_to_cpu(*(__be32 *)prop_data);
+			prop_data += vd + sizeof(vd);
+			nprops--;
+		}
+
+		for (i = 0; i < nprops; i++) {
+			char *prop_name;
+
+			prop_name = prop_data;
+			prop_data += strlen(prop_name) + 1;
+			vd = be32_to_cpu(*(__be32 *)prop_data);
+			prop_data += sizeof(vd);
+
+			switch (vd) {
+			case 0x00000000:
+				/* name only property, nothing to do */
+				break;
+
+			case 0x80000000:
+				of_remove_property(dn, of_find_property(dn,
+							prop_name, NULL));
+				prop = NULL;
+				break;
+
+			default:
+				rc = update_dt_property(dn, &prop, prop_name,
+							vd, prop_data);
+				if (rc) {
+					pr_err("updating %s property failed: %d\n",
+					       prop_name, rc);
+				}
+
+				prop_data += vd;
+				break;
+			}
+
+			cond_resched();
+		}
+
+		cond_resched();
+	} while (rtas_rc == 1);
+
+	kfree(rtas_buf);
+	return 0;
+}
+
+static int add_dt_node(struct device_node *parent_dn, __be32 drc_index)
+{
+	struct device_node *dn;
+	int rc;
+
+	dn = dlpar_configure_connector(drc_index, parent_dn);
+	if (!dn)
+		return -ENOENT;
+
+	/*
+	 * Since delete_dt_node() ignores this node type, this is the
+	 * necessary counterpart. We also know that a platform-facilities
+	 * node returned from dlpar_configure_connector() has children
+	 * attached, and dlpar_attach_node() only adds the parent, leaking
+	 * the children. So ignore these on the add side for now.
+	 */
+	if (of_node_is_type(dn, "ibm,platform-facilities")) {
+		pr_notice("ignoring add operation for %pOF\n", dn);
+		dlpar_free_cc_nodes(dn);
+		return 0;
+	}
+
+	rc = dlpar_attach_node(dn, parent_dn);
+	if (rc)
+		dlpar_free_cc_nodes(dn);
+
+	pr_debug("added node %pOFfp\n", dn);
+
+	return rc;
+}
+
+static int pseries_devicetree_update(s32 scope)
+{
+	char *rtas_buf;
+	__be32 *data;
+	int update_nodes_token;
+	int rc;
+
+	update_nodes_token = rtas_token("ibm,update-nodes");
+	if (update_nodes_token == RTAS_UNKNOWN_SERVICE)
+		return 0;
+
+	rtas_buf = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
+	if (!rtas_buf)
+		return -ENOMEM;
+
+	do {
+		rc = mobility_rtas_call(update_nodes_token, rtas_buf, scope);
+		if (rc && rc != 1)
+			break;
+
+		data = (__be32 *)rtas_buf + 4;
+		while (be32_to_cpu(*data) & NODE_ACTION_MASK) {
+			int i;
+			u32 action = be32_to_cpu(*data) & NODE_ACTION_MASK;
+			u32 node_count = be32_to_cpu(*data) & NODE_COUNT_MASK;
+
+			data++;
+
+			for (i = 0; i < node_count; i++) {
+				struct device_node *np;
+				__be32 phandle = *data++;
+				__be32 drc_index;
+
+				np = of_find_node_by_phandle(be32_to_cpu(phandle));
+				if (!np) {
+					pr_warn("Failed lookup: phandle 0x%x for action 0x%x\n",
+						be32_to_cpu(phandle), action);
+					continue;
+				}
+
+				switch (action) {
+				case DELETE_DT_NODE:
+					delete_dt_node(np);
+					break;
+				case UPDATE_DT_NODE:
+					update_dt_node(np, scope);
+					break;
+				case ADD_DT_NODE:
+					drc_index = *data++;
+					add_dt_node(np, drc_index);
+					break;
+				}
+
+				of_node_put(np);
+				cond_resched();
+			}
+		}
+
+		cond_resched();
+	} while (rc == 1);
+
+	kfree(rtas_buf);
+	return rc;
+}
+
+void post_mobility_fixup(void)
+{
+	int rc;
+
+	rtas_activate_firmware();
+
+	/*
+	 * We don't want CPUs to go online/offline while the device
+	 * tree is being updated.
+	 */
+	cpus_read_lock();
+
+	/*
+	 * It's common for the destination firmware to replace cache
+	 * nodes.  Release all of the cacheinfo hierarchy's references
+	 * before updating the device tree.
+	 */
+	cacheinfo_teardown();
+
+	rc = pseries_devicetree_update(MIGRATION_SCOPE);
+	if (rc)
+		pr_err("device tree update failed: %d\n", rc);
+
+	cacheinfo_rebuild();
+
+	cpus_read_unlock();
+
+	/* Possibly switch to a new L1 flush type */
+	pseries_setup_security_mitigations();
+
+	/* Reinitialise system information for hv-24x7 */
+	read_24x7_sys_info();
+
+	return;
+}
+
+static int poll_vasi_state(u64 handle, unsigned long *res)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+	long hvrc;
+	int ret;
+
+	hvrc = plpar_hcall(H_VASI_STATE, retbuf, handle);
+	switch (hvrc) {
+	case H_SUCCESS:
+		ret = 0;
+		*res = retbuf[0];
+		break;
+	case H_PARAMETER:
+		ret = -EINVAL;
+		break;
+	case H_FUNCTION:
+		ret = -EOPNOTSUPP;
+		break;
+	case H_HARDWARE:
+	default:
+		pr_err("unexpected H_VASI_STATE result %ld\n", hvrc);
+		ret = -EIO;
+		break;
+	}
+	return ret;
+}
+
+static int wait_for_vasi_session_suspending(u64 handle)
+{
+	unsigned long state;
+	int ret;
+
+	/*
+	 * Wait for transition from H_VASI_ENABLED to
+	 * H_VASI_SUSPENDING. Treat anything else as an error.
+	 */
+	while (true) {
+		ret = poll_vasi_state(handle, &state);
+
+		if (ret != 0 || state == H_VASI_SUSPENDING) {
+			break;
+		} else if (state == H_VASI_ENABLED) {
+			ssleep(1);
+		} else {
+			pr_err("unexpected H_VASI_STATE result %lu\n", state);
+			ret = -EIO;
+			break;
+		}
+	}
+
+	/*
+	 * Proceed even if H_VASI_STATE is unavailable. If H_JOIN or
+	 * ibm,suspend-me are also unimplemented, we'll recover then.
+	 */
+	if (ret == -EOPNOTSUPP)
+		ret = 0;
+
+	return ret;
+}
+
+static void wait_for_vasi_session_completed(u64 handle)
+{
+	unsigned long state = 0;
+	int ret;
+
+	pr_info("waiting for memory transfer to complete...\n");
+
+	/*
+	 * Wait for transition from H_VASI_RESUMED to H_VASI_COMPLETED.
+	 */
+	while (true) {
+		ret = poll_vasi_state(handle, &state);
+
+		/*
+		 * If the memory transfer is already complete and the migration
+		 * has been cleaned up by the hypervisor, H_PARAMETER is return,
+		 * which is translate in EINVAL by poll_vasi_state().
+		 */
+		if (ret == -EINVAL || (!ret && state == H_VASI_COMPLETED)) {
+			pr_info("memory transfer completed.\n");
+			break;
+		}
+
+		if (ret) {
+			pr_err("H_VASI_STATE return error (%d)\n", ret);
+			break;
+		}
+
+		if (state != H_VASI_RESUMED) {
+			pr_err("unexpected H_VASI_STATE result %lu\n", state);
+			break;
+		}
+
+		msleep(500);
+	}
+}
+
+static void prod_single(unsigned int target_cpu)
+{
+	long hvrc;
+	int hwid;
+
+	hwid = get_hard_smp_processor_id(target_cpu);
+	hvrc = plpar_hcall_norets(H_PROD, hwid);
+	if (hvrc == H_SUCCESS)
+		return;
+	pr_err_ratelimited("H_PROD of CPU %u (hwid %d) error: %ld\n",
+			   target_cpu, hwid, hvrc);
+}
+
+static void prod_others(void)
+{
+	unsigned int cpu;
+
+	for_each_online_cpu(cpu) {
+		if (cpu != smp_processor_id())
+			prod_single(cpu);
+	}
+}
+
+static u16 clamp_slb_size(void)
+{
+#ifdef CONFIG_PPC_64S_HASH_MMU
+	u16 prev = mmu_slb_size;
+
+	slb_set_size(SLB_MIN_SIZE);
+
+	return prev;
+#else
+	return 0;
+#endif
+}
+
+static int do_suspend(void)
+{
+	u16 saved_slb_size;
+	int status;
+	int ret;
+
+	pr_info("calling ibm,suspend-me on CPU %i\n", smp_processor_id());
+
+	/*
+	 * The destination processor model may have fewer SLB entries
+	 * than the source. We reduce mmu_slb_size to a safe minimum
+	 * before suspending in order to minimize the possibility of
+	 * programming non-existent entries on the destination. If
+	 * suspend fails, we restore it before returning. On success
+	 * the OF reconfig path will update it from the new device
+	 * tree after resuming on the destination.
+	 */
+	saved_slb_size = clamp_slb_size();
+
+	ret = rtas_ibm_suspend_me(&status);
+	if (ret != 0) {
+		pr_err("ibm,suspend-me error: %d\n", status);
+		slb_set_size(saved_slb_size);
+	}
+
+	return ret;
+}
+
+/**
+ * struct pseries_suspend_info - State shared between CPUs for join/suspend.
+ * @counter: Threads are to increment this upon resuming from suspend
+ *           or if an error is received from H_JOIN. The thread which performs
+ *           the first increment (i.e. sets it to 1) is responsible for
+ *           waking the other threads.
+ * @done: False if join/suspend is in progress. True if the operation is
+ *        complete (successful or not).
+ */
+struct pseries_suspend_info {
+	atomic_t counter;
+	bool done;
+};
+
+static int do_join(void *arg)
+{
+	struct pseries_suspend_info *info = arg;
+	atomic_t *counter = &info->counter;
+	long hvrc;
+	int ret;
+
+retry:
+	/* Must ensure MSR.EE off for H_JOIN. */
+	hard_irq_disable();
+	hvrc = plpar_hcall_norets(H_JOIN);
+
+	switch (hvrc) {
+	case H_CONTINUE:
+		/*
+		 * All other CPUs are offline or in H_JOIN. This CPU
+		 * attempts the suspend.
+		 */
+		ret = do_suspend();
+		break;
+	case H_SUCCESS:
+		/*
+		 * The suspend is complete and this cpu has received a
+		 * prod, or we've received a stray prod from unrelated
+		 * code (e.g. paravirt spinlocks) and we need to join
+		 * again.
+		 *
+		 * This barrier orders the return from H_JOIN above vs
+		 * the load of info->done. It pairs with the barrier
+		 * in the wakeup/prod path below.
+		 */
+		smp_mb();
+		if (READ_ONCE(info->done) == false) {
+			pr_info_ratelimited("premature return from H_JOIN on CPU %i, retrying",
+					    smp_processor_id());
+			goto retry;
+		}
+		ret = 0;
+		break;
+	case H_BAD_MODE:
+	case H_HARDWARE:
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("H_JOIN error %ld on CPU %i\n",
+				   hvrc, smp_processor_id());
+		break;
+	}
+
+	if (atomic_inc_return(counter) == 1) {
+		pr_info("CPU %u waking all threads\n", smp_processor_id());
+		WRITE_ONCE(info->done, true);
+		/*
+		 * This barrier orders the store to info->done vs subsequent
+		 * H_PRODs to wake the other CPUs. It pairs with the barrier
+		 * in the H_SUCCESS case above.
+		 */
+		smp_mb();
+		prod_others();
+	}
+	/*
+	 * Execution may have been suspended for several seconds, so
+	 * reset the watchdog.
+	 */
+	touch_nmi_watchdog();
+	return ret;
+}
+
+/*
+ * Abort reason code byte 0. We use only the 'Migrating partition' value.
+ */
+enum vasi_aborting_entity {
+	ORCHESTRATOR        = 1,
+	VSP_SOURCE          = 2,
+	PARTITION_FIRMWARE  = 3,
+	PLATFORM_FIRMWARE   = 4,
+	VSP_TARGET          = 5,
+	MIGRATING_PARTITION = 6,
+};
+
+static void pseries_cancel_migration(u64 handle, int err)
+{
+	u32 reason_code;
+	u32 detail;
+	u8 entity;
+	long hvrc;
+
+	entity = MIGRATING_PARTITION;
+	detail = abs(err) & 0xffffff;
+	reason_code = (entity << 24) | detail;
+
+	hvrc = plpar_hcall_norets(H_VASI_SIGNAL, handle,
+				  H_VASI_SIGNAL_CANCEL, reason_code);
+	if (hvrc)
+		pr_err("H_VASI_SIGNAL error: %ld\n", hvrc);
+}
+
+static int pseries_suspend(u64 handle)
+{
+	const unsigned int max_attempts = 5;
+	unsigned int retry_interval_ms = 1;
+	unsigned int attempt = 1;
+	int ret;
+
+	while (true) {
+		struct pseries_suspend_info info;
+		unsigned long vasi_state;
+		int vasi_err;
+
+		info = (struct pseries_suspend_info) {
+			.counter = ATOMIC_INIT(0),
+			.done = false,
+		};
+
+		ret = stop_machine(do_join, &info, cpu_online_mask);
+		if (ret == 0)
+			break;
+		/*
+		 * Encountered an error. If the VASI stream is still
+		 * in Suspending state, it's likely a transient
+		 * condition related to some device in the partition
+		 * and we can retry in the hope that the cause has
+		 * cleared after some delay.
+		 *
+		 * A better design would allow drivers etc to prepare
+		 * for the suspend and avoid conditions which prevent
+		 * the suspend from succeeding. For now, we have this
+		 * mitigation.
+		 */
+		pr_notice("Partition suspend attempt %u of %u error: %d\n",
+			  attempt, max_attempts, ret);
+
+		if (attempt == max_attempts)
+			break;
+
+		vasi_err = poll_vasi_state(handle, &vasi_state);
+		if (vasi_err == 0) {
+			if (vasi_state != H_VASI_SUSPENDING) {
+				pr_notice("VASI state %lu after failed suspend\n",
+					  vasi_state);
+				break;
+			}
+		} else if (vasi_err != -EOPNOTSUPP) {
+			pr_err("VASI state poll error: %d", vasi_err);
+			break;
+		}
+
+		pr_notice("Will retry partition suspend after %u ms\n",
+			  retry_interval_ms);
+
+		msleep(retry_interval_ms);
+		retry_interval_ms *= 10;
+		attempt++;
+	}
+
+	return ret;
+}
+
+static int pseries_migrate_partition(u64 handle)
+{
+	int ret;
+	unsigned int factor = 0;
+
+#ifdef CONFIG_PPC_WATCHDOG
+	factor = nmi_wd_lpm_factor;
+#endif
+	/*
+	 * When the migration is initiated, the hypervisor changes VAS
+	 * mappings to prepare before OS gets the notification and
+	 * closes all VAS windows. NX generates continuous faults during
+	 * this time and the user space can not differentiate these
+	 * faults from the migration event. So reduce this time window
+	 * by closing VAS windows at the beginning of this function.
+	 */
+	vas_migration_handler(VAS_SUSPEND);
+
+	ret = wait_for_vasi_session_suspending(handle);
+	if (ret)
+		goto out;
+
+	if (factor)
+		watchdog_nmi_set_timeout_pct(factor);
+
+	ret = pseries_suspend(handle);
+	if (ret == 0) {
+		post_mobility_fixup();
+		/*
+		 * Wait until the memory transfer is complete, so that the user
+		 * space process returns from the syscall after the transfer is
+		 * complete. This allows the user hooks to be executed at the
+		 * right time.
+		 */
+		wait_for_vasi_session_completed(handle);
+	} else
+		pseries_cancel_migration(handle, ret);
+
+	if (factor)
+		watchdog_nmi_set_timeout_pct(0);
+
+out:
+	vas_migration_handler(VAS_RESUME);
+
+	return ret;
+}
+
+int rtas_syscall_dispatch_ibm_suspend_me(u64 handle)
+{
+	return pseries_migrate_partition(handle);
+}
+
+static ssize_t migration_store(struct class *class,
+			       struct class_attribute *attr, const char *buf,
+			       size_t count)
+{
+	u64 streamid;
+	int rc;
+
+	rc = kstrtou64(buf, 0, &streamid);
+	if (rc)
+		return rc;
+
+	rc = pseries_migrate_partition(streamid);
+	if (rc)
+		return rc;
+
+	return count;
+}
+
+/*
+ * Used by drmgr to determine the kernel behavior of the migration interface.
+ *
+ * Version 1: Performs all PAPR requirements for migration including
+ *	firmware activation and device tree update.
+ */
+#define MIGRATION_API_VERSION	1
+
+static CLASS_ATTR_WO(migration);
+static CLASS_ATTR_STRING(api_version, 0444, __stringify(MIGRATION_API_VERSION));
+
+static int __init mobility_sysfs_init(void)
+{
+	int rc;
+
+	mobility_kobj = kobject_create_and_add("mobility", kernel_kobj);
+	if (!mobility_kobj)
+		return -ENOMEM;
+
+	rc = sysfs_create_file(mobility_kobj, &class_attr_migration.attr);
+	if (rc)
+		pr_err("unable to create migration sysfs file (%d)\n", rc);
+
+	rc = sysfs_create_file(mobility_kobj, &class_attr_api_version.attr.attr);
+	if (rc)
+		pr_err("unable to create api_version sysfs file (%d)\n", rc);
+
+	return 0;
+}
+machine_device_initcall(pseries, mobility_sysfs_init);