// 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 "../../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

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)
{
        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
                 * 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;

        rc = dlpar_attach_node(dn, parent_dn);
        if (rc)
                dlpar_free_cc_nodes(dn);

        pr_debug("added node %pOFfp\n", dn);

        return rc;
}

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 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)
{
        u16 prev = mmu_slb_size;

        slb_set_size(SLB_MIN_SIZE);

        return prev;
}

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;

        ret = wait_for_vasi_session_suspending(handle);
        if (ret)
                return ret;

        ret = pseries_suspend(handle);
        if (ret == 0)
                post_mobility_fixup();
        else
                pseries_cancel_migration(handle, ret);

        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);