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 // 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
          * 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
     ret = wait_for_vasi_session_suspending(handle);
     if (ret)
         return ret;
 
     vas_migration_handler(VAS_SUSPEND);
 
     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);
 
     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);

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