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

   1 /*
   2  * pseries CPU Hotplug infrastructure.
   3  *
   4  * Split out from arch/powerpc/platforms/pseries/setup.c
   5  *  arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
   6  *
   7  * Peter Bergner, IBM   March 2001.
   8  * Copyright (C) 2001 IBM.
   9  * Dave Engebretsen, Peter Bergner, and
  10  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
  11  * Plus various changes from other IBM teams...
  12  *
  13  * Copyright (C) 2006 Michael Ellerman, IBM Corporation
  14  *
  15  *      This program is free software; you can redistribute it and/or
  16  *      modify it under the terms of the GNU General Public License
  17  *      as published by the Free Software Foundation; either version
  18  *      2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/delay.h>
  23 #include <linux/cpu.h>
  24 #include <asm/system.h>
  25 #include <asm/prom.h>
  26 #include <asm/rtas.h>
  27 #include <asm/firmware.h>
  28 #include <asm/machdep.h>
  29 #include <asm/vdso_datapage.h>
  30 #include <asm/pSeries_reconfig.h>
  31 #include "xics.h"
  32 #include "plpar_wrappers.h"
  33
  34 /* This version can't take the spinlock, because it never returns */
  35 static struct rtas_args rtas_stop_self_args = {
  36         .token = RTAS_UNKNOWN_SERVICE,
  37         .nargs = 0,
  38         .nret = 1,
  39         .rets = &rtas_stop_self_args.args[0],
  40 };
  41
  42 static void rtas_stop_self(void)
  43 {
  44         struct rtas_args *args = &rtas_stop_self_args;
  45
  46         local_irq_disable();
  47
  48         BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
  49
  50         printk("cpu %u (hwid %u) Ready to die...\n",
  51                smp_processor_id(), hard_smp_processor_id());
  52         enter_rtas(__pa(args));
  53
  54         panic("Alas, I survived.\n");
  55 }
  56
  57 static void pseries_mach_cpu_die(void)
  58 {
  59         local_irq_disable();
  60         idle_task_exit();
  61         xics_teardown_cpu();
  62         unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
  63         rtas_stop_self();
  64         /* Should never get here... */
  65         BUG();
  66         for(;;);
  67 }
  68
  69 static int pseries_cpu_disable(void)
  70 {
  71         int cpu = smp_processor_id();
  72
  73         set_cpu_online(cpu, false);
  74         vdso_data->processorCount--;
  75
  76         /*fix boot_cpuid here*/
  77         if (cpu == boot_cpuid)
  78                 boot_cpuid = any_online_cpu(cpu_online_map);
  79
  80         /* FIXME: abstract this to not be platform specific later on */
  81         xics_migrate_irqs_away();
  82         return 0;
  83 }
  84
  85 static void pseries_cpu_die(unsigned int cpu)
  86 {
  87         int tries;
  88         int cpu_status;
  89         unsigned int pcpu = get_hard_smp_processor_id(cpu);
  90
  91         for (tries = 0; tries < 25; tries++) {
  92                 cpu_status = smp_query_cpu_stopped(pcpu);
  93                 if (cpu_status == QCSS_STOPPED ||
  94                     cpu_status == QCSS_HARDWARE_ERROR)
  95                         break;
  96                 cpu_relax();
  97         }
  98         if (cpu_status != 0) {
  99                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 100                        cpu, pcpu, cpu_status);
 101         }
 102
 103         /* Isolation and deallocation are definatly done by
 104          * drslot_chrp_cpu.  If they were not they would be
 105          * done here.  Change isolate state to Isolate and
 106          * change allocation-state to Unusable.
 107          */
 108         paca[cpu].cpu_start = 0;
 109 }
 110
 111 /*
 112  * Update cpu_present_map and paca(s) for a new cpu node.  The wrinkle
 113  * here is that a cpu device node may represent up to two logical cpus
 114  * in the SMT case.  We must honor the assumption in other code that
 115  * the logical ids for sibling SMT threads x and y are adjacent, such
 116  * that x^1 == y and y^1 == x.
 117  */
 118 static int pseries_add_processor(struct device_node *np)
 119 {
 120         unsigned int cpu;
 121         cpumask_t candidate_map, tmp = CPU_MASK_NONE;
 122         int err = -ENOSPC, len, nthreads, i;
 123         const u32 *intserv;
 124
 125         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 126         if (!intserv)
 127                 return 0;
 128
 129         nthreads = len / sizeof(u32);
 130         for (i = 0; i < nthreads; i++)
 131                 cpu_set(i, tmp);
 132
 133         cpu_maps_update_begin();
 134
 135         BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
 136
 137         /* Get a bitmap of unoccupied slots. */
 138         cpus_xor(candidate_map, cpu_possible_map, cpu_present_map);
 139         if (cpus_empty(candidate_map)) {
 140                 /* If we get here, it most likely means that NR_CPUS is
 141                  * less than the partition's max processors setting.
 142                  */
 143                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 144                        " supports %d logical cpus.\n", np->full_name,
 145                        cpus_weight(cpu_possible_map));
 146                 goto out_unlock;
 147         }
 148
 149         while (!cpus_empty(tmp))
 150                 if (cpus_subset(tmp, candidate_map))
 151                         /* Found a range where we can insert the new cpu(s) */
 152                         break;
 153                 else
 154                         cpus_shift_left(tmp, tmp, nthreads);
 155
 156         if (cpus_empty(tmp)) {
 157                 printk(KERN_ERR "Unable to find space in cpu_present_map for"
 158                        " processor %s with %d thread(s)\n", np->name,
 159                        nthreads);
 160                 goto out_unlock;
 161         }
 162
 163         for_each_cpu_mask(cpu, tmp) {
 164                 BUG_ON(cpu_isset(cpu, cpu_present_map));
 165                 set_cpu_present(cpu, true);
 166                 set_hard_smp_processor_id(cpu, *intserv++);
 167         }
 168         err = 0;
 169 out_unlock:
 170         cpu_maps_update_done();
 171         return err;
 172 }
 173
 174 /*
 175  * Update the present map for a cpu node which is going away, and set
 176  * the hard id in the paca(s) to -1 to be consistent with boot time
 177  * convention for non-present cpus.
 178  */
 179 static void pseries_remove_processor(struct device_node *np)
 180 {
 181         unsigned int cpu;
 182         int len, nthreads, i;
 183         const u32 *intserv;
 184
 185         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 186         if (!intserv)
 187                 return;
 188
 189         nthreads = len / sizeof(u32);
 190
 191         cpu_maps_update_begin();
 192         for (i = 0; i < nthreads; i++) {
 193                 for_each_present_cpu(cpu) {
 194                         if (get_hard_smp_processor_id(cpu) != intserv[i])
 195                                 continue;
 196                         BUG_ON(cpu_online(cpu));
 197                         set_cpu_present(cpu, false);
 198                         set_hard_smp_processor_id(cpu, -1);
 199                         break;
 200                 }
 201                 if (cpu == NR_CPUS)
 202                         printk(KERN_WARNING "Could not find cpu to remove "
 203                                "with physical id 0x%x\n", intserv[i]);
 204         }
 205         cpu_maps_update_done();
 206 }
 207
 208 static int pseries_smp_notifier(struct notifier_block *nb,
 209                                 unsigned long action, void *node)
 210 {
 211         int err = NOTIFY_OK;
 212
 213         switch (action) {
 214         case PSERIES_RECONFIG_ADD:
 215                 if (pseries_add_processor(node))
 216                         err = NOTIFY_BAD;
 217                 break;
 218         case PSERIES_RECONFIG_REMOVE:
 219                 pseries_remove_processor(node);
 220                 break;
 221         default:
 222                 err = NOTIFY_DONE;
 223                 break;
 224         }
 225         return err;
 226 }
 227
 228 static struct notifier_block pseries_smp_nb = {
 229         .notifier_call = pseries_smp_notifier,
 230 };
 231
 232 static int __init pseries_cpu_hotplug_init(void)
 233 {
 234         struct device_node *np;
 235         const char *typep;
 236         int qcss_tok;
 237
 238         for_each_node_by_name(np, "interrupt-controller") {
 239                 typep = of_get_property(np, "compatible", NULL);
 240                 if (strstr(typep, "open-pic")) {
 241                         of_node_put(np);
 242
 243                         printk(KERN_INFO "CPU Hotplug not supported on "
 244                                 "systems using MPIC\n");
 245                         return 0;
 246                 }
 247         }
 248
 249         rtas_stop_self_args.token = rtas_token("stop-self");
 250         qcss_tok = rtas_token("query-cpu-stopped-state");
 251
 252         if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
 253                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 254                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 255                                 "- disabling.\n");
 256                 return 0;
 257         }
 258
 259         ppc_md.cpu_die = pseries_mach_cpu_die;
 260         smp_ops->cpu_disable = pseries_cpu_disable;
 261         smp_ops->cpu_die = pseries_cpu_die;
 262
 263         /* Processors can be added/removed only on LPAR */
 264         if (firmware_has_feature(FW_FEATURE_LPAR))
 265                 pSeries_reconfig_notifier_register(&pseries_smp_nb);
 266
 267         return 0;
 268 }
 269 arch_initcall(pseries_cpu_hotplug_init);