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 #include "offline_states.h" 34 35 /* This version can't take the spinlock, because it never returns */ 36 static struct rtas_args rtas_stop_self_args = { 37 .token = RTAS_UNKNOWN_SERVICE, 38 .nargs = 0, 39 .nret = 1, 40 .rets = &rtas_stop_self_args.args[0], 41 }; 42 43 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) = 44 CPU_STATE_OFFLINE; 45 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE; 46 47 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE; 48 49 static int cede_offline_enabled __read_mostly = 1; 50 51 /* 52 * Enable/disable cede_offline when available. 53 */ 54 static int __init setup_cede_offline(char *str) 55 { 56 if (!strcmp(str, "off")) 57 cede_offline_enabled = 0; 58 else if (!strcmp(str, "on")) 59 cede_offline_enabled = 1; 60 else 61 return 0; 62 return 1; 63 } 64 65 __setup("cede_offline=", setup_cede_offline); 66 67 enum cpu_state_vals get_cpu_current_state(int cpu) 68 { 69 return per_cpu(current_state, cpu); 70 } 71 72 void set_cpu_current_state(int cpu, enum cpu_state_vals state) 73 { 74 per_cpu(current_state, cpu) = state; 75 } 76 77 enum cpu_state_vals get_preferred_offline_state(int cpu) 78 { 79 return per_cpu(preferred_offline_state, cpu); 80 } 81 82 void set_preferred_offline_state(int cpu, enum cpu_state_vals state) 83 { 84 per_cpu(preferred_offline_state, cpu) = state; 85 } 86 87 void set_default_offline_state(int cpu) 88 { 89 per_cpu(preferred_offline_state, cpu) = default_offline_state; 90 } 91 92 static void rtas_stop_self(void) 93 { 94 struct rtas_args *args = &rtas_stop_self_args; 95 96 local_irq_disable(); 97 98 BUG_ON(args->token == RTAS_UNKNOWN_SERVICE); 99 100 printk("cpu %u (hwid %u) Ready to die...\n", 101 smp_processor_id(), hard_smp_processor_id()); 102 enter_rtas(__pa(args)); 103 104 panic("Alas, I survived.\n"); 105 } 106 107 static void pseries_mach_cpu_die(void) 108 { 109 unsigned int cpu = smp_processor_id(); 110 unsigned int hwcpu = hard_smp_processor_id(); 111 u8 cede_latency_hint = 0; 112 113 local_irq_disable(); 114 idle_task_exit(); 115 xics_teardown_cpu(); 116 117 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 118 set_cpu_current_state(cpu, CPU_STATE_INACTIVE); 119 if (ppc_md.suspend_disable_cpu) 120 ppc_md.suspend_disable_cpu(); 121 122 cede_latency_hint = 2; 123 124 get_lppaca()->idle = 1; 125 if (!get_lppaca()->shared_proc) 126 get_lppaca()->donate_dedicated_cpu = 1; 127 128 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 129 extended_cede_processor(cede_latency_hint); 130 } 131 132 if (!get_lppaca()->shared_proc) 133 get_lppaca()->donate_dedicated_cpu = 0; 134 get_lppaca()->idle = 0; 135 136 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 137 unregister_slb_shadow(hwcpu, __pa(get_slb_shadow())); 138 139 /* 140 * Call to start_secondary_resume() will not return. 141 * Kernel stack will be reset and start_secondary() 142 * will be called to continue the online operation. 143 */ 144 start_secondary_resume(); 145 } 146 } 147 148 /* Requested state is CPU_STATE_OFFLINE at this point */ 149 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 150 151 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 152 unregister_slb_shadow(hwcpu, __pa(get_slb_shadow())); 153 rtas_stop_self(); 154 155 /* Should never get here... */ 156 BUG(); 157 for(;;); 158 } 159 160 static int pseries_cpu_disable(void) 161 { 162 int cpu = smp_processor_id(); 163 164 set_cpu_online(cpu, false); 165 vdso_data->processorCount--; 166 167 /*fix boot_cpuid here*/ 168 if (cpu == boot_cpuid) 169 boot_cpuid = cpumask_any(cpu_online_mask); 170 171 /* FIXME: abstract this to not be platform specific later on */ 172 xics_migrate_irqs_away(); 173 return 0; 174 } 175 176 /* 177 * pseries_cpu_die: Wait for the cpu to die. 178 * @cpu: logical processor id of the CPU whose death we're awaiting. 179 * 180 * This function is called from the context of the thread which is performing 181 * the cpu-offline. Here we wait for long enough to allow the cpu in question 182 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 183 * notifications. 184 * 185 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 186 * self-destruct. 187 */ 188 static void pseries_cpu_die(unsigned int cpu) 189 { 190 int tries; 191 int cpu_status = 1; 192 unsigned int pcpu = get_hard_smp_processor_id(cpu); 193 194 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 195 cpu_status = 1; 196 for (tries = 0; tries < 5000; tries++) { 197 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 198 cpu_status = 0; 199 break; 200 } 201 msleep(1); 202 } 203 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 204 205 for (tries = 0; tries < 25; tries++) { 206 cpu_status = smp_query_cpu_stopped(pcpu); 207 if (cpu_status == QCSS_STOPPED || 208 cpu_status == QCSS_HARDWARE_ERROR) 209 break; 210 cpu_relax(); 211 } 212 } 213 214 if (cpu_status != 0) { 215 printk("Querying DEAD? cpu %i (%i) shows %i\n", 216 cpu, pcpu, cpu_status); 217 } 218 219 /* Isolation and deallocation are definitely done by 220 * drslot_chrp_cpu. If they were not they would be 221 * done here. Change isolate state to Isolate and 222 * change allocation-state to Unusable. 223 */ 224 paca[cpu].cpu_start = 0; 225 } 226 227 /* 228 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 229 * here is that a cpu device node may represent up to two logical cpus 230 * in the SMT case. We must honor the assumption in other code that 231 * the logical ids for sibling SMT threads x and y are adjacent, such 232 * that x^1 == y and y^1 == x. 233 */ 234 static int pseries_add_processor(struct device_node *np) 235 { 236 unsigned int cpu; 237 cpumask_var_t candidate_mask, tmp; 238 int err = -ENOSPC, len, nthreads, i; 239 const u32 *intserv; 240 241 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 242 if (!intserv) 243 return 0; 244 245 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 246 zalloc_cpumask_var(&tmp, GFP_KERNEL); 247 248 nthreads = len / sizeof(u32); 249 for (i = 0; i < nthreads; i++) 250 cpumask_set_cpu(i, tmp); 251 252 cpu_maps_update_begin(); 253 254 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 255 256 /* Get a bitmap of unoccupied slots. */ 257 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 258 if (cpumask_empty(candidate_mask)) { 259 /* If we get here, it most likely means that NR_CPUS is 260 * less than the partition's max processors setting. 261 */ 262 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 263 " supports %d logical cpus.\n", np->full_name, 264 cpumask_weight(cpu_possible_mask)); 265 goto out_unlock; 266 } 267 268 while (!cpumask_empty(tmp)) 269 if (cpumask_subset(tmp, candidate_mask)) 270 /* Found a range where we can insert the new cpu(s) */ 271 break; 272 else 273 cpumask_shift_left(tmp, tmp, nthreads); 274 275 if (cpumask_empty(tmp)) { 276 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 277 " processor %s with %d thread(s)\n", np->name, 278 nthreads); 279 goto out_unlock; 280 } 281 282 for_each_cpu(cpu, tmp) { 283 BUG_ON(cpumask_test_cpu(cpu, cpu_present_mask)); 284 set_cpu_present(cpu, true); 285 set_hard_smp_processor_id(cpu, *intserv++); 286 } 287 err = 0; 288 out_unlock: 289 cpu_maps_update_done(); 290 free_cpumask_var(candidate_mask); 291 free_cpumask_var(tmp); 292 return err; 293 } 294 295 /* 296 * Update the present map for a cpu node which is going away, and set 297 * the hard id in the paca(s) to -1 to be consistent with boot time 298 * convention for non-present cpus. 299 */ 300 static void pseries_remove_processor(struct device_node *np) 301 { 302 unsigned int cpu; 303 int len, nthreads, i; 304 const u32 *intserv; 305 306 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 307 if (!intserv) 308 return; 309 310 nthreads = len / sizeof(u32); 311 312 cpu_maps_update_begin(); 313 for (i = 0; i < nthreads; i++) { 314 for_each_present_cpu(cpu) { 315 if (get_hard_smp_processor_id(cpu) != intserv[i]) 316 continue; 317 BUG_ON(cpu_online(cpu)); 318 set_cpu_present(cpu, false); 319 set_hard_smp_processor_id(cpu, -1); 320 break; 321 } 322 if (cpu >= nr_cpu_ids) 323 printk(KERN_WARNING "Could not find cpu to remove " 324 "with physical id 0x%x\n", intserv[i]); 325 } 326 cpu_maps_update_done(); 327 } 328 329 static int pseries_smp_notifier(struct notifier_block *nb, 330 unsigned long action, void *node) 331 { 332 int err = NOTIFY_OK; 333 334 switch (action) { 335 case PSERIES_RECONFIG_ADD: 336 if (pseries_add_processor(node)) 337 err = NOTIFY_BAD; 338 break; 339 case PSERIES_RECONFIG_REMOVE: 340 pseries_remove_processor(node); 341 break; 342 default: 343 err = NOTIFY_DONE; 344 break; 345 } 346 return err; 347 } 348 349 static struct notifier_block pseries_smp_nb = { 350 .notifier_call = pseries_smp_notifier, 351 }; 352 353 #define MAX_CEDE_LATENCY_LEVELS 4 354 #define CEDE_LATENCY_PARAM_LENGTH 10 355 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 356 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 357 #define CEDE_LATENCY_TOKEN 45 358 359 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 360 361 static int parse_cede_parameters(void) 362 { 363 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 364 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 365 NULL, 366 CEDE_LATENCY_TOKEN, 367 __pa(cede_parameters), 368 CEDE_LATENCY_PARAM_MAX_LENGTH); 369 } 370 371 static int __init pseries_cpu_hotplug_init(void) 372 { 373 struct device_node *np; 374 const char *typep; 375 int cpu; 376 int qcss_tok; 377 378 for_each_node_by_name(np, "interrupt-controller") { 379 typep = of_get_property(np, "compatible", NULL); 380 if (strstr(typep, "open-pic")) { 381 of_node_put(np); 382 383 printk(KERN_INFO "CPU Hotplug not supported on " 384 "systems using MPIC\n"); 385 return 0; 386 } 387 } 388 389 rtas_stop_self_args.token = rtas_token("stop-self"); 390 qcss_tok = rtas_token("query-cpu-stopped-state"); 391 392 if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE || 393 qcss_tok == RTAS_UNKNOWN_SERVICE) { 394 printk(KERN_INFO "CPU Hotplug not supported by firmware " 395 "- disabling.\n"); 396 return 0; 397 } 398 399 ppc_md.cpu_die = pseries_mach_cpu_die; 400 smp_ops->cpu_disable = pseries_cpu_disable; 401 smp_ops->cpu_die = pseries_cpu_die; 402 403 /* Processors can be added/removed only on LPAR */ 404 if (firmware_has_feature(FW_FEATURE_LPAR)) { 405 pSeries_reconfig_notifier_register(&pseries_smp_nb); 406 cpu_maps_update_begin(); 407 if (cede_offline_enabled && parse_cede_parameters() == 0) { 408 default_offline_state = CPU_STATE_INACTIVE; 409 for_each_online_cpu(cpu) 410 set_default_offline_state(cpu); 411 } 412 cpu_maps_update_done(); 413 } 414 415 return 0; 416 } 417 arch_initcall(pseries_cpu_hotplug_init); 418