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/interrupt.h> 23 #include <linux/delay.h> 24 #include <linux/sched.h> /* for idle_task_exit */ 25 #include <linux/cpu.h> 26 #include <linux/of.h> 27 #include <asm/prom.h> 28 #include <asm/rtas.h> 29 #include <asm/firmware.h> 30 #include <asm/machdep.h> 31 #include <asm/vdso_datapage.h> 32 #include <asm/xics.h> 33 #include "plpar_wrappers.h" 34 #include "offline_states.h" 35 36 /* This version can't take the spinlock, because it never returns */ 37 static struct rtas_args rtas_stop_self_args = { 38 .token = RTAS_UNKNOWN_SERVICE, 39 .nargs = 0, 40 .nret = 1, 41 .rets = &rtas_stop_self_args.args[0], 42 }; 43 44 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) = 45 CPU_STATE_OFFLINE; 46 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE; 47 48 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE; 49 50 static int cede_offline_enabled __read_mostly = 1; 51 52 /* 53 * Enable/disable cede_offline when available. 54 */ 55 static int __init setup_cede_offline(char *str) 56 { 57 if (!strcmp(str, "off")) 58 cede_offline_enabled = 0; 59 else if (!strcmp(str, "on")) 60 cede_offline_enabled = 1; 61 else 62 return 0; 63 return 1; 64 } 65 66 __setup("cede_offline=", setup_cede_offline); 67 68 enum cpu_state_vals get_cpu_current_state(int cpu) 69 { 70 return per_cpu(current_state, cpu); 71 } 72 73 void set_cpu_current_state(int cpu, enum cpu_state_vals state) 74 { 75 per_cpu(current_state, cpu) = state; 76 } 77 78 enum cpu_state_vals get_preferred_offline_state(int cpu) 79 { 80 return per_cpu(preferred_offline_state, cpu); 81 } 82 83 void set_preferred_offline_state(int cpu, enum cpu_state_vals state) 84 { 85 per_cpu(preferred_offline_state, cpu) = state; 86 } 87 88 void set_default_offline_state(int cpu) 89 { 90 per_cpu(preferred_offline_state, cpu) = default_offline_state; 91 } 92 93 static void rtas_stop_self(void) 94 { 95 struct rtas_args *args = &rtas_stop_self_args; 96 97 local_irq_disable(); 98 99 BUG_ON(args->token == RTAS_UNKNOWN_SERVICE); 100 101 printk("cpu %u (hwid %u) Ready to die...\n", 102 smp_processor_id(), hard_smp_processor_id()); 103 enter_rtas(__pa(args)); 104 105 panic("Alas, I survived.\n"); 106 } 107 108 static void pseries_mach_cpu_die(void) 109 { 110 unsigned int cpu = smp_processor_id(); 111 unsigned int hwcpu = hard_smp_processor_id(); 112 u8 cede_latency_hint = 0; 113 114 local_irq_disable(); 115 idle_task_exit(); 116 xics_teardown_cpu(); 117 118 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 119 set_cpu_current_state(cpu, CPU_STATE_INACTIVE); 120 if (ppc_md.suspend_disable_cpu) 121 ppc_md.suspend_disable_cpu(); 122 123 cede_latency_hint = 2; 124 125 get_lppaca()->idle = 1; 126 if (!get_lppaca()->shared_proc) 127 get_lppaca()->donate_dedicated_cpu = 1; 128 129 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 130 while (!prep_irq_for_idle()) { 131 local_irq_enable(); 132 local_irq_disable(); 133 } 134 135 extended_cede_processor(cede_latency_hint); 136 } 137 138 local_irq_disable(); 139 140 if (!get_lppaca()->shared_proc) 141 get_lppaca()->donate_dedicated_cpu = 0; 142 get_lppaca()->idle = 0; 143 144 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 145 unregister_slb_shadow(hwcpu); 146 147 hard_irq_disable(); 148 /* 149 * Call to start_secondary_resume() will not return. 150 * Kernel stack will be reset and start_secondary() 151 * will be called to continue the online operation. 152 */ 153 start_secondary_resume(); 154 } 155 } 156 157 /* Requested state is CPU_STATE_OFFLINE at this point */ 158 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 159 160 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 161 unregister_slb_shadow(hwcpu); 162 rtas_stop_self(); 163 164 /* Should never get here... */ 165 BUG(); 166 for(;;); 167 } 168 169 static int pseries_cpu_disable(void) 170 { 171 int cpu = smp_processor_id(); 172 173 set_cpu_online(cpu, false); 174 vdso_data->processorCount--; 175 176 /*fix boot_cpuid here*/ 177 if (cpu == boot_cpuid) 178 boot_cpuid = cpumask_any(cpu_online_mask); 179 180 /* FIXME: abstract this to not be platform specific later on */ 181 xics_migrate_irqs_away(); 182 return 0; 183 } 184 185 /* 186 * pseries_cpu_die: Wait for the cpu to die. 187 * @cpu: logical processor id of the CPU whose death we're awaiting. 188 * 189 * This function is called from the context of the thread which is performing 190 * the cpu-offline. Here we wait for long enough to allow the cpu in question 191 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 192 * notifications. 193 * 194 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 195 * self-destruct. 196 */ 197 static void pseries_cpu_die(unsigned int cpu) 198 { 199 int tries; 200 int cpu_status = 1; 201 unsigned int pcpu = get_hard_smp_processor_id(cpu); 202 203 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 204 cpu_status = 1; 205 for (tries = 0; tries < 5000; tries++) { 206 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 207 cpu_status = 0; 208 break; 209 } 210 msleep(1); 211 } 212 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 213 214 for (tries = 0; tries < 25; tries++) { 215 cpu_status = smp_query_cpu_stopped(pcpu); 216 if (cpu_status == QCSS_STOPPED || 217 cpu_status == QCSS_HARDWARE_ERROR) 218 break; 219 cpu_relax(); 220 } 221 } 222 223 if (cpu_status != 0) { 224 printk("Querying DEAD? cpu %i (%i) shows %i\n", 225 cpu, pcpu, cpu_status); 226 } 227 228 /* Isolation and deallocation are definitely done by 229 * drslot_chrp_cpu. If they were not they would be 230 * done here. Change isolate state to Isolate and 231 * change allocation-state to Unusable. 232 */ 233 paca[cpu].cpu_start = 0; 234 } 235 236 /* 237 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 238 * here is that a cpu device node may represent up to two logical cpus 239 * in the SMT case. We must honor the assumption in other code that 240 * the logical ids for sibling SMT threads x and y are adjacent, such 241 * that x^1 == y and y^1 == x. 242 */ 243 static int pseries_add_processor(struct device_node *np) 244 { 245 unsigned int cpu; 246 cpumask_var_t candidate_mask, tmp; 247 int err = -ENOSPC, len, nthreads, i; 248 const u32 *intserv; 249 250 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 251 if (!intserv) 252 return 0; 253 254 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 255 zalloc_cpumask_var(&tmp, GFP_KERNEL); 256 257 nthreads = len / sizeof(u32); 258 for (i = 0; i < nthreads; i++) 259 cpumask_set_cpu(i, tmp); 260 261 cpu_maps_update_begin(); 262 263 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 264 265 /* Get a bitmap of unoccupied slots. */ 266 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 267 if (cpumask_empty(candidate_mask)) { 268 /* If we get here, it most likely means that NR_CPUS is 269 * less than the partition's max processors setting. 270 */ 271 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 272 " supports %d logical cpus.\n", np->full_name, 273 cpumask_weight(cpu_possible_mask)); 274 goto out_unlock; 275 } 276 277 while (!cpumask_empty(tmp)) 278 if (cpumask_subset(tmp, candidate_mask)) 279 /* Found a range where we can insert the new cpu(s) */ 280 break; 281 else 282 cpumask_shift_left(tmp, tmp, nthreads); 283 284 if (cpumask_empty(tmp)) { 285 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 286 " processor %s with %d thread(s)\n", np->name, 287 nthreads); 288 goto out_unlock; 289 } 290 291 for_each_cpu(cpu, tmp) { 292 BUG_ON(cpu_present(cpu)); 293 set_cpu_present(cpu, true); 294 set_hard_smp_processor_id(cpu, *intserv++); 295 } 296 err = 0; 297 out_unlock: 298 cpu_maps_update_done(); 299 free_cpumask_var(candidate_mask); 300 free_cpumask_var(tmp); 301 return err; 302 } 303 304 /* 305 * Update the present map for a cpu node which is going away, and set 306 * the hard id in the paca(s) to -1 to be consistent with boot time 307 * convention for non-present cpus. 308 */ 309 static void pseries_remove_processor(struct device_node *np) 310 { 311 unsigned int cpu; 312 int len, nthreads, i; 313 const u32 *intserv; 314 315 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 316 if (!intserv) 317 return; 318 319 nthreads = len / sizeof(u32); 320 321 cpu_maps_update_begin(); 322 for (i = 0; i < nthreads; i++) { 323 for_each_present_cpu(cpu) { 324 if (get_hard_smp_processor_id(cpu) != intserv[i]) 325 continue; 326 BUG_ON(cpu_online(cpu)); 327 set_cpu_present(cpu, false); 328 set_hard_smp_processor_id(cpu, -1); 329 break; 330 } 331 if (cpu >= nr_cpu_ids) 332 printk(KERN_WARNING "Could not find cpu to remove " 333 "with physical id 0x%x\n", intserv[i]); 334 } 335 cpu_maps_update_done(); 336 } 337 338 static int pseries_smp_notifier(struct notifier_block *nb, 339 unsigned long action, void *node) 340 { 341 int err = 0; 342 343 switch (action) { 344 case OF_RECONFIG_ATTACH_NODE: 345 err = pseries_add_processor(node); 346 break; 347 case OF_RECONFIG_DETACH_NODE: 348 pseries_remove_processor(node); 349 break; 350 } 351 return notifier_from_errno(err); 352 } 353 354 static struct notifier_block pseries_smp_nb = { 355 .notifier_call = pseries_smp_notifier, 356 }; 357 358 #define MAX_CEDE_LATENCY_LEVELS 4 359 #define CEDE_LATENCY_PARAM_LENGTH 10 360 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 361 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 362 #define CEDE_LATENCY_TOKEN 45 363 364 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 365 366 static int parse_cede_parameters(void) 367 { 368 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 369 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 370 NULL, 371 CEDE_LATENCY_TOKEN, 372 __pa(cede_parameters), 373 CEDE_LATENCY_PARAM_MAX_LENGTH); 374 } 375 376 static int __init pseries_cpu_hotplug_init(void) 377 { 378 struct device_node *np; 379 const char *typep; 380 int cpu; 381 int qcss_tok; 382 383 for_each_node_by_name(np, "interrupt-controller") { 384 typep = of_get_property(np, "compatible", NULL); 385 if (strstr(typep, "open-pic")) { 386 of_node_put(np); 387 388 printk(KERN_INFO "CPU Hotplug not supported on " 389 "systems using MPIC\n"); 390 return 0; 391 } 392 } 393 394 rtas_stop_self_args.token = rtas_token("stop-self"); 395 qcss_tok = rtas_token("query-cpu-stopped-state"); 396 397 if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE || 398 qcss_tok == RTAS_UNKNOWN_SERVICE) { 399 printk(KERN_INFO "CPU Hotplug not supported by firmware " 400 "- disabling.\n"); 401 return 0; 402 } 403 404 ppc_md.cpu_die = pseries_mach_cpu_die; 405 smp_ops->cpu_disable = pseries_cpu_disable; 406 smp_ops->cpu_die = pseries_cpu_die; 407 408 /* Processors can be added/removed only on LPAR */ 409 if (firmware_has_feature(FW_FEATURE_LPAR)) { 410 of_reconfig_notifier_register(&pseries_smp_nb); 411 cpu_maps_update_begin(); 412 if (cede_offline_enabled && parse_cede_parameters() == 0) { 413 default_offline_state = CPU_STATE_INACTIVE; 414 for_each_online_cpu(cpu) 415 set_default_offline_state(cpu); 416 } 417 cpu_maps_update_done(); 418 } 419 420 return 0; 421 } 422 arch_initcall(pseries_cpu_hotplug_init); 423