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 <asm/plpar_wrappers.h> 34 35 #include "offline_states.h" 36 37 /* This version can't take the spinlock, because it never returns */ 38 static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE; 39 40 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) = 41 CPU_STATE_OFFLINE; 42 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE; 43 44 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE; 45 46 static int cede_offline_enabled __read_mostly = 1; 47 48 /* 49 * Enable/disable cede_offline when available. 50 */ 51 static int __init setup_cede_offline(char *str) 52 { 53 if (!strcmp(str, "off")) 54 cede_offline_enabled = 0; 55 else if (!strcmp(str, "on")) 56 cede_offline_enabled = 1; 57 else 58 return 0; 59 return 1; 60 } 61 62 __setup("cede_offline=", setup_cede_offline); 63 64 enum cpu_state_vals get_cpu_current_state(int cpu) 65 { 66 return per_cpu(current_state, cpu); 67 } 68 69 void set_cpu_current_state(int cpu, enum cpu_state_vals state) 70 { 71 per_cpu(current_state, cpu) = state; 72 } 73 74 enum cpu_state_vals get_preferred_offline_state(int cpu) 75 { 76 return per_cpu(preferred_offline_state, cpu); 77 } 78 79 void set_preferred_offline_state(int cpu, enum cpu_state_vals state) 80 { 81 per_cpu(preferred_offline_state, cpu) = state; 82 } 83 84 void set_default_offline_state(int cpu) 85 { 86 per_cpu(preferred_offline_state, cpu) = default_offline_state; 87 } 88 89 static void rtas_stop_self(void) 90 { 91 struct rtas_args args = { 92 .token = cpu_to_be32(rtas_stop_self_token), 93 .nargs = 0, 94 .nret = 1, 95 .rets = &args.args[0], 96 }; 97 98 local_irq_disable(); 99 100 BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE); 101 102 printk("cpu %u (hwid %u) Ready to die...\n", 103 smp_processor_id(), hard_smp_processor_id()); 104 enter_rtas(__pa(&args)); 105 106 panic("Alas, I survived.\n"); 107 } 108 109 static void pseries_mach_cpu_die(void) 110 { 111 unsigned int cpu = smp_processor_id(); 112 unsigned int hwcpu = hard_smp_processor_id(); 113 u8 cede_latency_hint = 0; 114 115 local_irq_disable(); 116 idle_task_exit(); 117 xics_teardown_cpu(); 118 119 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 120 set_cpu_current_state(cpu, CPU_STATE_INACTIVE); 121 if (ppc_md.suspend_disable_cpu) 122 ppc_md.suspend_disable_cpu(); 123 124 cede_latency_hint = 2; 125 126 get_lppaca()->idle = 1; 127 if (!lppaca_shared_proc(get_lppaca())) 128 get_lppaca()->donate_dedicated_cpu = 1; 129 130 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 131 while (!prep_irq_for_idle()) { 132 local_irq_enable(); 133 local_irq_disable(); 134 } 135 136 extended_cede_processor(cede_latency_hint); 137 } 138 139 local_irq_disable(); 140 141 if (!lppaca_shared_proc(get_lppaca())) 142 get_lppaca()->donate_dedicated_cpu = 0; 143 get_lppaca()->idle = 0; 144 145 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 146 unregister_slb_shadow(hwcpu); 147 148 hard_irq_disable(); 149 /* 150 * Call to start_secondary_resume() will not return. 151 * Kernel stack will be reset and start_secondary() 152 * will be called to continue the online operation. 153 */ 154 start_secondary_resume(); 155 } 156 } 157 158 /* Requested state is CPU_STATE_OFFLINE at this point */ 159 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 160 161 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 162 unregister_slb_shadow(hwcpu); 163 rtas_stop_self(); 164 165 /* Should never get here... */ 166 BUG(); 167 for(;;); 168 } 169 170 static int pseries_cpu_disable(void) 171 { 172 int cpu = smp_processor_id(); 173 174 set_cpu_online(cpu, false); 175 vdso_data->processorCount--; 176 177 /*fix boot_cpuid here*/ 178 if (cpu == boot_cpuid) 179 boot_cpuid = cpumask_any(cpu_online_mask); 180 181 /* FIXME: abstract this to not be platform specific later on */ 182 xics_migrate_irqs_away(); 183 return 0; 184 } 185 186 /* 187 * pseries_cpu_die: Wait for the cpu to die. 188 * @cpu: logical processor id of the CPU whose death we're awaiting. 189 * 190 * This function is called from the context of the thread which is performing 191 * the cpu-offline. Here we wait for long enough to allow the cpu in question 192 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 193 * notifications. 194 * 195 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 196 * self-destruct. 197 */ 198 static void pseries_cpu_die(unsigned int cpu) 199 { 200 int tries; 201 int cpu_status = 1; 202 unsigned int pcpu = get_hard_smp_processor_id(cpu); 203 204 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 205 cpu_status = 1; 206 for (tries = 0; tries < 5000; tries++) { 207 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 208 cpu_status = 0; 209 break; 210 } 211 msleep(1); 212 } 213 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 214 215 for (tries = 0; tries < 25; tries++) { 216 cpu_status = smp_query_cpu_stopped(pcpu); 217 if (cpu_status == QCSS_STOPPED || 218 cpu_status == QCSS_HARDWARE_ERROR) 219 break; 220 cpu_relax(); 221 } 222 } 223 224 if (cpu_status != 0) { 225 printk("Querying DEAD? cpu %i (%i) shows %i\n", 226 cpu, pcpu, cpu_status); 227 } 228 229 /* Isolation and deallocation are definitely done by 230 * drslot_chrp_cpu. If they were not they would be 231 * done here. Change isolate state to Isolate and 232 * change allocation-state to Unusable. 233 */ 234 paca[cpu].cpu_start = 0; 235 } 236 237 /* 238 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 239 * here is that a cpu device node may represent up to two logical cpus 240 * in the SMT case. We must honor the assumption in other code that 241 * the logical ids for sibling SMT threads x and y are adjacent, such 242 * that x^1 == y and y^1 == x. 243 */ 244 static int pseries_add_processor(struct device_node *np) 245 { 246 unsigned int cpu; 247 cpumask_var_t candidate_mask, tmp; 248 int err = -ENOSPC, len, nthreads, i; 249 const u32 *intserv; 250 251 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 252 if (!intserv) 253 return 0; 254 255 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 256 zalloc_cpumask_var(&tmp, GFP_KERNEL); 257 258 nthreads = len / sizeof(u32); 259 for (i = 0; i < nthreads; i++) 260 cpumask_set_cpu(i, tmp); 261 262 cpu_maps_update_begin(); 263 264 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 265 266 /* Get a bitmap of unoccupied slots. */ 267 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 268 if (cpumask_empty(candidate_mask)) { 269 /* If we get here, it most likely means that NR_CPUS is 270 * less than the partition's max processors setting. 271 */ 272 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 273 " supports %d logical cpus.\n", np->full_name, 274 cpumask_weight(cpu_possible_mask)); 275 goto out_unlock; 276 } 277 278 while (!cpumask_empty(tmp)) 279 if (cpumask_subset(tmp, candidate_mask)) 280 /* Found a range where we can insert the new cpu(s) */ 281 break; 282 else 283 cpumask_shift_left(tmp, tmp, nthreads); 284 285 if (cpumask_empty(tmp)) { 286 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 287 " processor %s with %d thread(s)\n", np->name, 288 nthreads); 289 goto out_unlock; 290 } 291 292 for_each_cpu(cpu, tmp) { 293 BUG_ON(cpu_present(cpu)); 294 set_cpu_present(cpu, true); 295 set_hard_smp_processor_id(cpu, *intserv++); 296 } 297 err = 0; 298 out_unlock: 299 cpu_maps_update_done(); 300 free_cpumask_var(candidate_mask); 301 free_cpumask_var(tmp); 302 return err; 303 } 304 305 /* 306 * Update the present map for a cpu node which is going away, and set 307 * the hard id in the paca(s) to -1 to be consistent with boot time 308 * convention for non-present cpus. 309 */ 310 static void pseries_remove_processor(struct device_node *np) 311 { 312 unsigned int cpu; 313 int len, nthreads, i; 314 const u32 *intserv; 315 316 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 317 if (!intserv) 318 return; 319 320 nthreads = len / sizeof(u32); 321 322 cpu_maps_update_begin(); 323 for (i = 0; i < nthreads; i++) { 324 for_each_present_cpu(cpu) { 325 if (get_hard_smp_processor_id(cpu) != intserv[i]) 326 continue; 327 BUG_ON(cpu_online(cpu)); 328 set_cpu_present(cpu, false); 329 set_hard_smp_processor_id(cpu, -1); 330 break; 331 } 332 if (cpu >= nr_cpu_ids) 333 printk(KERN_WARNING "Could not find cpu to remove " 334 "with physical id 0x%x\n", intserv[i]); 335 } 336 cpu_maps_update_done(); 337 } 338 339 static int pseries_smp_notifier(struct notifier_block *nb, 340 unsigned long action, void *node) 341 { 342 int err = 0; 343 344 switch (action) { 345 case OF_RECONFIG_ATTACH_NODE: 346 err = pseries_add_processor(node); 347 break; 348 case OF_RECONFIG_DETACH_NODE: 349 pseries_remove_processor(node); 350 break; 351 } 352 return notifier_from_errno(err); 353 } 354 355 static struct notifier_block pseries_smp_nb = { 356 .notifier_call = pseries_smp_notifier, 357 }; 358 359 #define MAX_CEDE_LATENCY_LEVELS 4 360 #define CEDE_LATENCY_PARAM_LENGTH 10 361 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 362 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 363 #define CEDE_LATENCY_TOKEN 45 364 365 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 366 367 static int parse_cede_parameters(void) 368 { 369 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 370 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 371 NULL, 372 CEDE_LATENCY_TOKEN, 373 __pa(cede_parameters), 374 CEDE_LATENCY_PARAM_MAX_LENGTH); 375 } 376 377 static int __init pseries_cpu_hotplug_init(void) 378 { 379 struct device_node *np; 380 const char *typep; 381 int cpu; 382 int qcss_tok; 383 384 for_each_node_by_name(np, "interrupt-controller") { 385 typep = of_get_property(np, "compatible", NULL); 386 if (strstr(typep, "open-pic")) { 387 of_node_put(np); 388 389 printk(KERN_INFO "CPU Hotplug not supported on " 390 "systems using MPIC\n"); 391 return 0; 392 } 393 } 394 395 rtas_stop_self_token = rtas_token("stop-self"); 396 qcss_tok = rtas_token("query-cpu-stopped-state"); 397 398 if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE || 399 qcss_tok == RTAS_UNKNOWN_SERVICE) { 400 printk(KERN_INFO "CPU Hotplug not supported by firmware " 401 "- disabling.\n"); 402 return 0; 403 } 404 405 ppc_md.cpu_die = pseries_mach_cpu_die; 406 smp_ops->cpu_disable = pseries_cpu_disable; 407 smp_ops->cpu_die = pseries_cpu_die; 408 409 /* Processors can be added/removed only on LPAR */ 410 if (firmware_has_feature(FW_FEATURE_LPAR)) { 411 of_reconfig_notifier_register(&pseries_smp_nb); 412 cpu_maps_update_begin(); 413 if (cede_offline_enabled && parse_cede_parameters() == 0) { 414 default_offline_state = CPU_STATE_INACTIVE; 415 for_each_online_cpu(cpu) 416 set_default_offline_state(cpu); 417 } 418 cpu_maps_update_done(); 419 } 420 421 return 0; 422 } 423 machine_arch_initcall(pseries, pseries_cpu_hotplug_init); 424