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 static struct rtas_args args = { 92 .nargs = 0, 93 .nret = cpu_to_be32(1), 94 .rets = &args.args[0], 95 }; 96 97 args.token = cpu_to_be32(rtas_stop_self_token); 98 99 local_irq_disable(); 100 101 BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE); 102 103 printk("cpu %u (hwid %u) Ready to die...\n", 104 smp_processor_id(), hard_smp_processor_id()); 105 enter_rtas(__pa(&args)); 106 107 panic("Alas, I survived.\n"); 108 } 109 110 static void pseries_mach_cpu_die(void) 111 { 112 unsigned int cpu = smp_processor_id(); 113 unsigned int hwcpu = hard_smp_processor_id(); 114 u8 cede_latency_hint = 0; 115 116 local_irq_disable(); 117 idle_task_exit(); 118 xics_teardown_cpu(); 119 120 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 121 set_cpu_current_state(cpu, CPU_STATE_INACTIVE); 122 if (ppc_md.suspend_disable_cpu) 123 ppc_md.suspend_disable_cpu(); 124 125 cede_latency_hint = 2; 126 127 get_lppaca()->idle = 1; 128 if (!lppaca_shared_proc(get_lppaca())) 129 get_lppaca()->donate_dedicated_cpu = 1; 130 131 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 132 while (!prep_irq_for_idle()) { 133 local_irq_enable(); 134 local_irq_disable(); 135 } 136 137 extended_cede_processor(cede_latency_hint); 138 } 139 140 local_irq_disable(); 141 142 if (!lppaca_shared_proc(get_lppaca())) 143 get_lppaca()->donate_dedicated_cpu = 0; 144 get_lppaca()->idle = 0; 145 146 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 147 unregister_slb_shadow(hwcpu); 148 149 hard_irq_disable(); 150 /* 151 * Call to start_secondary_resume() will not return. 152 * Kernel stack will be reset and start_secondary() 153 * will be called to continue the online operation. 154 */ 155 start_secondary_resume(); 156 } 157 } 158 159 /* Requested state is CPU_STATE_OFFLINE at this point */ 160 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 161 162 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 163 unregister_slb_shadow(hwcpu); 164 rtas_stop_self(); 165 166 /* Should never get here... */ 167 BUG(); 168 for(;;); 169 } 170 171 static int pseries_cpu_disable(void) 172 { 173 int cpu = smp_processor_id(); 174 175 set_cpu_online(cpu, false); 176 vdso_data->processorCount--; 177 178 /*fix boot_cpuid here*/ 179 if (cpu == boot_cpuid) 180 boot_cpuid = cpumask_any(cpu_online_mask); 181 182 /* FIXME: abstract this to not be platform specific later on */ 183 xics_migrate_irqs_away(); 184 return 0; 185 } 186 187 /* 188 * pseries_cpu_die: Wait for the cpu to die. 189 * @cpu: logical processor id of the CPU whose death we're awaiting. 190 * 191 * This function is called from the context of the thread which is performing 192 * the cpu-offline. Here we wait for long enough to allow the cpu in question 193 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 194 * notifications. 195 * 196 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 197 * self-destruct. 198 */ 199 static void pseries_cpu_die(unsigned int cpu) 200 { 201 int tries; 202 int cpu_status = 1; 203 unsigned int pcpu = get_hard_smp_processor_id(cpu); 204 205 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 206 cpu_status = 1; 207 for (tries = 0; tries < 5000; tries++) { 208 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 209 cpu_status = 0; 210 break; 211 } 212 msleep(1); 213 } 214 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 215 216 for (tries = 0; tries < 25; tries++) { 217 cpu_status = smp_query_cpu_stopped(pcpu); 218 if (cpu_status == QCSS_STOPPED || 219 cpu_status == QCSS_HARDWARE_ERROR) 220 break; 221 cpu_relax(); 222 } 223 } 224 225 if (cpu_status != 0) { 226 printk("Querying DEAD? cpu %i (%i) shows %i\n", 227 cpu, pcpu, cpu_status); 228 } 229 230 /* Isolation and deallocation are definitely done by 231 * drslot_chrp_cpu. If they were not they would be 232 * done here. Change isolate state to Isolate and 233 * change allocation-state to Unusable. 234 */ 235 paca[cpu].cpu_start = 0; 236 } 237 238 /* 239 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 240 * here is that a cpu device node may represent up to two logical cpus 241 * in the SMT case. We must honor the assumption in other code that 242 * the logical ids for sibling SMT threads x and y are adjacent, such 243 * that x^1 == y and y^1 == x. 244 */ 245 static int pseries_add_processor(struct device_node *np) 246 { 247 unsigned int cpu; 248 cpumask_var_t candidate_mask, tmp; 249 int err = -ENOSPC, len, nthreads, i; 250 const __be32 *intserv; 251 252 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 253 if (!intserv) 254 return 0; 255 256 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 257 zalloc_cpumask_var(&tmp, GFP_KERNEL); 258 259 nthreads = len / sizeof(u32); 260 for (i = 0; i < nthreads; i++) 261 cpumask_set_cpu(i, tmp); 262 263 cpu_maps_update_begin(); 264 265 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 266 267 /* Get a bitmap of unoccupied slots. */ 268 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 269 if (cpumask_empty(candidate_mask)) { 270 /* If we get here, it most likely means that NR_CPUS is 271 * less than the partition's max processors setting. 272 */ 273 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 274 " supports %d logical cpus.\n", np->full_name, 275 cpumask_weight(cpu_possible_mask)); 276 goto out_unlock; 277 } 278 279 while (!cpumask_empty(tmp)) 280 if (cpumask_subset(tmp, candidate_mask)) 281 /* Found a range where we can insert the new cpu(s) */ 282 break; 283 else 284 cpumask_shift_left(tmp, tmp, nthreads); 285 286 if (cpumask_empty(tmp)) { 287 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 288 " processor %s with %d thread(s)\n", np->name, 289 nthreads); 290 goto out_unlock; 291 } 292 293 for_each_cpu(cpu, tmp) { 294 BUG_ON(cpu_present(cpu)); 295 set_cpu_present(cpu, true); 296 set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++)); 297 } 298 err = 0; 299 out_unlock: 300 cpu_maps_update_done(); 301 free_cpumask_var(candidate_mask); 302 free_cpumask_var(tmp); 303 return err; 304 } 305 306 /* 307 * Update the present map for a cpu node which is going away, and set 308 * the hard id in the paca(s) to -1 to be consistent with boot time 309 * convention for non-present cpus. 310 */ 311 static void pseries_remove_processor(struct device_node *np) 312 { 313 unsigned int cpu; 314 int len, nthreads, i; 315 const __be32 *intserv; 316 u32 thread; 317 318 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 319 if (!intserv) 320 return; 321 322 nthreads = len / sizeof(u32); 323 324 cpu_maps_update_begin(); 325 for (i = 0; i < nthreads; i++) { 326 thread = be32_to_cpu(intserv[i]); 327 for_each_present_cpu(cpu) { 328 if (get_hard_smp_processor_id(cpu) != thread) 329 continue; 330 BUG_ON(cpu_online(cpu)); 331 set_cpu_present(cpu, false); 332 set_hard_smp_processor_id(cpu, -1); 333 break; 334 } 335 if (cpu >= nr_cpu_ids) 336 printk(KERN_WARNING "Could not find cpu to remove " 337 "with physical id 0x%x\n", thread); 338 } 339 cpu_maps_update_done(); 340 } 341 342 static int pseries_smp_notifier(struct notifier_block *nb, 343 unsigned long action, void *data) 344 { 345 struct of_reconfig_data *rd = data; 346 int err = 0; 347 348 switch (action) { 349 case OF_RECONFIG_ATTACH_NODE: 350 err = pseries_add_processor(rd->dn); 351 break; 352 case OF_RECONFIG_DETACH_NODE: 353 pseries_remove_processor(rd->dn); 354 break; 355 } 356 return notifier_from_errno(err); 357 } 358 359 static struct notifier_block pseries_smp_nb = { 360 .notifier_call = pseries_smp_notifier, 361 }; 362 363 #define MAX_CEDE_LATENCY_LEVELS 4 364 #define CEDE_LATENCY_PARAM_LENGTH 10 365 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 366 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 367 #define CEDE_LATENCY_TOKEN 45 368 369 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 370 371 static int parse_cede_parameters(void) 372 { 373 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 374 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 375 NULL, 376 CEDE_LATENCY_TOKEN, 377 __pa(cede_parameters), 378 CEDE_LATENCY_PARAM_MAX_LENGTH); 379 } 380 381 static int __init pseries_cpu_hotplug_init(void) 382 { 383 struct device_node *np; 384 const char *typep; 385 int cpu; 386 int qcss_tok; 387 388 for_each_node_by_name(np, "interrupt-controller") { 389 typep = of_get_property(np, "compatible", NULL); 390 if (strstr(typep, "open-pic")) { 391 of_node_put(np); 392 393 printk(KERN_INFO "CPU Hotplug not supported on " 394 "systems using MPIC\n"); 395 return 0; 396 } 397 } 398 399 rtas_stop_self_token = rtas_token("stop-self"); 400 qcss_tok = rtas_token("query-cpu-stopped-state"); 401 402 if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE || 403 qcss_tok == RTAS_UNKNOWN_SERVICE) { 404 printk(KERN_INFO "CPU Hotplug not supported by firmware " 405 "- disabling.\n"); 406 return 0; 407 } 408 409 ppc_md.cpu_die = pseries_mach_cpu_die; 410 smp_ops->cpu_disable = pseries_cpu_disable; 411 smp_ops->cpu_die = pseries_cpu_die; 412 413 /* Processors can be added/removed only on LPAR */ 414 if (firmware_has_feature(FW_FEATURE_LPAR)) { 415 of_reconfig_notifier_register(&pseries_smp_nb); 416 cpu_maps_update_begin(); 417 if (cede_offline_enabled && parse_cede_parameters() == 0) { 418 default_offline_state = CPU_STATE_INACTIVE; 419 for_each_online_cpu(cpu) 420 set_default_offline_state(cpu); 421 } 422 cpu_maps_update_done(); 423 } 424 425 return 0; 426 } 427 machine_arch_initcall(pseries, pseries_cpu_hotplug_init); 428