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 cede_latency_hint = 2; 120 121 get_lppaca()->idle = 1; 122 if (!get_lppaca()->shared_proc) 123 get_lppaca()->donate_dedicated_cpu = 1; 124 125 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 126 extended_cede_processor(cede_latency_hint); 127 } 128 129 if (!get_lppaca()->shared_proc) 130 get_lppaca()->donate_dedicated_cpu = 0; 131 get_lppaca()->idle = 0; 132 133 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 134 unregister_slb_shadow(hwcpu, __pa(get_slb_shadow())); 135 136 /* 137 * Call to start_secondary_resume() will not return. 138 * Kernel stack will be reset and start_secondary() 139 * will be called to continue the online operation. 140 */ 141 start_secondary_resume(); 142 } 143 } 144 145 /* Requested state is CPU_STATE_OFFLINE at this point */ 146 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 147 148 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 149 unregister_slb_shadow(hwcpu, __pa(get_slb_shadow())); 150 rtas_stop_self(); 151 152 /* Should never get here... */ 153 BUG(); 154 for(;;); 155 } 156 157 static int pseries_cpu_disable(void) 158 { 159 int cpu = smp_processor_id(); 160 161 set_cpu_online(cpu, false); 162 vdso_data->processorCount--; 163 164 /*fix boot_cpuid here*/ 165 if (cpu == boot_cpuid) 166 boot_cpuid = cpumask_any(cpu_online_mask); 167 168 /* FIXME: abstract this to not be platform specific later on */ 169 xics_migrate_irqs_away(); 170 return 0; 171 } 172 173 /* 174 * pseries_cpu_die: Wait for the cpu to die. 175 * @cpu: logical processor id of the CPU whose death we're awaiting. 176 * 177 * This function is called from the context of the thread which is performing 178 * the cpu-offline. Here we wait for long enough to allow the cpu in question 179 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 180 * notifications. 181 * 182 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 183 * self-destruct. 184 */ 185 static void pseries_cpu_die(unsigned int cpu) 186 { 187 int tries; 188 int cpu_status = 1; 189 unsigned int pcpu = get_hard_smp_processor_id(cpu); 190 191 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 192 cpu_status = 1; 193 for (tries = 0; tries < 1000; tries++) { 194 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 195 cpu_status = 0; 196 break; 197 } 198 cpu_relax(); 199 } 200 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 201 202 for (tries = 0; tries < 25; tries++) { 203 cpu_status = smp_query_cpu_stopped(pcpu); 204 if (cpu_status == QCSS_STOPPED || 205 cpu_status == QCSS_HARDWARE_ERROR) 206 break; 207 cpu_relax(); 208 } 209 } 210 211 if (cpu_status != 0) { 212 printk("Querying DEAD? cpu %i (%i) shows %i\n", 213 cpu, pcpu, cpu_status); 214 } 215 216 /* Isolation and deallocation are definatly done by 217 * drslot_chrp_cpu. If they were not they would be 218 * done here. Change isolate state to Isolate and 219 * change allocation-state to Unusable. 220 */ 221 paca[cpu].cpu_start = 0; 222 } 223 224 /* 225 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 226 * here is that a cpu device node may represent up to two logical cpus 227 * in the SMT case. We must honor the assumption in other code that 228 * the logical ids for sibling SMT threads x and y are adjacent, such 229 * that x^1 == y and y^1 == x. 230 */ 231 static int pseries_add_processor(struct device_node *np) 232 { 233 unsigned int cpu; 234 cpumask_var_t candidate_mask, tmp; 235 int err = -ENOSPC, len, nthreads, i; 236 const u32 *intserv; 237 238 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 239 if (!intserv) 240 return 0; 241 242 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 243 zalloc_cpumask_var(&tmp, GFP_KERNEL); 244 245 nthreads = len / sizeof(u32); 246 for (i = 0; i < nthreads; i++) 247 cpumask_set_cpu(i, tmp); 248 249 cpu_maps_update_begin(); 250 251 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 252 253 /* Get a bitmap of unoccupied slots. */ 254 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 255 if (cpumask_empty(candidate_mask)) { 256 /* If we get here, it most likely means that NR_CPUS is 257 * less than the partition's max processors setting. 258 */ 259 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 260 " supports %d logical cpus.\n", np->full_name, 261 cpumask_weight(cpu_possible_mask)); 262 goto out_unlock; 263 } 264 265 while (!cpumask_empty(tmp)) 266 if (cpumask_subset(tmp, candidate_mask)) 267 /* Found a range where we can insert the new cpu(s) */ 268 break; 269 else 270 cpumask_shift_left(tmp, tmp, nthreads); 271 272 if (cpumask_empty(tmp)) { 273 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 274 " processor %s with %d thread(s)\n", np->name, 275 nthreads); 276 goto out_unlock; 277 } 278 279 for_each_cpu(cpu, tmp) { 280 BUG_ON(cpumask_test_cpu(cpu, cpu_present_mask)); 281 set_cpu_present(cpu, true); 282 set_hard_smp_processor_id(cpu, *intserv++); 283 } 284 err = 0; 285 out_unlock: 286 cpu_maps_update_done(); 287 free_cpumask_var(candidate_mask); 288 free_cpumask_var(tmp); 289 return err; 290 } 291 292 /* 293 * Update the present map for a cpu node which is going away, and set 294 * the hard id in the paca(s) to -1 to be consistent with boot time 295 * convention for non-present cpus. 296 */ 297 static void pseries_remove_processor(struct device_node *np) 298 { 299 unsigned int cpu; 300 int len, nthreads, i; 301 const u32 *intserv; 302 303 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 304 if (!intserv) 305 return; 306 307 nthreads = len / sizeof(u32); 308 309 cpu_maps_update_begin(); 310 for (i = 0; i < nthreads; i++) { 311 for_each_present_cpu(cpu) { 312 if (get_hard_smp_processor_id(cpu) != intserv[i]) 313 continue; 314 BUG_ON(cpu_online(cpu)); 315 set_cpu_present(cpu, false); 316 set_hard_smp_processor_id(cpu, -1); 317 break; 318 } 319 if (cpu >= nr_cpu_ids) 320 printk(KERN_WARNING "Could not find cpu to remove " 321 "with physical id 0x%x\n", intserv[i]); 322 } 323 cpu_maps_update_done(); 324 } 325 326 static int pseries_smp_notifier(struct notifier_block *nb, 327 unsigned long action, void *node) 328 { 329 int err = NOTIFY_OK; 330 331 switch (action) { 332 case PSERIES_RECONFIG_ADD: 333 if (pseries_add_processor(node)) 334 err = NOTIFY_BAD; 335 break; 336 case PSERIES_RECONFIG_REMOVE: 337 pseries_remove_processor(node); 338 break; 339 default: 340 err = NOTIFY_DONE; 341 break; 342 } 343 return err; 344 } 345 346 static struct notifier_block pseries_smp_nb = { 347 .notifier_call = pseries_smp_notifier, 348 }; 349 350 #define MAX_CEDE_LATENCY_LEVELS 4 351 #define CEDE_LATENCY_PARAM_LENGTH 10 352 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 353 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 354 #define CEDE_LATENCY_TOKEN 45 355 356 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 357 358 static int parse_cede_parameters(void) 359 { 360 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 361 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 362 NULL, 363 CEDE_LATENCY_TOKEN, 364 __pa(cede_parameters), 365 CEDE_LATENCY_PARAM_MAX_LENGTH); 366 } 367 368 static int __init pseries_cpu_hotplug_init(void) 369 { 370 struct device_node *np; 371 const char *typep; 372 int cpu; 373 int qcss_tok; 374 375 for_each_node_by_name(np, "interrupt-controller") { 376 typep = of_get_property(np, "compatible", NULL); 377 if (strstr(typep, "open-pic")) { 378 of_node_put(np); 379 380 printk(KERN_INFO "CPU Hotplug not supported on " 381 "systems using MPIC\n"); 382 return 0; 383 } 384 } 385 386 rtas_stop_self_args.token = rtas_token("stop-self"); 387 qcss_tok = rtas_token("query-cpu-stopped-state"); 388 389 if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE || 390 qcss_tok == RTAS_UNKNOWN_SERVICE) { 391 printk(KERN_INFO "CPU Hotplug not supported by firmware " 392 "- disabling.\n"); 393 return 0; 394 } 395 396 ppc_md.cpu_die = pseries_mach_cpu_die; 397 smp_ops->cpu_disable = pseries_cpu_disable; 398 smp_ops->cpu_die = pseries_cpu_die; 399 400 /* Processors can be added/removed only on LPAR */ 401 if (firmware_has_feature(FW_FEATURE_LPAR)) { 402 pSeries_reconfig_notifier_register(&pseries_smp_nb); 403 cpu_maps_update_begin(); 404 if (cede_offline_enabled && parse_cede_parameters() == 0) { 405 default_offline_state = CPU_STATE_INACTIVE; 406 for_each_online_cpu(cpu) 407 set_default_offline_state(cpu); 408 } 409 cpu_maps_update_done(); 410 } 411 412 return 0; 413 } 414 arch_initcall(pseries_cpu_hotplug_init); 415