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