1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * SMP support for PowerNV machines. 4 * 5 * Copyright 2011 IBM Corp. 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/sched.h> 11 #include <linux/sched/hotplug.h> 12 #include <linux/smp.h> 13 #include <linux/interrupt.h> 14 #include <linux/delay.h> 15 #include <linux/init.h> 16 #include <linux/spinlock.h> 17 #include <linux/cpu.h> 18 19 #include <asm/irq.h> 20 #include <asm/smp.h> 21 #include <asm/paca.h> 22 #include <asm/machdep.h> 23 #include <asm/cputable.h> 24 #include <asm/firmware.h> 25 #include <asm/vdso_datapage.h> 26 #include <asm/cputhreads.h> 27 #include <asm/xics.h> 28 #include <asm/xive.h> 29 #include <asm/opal.h> 30 #include <asm/runlatch.h> 31 #include <asm/code-patching.h> 32 #include <asm/dbell.h> 33 #include <asm/kvm_ppc.h> 34 #include <asm/ppc-opcode.h> 35 #include <asm/cpuidle.h> 36 #include <asm/kexec.h> 37 #include <asm/reg.h> 38 #include <asm/powernv.h> 39 40 #include "powernv.h" 41 42 #ifdef DEBUG 43 #include <asm/udbg.h> 44 #define DBG(fmt...) udbg_printf(fmt) 45 #else 46 #define DBG(fmt...) 47 #endif 48 49 static void pnv_smp_setup_cpu(int cpu) 50 { 51 /* 52 * P9 workaround for CI vector load (see traps.c), 53 * enable the corresponding HMI interrupt 54 */ 55 if (pvr_version_is(PVR_POWER9)) 56 mtspr(SPRN_HMEER, mfspr(SPRN_HMEER) | PPC_BIT(17)); 57 58 if (xive_enabled()) 59 xive_smp_setup_cpu(); 60 else if (cpu != boot_cpuid) 61 xics_setup_cpu(); 62 } 63 64 static int pnv_smp_kick_cpu(int nr) 65 { 66 unsigned int pcpu; 67 unsigned long start_here = 68 __pa(ppc_function_entry(generic_secondary_smp_init)); 69 long rc; 70 uint8_t status; 71 72 if (nr < 0 || nr >= nr_cpu_ids) 73 return -EINVAL; 74 75 pcpu = get_hard_smp_processor_id(nr); 76 /* 77 * If we already started or OPAL is not supported, we just 78 * kick the CPU via the PACA 79 */ 80 if (paca_ptrs[nr]->cpu_start || !firmware_has_feature(FW_FEATURE_OPAL)) 81 goto kick; 82 83 /* 84 * At this point, the CPU can either be spinning on the way in 85 * from kexec or be inside OPAL waiting to be started for the 86 * first time. OPAL v3 allows us to query OPAL to know if it 87 * has the CPUs, so we do that 88 */ 89 rc = opal_query_cpu_status(pcpu, &status); 90 if (rc != OPAL_SUCCESS) { 91 pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr); 92 return -ENODEV; 93 } 94 95 /* 96 * Already started, just kick it, probably coming from 97 * kexec and spinning 98 */ 99 if (status == OPAL_THREAD_STARTED) 100 goto kick; 101 102 /* 103 * Available/inactive, let's kick it 104 */ 105 if (status == OPAL_THREAD_INACTIVE) { 106 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu); 107 rc = opal_start_cpu(pcpu, start_here); 108 if (rc != OPAL_SUCCESS) { 109 pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr); 110 return -ENODEV; 111 } 112 } else { 113 /* 114 * An unavailable CPU (or any other unknown status) 115 * shouldn't be started. It should also 116 * not be in the possible map but currently it can 117 * happen 118 */ 119 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" 120 " (status %d)...\n", nr, pcpu, status); 121 return -ENODEV; 122 } 123 124 kick: 125 return smp_generic_kick_cpu(nr); 126 } 127 128 #ifdef CONFIG_HOTPLUG_CPU 129 130 static int pnv_smp_cpu_disable(void) 131 { 132 int cpu = smp_processor_id(); 133 134 /* This is identical to pSeries... might consolidate by 135 * moving migrate_irqs_away to a ppc_md with default to 136 * the generic fixup_irqs. --BenH. 137 */ 138 set_cpu_online(cpu, false); 139 vdso_data->processorCount--; 140 if (cpu == boot_cpuid) 141 boot_cpuid = cpumask_any(cpu_online_mask); 142 if (xive_enabled()) 143 xive_smp_disable_cpu(); 144 else 145 xics_migrate_irqs_away(); 146 return 0; 147 } 148 149 static void pnv_smp_cpu_kill_self(void) 150 { 151 unsigned int cpu; 152 unsigned long srr1, wmask; 153 u64 lpcr_val; 154 155 /* Standard hot unplug procedure */ 156 /* 157 * This hard disables local interurpts, ensuring we have no lazy 158 * irqs pending. 159 */ 160 WARN_ON(irqs_disabled()); 161 hard_irq_disable(); 162 WARN_ON(lazy_irq_pending()); 163 164 idle_task_exit(); 165 current->active_mm = NULL; /* for sanity */ 166 cpu = smp_processor_id(); 167 DBG("CPU%d offline\n", cpu); 168 generic_set_cpu_dead(cpu); 169 smp_wmb(); 170 171 wmask = SRR1_WAKEMASK; 172 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 173 wmask = SRR1_WAKEMASK_P8; 174 175 /* 176 * We don't want to take decrementer interrupts while we are 177 * offline, so clear LPCR:PECE1. We keep PECE2 (and 178 * LPCR_PECE_HVEE on P9) enabled so as to let IPIs in. 179 * 180 * If the CPU gets woken up by a special wakeup, ensure that 181 * the SLW engine sets LPCR with decrementer bit cleared, else 182 * the CPU will come back to the kernel due to a spurious 183 * wakeup. 184 */ 185 lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1; 186 pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val); 187 188 while (!generic_check_cpu_restart(cpu)) { 189 /* 190 * Clear IPI flag, since we don't handle IPIs while 191 * offline, except for those when changing micro-threading 192 * mode, which are handled explicitly below, and those 193 * for coming online, which are handled via 194 * generic_check_cpu_restart() calls. 195 */ 196 kvmppc_clear_host_ipi(cpu); 197 198 srr1 = pnv_cpu_offline(cpu); 199 200 WARN_ON(lazy_irq_pending()); 201 202 /* 203 * If the SRR1 value indicates that we woke up due to 204 * an external interrupt, then clear the interrupt. 205 * We clear the interrupt before checking for the 206 * reason, so as to avoid a race where we wake up for 207 * some other reason, find nothing and clear the interrupt 208 * just as some other cpu is sending us an interrupt. 209 * If we returned from power7_nap as a result of 210 * having finished executing in a KVM guest, then srr1 211 * contains 0. 212 */ 213 if (((srr1 & wmask) == SRR1_WAKEEE) || 214 ((srr1 & wmask) == SRR1_WAKEHVI)) { 215 if (cpu_has_feature(CPU_FTR_ARCH_300)) { 216 if (xive_enabled()) 217 xive_flush_interrupt(); 218 else 219 icp_opal_flush_interrupt(); 220 } else 221 icp_native_flush_interrupt(); 222 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) { 223 unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER); 224 asm volatile(PPC_MSGCLR(%0) : : "r" (msg)); 225 } else if ((srr1 & wmask) == SRR1_WAKERESET) { 226 irq_set_pending_from_srr1(srr1); 227 /* Does not return */ 228 } 229 230 smp_mb(); 231 232 /* 233 * For kdump kernels, we process the ipi and jump to 234 * crash_ipi_callback 235 */ 236 if (kdump_in_progress()) { 237 /* 238 * If we got to this point, we've not used 239 * NMI's, otherwise we would have gone 240 * via the SRR1_WAKERESET path. We are 241 * using regular IPI's for waking up offline 242 * threads. 243 */ 244 struct pt_regs regs; 245 246 ppc_save_regs(®s); 247 crash_ipi_callback(®s); 248 /* Does not return */ 249 } 250 251 if (cpu_core_split_required()) 252 continue; 253 254 if (srr1 && !generic_check_cpu_restart(cpu)) 255 DBG("CPU%d Unexpected exit while offline srr1=%lx!\n", 256 cpu, srr1); 257 258 } 259 260 /* 261 * Re-enable decrementer interrupts in LPCR. 262 * 263 * Further, we want stop states to be woken up by decrementer 264 * for non-hotplug cases. So program the LPCR via stop api as 265 * well. 266 */ 267 lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1; 268 pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val); 269 270 DBG("CPU%d coming online...\n", cpu); 271 } 272 273 #endif /* CONFIG_HOTPLUG_CPU */ 274 275 static int pnv_cpu_bootable(unsigned int nr) 276 { 277 /* 278 * Starting with POWER8, the subcore logic relies on all threads of a 279 * core being booted so that they can participate in split mode 280 * switches. So on those machines we ignore the smt_enabled_at_boot 281 * setting (smt-enabled on the kernel command line). 282 */ 283 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 284 return 1; 285 286 return smp_generic_cpu_bootable(nr); 287 } 288 289 static int pnv_smp_prepare_cpu(int cpu) 290 { 291 if (xive_enabled()) 292 return xive_smp_prepare_cpu(cpu); 293 return 0; 294 } 295 296 /* Cause IPI as setup by the interrupt controller (xics or xive) */ 297 static void (*ic_cause_ipi)(int cpu); 298 299 static void pnv_cause_ipi(int cpu) 300 { 301 if (doorbell_try_core_ipi(cpu)) 302 return; 303 304 ic_cause_ipi(cpu); 305 } 306 307 static void __init pnv_smp_probe(void) 308 { 309 if (xive_enabled()) 310 xive_smp_probe(); 311 else 312 xics_smp_probe(); 313 314 if (cpu_has_feature(CPU_FTR_DBELL)) { 315 ic_cause_ipi = smp_ops->cause_ipi; 316 WARN_ON(!ic_cause_ipi); 317 318 if (cpu_has_feature(CPU_FTR_ARCH_300)) 319 smp_ops->cause_ipi = doorbell_global_ipi; 320 else 321 smp_ops->cause_ipi = pnv_cause_ipi; 322 } 323 } 324 325 static int pnv_system_reset_exception(struct pt_regs *regs) 326 { 327 if (smp_handle_nmi_ipi(regs)) 328 return 1; 329 return 0; 330 } 331 332 static int pnv_cause_nmi_ipi(int cpu) 333 { 334 int64_t rc; 335 336 if (cpu >= 0) { 337 int h = get_hard_smp_processor_id(cpu); 338 339 if (opal_check_token(OPAL_QUIESCE)) 340 opal_quiesce(QUIESCE_HOLD, h); 341 342 rc = opal_signal_system_reset(h); 343 344 if (opal_check_token(OPAL_QUIESCE)) 345 opal_quiesce(QUIESCE_RESUME, h); 346 347 if (rc != OPAL_SUCCESS) 348 return 0; 349 return 1; 350 351 } else if (cpu == NMI_IPI_ALL_OTHERS) { 352 bool success = true; 353 int c; 354 355 if (opal_check_token(OPAL_QUIESCE)) 356 opal_quiesce(QUIESCE_HOLD, -1); 357 358 /* 359 * We do not use broadcasts (yet), because it's not clear 360 * exactly what semantics Linux wants or the firmware should 361 * provide. 362 */ 363 for_each_online_cpu(c) { 364 if (c == smp_processor_id()) 365 continue; 366 367 rc = opal_signal_system_reset( 368 get_hard_smp_processor_id(c)); 369 if (rc != OPAL_SUCCESS) 370 success = false; 371 } 372 373 if (opal_check_token(OPAL_QUIESCE)) 374 opal_quiesce(QUIESCE_RESUME, -1); 375 376 if (success) 377 return 1; 378 379 /* 380 * Caller will fall back to doorbells, which may pick 381 * up the remainders. 382 */ 383 } 384 385 return 0; 386 } 387 388 static struct smp_ops_t pnv_smp_ops = { 389 .message_pass = NULL, /* Use smp_muxed_ipi_message_pass */ 390 .cause_ipi = NULL, /* Filled at runtime by pnv_smp_probe() */ 391 .cause_nmi_ipi = NULL, 392 .probe = pnv_smp_probe, 393 .prepare_cpu = pnv_smp_prepare_cpu, 394 .kick_cpu = pnv_smp_kick_cpu, 395 .setup_cpu = pnv_smp_setup_cpu, 396 .cpu_bootable = pnv_cpu_bootable, 397 #ifdef CONFIG_HOTPLUG_CPU 398 .cpu_disable = pnv_smp_cpu_disable, 399 .cpu_die = generic_cpu_die, 400 #endif /* CONFIG_HOTPLUG_CPU */ 401 }; 402 403 /* This is called very early during platform setup_arch */ 404 void __init pnv_smp_init(void) 405 { 406 if (opal_check_token(OPAL_SIGNAL_SYSTEM_RESET)) { 407 ppc_md.system_reset_exception = pnv_system_reset_exception; 408 pnv_smp_ops.cause_nmi_ipi = pnv_cause_nmi_ipi; 409 } 410 smp_ops = &pnv_smp_ops; 411 412 #ifdef CONFIG_HOTPLUG_CPU 413 ppc_md.cpu_die = pnv_smp_cpu_kill_self; 414 #ifdef CONFIG_KEXEC_CORE 415 crash_wake_offline = 1; 416 #endif 417 #endif 418 } 419