arch/powerpc/platforms/powernv/smp.c

   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_set_host_ipi(cpu, 0);
 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(&regs);
 247                         crash_ipi_callback(&regs);
 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 }