arch/powerpc/platforms/pseries/smp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * SMP support for pSeries machines.
   4  *
   5  * Dave Engebretsen, Peter Bergner, and
   6  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
   7  *
   8  * Plus various changes from other IBM teams...
   9  */
  10
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/smp.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/delay.h>
  17 #include <linux/init.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/cache.h>
  20 #include <linux/err.h>
  21 #include <linux/device.h>
  22 #include <linux/cpu.h>
  23 #include <linux/pgtable.h>
  24
  25 #include <asm/ptrace.h>
  26 #include <linux/atomic.h>
  27 #include <asm/irq.h>
  28 #include <asm/page.h>
  29 #include <asm/io.h>
  30 #include <asm/prom.h>
  31 #include <asm/smp.h>
  32 #include <asm/paca.h>
  33 #include <asm/machdep.h>
  34 #include <asm/cputable.h>
  35 #include <asm/firmware.h>
  36 #include <asm/rtas.h>
  37 #include <asm/vdso_datapage.h>
  38 #include <asm/cputhreads.h>
  39 #include <asm/xics.h>
  40 #include <asm/xive.h>
  41 #include <asm/dbell.h>
  42 #include <asm/plpar_wrappers.h>
  43 #include <asm/code-patching.h>
  44 #include <asm/svm.h>
  45
  46 #include "pseries.h"
  47 #include "offline_states.h"
  48
  49
  50 /*
  51  * The Primary thread of each non-boot processor was started from the OF client
  52  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  53  */
  54 static cpumask_var_t of_spin_mask;
  55
  56 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
  57 int smp_query_cpu_stopped(unsigned int pcpu)
  58 {
  59         int cpu_status, status;
  60         int qcss_tok = rtas_token("query-cpu-stopped-state");
  61
  62         if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
  63                 printk_once(KERN_INFO
  64                         "Firmware doesn't support query-cpu-stopped-state\n");
  65                 return QCSS_HARDWARE_ERROR;
  66         }
  67
  68         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  69         if (status != 0) {
  70                 printk(KERN_ERR
  71                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  72                 return status;
  73         }
  74
  75         return cpu_status;
  76 }
  77
  78 /**
  79  * smp_startup_cpu() - start the given cpu
  80  *
  81  * At boot time, there is nothing to do for primary threads which were
  82  * started from Open Firmware.  For anything else, call RTAS with the
  83  * appropriate start location.
  84  *
  85  * Returns:
  86  *      0       - failure
  87  *      1       - success
  88  */
  89 static inline int smp_startup_cpu(unsigned int lcpu)
  90 {
  91         int status;
  92         unsigned long start_here =
  93                         __pa(ppc_function_entry(generic_secondary_smp_init));
  94         unsigned int pcpu;
  95         int start_cpu;
  96
  97         if (cpumask_test_cpu(lcpu, of_spin_mask))
  98                 /* Already started by OF and sitting in spin loop */
  99                 return 1;
 100
 101         pcpu = get_hard_smp_processor_id(lcpu);
 102
 103         /* Check to see if the CPU out of FW already for kexec */
 104         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
 105                 cpumask_set_cpu(lcpu, of_spin_mask);
 106                 return 1;
 107         }
 108
 109         /* Fixup atomic count: it exited inside IRQ handler. */
 110         task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count     = 0;
 111 #ifdef CONFIG_HOTPLUG_CPU
 112         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
 113                 goto out;
 114 #endif
 115         /*
 116          * If the RTAS start-cpu token does not exist then presume the
 117          * cpu is already spinning.
 118          */
 119         start_cpu = rtas_token("start-cpu");
 120         if (start_cpu == RTAS_UNKNOWN_SERVICE)
 121                 return 1;
 122
 123         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 124         if (status != 0) {
 125                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 126                 return 0;
 127         }
 128
 129 #ifdef CONFIG_HOTPLUG_CPU
 130 out:
 131 #endif
 132         return 1;
 133 }
 134
 135 static void smp_setup_cpu(int cpu)
 136 {
 137         if (xive_enabled())
 138                 xive_smp_setup_cpu();
 139         else if (cpu != boot_cpuid)
 140                 xics_setup_cpu();
 141
 142         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 143                 vpa_init(cpu);
 144
 145         cpumask_clear_cpu(cpu, of_spin_mask);
 146 #ifdef CONFIG_HOTPLUG_CPU
 147         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
 148         set_default_offline_state(cpu);
 149 #endif
 150 }
 151
 152 static int smp_pSeries_kick_cpu(int nr)
 153 {
 154         if (nr < 0 || nr >= nr_cpu_ids)
 155                 return -EINVAL;
 156
 157         if (!smp_startup_cpu(nr))
 158                 return -ENOENT;
 159
 160         /*
 161          * The processor is currently spinning, waiting for the
 162          * cpu_start field to become non-zero After we set cpu_start,
 163          * the processor will continue on to secondary_start
 164          */
 165         paca_ptrs[nr]->cpu_start = 1;
 166 #ifdef CONFIG_HOTPLUG_CPU
 167         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
 168
 169         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
 170                 long rc;
 171                 unsigned long hcpuid;
 172
 173                 hcpuid = get_hard_smp_processor_id(nr);
 174                 rc = plpar_hcall_norets(H_PROD, hcpuid);
 175                 if (rc != H_SUCCESS)
 176                         printk(KERN_ERR "Error: Prod to wake up processor %d "
 177                                                 "Ret= %ld\n", nr, rc);
 178         }
 179 #endif
 180
 181         return 0;
 182 }
 183
 184 static int pseries_smp_prepare_cpu(int cpu)
 185 {
 186         if (xive_enabled())
 187                 return xive_smp_prepare_cpu(cpu);
 188         return 0;
 189 }
 190
 191 static void smp_pseries_cause_ipi(int cpu)
 192 {
 193         /* POWER9 should not use this handler */
 194         if (doorbell_try_core_ipi(cpu))
 195                 return;
 196
 197         icp_ops->cause_ipi(cpu);
 198 }
 199
 200 static int pseries_cause_nmi_ipi(int cpu)
 201 {
 202         int hwcpu;
 203
 204         if (cpu == NMI_IPI_ALL_OTHERS) {
 205                 hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
 206         } else {
 207                 if (cpu < 0) {
 208                         WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
 209                         return 0;
 210                 }
 211
 212                 hwcpu = get_hard_smp_processor_id(cpu);
 213         }
 214
 215         if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS)
 216                 return 1;
 217
 218         return 0;
 219 }
 220
 221 static __init void pSeries_smp_probe_xics(void)
 222 {
 223         xics_smp_probe();
 224
 225         if (cpu_has_feature(CPU_FTR_DBELL) && !is_secure_guest())
 226                 smp_ops->cause_ipi = smp_pseries_cause_ipi;
 227         else
 228                 smp_ops->cause_ipi = icp_ops->cause_ipi;
 229 }
 230
 231 static __init void pSeries_smp_probe(void)
 232 {
 233         if (xive_enabled())
 234                 /*
 235                  * Don't use P9 doorbells when XIVE is enabled. IPIs
 236                  * using MMIOs should be faster
 237                  */
 238                 xive_smp_probe();
 239         else
 240                 pSeries_smp_probe_xics();
 241 }
 242
 243 static struct smp_ops_t pseries_smp_ops = {
 244         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 245         .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
 246         .cause_nmi_ipi  = pseries_cause_nmi_ipi,
 247         .probe          = pSeries_smp_probe,
 248         .prepare_cpu    = pseries_smp_prepare_cpu,
 249         .kick_cpu       = smp_pSeries_kick_cpu,
 250         .setup_cpu      = smp_setup_cpu,
 251         .cpu_bootable   = smp_generic_cpu_bootable,
 252 };
 253
 254 /* This is called very early */
 255 void __init smp_init_pseries(void)
 256 {
 257         int i;
 258
 259         pr_debug(" -> smp_init_pSeries()\n");
 260         smp_ops = &pseries_smp_ops;
 261
 262         alloc_bootmem_cpumask_var(&of_spin_mask);
 263
 264         /*
 265          * Mark threads which are still spinning in hold loops
 266          *
 267          * We know prom_init will not have started them if RTAS supports
 268          * query-cpu-stopped-state.
 269          */
 270         if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
 271                 if (cpu_has_feature(CPU_FTR_SMT)) {
 272                         for_each_present_cpu(i) {
 273                                 if (cpu_thread_in_core(i) == 0)
 274                                         cpumask_set_cpu(i, of_spin_mask);
 275                         }
 276                 } else
 277                         cpumask_copy(of_spin_mask, cpu_present_mask);
 278
 279                 cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 280         }
 281
 282         /* Non-lpar has additional take/give timebase */
 283         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 284                 smp_ops->give_timebase = rtas_give_timebase;
 285                 smp_ops->take_timebase = rtas_take_timebase;
 286         }
 287
 288         pr_debug(" <- smp_init_pSeries()\n");
 289 }