1 /* 2 * SMP support for PowerNV machines. 3 * 4 * Copyright 2011 IBM Corp. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/sched.h> 15 #include <linux/smp.h> 16 #include <linux/interrupt.h> 17 #include <linux/delay.h> 18 #include <linux/init.h> 19 #include <linux/spinlock.h> 20 #include <linux/cpu.h> 21 22 #include <asm/irq.h> 23 #include <asm/smp.h> 24 #include <asm/paca.h> 25 #include <asm/machdep.h> 26 #include <asm/cputable.h> 27 #include <asm/firmware.h> 28 #include <asm/rtas.h> 29 #include <asm/vdso_datapage.h> 30 #include <asm/cputhreads.h> 31 #include <asm/xics.h> 32 #include <asm/opal.h> 33 34 #include "powernv.h" 35 36 #ifdef DEBUG 37 #include <asm/udbg.h> 38 #define DBG(fmt...) udbg_printf(fmt) 39 #else 40 #define DBG(fmt...) 41 #endif 42 43 static void __cpuinit pnv_smp_setup_cpu(int cpu) 44 { 45 if (cpu != boot_cpuid) 46 xics_setup_cpu(); 47 } 48 49 static int pnv_smp_cpu_bootable(unsigned int nr) 50 { 51 /* Special case - we inhibit secondary thread startup 52 * during boot if the user requests it. 53 */ 54 if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) { 55 if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) 56 return 0; 57 if (smt_enabled_at_boot 58 && cpu_thread_in_core(nr) >= smt_enabled_at_boot) 59 return 0; 60 } 61 62 return 1; 63 } 64 65 int pnv_smp_kick_cpu(int nr) 66 { 67 unsigned int pcpu = get_hard_smp_processor_id(nr); 68 unsigned long start_here = __pa(*((unsigned long *) 69 generic_secondary_smp_init)); 70 long rc; 71 72 BUG_ON(nr < 0 || nr >= NR_CPUS); 73 74 /* 75 * If we already started or OPALv2 is not supported, we just 76 * kick the CPU via the PACA 77 */ 78 if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2)) 79 goto kick; 80 81 /* 82 * At this point, the CPU can either be spinning on the way in 83 * from kexec or be inside OPAL waiting to be started for the 84 * first time. OPAL v3 allows us to query OPAL to know if it 85 * has the CPUs, so we do that 86 */ 87 if (firmware_has_feature(FW_FEATURE_OPALv3)) { 88 uint8_t status; 89 90 rc = opal_query_cpu_status(pcpu, &status); 91 if (rc != OPAL_SUCCESS) { 92 pr_warn("OPAL Error %ld querying CPU %d state\n", 93 rc, nr); 94 return -ENODEV; 95 } 96 97 /* 98 * Already started, just kick it, probably coming from 99 * kexec and spinning 100 */ 101 if (status == OPAL_THREAD_STARTED) 102 goto kick; 103 104 /* 105 * Available/inactive, let's kick it 106 */ 107 if (status == OPAL_THREAD_INACTIVE) { 108 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", 109 nr, pcpu); 110 rc = opal_start_cpu(pcpu, start_here); 111 if (rc != OPAL_SUCCESS) { 112 pr_warn("OPAL Error %ld starting CPU %d\n", 113 rc, nr); 114 return -ENODEV; 115 } 116 } else { 117 /* 118 * An unavailable CPU (or any other unknown status) 119 * shouldn't be started. It should also 120 * not be in the possible map but currently it can 121 * happen 122 */ 123 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" 124 " (status %d)...\n", nr, pcpu, status); 125 return -ENODEV; 126 } 127 } else { 128 /* 129 * On OPAL v2, we just kick it and hope for the best, 130 * we must not test the error from opal_start_cpu() or 131 * we would fail to get CPUs from kexec. 132 */ 133 opal_start_cpu(pcpu, start_here); 134 } 135 kick: 136 return smp_generic_kick_cpu(nr); 137 } 138 139 #ifdef CONFIG_HOTPLUG_CPU 140 141 static int pnv_smp_cpu_disable(void) 142 { 143 int cpu = smp_processor_id(); 144 145 /* This is identical to pSeries... might consolidate by 146 * moving migrate_irqs_away to a ppc_md with default to 147 * the generic fixup_irqs. --BenH. 148 */ 149 set_cpu_online(cpu, false); 150 vdso_data->processorCount--; 151 if (cpu == boot_cpuid) 152 boot_cpuid = cpumask_any(cpu_online_mask); 153 xics_migrate_irqs_away(); 154 return 0; 155 } 156 157 static void pnv_smp_cpu_kill_self(void) 158 { 159 unsigned int cpu; 160 161 /* Standard hot unplug procedure */ 162 local_irq_disable(); 163 idle_task_exit(); 164 current->active_mm = NULL; /* for sanity */ 165 cpu = smp_processor_id(); 166 DBG("CPU%d offline\n", cpu); 167 generic_set_cpu_dead(cpu); 168 smp_wmb(); 169 170 /* We don't want to take decrementer interrupts while we are offline, 171 * so clear LPCR:PECE1. We keep PECE2 enabled. 172 */ 173 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1); 174 while (!generic_check_cpu_restart(cpu)) { 175 power7_nap(); 176 if (!generic_check_cpu_restart(cpu)) { 177 DBG("CPU%d Unexpected exit while offline !\n", cpu); 178 /* We may be getting an IPI, so we re-enable 179 * interrupts to process it, it will be ignored 180 * since we aren't online (hopefully) 181 */ 182 local_irq_enable(); 183 local_irq_disable(); 184 } 185 } 186 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1); 187 DBG("CPU%d coming online...\n", cpu); 188 } 189 190 #endif /* CONFIG_HOTPLUG_CPU */ 191 192 static struct smp_ops_t pnv_smp_ops = { 193 .message_pass = smp_muxed_ipi_message_pass, 194 .cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */ 195 .probe = xics_smp_probe, 196 .kick_cpu = pnv_smp_kick_cpu, 197 .setup_cpu = pnv_smp_setup_cpu, 198 .cpu_bootable = pnv_smp_cpu_bootable, 199 #ifdef CONFIG_HOTPLUG_CPU 200 .cpu_disable = pnv_smp_cpu_disable, 201 .cpu_die = generic_cpu_die, 202 #endif /* CONFIG_HOTPLUG_CPU */ 203 }; 204 205 /* This is called very early during platform setup_arch */ 206 void __init pnv_smp_init(void) 207 { 208 smp_ops = &pnv_smp_ops; 209 210 /* XXX We don't yet have a proper entry point from HAL, for 211 * now we rely on kexec-style entry from BML 212 */ 213 214 #ifdef CONFIG_PPC_RTAS 215 /* Non-lpar has additional take/give timebase */ 216 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 217 smp_ops->give_timebase = rtas_give_timebase; 218 smp_ops->take_timebase = rtas_take_timebase; 219 } 220 #endif /* CONFIG_PPC_RTAS */ 221 222 #ifdef CONFIG_HOTPLUG_CPU 223 ppc_md.cpu_die = pnv_smp_cpu_kill_self; 224 #endif 225 } 226