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 pnv_smp_setup_cpu(int cpu) 44 { 45 if (cpu != boot_cpuid) 46 xics_setup_cpu(); 47 } 48 49 int pnv_smp_kick_cpu(int nr) 50 { 51 unsigned int pcpu = get_hard_smp_processor_id(nr); 52 unsigned long start_here = __pa(*((unsigned long *) 53 generic_secondary_smp_init)); 54 long rc; 55 56 BUG_ON(nr < 0 || nr >= NR_CPUS); 57 58 /* 59 * If we already started or OPALv2 is not supported, we just 60 * kick the CPU via the PACA 61 */ 62 if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2)) 63 goto kick; 64 65 /* 66 * At this point, the CPU can either be spinning on the way in 67 * from kexec or be inside OPAL waiting to be started for the 68 * first time. OPAL v3 allows us to query OPAL to know if it 69 * has the CPUs, so we do that 70 */ 71 if (firmware_has_feature(FW_FEATURE_OPALv3)) { 72 uint8_t status; 73 74 rc = opal_query_cpu_status(pcpu, &status); 75 if (rc != OPAL_SUCCESS) { 76 pr_warn("OPAL Error %ld querying CPU %d state\n", 77 rc, nr); 78 return -ENODEV; 79 } 80 81 /* 82 * Already started, just kick it, probably coming from 83 * kexec and spinning 84 */ 85 if (status == OPAL_THREAD_STARTED) 86 goto kick; 87 88 /* 89 * Available/inactive, let's kick it 90 */ 91 if (status == OPAL_THREAD_INACTIVE) { 92 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", 93 nr, pcpu); 94 rc = opal_start_cpu(pcpu, start_here); 95 if (rc != OPAL_SUCCESS) { 96 pr_warn("OPAL Error %ld starting CPU %d\n", 97 rc, nr); 98 return -ENODEV; 99 } 100 } else { 101 /* 102 * An unavailable CPU (or any other unknown status) 103 * shouldn't be started. It should also 104 * not be in the possible map but currently it can 105 * happen 106 */ 107 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" 108 " (status %d)...\n", nr, pcpu, status); 109 return -ENODEV; 110 } 111 } else { 112 /* 113 * On OPAL v2, we just kick it and hope for the best, 114 * we must not test the error from opal_start_cpu() or 115 * we would fail to get CPUs from kexec. 116 */ 117 opal_start_cpu(pcpu, start_here); 118 } 119 kick: 120 return smp_generic_kick_cpu(nr); 121 } 122 123 #ifdef CONFIG_HOTPLUG_CPU 124 125 static int pnv_smp_cpu_disable(void) 126 { 127 int cpu = smp_processor_id(); 128 129 /* This is identical to pSeries... might consolidate by 130 * moving migrate_irqs_away to a ppc_md with default to 131 * the generic fixup_irqs. --BenH. 132 */ 133 set_cpu_online(cpu, false); 134 vdso_data->processorCount--; 135 if (cpu == boot_cpuid) 136 boot_cpuid = cpumask_any(cpu_online_mask); 137 xics_migrate_irqs_away(); 138 return 0; 139 } 140 141 static void pnv_smp_cpu_kill_self(void) 142 { 143 unsigned int cpu; 144 145 /* Standard hot unplug procedure */ 146 local_irq_disable(); 147 idle_task_exit(); 148 current->active_mm = NULL; /* for sanity */ 149 cpu = smp_processor_id(); 150 DBG("CPU%d offline\n", cpu); 151 generic_set_cpu_dead(cpu); 152 smp_wmb(); 153 154 /* We don't want to take decrementer interrupts while we are offline, 155 * so clear LPCR:PECE1. We keep PECE2 enabled. 156 */ 157 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1); 158 while (!generic_check_cpu_restart(cpu)) { 159 power7_nap(); 160 if (!generic_check_cpu_restart(cpu)) { 161 DBG("CPU%d Unexpected exit while offline !\n", cpu); 162 /* We may be getting an IPI, so we re-enable 163 * interrupts to process it, it will be ignored 164 * since we aren't online (hopefully) 165 */ 166 local_irq_enable(); 167 local_irq_disable(); 168 } 169 } 170 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1); 171 DBG("CPU%d coming online...\n", cpu); 172 } 173 174 #endif /* CONFIG_HOTPLUG_CPU */ 175 176 static struct smp_ops_t pnv_smp_ops = { 177 .message_pass = smp_muxed_ipi_message_pass, 178 .cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */ 179 .probe = xics_smp_probe, 180 .kick_cpu = pnv_smp_kick_cpu, 181 .setup_cpu = pnv_smp_setup_cpu, 182 .cpu_bootable = smp_generic_cpu_bootable, 183 #ifdef CONFIG_HOTPLUG_CPU 184 .cpu_disable = pnv_smp_cpu_disable, 185 .cpu_die = generic_cpu_die, 186 #endif /* CONFIG_HOTPLUG_CPU */ 187 }; 188 189 /* This is called very early during platform setup_arch */ 190 void __init pnv_smp_init(void) 191 { 192 smp_ops = &pnv_smp_ops; 193 194 /* XXX We don't yet have a proper entry point from HAL, for 195 * now we rely on kexec-style entry from BML 196 */ 197 198 #ifdef CONFIG_PPC_RTAS 199 /* Non-lpar has additional take/give timebase */ 200 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 201 smp_ops->give_timebase = rtas_give_timebase; 202 smp_ops->take_timebase = rtas_take_timebase; 203 } 204 #endif /* CONFIG_PPC_RTAS */ 205 206 #ifdef CONFIG_HOTPLUG_CPU 207 ppc_md.cpu_die = pnv_smp_cpu_kill_self; 208 #endif 209 } 210