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