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/vdso_datapage.h> 29 #include <asm/cputhreads.h> 30 #include <asm/xics.h> 31 #include <asm/opal.h> 32 #include <asm/runlatch.h> 33 #include <asm/code-patching.h> 34 #include <asm/dbell.h> 35 #include <asm/kvm_ppc.h> 36 #include <asm/ppc-opcode.h> 37 38 #include "powernv.h" 39 40 #ifdef DEBUG 41 #include <asm/udbg.h> 42 #define DBG(fmt...) udbg_printf(fmt) 43 #else 44 #define DBG(fmt...) 45 #endif 46 47 static void pnv_smp_setup_cpu(int cpu) 48 { 49 if (cpu != boot_cpuid) 50 xics_setup_cpu(); 51 52 #ifdef CONFIG_PPC_DOORBELL 53 if (cpu_has_feature(CPU_FTR_DBELL)) 54 doorbell_setup_this_cpu(); 55 #endif 56 } 57 58 static int pnv_smp_kick_cpu(int nr) 59 { 60 unsigned int pcpu = get_hard_smp_processor_id(nr); 61 unsigned long start_here = 62 __pa(ppc_function_entry(generic_secondary_smp_init)); 63 long rc; 64 65 BUG_ON(nr < 0 || nr >= NR_CPUS); 66 67 /* 68 * If we already started or OPALv2 is not supported, we just 69 * kick the CPU via the PACA 70 */ 71 if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2)) 72 goto kick; 73 74 /* 75 * At this point, the CPU can either be spinning on the way in 76 * from kexec or be inside OPAL waiting to be started for the 77 * first time. OPAL v3 allows us to query OPAL to know if it 78 * has the CPUs, so we do that 79 */ 80 if (firmware_has_feature(FW_FEATURE_OPALv3)) { 81 uint8_t status; 82 83 rc = opal_query_cpu_status(pcpu, &status); 84 if (rc != OPAL_SUCCESS) { 85 pr_warn("OPAL Error %ld querying CPU %d state\n", 86 rc, nr); 87 return -ENODEV; 88 } 89 90 /* 91 * Already started, just kick it, probably coming from 92 * kexec and spinning 93 */ 94 if (status == OPAL_THREAD_STARTED) 95 goto kick; 96 97 /* 98 * Available/inactive, let's kick it 99 */ 100 if (status == OPAL_THREAD_INACTIVE) { 101 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", 102 nr, pcpu); 103 rc = opal_start_cpu(pcpu, start_here); 104 if (rc != OPAL_SUCCESS) { 105 pr_warn("OPAL Error %ld starting CPU %d\n", 106 rc, nr); 107 return -ENODEV; 108 } 109 } else { 110 /* 111 * An unavailable CPU (or any other unknown status) 112 * shouldn't be started. It should also 113 * not be in the possible map but currently it can 114 * happen 115 */ 116 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" 117 " (status %d)...\n", nr, pcpu, status); 118 return -ENODEV; 119 } 120 } else { 121 /* 122 * On OPAL v2, we just kick it and hope for the best, 123 * we must not test the error from opal_start_cpu() or 124 * we would fail to get CPUs from kexec. 125 */ 126 opal_start_cpu(pcpu, start_here); 127 } 128 kick: 129 return smp_generic_kick_cpu(nr); 130 } 131 132 #ifdef CONFIG_HOTPLUG_CPU 133 134 static int pnv_smp_cpu_disable(void) 135 { 136 int cpu = smp_processor_id(); 137 138 /* This is identical to pSeries... might consolidate by 139 * moving migrate_irqs_away to a ppc_md with default to 140 * the generic fixup_irqs. --BenH. 141 */ 142 set_cpu_online(cpu, false); 143 vdso_data->processorCount--; 144 if (cpu == boot_cpuid) 145 boot_cpuid = cpumask_any(cpu_online_mask); 146 xics_migrate_irqs_away(); 147 return 0; 148 } 149 150 static void pnv_smp_cpu_kill_self(void) 151 { 152 unsigned int cpu; 153 unsigned long srr1, wmask; 154 u32 idle_states; 155 156 /* Standard hot unplug procedure */ 157 local_irq_disable(); 158 idle_task_exit(); 159 current->active_mm = NULL; /* for sanity */ 160 cpu = smp_processor_id(); 161 DBG("CPU%d offline\n", cpu); 162 generic_set_cpu_dead(cpu); 163 smp_wmb(); 164 165 wmask = SRR1_WAKEMASK; 166 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 167 wmask = SRR1_WAKEMASK_P8; 168 169 idle_states = pnv_get_supported_cpuidle_states(); 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); 174 175 /* 176 * Hard-disable interrupts, and then clear irq_happened flags 177 * that we can safely ignore while off-line, since they 178 * are for things for which we do no processing when off-line 179 * (or in the case of HMI, all the processing we need to do 180 * is done in lower-level real-mode code). 181 */ 182 hard_irq_disable(); 183 local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI); 184 185 while (!generic_check_cpu_restart(cpu)) { 186 /* 187 * Clear IPI flag, since we don't handle IPIs while 188 * offline, except for those when changing micro-threading 189 * mode, which are handled explicitly below, and those 190 * for coming online, which are handled via 191 * generic_check_cpu_restart() calls. 192 */ 193 kvmppc_set_host_ipi(cpu, 0); 194 195 ppc64_runlatch_off(); 196 197 if (idle_states & OPAL_PM_WINKLE_ENABLED) 198 srr1 = power7_winkle(); 199 else if ((idle_states & OPAL_PM_SLEEP_ENABLED) || 200 (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) 201 srr1 = power7_sleep(); 202 else 203 srr1 = power7_nap(1); 204 205 ppc64_runlatch_on(); 206 207 /* 208 * If the SRR1 value indicates that we woke up due to 209 * an external interrupt, then clear the interrupt. 210 * We clear the interrupt before checking for the 211 * reason, so as to avoid a race where we wake up for 212 * some other reason, find nothing and clear the interrupt 213 * just as some other cpu is sending us an interrupt. 214 * If we returned from power7_nap as a result of 215 * having finished executing in a KVM guest, then srr1 216 * contains 0. 217 */ 218 if (((srr1 & wmask) == SRR1_WAKEEE) || 219 (local_paca->irq_happened & PACA_IRQ_EE)) { 220 icp_native_flush_interrupt(); 221 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) { 222 unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER); 223 asm volatile(PPC_MSGCLR(%0) : : "r" (msg)); 224 } 225 local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL); 226 smp_mb(); 227 228 if (cpu_core_split_required()) 229 continue; 230 231 if (srr1 && !generic_check_cpu_restart(cpu)) 232 DBG("CPU%d Unexpected exit while offline !\n", cpu); 233 } 234 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1); 235 DBG("CPU%d coming online...\n", cpu); 236 } 237 238 #endif /* CONFIG_HOTPLUG_CPU */ 239 240 static int pnv_cpu_bootable(unsigned int nr) 241 { 242 /* 243 * Starting with POWER8, the subcore logic relies on all threads of a 244 * core being booted so that they can participate in split mode 245 * switches. So on those machines we ignore the smt_enabled_at_boot 246 * setting (smt-enabled on the kernel command line). 247 */ 248 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 249 return 1; 250 251 return smp_generic_cpu_bootable(nr); 252 } 253 254 static struct smp_ops_t pnv_smp_ops = { 255 .message_pass = smp_muxed_ipi_message_pass, 256 .cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */ 257 .probe = xics_smp_probe, 258 .kick_cpu = pnv_smp_kick_cpu, 259 .setup_cpu = pnv_smp_setup_cpu, 260 .cpu_bootable = pnv_cpu_bootable, 261 #ifdef CONFIG_HOTPLUG_CPU 262 .cpu_disable = pnv_smp_cpu_disable, 263 .cpu_die = generic_cpu_die, 264 #endif /* CONFIG_HOTPLUG_CPU */ 265 }; 266 267 /* This is called very early during platform setup_arch */ 268 void __init pnv_smp_init(void) 269 { 270 smp_ops = &pnv_smp_ops; 271 272 #ifdef CONFIG_HOTPLUG_CPU 273 ppc_md.cpu_die = pnv_smp_cpu_kill_self; 274 #endif 275 } 276