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 uint8_t status; 65 66 BUG_ON(nr < 0 || nr >= NR_CPUS); 67 68 /* 69 * If we already started or OPAL is not supported, we just 70 * kick the CPU via the PACA 71 */ 72 if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPAL)) 73 goto kick; 74 75 /* 76 * At this point, the CPU can either be spinning on the way in 77 * from kexec or be inside OPAL waiting to be started for the 78 * first time. OPAL v3 allows us to query OPAL to know if it 79 * has the CPUs, so we do that 80 */ 81 rc = opal_query_cpu_status(pcpu, &status); 82 if (rc != OPAL_SUCCESS) { 83 pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr); 84 return -ENODEV; 85 } 86 87 /* 88 * Already started, just kick it, probably coming from 89 * kexec and spinning 90 */ 91 if (status == OPAL_THREAD_STARTED) 92 goto kick; 93 94 /* 95 * Available/inactive, let's kick it 96 */ 97 if (status == OPAL_THREAD_INACTIVE) { 98 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu); 99 rc = opal_start_cpu(pcpu, start_here); 100 if (rc != OPAL_SUCCESS) { 101 pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr); 102 return -ENODEV; 103 } 104 } else { 105 /* 106 * An unavailable CPU (or any other unknown status) 107 * shouldn't be started. It should also 108 * not be in the possible map but currently it can 109 * happen 110 */ 111 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" 112 " (status %d)...\n", nr, pcpu, status); 113 return -ENODEV; 114 } 115 116 kick: 117 return smp_generic_kick_cpu(nr); 118 } 119 120 #ifdef CONFIG_HOTPLUG_CPU 121 122 static int pnv_smp_cpu_disable(void) 123 { 124 int cpu = smp_processor_id(); 125 126 /* This is identical to pSeries... might consolidate by 127 * moving migrate_irqs_away to a ppc_md with default to 128 * the generic fixup_irqs. --BenH. 129 */ 130 set_cpu_online(cpu, false); 131 vdso_data->processorCount--; 132 if (cpu == boot_cpuid) 133 boot_cpuid = cpumask_any(cpu_online_mask); 134 xics_migrate_irqs_away(); 135 return 0; 136 } 137 138 static void pnv_smp_cpu_kill_self(void) 139 { 140 unsigned int cpu; 141 unsigned long srr1, wmask; 142 u32 idle_states; 143 144 /* Standard hot unplug procedure */ 145 local_irq_disable(); 146 idle_task_exit(); 147 current->active_mm = NULL; /* for sanity */ 148 cpu = smp_processor_id(); 149 DBG("CPU%d offline\n", cpu); 150 generic_set_cpu_dead(cpu); 151 smp_wmb(); 152 153 wmask = SRR1_WAKEMASK; 154 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 155 wmask = SRR1_WAKEMASK_P8; 156 157 idle_states = pnv_get_supported_cpuidle_states(); 158 /* We don't want to take decrementer interrupts while we are offline, 159 * so clear LPCR:PECE1. We keep PECE2 enabled. 160 */ 161 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1); 162 163 /* 164 * Hard-disable interrupts, and then clear irq_happened flags 165 * that we can safely ignore while off-line, since they 166 * are for things for which we do no processing when off-line 167 * (or in the case of HMI, all the processing we need to do 168 * is done in lower-level real-mode code). 169 */ 170 hard_irq_disable(); 171 local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI); 172 173 while (!generic_check_cpu_restart(cpu)) { 174 /* 175 * Clear IPI flag, since we don't handle IPIs while 176 * offline, except for those when changing micro-threading 177 * mode, which are handled explicitly below, and those 178 * for coming online, which are handled via 179 * generic_check_cpu_restart() calls. 180 */ 181 kvmppc_set_host_ipi(cpu, 0); 182 183 ppc64_runlatch_off(); 184 185 if (idle_states & OPAL_PM_WINKLE_ENABLED) 186 srr1 = power7_winkle(); 187 else if ((idle_states & OPAL_PM_SLEEP_ENABLED) || 188 (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) 189 srr1 = power7_sleep(); 190 else 191 srr1 = power7_nap(1); 192 193 ppc64_runlatch_on(); 194 195 /* 196 * If the SRR1 value indicates that we woke up due to 197 * an external interrupt, then clear the interrupt. 198 * We clear the interrupt before checking for the 199 * reason, so as to avoid a race where we wake up for 200 * some other reason, find nothing and clear the interrupt 201 * just as some other cpu is sending us an interrupt. 202 * If we returned from power7_nap as a result of 203 * having finished executing in a KVM guest, then srr1 204 * contains 0. 205 */ 206 if (((srr1 & wmask) == SRR1_WAKEEE) || 207 (local_paca->irq_happened & PACA_IRQ_EE)) { 208 icp_native_flush_interrupt(); 209 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) { 210 unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER); 211 asm volatile(PPC_MSGCLR(%0) : : "r" (msg)); 212 } 213 local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL); 214 smp_mb(); 215 216 if (cpu_core_split_required()) 217 continue; 218 219 if (srr1 && !generic_check_cpu_restart(cpu)) 220 DBG("CPU%d Unexpected exit while offline !\n", cpu); 221 } 222 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1); 223 DBG("CPU%d coming online...\n", cpu); 224 } 225 226 #endif /* CONFIG_HOTPLUG_CPU */ 227 228 static int pnv_cpu_bootable(unsigned int nr) 229 { 230 /* 231 * Starting with POWER8, the subcore logic relies on all threads of a 232 * core being booted so that they can participate in split mode 233 * switches. So on those machines we ignore the smt_enabled_at_boot 234 * setting (smt-enabled on the kernel command line). 235 */ 236 if (cpu_has_feature(CPU_FTR_ARCH_207S)) 237 return 1; 238 239 return smp_generic_cpu_bootable(nr); 240 } 241 242 static struct smp_ops_t pnv_smp_ops = { 243 .message_pass = smp_muxed_ipi_message_pass, 244 .cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */ 245 .probe = xics_smp_probe, 246 .kick_cpu = pnv_smp_kick_cpu, 247 .setup_cpu = pnv_smp_setup_cpu, 248 .cpu_bootable = pnv_cpu_bootable, 249 #ifdef CONFIG_HOTPLUG_CPU 250 .cpu_disable = pnv_smp_cpu_disable, 251 .cpu_die = generic_cpu_die, 252 #endif /* CONFIG_HOTPLUG_CPU */ 253 }; 254 255 /* This is called very early during platform setup_arch */ 256 void __init pnv_smp_init(void) 257 { 258 smp_ops = &pnv_smp_ops; 259 260 #ifdef CONFIG_HOTPLUG_CPU 261 ppc_md.cpu_die = pnv_smp_cpu_kill_self; 262 #endif 263 } 264