1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * SMP support for pSeries machines. 4 * 5 * Dave Engebretsen, Peter Bergner, and 6 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com 7 * 8 * Plus various changes from other IBM teams... 9 */ 10 11 12 #include <linux/kernel.h> 13 #include <linux/sched.h> 14 #include <linux/smp.h> 15 #include <linux/interrupt.h> 16 #include <linux/delay.h> 17 #include <linux/init.h> 18 #include <linux/spinlock.h> 19 #include <linux/cache.h> 20 #include <linux/err.h> 21 #include <linux/device.h> 22 #include <linux/cpu.h> 23 24 #include <asm/ptrace.h> 25 #include <linux/atomic.h> 26 #include <asm/irq.h> 27 #include <asm/page.h> 28 #include <asm/pgtable.h> 29 #include <asm/io.h> 30 #include <asm/prom.h> 31 #include <asm/smp.h> 32 #include <asm/paca.h> 33 #include <asm/machdep.h> 34 #include <asm/cputable.h> 35 #include <asm/firmware.h> 36 #include <asm/rtas.h> 37 #include <asm/vdso_datapage.h> 38 #include <asm/cputhreads.h> 39 #include <asm/xics.h> 40 #include <asm/xive.h> 41 #include <asm/dbell.h> 42 #include <asm/plpar_wrappers.h> 43 #include <asm/code-patching.h> 44 #include <asm/svm.h> 45 46 #include "pseries.h" 47 #include "offline_states.h" 48 49 50 /* 51 * The Primary thread of each non-boot processor was started from the OF client 52 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. 53 */ 54 static cpumask_var_t of_spin_mask; 55 56 /* Query where a cpu is now. Return codes #defined in plpar_wrappers.h */ 57 int smp_query_cpu_stopped(unsigned int pcpu) 58 { 59 int cpu_status, status; 60 int qcss_tok = rtas_token("query-cpu-stopped-state"); 61 62 if (qcss_tok == RTAS_UNKNOWN_SERVICE) { 63 printk_once(KERN_INFO 64 "Firmware doesn't support query-cpu-stopped-state\n"); 65 return QCSS_HARDWARE_ERROR; 66 } 67 68 status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu); 69 if (status != 0) { 70 printk(KERN_ERR 71 "RTAS query-cpu-stopped-state failed: %i\n", status); 72 return status; 73 } 74 75 return cpu_status; 76 } 77 78 /** 79 * smp_startup_cpu() - start the given cpu 80 * 81 * At boot time, there is nothing to do for primary threads which were 82 * started from Open Firmware. For anything else, call RTAS with the 83 * appropriate start location. 84 * 85 * Returns: 86 * 0 - failure 87 * 1 - success 88 */ 89 static inline int smp_startup_cpu(unsigned int lcpu) 90 { 91 int status; 92 unsigned long start_here = 93 __pa(ppc_function_entry(generic_secondary_smp_init)); 94 unsigned int pcpu; 95 int start_cpu; 96 97 if (cpumask_test_cpu(lcpu, of_spin_mask)) 98 /* Already started by OF and sitting in spin loop */ 99 return 1; 100 101 pcpu = get_hard_smp_processor_id(lcpu); 102 103 /* Check to see if the CPU out of FW already for kexec */ 104 if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){ 105 cpumask_set_cpu(lcpu, of_spin_mask); 106 return 1; 107 } 108 109 /* Fixup atomic count: it exited inside IRQ handler. */ 110 task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count = 0; 111 #ifdef CONFIG_HOTPLUG_CPU 112 if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE) 113 goto out; 114 #endif 115 /* 116 * If the RTAS start-cpu token does not exist then presume the 117 * cpu is already spinning. 118 */ 119 start_cpu = rtas_token("start-cpu"); 120 if (start_cpu == RTAS_UNKNOWN_SERVICE) 121 return 1; 122 123 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu); 124 if (status != 0) { 125 printk(KERN_ERR "start-cpu failed: %i\n", status); 126 return 0; 127 } 128 129 #ifdef CONFIG_HOTPLUG_CPU 130 out: 131 #endif 132 return 1; 133 } 134 135 static void smp_setup_cpu(int cpu) 136 { 137 if (xive_enabled()) 138 xive_smp_setup_cpu(); 139 else if (cpu != boot_cpuid) 140 xics_setup_cpu(); 141 142 if (firmware_has_feature(FW_FEATURE_SPLPAR)) 143 vpa_init(cpu); 144 145 cpumask_clear_cpu(cpu, of_spin_mask); 146 #ifdef CONFIG_HOTPLUG_CPU 147 set_cpu_current_state(cpu, CPU_STATE_ONLINE); 148 set_default_offline_state(cpu); 149 #endif 150 } 151 152 static int smp_pSeries_kick_cpu(int nr) 153 { 154 if (nr < 0 || nr >= nr_cpu_ids) 155 return -EINVAL; 156 157 if (!smp_startup_cpu(nr)) 158 return -ENOENT; 159 160 /* 161 * The processor is currently spinning, waiting for the 162 * cpu_start field to become non-zero After we set cpu_start, 163 * the processor will continue on to secondary_start 164 */ 165 paca_ptrs[nr]->cpu_start = 1; 166 #ifdef CONFIG_HOTPLUG_CPU 167 set_preferred_offline_state(nr, CPU_STATE_ONLINE); 168 169 if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) { 170 long rc; 171 unsigned long hcpuid; 172 173 hcpuid = get_hard_smp_processor_id(nr); 174 rc = plpar_hcall_norets(H_PROD, hcpuid); 175 if (rc != H_SUCCESS) 176 printk(KERN_ERR "Error: Prod to wake up processor %d " 177 "Ret= %ld\n", nr, rc); 178 } 179 #endif 180 181 return 0; 182 } 183 184 static int pseries_smp_prepare_cpu(int cpu) 185 { 186 if (xive_enabled()) 187 return xive_smp_prepare_cpu(cpu); 188 return 0; 189 } 190 191 static void smp_pseries_cause_ipi(int cpu) 192 { 193 /* POWER9 should not use this handler */ 194 if (doorbell_try_core_ipi(cpu)) 195 return; 196 197 icp_ops->cause_ipi(cpu); 198 } 199 200 static int pseries_cause_nmi_ipi(int cpu) 201 { 202 int hwcpu; 203 204 if (cpu == NMI_IPI_ALL_OTHERS) { 205 hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS; 206 } else { 207 if (cpu < 0) { 208 WARN_ONCE(true, "incorrect cpu parameter %d", cpu); 209 return 0; 210 } 211 212 hwcpu = get_hard_smp_processor_id(cpu); 213 } 214 215 if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS) 216 return 1; 217 218 return 0; 219 } 220 221 static __init void pSeries_smp_probe_xics(void) 222 { 223 xics_smp_probe(); 224 225 if (cpu_has_feature(CPU_FTR_DBELL) && !is_secure_guest()) 226 smp_ops->cause_ipi = smp_pseries_cause_ipi; 227 else 228 smp_ops->cause_ipi = icp_ops->cause_ipi; 229 } 230 231 static __init void pSeries_smp_probe(void) 232 { 233 if (xive_enabled()) 234 /* 235 * Don't use P9 doorbells when XIVE is enabled. IPIs 236 * using MMIOs should be faster 237 */ 238 xive_smp_probe(); 239 else 240 pSeries_smp_probe_xics(); 241 } 242 243 static struct smp_ops_t pseries_smp_ops = { 244 .message_pass = NULL, /* Use smp_muxed_ipi_message_pass */ 245 .cause_ipi = NULL, /* Filled at runtime by pSeries_smp_probe() */ 246 .cause_nmi_ipi = pseries_cause_nmi_ipi, 247 .probe = pSeries_smp_probe, 248 .prepare_cpu = pseries_smp_prepare_cpu, 249 .kick_cpu = smp_pSeries_kick_cpu, 250 .setup_cpu = smp_setup_cpu, 251 .cpu_bootable = smp_generic_cpu_bootable, 252 }; 253 254 /* This is called very early */ 255 void __init smp_init_pseries(void) 256 { 257 int i; 258 259 pr_debug(" -> smp_init_pSeries()\n"); 260 smp_ops = &pseries_smp_ops; 261 262 alloc_bootmem_cpumask_var(&of_spin_mask); 263 264 /* 265 * Mark threads which are still spinning in hold loops 266 * 267 * We know prom_init will not have started them if RTAS supports 268 * query-cpu-stopped-state. 269 */ 270 if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) { 271 if (cpu_has_feature(CPU_FTR_SMT)) { 272 for_each_present_cpu(i) { 273 if (cpu_thread_in_core(i) == 0) 274 cpumask_set_cpu(i, of_spin_mask); 275 } 276 } else 277 cpumask_copy(of_spin_mask, cpu_present_mask); 278 279 cpumask_clear_cpu(boot_cpuid, of_spin_mask); 280 } 281 282 /* Non-lpar has additional take/give timebase */ 283 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 284 smp_ops->give_timebase = rtas_give_timebase; 285 smp_ops->take_timebase = rtas_take_timebase; 286 } 287 288 pr_debug(" <- smp_init_pSeries()\n"); 289 } 290