// SPDX-License-Identifier: GPL-2.0-or-later /* * SMP support for pSeries machines. * * Dave Engebretsen, Peter Bergner, and * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com * * Plus various changes from other IBM teams... */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "pseries.h" /* * The Primary thread of each non-boot processor was started from the OF client * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. */ static cpumask_var_t of_spin_mask; /* Query where a cpu is now. Return codes #defined in plpar_wrappers.h */ int smp_query_cpu_stopped(unsigned int pcpu) { int cpu_status, status; int qcss_tok = rtas_token("query-cpu-stopped-state"); if (qcss_tok == RTAS_UNKNOWN_SERVICE) { printk_once(KERN_INFO "Firmware doesn't support query-cpu-stopped-state\n"); return QCSS_HARDWARE_ERROR; } status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu); if (status != 0) { printk(KERN_ERR "RTAS query-cpu-stopped-state failed: %i\n", status); return status; } return cpu_status; } /** * smp_startup_cpu() - start the given cpu * * At boot time, there is nothing to do for primary threads which were * started from Open Firmware. For anything else, call RTAS with the * appropriate start location. * * Returns: * 0 - failure * 1 - success */ static inline int smp_startup_cpu(unsigned int lcpu) { int status; unsigned long start_here = __pa(ppc_function_entry(generic_secondary_smp_init)); unsigned int pcpu; int start_cpu; if (cpumask_test_cpu(lcpu, of_spin_mask)) /* Already started by OF and sitting in spin loop */ return 1; pcpu = get_hard_smp_processor_id(lcpu); /* Check to see if the CPU out of FW already for kexec */ if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){ cpumask_set_cpu(lcpu, of_spin_mask); return 1; } /* * If the RTAS start-cpu token does not exist then presume the * cpu is already spinning. */ start_cpu = rtas_token("start-cpu"); if (start_cpu == RTAS_UNKNOWN_SERVICE) return 1; status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu); if (status != 0) { printk(KERN_ERR "start-cpu failed: %i\n", status); return 0; } return 1; } static void smp_setup_cpu(int cpu) { if (xive_enabled()) xive_smp_setup_cpu(); else if (cpu != boot_cpuid) xics_setup_cpu(); if (firmware_has_feature(FW_FEATURE_SPLPAR)) vpa_init(cpu); cpumask_clear_cpu(cpu, of_spin_mask); } static int smp_pSeries_kick_cpu(int nr) { if (nr < 0 || nr >= nr_cpu_ids) return -EINVAL; if (!smp_startup_cpu(nr)) return -ENOENT; /* * The processor is currently spinning, waiting for the * cpu_start field to become non-zero After we set cpu_start, * the processor will continue on to secondary_start */ paca_ptrs[nr]->cpu_start = 1; return 0; } static int pseries_smp_prepare_cpu(int cpu) { if (xive_enabled()) return xive_smp_prepare_cpu(cpu); return 0; } /* Cause IPI as setup by the interrupt controller (xics or xive) */ static void (*ic_cause_ipi)(int cpu) __ro_after_init; /* Use msgsndp doorbells target is a sibling, else use interrupt controller */ static void dbell_or_ic_cause_ipi(int cpu) { if (doorbell_try_core_ipi(cpu)) return; ic_cause_ipi(cpu); } static int pseries_cause_nmi_ipi(int cpu) { int hwcpu; if (cpu == NMI_IPI_ALL_OTHERS) { hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS; } else { if (cpu < 0) { WARN_ONCE(true, "incorrect cpu parameter %d", cpu); return 0; } hwcpu = get_hard_smp_processor_id(cpu); } if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS) return 1; return 0; } static __init void pSeries_smp_probe(void) { if (xive_enabled()) xive_smp_probe(); else xics_smp_probe(); /* No doorbell facility, must use the interrupt controller for IPIs */ if (!cpu_has_feature(CPU_FTR_DBELL)) return; /* Doorbells can only be used for IPIs between SMT siblings */ if (!cpu_has_feature(CPU_FTR_SMT)) return; check_kvm_guest(); if (is_kvm_guest()) { /* * KVM emulates doorbells by disabling FSCR[MSGP] so msgsndp * faults to the hypervisor which then reads the instruction * from guest memory, which tends to be slower than using XIVE. */ if (xive_enabled()) return; /* * XICS hcalls aren't as fast, so we can use msgsndp (which * also helps exercise KVM emulation), however KVM can't * emulate secure guests because it can't read the instruction * out of their memory. */ if (is_secure_guest()) return; } /* * Under PowerVM, FSCR[MSGP] is enabled as guest vCPU siblings are * gang scheduled on the same physical core, so doorbells are always * faster than the interrupt controller, and they can be used by * secure guests. */ ic_cause_ipi = smp_ops->cause_ipi; smp_ops->cause_ipi = dbell_or_ic_cause_ipi; } static struct smp_ops_t pseries_smp_ops = { .message_pass = NULL, /* Use smp_muxed_ipi_message_pass */ .cause_ipi = NULL, /* Filled at runtime by pSeries_smp_probe() */ .cause_nmi_ipi = pseries_cause_nmi_ipi, .probe = pSeries_smp_probe, .prepare_cpu = pseries_smp_prepare_cpu, .kick_cpu = smp_pSeries_kick_cpu, .setup_cpu = smp_setup_cpu, .cpu_bootable = smp_generic_cpu_bootable, }; /* This is called very early */ void __init smp_init_pseries(void) { int i; pr_debug(" -> smp_init_pSeries()\n"); smp_ops = &pseries_smp_ops; alloc_bootmem_cpumask_var(&of_spin_mask); /* * Mark threads which are still spinning in hold loops * * We know prom_init will not have started them if RTAS supports * query-cpu-stopped-state. */ if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) { if (cpu_has_feature(CPU_FTR_SMT)) { for_each_present_cpu(i) { if (cpu_thread_in_core(i) == 0) cpumask_set_cpu(i, of_spin_mask); } } else cpumask_copy(of_spin_mask, cpu_present_mask); cpumask_clear_cpu(boot_cpuid, of_spin_mask); } /* Non-lpar has additional take/give timebase */ if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { smp_ops->give_timebase = rtas_give_timebase; smp_ops->take_timebase = rtas_take_timebase; } pr_debug(" <- smp_init_pSeries()\n"); }