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Diffstat (limited to '')
-rw-r--r-- | arch/powerpc/platforms/powernv/smp.c | 441 |
1 files changed, 441 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c new file mode 100644 index 000000000..9e1a25398 --- /dev/null +++ b/arch/powerpc/platforms/powernv/smp.c @@ -0,0 +1,441 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * SMP support for PowerNV machines. + * + * Copyright 2011 IBM Corp. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/sched/hotplug.h> +#include <linux/smp.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/cpu.h> + +#include <asm/irq.h> +#include <asm/smp.h> +#include <asm/paca.h> +#include <asm/machdep.h> +#include <asm/cputable.h> +#include <asm/firmware.h> +#include <asm/vdso_datapage.h> +#include <asm/cputhreads.h> +#include <asm/xics.h> +#include <asm/xive.h> +#include <asm/opal.h> +#include <asm/runlatch.h> +#include <asm/code-patching.h> +#include <asm/dbell.h> +#include <asm/kvm_ppc.h> +#include <asm/ppc-opcode.h> +#include <asm/cpuidle.h> +#include <asm/kexec.h> +#include <asm/reg.h> +#include <asm/powernv.h> + +#include "powernv.h" + +#ifdef DEBUG +#include <asm/udbg.h> +#define DBG(fmt...) udbg_printf(fmt) +#else +#define DBG(fmt...) do { } while (0) +#endif + +static void pnv_smp_setup_cpu(int cpu) +{ + /* + * P9 workaround for CI vector load (see traps.c), + * enable the corresponding HMI interrupt + */ + if (pvr_version_is(PVR_POWER9)) + mtspr(SPRN_HMEER, mfspr(SPRN_HMEER) | PPC_BIT(17)); + + if (xive_enabled()) + xive_smp_setup_cpu(); + else if (cpu != boot_cpuid) + xics_setup_cpu(); +} + +static int pnv_smp_kick_cpu(int nr) +{ + unsigned int pcpu; + unsigned long start_here = + __pa(ppc_function_entry(generic_secondary_smp_init)); + long rc; + uint8_t status; + + if (nr < 0 || nr >= nr_cpu_ids) + return -EINVAL; + + pcpu = get_hard_smp_processor_id(nr); + /* + * If we already started or OPAL is not supported, we just + * kick the CPU via the PACA + */ + if (paca_ptrs[nr]->cpu_start || !firmware_has_feature(FW_FEATURE_OPAL)) + goto kick; + + /* + * At this point, the CPU can either be spinning on the way in + * from kexec or be inside OPAL waiting to be started for the + * first time. OPAL v3 allows us to query OPAL to know if it + * has the CPUs, so we do that + */ + rc = opal_query_cpu_status(pcpu, &status); + if (rc != OPAL_SUCCESS) { + pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr); + return -ENODEV; + } + + /* + * Already started, just kick it, probably coming from + * kexec and spinning + */ + if (status == OPAL_THREAD_STARTED) + goto kick; + + /* + * Available/inactive, let's kick it + */ + if (status == OPAL_THREAD_INACTIVE) { + pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu); + rc = opal_start_cpu(pcpu, start_here); + if (rc != OPAL_SUCCESS) { + pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr); + return -ENODEV; + } + } else { + /* + * An unavailable CPU (or any other unknown status) + * shouldn't be started. It should also + * not be in the possible map but currently it can + * happen + */ + pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable" + " (status %d)...\n", nr, pcpu, status); + return -ENODEV; + } + +kick: + return smp_generic_kick_cpu(nr); +} + +#ifdef CONFIG_HOTPLUG_CPU + +static int pnv_smp_cpu_disable(void) +{ + int cpu = smp_processor_id(); + + /* This is identical to pSeries... might consolidate by + * moving migrate_irqs_away to a ppc_md with default to + * the generic fixup_irqs. --BenH. + */ + set_cpu_online(cpu, false); + vdso_data->processorCount--; + if (cpu == boot_cpuid) + boot_cpuid = cpumask_any(cpu_online_mask); + if (xive_enabled()) + xive_smp_disable_cpu(); + else + xics_migrate_irqs_away(); + + cleanup_cpu_mmu_context(); + + return 0; +} + +static void pnv_flush_interrupts(void) +{ + if (cpu_has_feature(CPU_FTR_ARCH_300)) { + if (xive_enabled()) + xive_flush_interrupt(); + else + icp_opal_flush_interrupt(); + } else { + icp_native_flush_interrupt(); + } +} + +static void pnv_cpu_offline_self(void) +{ + unsigned long srr1, unexpected_mask, wmask; + unsigned int cpu; + u64 lpcr_val; + + /* Standard hot unplug procedure */ + + idle_task_exit(); + cpu = smp_processor_id(); + DBG("CPU%d offline\n", cpu); + generic_set_cpu_dead(cpu); + smp_wmb(); + + wmask = SRR1_WAKEMASK; + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + wmask = SRR1_WAKEMASK_P8; + + /* + * This turns the irq soft-disabled state we're called with, into a + * hard-disabled state with pending irq_happened interrupts cleared. + * + * PACA_IRQ_DEC - Decrementer should be ignored. + * PACA_IRQ_HMI - Can be ignored, processing is done in real mode. + * PACA_IRQ_DBELL, EE, PMI - Unexpected. + */ + hard_irq_disable(); + if (generic_check_cpu_restart(cpu)) + goto out; + + unexpected_mask = ~(PACA_IRQ_DEC | PACA_IRQ_HMI | PACA_IRQ_HARD_DIS); + if (local_paca->irq_happened & unexpected_mask) { + if (local_paca->irq_happened & PACA_IRQ_EE) + pnv_flush_interrupts(); + DBG("CPU%d Unexpected exit while offline irq_happened=%lx!\n", + cpu, local_paca->irq_happened); + } + local_paca->irq_happened = PACA_IRQ_HARD_DIS; + + /* + * We don't want to take decrementer interrupts while we are + * offline, so clear LPCR:PECE1. We keep PECE2 (and + * LPCR_PECE_HVEE on P9) enabled so as to let IPIs in. + * + * If the CPU gets woken up by a special wakeup, ensure that + * the SLW engine sets LPCR with decrementer bit cleared, else + * the CPU will come back to the kernel due to a spurious + * wakeup. + */ + lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1; + pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val); + + while (!generic_check_cpu_restart(cpu)) { + /* + * Clear IPI flag, since we don't handle IPIs while + * offline, except for those when changing micro-threading + * mode, which are handled explicitly below, and those + * for coming online, which are handled via + * generic_check_cpu_restart() calls. + */ + kvmppc_clear_host_ipi(cpu); + + srr1 = pnv_cpu_offline(cpu); + + WARN_ON_ONCE(!irqs_disabled()); + WARN_ON(lazy_irq_pending()); + + /* + * If the SRR1 value indicates that we woke up due to + * an external interrupt, then clear the interrupt. + * We clear the interrupt before checking for the + * reason, so as to avoid a race where we wake up for + * some other reason, find nothing and clear the interrupt + * just as some other cpu is sending us an interrupt. + * If we returned from power7_nap as a result of + * having finished executing in a KVM guest, then srr1 + * contains 0. + */ + if (((srr1 & wmask) == SRR1_WAKEEE) || + ((srr1 & wmask) == SRR1_WAKEHVI)) { + pnv_flush_interrupts(); + } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) { + unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER); + asm volatile(PPC_MSGCLR(%0) : : "r" (msg)); + } else if ((srr1 & wmask) == SRR1_WAKERESET) { + irq_set_pending_from_srr1(srr1); + /* Does not return */ + } + + smp_mb(); + + /* + * For kdump kernels, we process the ipi and jump to + * crash_ipi_callback + */ + if (kdump_in_progress()) { + /* + * If we got to this point, we've not used + * NMI's, otherwise we would have gone + * via the SRR1_WAKERESET path. We are + * using regular IPI's for waking up offline + * threads. + */ + struct pt_regs regs; + + ppc_save_regs(®s); + crash_ipi_callback(®s); + /* Does not return */ + } + + if (cpu_core_split_required()) + continue; + + if (srr1 && !generic_check_cpu_restart(cpu)) + DBG("CPU%d Unexpected exit while offline srr1=%lx!\n", + cpu, srr1); + + } + + /* + * Re-enable decrementer interrupts in LPCR. + * + * Further, we want stop states to be woken up by decrementer + * for non-hotplug cases. So program the LPCR via stop api as + * well. + */ + lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1; + pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val); +out: + DBG("CPU%d coming online...\n", cpu); +} + +#endif /* CONFIG_HOTPLUG_CPU */ + +static int pnv_cpu_bootable(unsigned int nr) +{ + /* + * Starting with POWER8, the subcore logic relies on all threads of a + * core being booted so that they can participate in split mode + * switches. So on those machines we ignore the smt_enabled_at_boot + * setting (smt-enabled on the kernel command line). + */ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return 1; + + return smp_generic_cpu_bootable(nr); +} + +static int pnv_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); + +static void pnv_cause_ipi(int cpu) +{ + if (doorbell_try_core_ipi(cpu)) + return; + + ic_cause_ipi(cpu); +} + +static void __init pnv_smp_probe(void) +{ + if (xive_enabled()) + xive_smp_probe(); + else + xics_smp_probe(); + + if (cpu_has_feature(CPU_FTR_DBELL)) { + ic_cause_ipi = smp_ops->cause_ipi; + WARN_ON(!ic_cause_ipi); + + if (cpu_has_feature(CPU_FTR_ARCH_300)) + smp_ops->cause_ipi = doorbell_global_ipi; + else + smp_ops->cause_ipi = pnv_cause_ipi; + } +} + +noinstr static int pnv_system_reset_exception(struct pt_regs *regs) +{ + if (smp_handle_nmi_ipi(regs)) + return 1; + return 0; +} + +static int pnv_cause_nmi_ipi(int cpu) +{ + int64_t rc; + + if (cpu >= 0) { + int h = get_hard_smp_processor_id(cpu); + + if (opal_check_token(OPAL_QUIESCE)) + opal_quiesce(QUIESCE_HOLD, h); + + rc = opal_signal_system_reset(h); + + if (opal_check_token(OPAL_QUIESCE)) + opal_quiesce(QUIESCE_RESUME, h); + + if (rc != OPAL_SUCCESS) + return 0; + return 1; + + } else if (cpu == NMI_IPI_ALL_OTHERS) { + bool success = true; + int c; + + if (opal_check_token(OPAL_QUIESCE)) + opal_quiesce(QUIESCE_HOLD, -1); + + /* + * We do not use broadcasts (yet), because it's not clear + * exactly what semantics Linux wants or the firmware should + * provide. + */ + for_each_online_cpu(c) { + if (c == smp_processor_id()) + continue; + + rc = opal_signal_system_reset( + get_hard_smp_processor_id(c)); + if (rc != OPAL_SUCCESS) + success = false; + } + + if (opal_check_token(OPAL_QUIESCE)) + opal_quiesce(QUIESCE_RESUME, -1); + + if (success) + return 1; + + /* + * Caller will fall back to doorbells, which may pick + * up the remainders. + */ + } + + return 0; +} + +static struct smp_ops_t pnv_smp_ops = { + .message_pass = NULL, /* Use smp_muxed_ipi_message_pass */ + .cause_ipi = NULL, /* Filled at runtime by pnv_smp_probe() */ + .cause_nmi_ipi = NULL, + .probe = pnv_smp_probe, + .prepare_cpu = pnv_smp_prepare_cpu, + .kick_cpu = pnv_smp_kick_cpu, + .setup_cpu = pnv_smp_setup_cpu, + .cpu_bootable = pnv_cpu_bootable, +#ifdef CONFIG_HOTPLUG_CPU + .cpu_disable = pnv_smp_cpu_disable, + .cpu_die = generic_cpu_die, + .cpu_offline_self = pnv_cpu_offline_self, +#endif /* CONFIG_HOTPLUG_CPU */ +}; + +/* This is called very early during platform setup_arch */ +void __init pnv_smp_init(void) +{ + if (opal_check_token(OPAL_SIGNAL_SYSTEM_RESET)) { + ppc_md.system_reset_exception = pnv_system_reset_exception; + pnv_smp_ops.cause_nmi_ipi = pnv_cause_nmi_ipi; + } + smp_ops = &pnv_smp_ops; + +#ifdef CONFIG_HOTPLUG_CPU +#ifdef CONFIG_KEXEC_CORE + crash_wake_offline = 1; +#endif +#endif +} |