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