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Release 4.11 arch/powerpc/platforms/powernv/smp.c

Directory: arch/powerpc/platforms/powernv
/*
 * SMP support for PowerNV machines.
 *
 * Copyright 2011 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#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/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 "powernv.h"

#ifdef DEBUG
#include <asm/udbg.h>

#define DBG(fmt...) udbg_printf(fmt)
#else

#define DBG(fmt...)
#endif




static void pnv_smp_setup_cpu(int cpu)
{
	if (cpu != boot_cpuid)
		xics_setup_cpu();

#ifdef CONFIG_PPC_DOORBELL
	if (cpu_has_feature(CPU_FTR_DBELL))
		doorbell_setup_this_cpu();
#endif
}


Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt1854.55%150.00%


Michael Neuling1545.45%150.00%


Total33100.00%2100.00%






static int pnv_smp_kick_cpu(int nr)
{
	unsigned int pcpu = get_hard_smp_processor_id(nr);
	unsigned long start_here =
			__pa(ppc_function_entry(generic_secondary_smp_init));
	long rc;
	uint8_t status;

	BUG_ON(nr < 0 || nr >= NR_CPUS);

	/*
         * If we already started or OPAL is not supported, we just
         * kick the CPU via the PACA
         */
	if (paca[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);
}


Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt16690.22%342.86%


Stewart Smith84.35%114.29%


Paul Mackerras63.26%114.29%


Anton Blanchard42.17%228.57%


Total184100.00%7100.00%



#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);
	xics_migrate_irqs_away();
	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt46100.00%1100.00%


Total46100.00%1100.00%






static void pnv_smp_cpu_kill_self(void)
{
	unsigned int cpu;
	unsigned long srr1, wmask;
	u32 idle_states;

	/* Standard hot unplug procedure */
	local_irq_disable();
	idle_task_exit();
	current->active_mm = NULL; /* for sanity */
	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;

	idle_states = pnv_get_supported_cpuidle_states();

	/* 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 as to let IPIs in.
         */
	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);

	/*
         * Hard-disable interrupts, and then clear irq_happened flags
         * that we can safely ignore while off-line, since they
         * are for things for which we do no processing when off-line
         * (or in the case of HMI, all the processing we need to do
         * is done in lower-level real-mode code).
         */
	hard_irq_disable();
	local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI);

	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_set_host_ipi(cpu, 0);

		ppc64_runlatch_off();

		if (cpu_has_feature(CPU_FTR_ARCH_300)) {
			srr1 = power9_idle_stop(pnv_deepest_stop_psscr_val,
						pnv_deepest_stop_psscr_mask);
		} else if (idle_states & OPAL_PM_WINKLE_ENABLED) {
			srr1 = power7_winkle();
		} else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
			   (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
			srr1 = power7_sleep();
		} else {
			srr1 = power7_nap(1);
		}

		ppc64_runlatch_on();

		/*
                 * 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) ||
		    (local_paca->irq_happened & PACA_IRQ_EE)) {
			if (cpu_has_feature(CPU_FTR_ARCH_300))
				icp_opal_flush_interrupt();
			else
				icp_native_flush_interrupt();
		} else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
			unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
			asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
		}
		local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL);
		smp_mb();

		if (cpu_core_split_required())
			continue;

		if (srr1 && !generic_check_cpu_restart(cpu))
			DBG("CPU%d Unexpected exit while offline !\n", cpu);
	}

	/* Re-enable decrementer interrupts */
	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
	DBG("CPU%d coming online...\n", cpu);
}


Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt13040.12%213.33%


Paul Mackerras11234.57%533.33%


Shreyas B. Prabhu5416.67%426.67%


Michael Ellerman113.40%213.33%


Gautham R. Shenoy113.40%16.67%


Preeti U. Murthy61.85%16.67%


Total324100.00%15100.00%



#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);
}


Contributors
PersonTokensPropCommitsCommitProp
Greg Kurz27100.00%1100.00%


Total27100.00%1100.00%




static struct smp_ops_t pnv_smp_ops = {
	.message_pass	= smp_muxed_ipi_message_pass,
	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
	.probe		= xics_smp_probe,
	.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,
#endif /* CONFIG_HOTPLUG_CPU */
};

/* This is called very early during platform setup_arch */



void __init pnv_smp_init(void)
{
	smp_ops = &pnv_smp_ops;

#ifdef CONFIG_HOTPLUG_CPU
	ppc_md.cpu_die	= pnv_smp_cpu_kill_self;
#endif
}

Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt24100.00%2100.00%


Total24100.00%2100.00%




Overall Contributors
PersonTokensPropCommitsCommitProp
Benjamin Herrenschmidt53166.04%623.08%


Paul Mackerras12415.42%623.08%


Shreyas B. Prabhu546.72%415.38%


Greg Kurz283.48%13.85%


Michael Neuling182.24%13.85%


Michael Ellerman111.37%27.69%


Gautham R. Shenoy111.37%13.85%


Preeti U. Murthy91.12%13.85%


Stewart Smith81.00%13.85%


Anton Blanchard70.87%27.69%


Ingo Molnar30.37%13.85%


Total804100.00%26100.00%


Directory: arch/powerpc/platforms/powernv



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