arch/powerpc/platforms/powernv/smp.c - kernel/mindspeed - Git at Google

 /*
  * 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/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
 }

 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;

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

 	/*
 	 * If we already started or OPALv2 is not supported, we just
 	 * kick the CPU via the PACA
 	 */
 	if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
 		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
 	 */
 	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 		uint8_t status;

 		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;
 		}
 	} else {
 		/*
 		 * On OPAL v2, we just kick it and hope for the best,
 		 * we must not test the error from opal_start_cpu() or
 		 * we would fail to get CPUs from kexec.
 		 */
 		opal_start_cpu(pcpu, start_here);
 	}
  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);
 	xics_migrate_irqs_away();
 	return 0;
 }

 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 enabled.
 	 */
 	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
 	while (!generic_check_cpu_restart(cpu)) {

 		ppc64_runlatch_off();

 		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) {
 			icp_native_flush_interrupt();
 			local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
 			smp_mb();
 		} else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
 			unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
 			asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
 			kvmppc_set_host_ipi(cpu, 0);
 		}

 		if (cpu_core_split_required())
 			continue;

 		if (!generic_check_cpu_restart(cpu))
 			DBG("CPU%d Unexpected exit while offline !\n", cpu);
 	}
 	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
 	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 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
 }
	/*
	* 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/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
	}

	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;

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

	/*
	* If we already started or OPALv2 is not supported, we just
	* kick the CPU via the PACA
	*/
	if (paca[nr].cpu_start \|\| !firmware_has_feature(FW_FEATURE_OPALv2))
	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
	*/
	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
	uint8_t status;

	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;
	}
	} else {
	/*
	* On OPAL v2, we just kick it and hope for the best,
	* we must not test the error from opal_start_cpu() or
	* we would fail to get CPUs from kexec.
	*/
	opal_start_cpu(pcpu, start_here);
	}
	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);
	xics_migrate_irqs_away();
	return 0;
	}

	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 enabled.
	*/
	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
	while (!generic_check_cpu_restart(cpu)) {

	ppc64_runlatch_off();

	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) {
	icp_native_flush_interrupt();
	local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
	smp_mb();
	} else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
	unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
	asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
	kvmppc_set_host_ipi(cpu, 0);
	}

	if (cpu_core_split_required())
	continue;

	if (!generic_check_cpu_restart(cpu))
	DBG("CPU%d Unexpected exit while offline !\n", cpu);
	}
	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) \| LPCR_PECE1);
	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 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
	}