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/*
* 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);
/*
* 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 (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) ||
(local_paca->irq_happened & PACA_IRQ_EE)) {
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);
}
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
}
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