android_kernel_xiaomi_sm8350/arch/powerpc/platforms/pseries/smp.c
Gautham R Shenoy 3aa565f53c powerpc/pseries: Add hooks to put the CPU into an appropriate offline state
When a CPU is offlined on POWER currently, we call rtas_stop_self() and hand
the CPU back to the resource pool. This path is used for DLPAR which will
cause a change in the LPAR configuration which will be visible outside.

This patch changes the default state a CPU is put into when it is offlined.
On platforms which support ceding the processor to the hypervisor with
latency hint specifier value, during a cpu offline operation,
instead of calling rtas_stop_self(), we cede the vCPU to the hypervisor
while passing a latency hint specifier value. The Hypervisor can use this hint
to provide better energy savings. Also, during the offline
operation, the control of the vCPU remains with the LPAR as oppposed to
returning it to the resource pool.

The patch achieves this by creating an infrastructure to set the
preferred_offline_state() which can be either
- CPU_STATE_OFFLINE: which is the current behaviour of calling
  rtas_stop_self()

- CPU_STATE_INACTIVE: which cedes the vCPU to the hypervisor with the latency
  hint specifier.

The codepath which wants to perform a DLPAR operation can set the
preferred_offline_state() of a CPU to CPU_STATE_OFFLINE before invoking
cpu_down().

The patch also provides a boot-time command line argument to disable/enable
CPU_STATE_INACTIVE.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-11-24 14:33:04 +11:00

225 lines
5.2 KiB
C

/*
* SMP support for pSeries machines.
*
* Dave Engebretsen, Peter Bergner, and
* Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
*
* Plus various changes from other IBM teams...
*
* 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/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/paca.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/system.h>
#include <asm/rtas.h>
#include <asm/pSeries_reconfig.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#include <asm/cputhreads.h>
#include "plpar_wrappers.h"
#include "pseries.h"
#include "xics.h"
#include "offline_states.h"
/*
* The Primary thread of each non-boot processor was started from the OF client
* interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
*/
static cpumask_t of_spin_map;
/**
* smp_startup_cpu() - start the given cpu
*
* At boot time, there is nothing to do for primary threads which were
* started from Open Firmware. For anything else, call RTAS with the
* appropriate start location.
*
* Returns:
* 0 - failure
* 1 - success
*/
static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
int status;
unsigned long start_here = __pa((u32)*((unsigned long *)
generic_secondary_smp_init));
unsigned int pcpu;
int start_cpu;
if (cpu_isset(lcpu, of_spin_map))
/* Already started by OF and sitting in spin loop */
return 1;
pcpu = get_hard_smp_processor_id(lcpu);
/* Fixup atomic count: it exited inside IRQ handler. */
task_thread_info(paca[lcpu].__current)->preempt_count = 0;
if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
goto out;
/*
* If the RTAS start-cpu token does not exist then presume the
* cpu is already spinning.
*/
start_cpu = rtas_token("start-cpu");
if (start_cpu == RTAS_UNKNOWN_SERVICE)
return 1;
status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
if (status != 0) {
printk(KERN_ERR "start-cpu failed: %i\n", status);
return 0;
}
out:
return 1;
}
#ifdef CONFIG_XICS
static void __devinit smp_xics_setup_cpu(int cpu)
{
if (cpu != boot_cpuid)
xics_setup_cpu();
if (firmware_has_feature(FW_FEATURE_SPLPAR))
vpa_init(cpu);
cpu_clear(cpu, of_spin_map);
set_cpu_current_state(cpu, CPU_STATE_ONLINE);
set_default_offline_state(cpu);
}
#endif /* CONFIG_XICS */
static void __devinit smp_pSeries_kick_cpu(int nr)
{
long rc;
unsigned long hcpuid;
BUG_ON(nr < 0 || nr >= NR_CPUS);
if (!smp_startup_cpu(nr))
return;
/*
* The processor is currently spinning, waiting for the
* cpu_start field to become non-zero After we set cpu_start,
* the processor will continue on to secondary_start
*/
paca[nr].cpu_start = 1;
set_preferred_offline_state(nr, CPU_STATE_ONLINE);
if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
hcpuid = get_hard_smp_processor_id(nr);
rc = plpar_hcall_norets(H_PROD, hcpuid);
if (rc != H_SUCCESS)
panic("Error: Prod to wake up processor %d Ret= %ld\n",
nr, rc);
}
}
static int smp_pSeries_cpu_bootable(unsigned int nr)
{
/* Special case - we inhibit secondary thread startup
* during boot if the user requests it.
*/
if (system_state < SYSTEM_RUNNING &&
cpu_has_feature(CPU_FTR_SMT) &&
!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
return 0;
return 1;
}
#ifdef CONFIG_MPIC
static struct smp_ops_t pSeries_mpic_smp_ops = {
.message_pass = smp_mpic_message_pass,
.probe = smp_mpic_probe,
.kick_cpu = smp_pSeries_kick_cpu,
.setup_cpu = smp_mpic_setup_cpu,
};
#endif
#ifdef CONFIG_XICS
static struct smp_ops_t pSeries_xics_smp_ops = {
.message_pass = smp_xics_message_pass,
.probe = smp_xics_probe,
.kick_cpu = smp_pSeries_kick_cpu,
.setup_cpu = smp_xics_setup_cpu,
.cpu_bootable = smp_pSeries_cpu_bootable,
};
#endif
/* This is called very early */
static void __init smp_init_pseries(void)
{
int i;
pr_debug(" -> smp_init_pSeries()\n");
/* Mark threads which are still spinning in hold loops. */
if (cpu_has_feature(CPU_FTR_SMT)) {
for_each_present_cpu(i) {
if (cpu_thread_in_core(i) == 0)
cpu_set(i, of_spin_map);
}
} else {
of_spin_map = cpu_present_map;
}
cpu_clear(boot_cpuid, of_spin_map);
/* Non-lpar has additional take/give timebase */
if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
smp_ops->give_timebase = rtas_give_timebase;
smp_ops->take_timebase = rtas_take_timebase;
}
pr_debug(" <- smp_init_pSeries()\n");
}
#ifdef CONFIG_MPIC
void __init smp_init_pseries_mpic(void)
{
smp_ops = &pSeries_mpic_smp_ops;
smp_init_pseries();
}
#endif
void __init smp_init_pseries_xics(void)
{
smp_ops = &pSeries_xics_smp_ops;
smp_init_pseries();
}