[PATCH 3/3] pSeries: cpu: Cede CPU during a deactivate-offline
Gautham R Shenoy
ego at in.ibm.com
Thu Aug 6 00:26:08 EST 2009
Implements the pSeries specific code bits to put the CPU into
rtas_stop_self() state or H_CEDE state depending on the
preferred_offline_state value for that CPU.
Signed-off-by: Gautham R Shenoy <ego at in.ibm.com>
---
arch/powerpc/platforms/pseries/hotplug-cpu.c | 70 +++++++++++++++++++++--
arch/powerpc/platforms/pseries/offline_driver.h | 3 +
arch/powerpc/platforms/pseries/plpar_wrappers.h | 6 ++
arch/powerpc/platforms/pseries/smp.c | 18 ++++++
4 files changed, 88 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index f15de99..5b47d6c 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -41,6 +41,8 @@ struct cpu_offline_state {
};
DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) = CPU_DEALLOCATE;
+DEFINE_PER_CPU(enum cpu_state_vals, cpu_current_state);
+DEFINE_PER_CPU(int, cpu_offline_ack);
ssize_t pSeries_show_available_states(struct sys_device *dev,
struct sysdev_attribute *attr, char *buf)
@@ -148,8 +150,47 @@ static void pseries_mach_cpu_die(void)
local_irq_disable();
idle_task_exit();
xics_teardown_cpu();
- unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
- rtas_stop_self();
+ if (__get_cpu_var(preferred_offline_state) == CPU_DEACTIVATE) {
+
+ __get_cpu_var(cpu_offline_ack) = 1;
+ get_lppaca()->idle = 1;
+ if (!get_lppaca()->shared_proc)
+ get_lppaca()->donate_dedicated_cpu = 1;
+
+ printk(KERN_INFO "cpu %u (hwid %u) ceding\n",
+ smp_processor_id(), hard_smp_processor_id());
+
+ while (__get_cpu_var(cpu_current_state) == CPU_DEACTIVATE) {
+ cede_processor();
+ printk(KERN_INFO "cpu %u (hwid %u) Returned from cede.\
+ Decrementer value: %x. Timebase value:%llx \n",
+ smp_processor_id(), hard_smp_processor_id(),
+ get_dec(), get_tb());
+ }
+
+ printk(KERN_INFO "cpu %u (hwid %u) Received online PROD \n",
+ smp_processor_id(), hard_smp_processor_id());
+
+ if (!get_lppaca()->shared_proc)
+ get_lppaca()->donate_dedicated_cpu = 0;
+ get_lppaca()->idle = 0;
+
+ unregister_slb_shadow(hard_smp_processor_id(),
+ __pa(get_slb_shadow()));
+
+ /**
+ * NOTE: Calling start_secondary() here, is not a very nice
+ * way of beginning a new context.
+ *
+ * We need to reset the stack-pointer.
+ * Find a cleaner way to do this.
+ */
+ start_secondary(NULL);
+ } else {
+ unregister_slb_shadow(hard_smp_processor_id(),
+ __pa(get_slb_shadow()));
+ rtas_stop_self();
+ }
/* Should never get here... */
BUG();
for(;;);
@@ -192,6 +233,10 @@ static int pseries_cpu_disable(void)
/* FIXME: abstract this to not be platform specific later on */
xics_migrate_irqs_away();
+ __get_cpu_var(cpu_current_state) =
+ __get_cpu_var(preferred_offline_state);
+
+ __get_cpu_var(cpu_offline_ack) = 0;
return 0;
}
@@ -201,11 +246,22 @@ static void pseries_cpu_die(unsigned int cpu)
int cpu_status;
unsigned int pcpu = get_hard_smp_processor_id(cpu);
- for (tries = 0; tries < 25; tries++) {
- cpu_status = query_cpu_stopped(pcpu);
- if (cpu_status == 0 || cpu_status == -1)
- break;
- cpu_relax();
+ if (per_cpu(preferred_offline_state, cpu) == CPU_DEACTIVATE) {
+ /* Wait for some Ack */
+ for (tries = 0; tries < 10000; tries++) {
+ cpu_status = !per_cpu(cpu_offline_ack, cpu);
+ if (!cpu_status)
+ break;
+ cpu_relax();
+ }
+
+ } else {
+ for (tries = 0; tries < 25; tries++) {
+ cpu_status = query_cpu_stopped(pcpu);
+ if (cpu_status == 0 || cpu_status == -1)
+ break;
+ cpu_relax();
+ }
}
if (cpu_status != 0) {
printk("Querying DEAD? cpu %i (%i) shows %i\n",
diff --git a/arch/powerpc/platforms/pseries/offline_driver.h b/arch/powerpc/platforms/pseries/offline_driver.h
index bdae76a..571e085 100644
--- a/arch/powerpc/platforms/pseries/offline_driver.h
+++ b/arch/powerpc/platforms/pseries/offline_driver.h
@@ -12,5 +12,6 @@ enum cpu_state_vals {
};
DECLARE_PER_CPU(enum cpu_state_vals, preferred_offline_state);
-
+DECLARE_PER_CPU(enum cpu_state_vals, cpu_current_state);
+extern int start_secondary(void *unused);
#endif
diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index a24a6b2..ab7f5ab 100644
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -14,6 +14,12 @@ static inline long cede_processor(void)
return plpar_hcall_norets(H_CEDE);
}
+static inline long prod_processor(unsigned long cpu)
+{
+ unsigned long hcpuid = get_hard_smp_processor_id(cpu);
+ return plpar_hcall_norets(H_PROD, hcpuid);
+}
+
static inline long vpa_call(unsigned long flags, unsigned long cpu,
unsigned long vpa)
{
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c
index 1f8f6cf..15d96a2 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -48,6 +48,7 @@
#include "plpar_wrappers.h"
#include "pseries.h"
#include "xics.h"
+#include "offline_driver.h"
/*
@@ -86,7 +87,10 @@ static inline int __devinit smp_startup_cpu(unsigned int lcpu)
/* Fixup atomic count: it exited inside IRQ handler. */
task_thread_info(paca[lcpu].__current)->preempt_count = 0;
- /*
+ if (per_cpu(preferred_offline_state, lcpu) == CPU_DEACTIVATE)
+ goto out;
+
+ /*
* If the RTAS start-cpu token does not exist then presume the
* cpu is already spinning.
*/
@@ -100,6 +104,7 @@ static inline int __devinit smp_startup_cpu(unsigned int lcpu)
return 0;
}
+out:
return 1;
}
@@ -119,6 +124,7 @@ static void __devinit smp_xics_setup_cpu(int cpu)
static void __devinit smp_pSeries_kick_cpu(int nr)
{
+ long rc;
BUG_ON(nr < 0 || nr >= NR_CPUS);
if (!smp_startup_cpu(nr))
@@ -130,6 +136,16 @@ static void __devinit smp_pSeries_kick_cpu(int nr)
* the processor will continue on to secondary_start
*/
paca[nr].cpu_start = 1;
+
+ per_cpu(cpu_current_state, nr) = CPU_STATE_ONLINE;
+ if (per_cpu(preferred_offline_state, nr) == CPU_DEACTIVATE) {
+
+ printk(KERN_INFO "Prodding processor %d to go online\n", nr);
+ rc = prod_processor(nr);
+ if (rc != H_SUCCESS)
+ panic("Prod to wake up processor %d returned \
+ with error code: %ld. Dying\n", nr, rc);
+ }
}
static int smp_pSeries_cpu_bootable(unsigned int nr)
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