[PATCH 10/11] firmware: arm_sdei: add support for CPU private events
James Morse
james.morse at arm.com
Mon May 15 10:43:58 PDT 2017
Private SDE events are per-cpu, and need to be registered and enabled
on each CPU.
Hide this detail from the caller by adapting our {,un}register and
{en,dis}able calls to send an IPI to each CPU if the event is private.
CPU private events are unregistered when the CPU is powered-off, and
re-registered when the CPU is brought back online. This saves bringing
secondary cores back online to call private_reset() on shutdown, kexec
and resume from hibernate.
Signed-off-by: James Morse <james.morse at arm.com>
---
drivers/firmware/arm_sdei.c | 237 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 232 insertions(+), 5 deletions(-)
diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index f9912d2ba2d3..6f4a43cb1672 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -20,9 +20,11 @@
#include <linux/acpi.h>
#include <linux/arm-smccc.h>
+#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/cpuhotplug.h>
+#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
@@ -63,12 +65,49 @@ struct sdei_event {
u64 priority;
/* This pointer is handed to firmware as the event argument. */
- struct sdei_registered_event *registered;
+ union {
+ /* Shared events */
+ struct sdei_registered_event *registered;
+
+ /* CPU private events */
+ struct sdei_registered_event __percpu *private_registered;
+ };
};
static LIST_HEAD(sdei_events);
static DEFINE_SPINLOCK(sdei_events_lock);
+/* When frozen, cpu-hotplug notifiers shouldn't unregister/re-register events */
+static bool frozen;
+
+/* Private events are registered/enabled via IPI passing one of these */
+struct sdei_crosscall_args {
+ struct sdei_event *event;
+ atomic_t errors;
+ int first_error;
+};
+
+#define CROSSCALL_INIT(arg, event) (arg.event = event, \
+ arg.first_error = 0, \
+ atomic_set(&arg.errors, 0))
+
+static inline int sdei_do_cross_call(void *fn, struct sdei_event * event)
+{
+ struct sdei_crosscall_args arg;
+
+ CROSSCALL_INIT(arg, event);
+ on_each_cpu(fn, &arg, true);
+
+ return arg.first_error;
+}
+
+static inline void
+sdei_cross_call_return(struct sdei_crosscall_args *arg, int err)
+{
+ if (err && (atomic_inc_return(&arg->errors) == 1))
+ arg->first_error = err;
+}
+
static int sdei_to_linux_errno(unsigned long sdei_err)
{
switch (sdei_err) {
@@ -213,6 +252,25 @@ static struct sdei_event *sdei_event_create(u32 event_num,
reg->callback = cb;
reg->callback_arg = cb_arg;
event->registered = reg;
+ } else {
+ int cpu;
+ struct sdei_registered_event __percpu *regs;
+
+ regs = alloc_percpu(struct sdei_registered_event);
+ if (!regs) {
+ kfree(event);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ for_each_possible_cpu(cpu) {
+ reg = per_cpu_ptr(regs, cpu);
+
+ reg->event_num = event->event_num;
+ reg->callback = cb;
+ reg->callback_arg = cb_arg;
+ }
+
+ event->private_registered = regs;
}
if (sdei_event_find(event_num)) {
@@ -234,6 +292,8 @@ static void sdei_event_destroy(struct sdei_event *event)
if (event->type == SDEI_EVENT_TYPE_SHARED)
kfree(event->registered);
+ else
+ free_percpu(event->private_registered);
kfree(event);
}
@@ -356,6 +416,16 @@ static int sdei_api_event_enable(u32 event_num)
0, 0, 0);
}
+static void _ipi_event_enable(void *data)
+{
+ int err;
+ struct sdei_crosscall_args *arg = data;
+
+ err = sdei_api_event_enable(arg->event->event_num);
+
+ sdei_cross_call_return(arg, err);
+}
+
int sdei_event_enable(u32 event_num)
{
int err = -EINVAL;
@@ -367,6 +437,8 @@ int sdei_event_enable(u32 event_num)
err = -ENOENT;
else if (event->type == SDEI_EVENT_TYPE_SHARED)
err = sdei_api_event_enable(event->event_num);
+ else
+ err = sdei_do_cross_call(_ipi_event_enable, event);
spin_unlock(&sdei_events_lock);
return err;
@@ -384,6 +456,16 @@ static int sdei_api_event_disable(u32 event_num)
return err;
}
+static void _ipi_event_disable(void *data)
+{
+ int err;
+ struct sdei_crosscall_args *arg = data;
+
+ err = sdei_api_event_disable(arg->event->event_num);
+
+ sdei_cross_call_return(arg, err);
+}
+
int sdei_event_disable(u32 event_num)
{
int err = -EINVAL;
@@ -395,6 +477,9 @@ int sdei_event_disable(u32 event_num)
err = -ENOENT;
else if (event->type == SDEI_EVENT_TYPE_SHARED)
err = sdei_api_event_disable(event->event_num);
+ else
+ err = sdei_do_cross_call(_ipi_event_disable, event);
+
spin_unlock(&sdei_events_lock);
return err;
@@ -409,6 +494,27 @@ static int sdei_api_event_unregister(u32 event_num)
event_num, 0, 0, 0, 0);
}
+static void _local_event_unregister(void *data)
+{
+ int err;
+ u64 result;
+ struct sdei_registered_event *reg;
+ struct sdei_crosscall_args *arg = data;
+
+ WARN_ON_ONCE(preemptible());
+ WARN_ON(!spin_is_locked(&sdei_events_lock));
+
+ reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
+ err = sdei_api_event_status(reg->event_num, &result);
+ if (!err) {
+ reg->was_enabled = !!(result & BIT(SDEI_EVENT_STATUS_ENABLED));
+
+ err = sdei_api_event_unregister(arg->event->event_num);
+ }
+
+ sdei_cross_call_return(arg, err);
+}
+
static int _sdei_event_unregister(struct sdei_event *event)
{
int err;
@@ -429,7 +535,7 @@ static int _sdei_event_unregister(struct sdei_event *event)
return sdei_api_event_unregister(event->event_num);
}
- return -EINVAL;
+ return sdei_do_cross_call(_local_event_unregister, event);
}
int sdei_event_unregister(u32 event_num)
@@ -490,15 +596,41 @@ static int sdei_api_event_register(u32 event_num, void *entry_point, void *arg,
flags, affinity);
}
+static void _local_event_register(void *data)
+{
+ int err;
+ struct sdei_registered_event *reg;
+ struct sdei_crosscall_args *arg = data;
+
+ WARN_ON(preemptible());
+ WARN_ON(!spin_is_locked(&sdei_events_lock));
+
+ reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
+ err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
+ reg, 0, 0);
+
+ sdei_cross_call_return(arg, err);
+}
+
static int _sdei_event_register(struct sdei_event *event)
{
+ int err;
+
if (event->type == SDEI_EVENT_TYPE_SHARED)
return sdei_api_event_register(event->event_num,
sdei_entry_point,
event->registered,
SDEI_EVENT_REGISTER_RM_ANY, 0);
- return -EINVAL;
+ get_online_cpus();
+
+ err = sdei_do_cross_call(_local_event_register, event);
+ if (err)
+ sdei_do_cross_call(_local_event_unregister, event);
+
+ put_online_cpus();
+
+ return err;
}
int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
@@ -535,6 +667,22 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
}
EXPORT_SYMBOL(sdei_event_register);
+static void _local_event_reenable(void *data)
+{
+ int err = 0;
+ struct sdei_registered_event *reg;
+ struct sdei_crosscall_args *arg = data;
+
+ WARN_ON_ONCE(preemptible());
+ WARN_ON(!spin_is_locked(&sdei_events_lock));
+
+ reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
+ if (reg->was_enabled)
+ err = sdei_api_event_enable(arg->event->event_num);
+
+ sdei_cross_call_return(arg, err);
+}
+
static int sdei_reregister_event(struct sdei_event *event)
{
int err;
@@ -551,6 +699,8 @@ static int sdei_reregister_event(struct sdei_event *event)
if (event->type == SDEI_EVENT_TYPE_SHARED) {
if (event->registered->was_enabled)
err = sdei_api_event_enable(event->event_num);
+ } else {
+ err = sdei_do_cross_call(_local_event_reenable, event);
}
if (err)
@@ -575,6 +725,72 @@ static int sdei_reregister_events(void)
return err;
}
+static int sdei_cpuhp_down(unsigned int cpu)
+{
+ int err = 0;
+ struct sdei_event *event;
+ struct sdei_crosscall_args arg;
+
+ if (frozen)
+ return 0;
+
+ /* un-register private events */
+ spin_lock(&sdei_events_lock);
+ list_for_each_entry(event, &sdei_events, list) {
+ if (event->type == SDEI_EVENT_TYPE_SHARED)
+ continue;
+
+ CROSSCALL_INIT(arg, event);
+ /* call the cross-call function locally... */
+ _local_event_unregister(&arg);
+ err = arg.first_error;
+ if (err)
+ break;
+ }
+ spin_unlock(&sdei_events_lock);
+
+ if (err)
+ return err;
+
+ return sdei_mask_local_cpu(cpu);
+}
+
+static int sdei_cpuhp_up(unsigned int cpu)
+{
+ int err = 0;
+ struct sdei_event *event;
+ struct sdei_crosscall_args arg;
+
+ if (frozen)
+ return 0;
+
+ /* re-register/enable private events */
+ spin_lock(&sdei_events_lock);
+ list_for_each_entry(event, &sdei_events, list) {
+ if (event->type == SDEI_EVENT_TYPE_SHARED)
+ continue;
+
+ CROSSCALL_INIT(arg, event);
+ /* call the cross-call function locally... */
+ _local_event_register(&arg);
+ err = arg.first_error;
+ if (err)
+ break;
+
+ CROSSCALL_INIT(arg, event);
+ _local_event_reenable(&arg);
+ err = arg.first_error;
+ if (err)
+ break;
+ }
+ spin_unlock(&sdei_events_lock);
+
+ if (err)
+ return err;
+
+ return sdei_unmask_local_cpu(cpu);
+}
+
/* When entering idle, mask/unmask events for this cpu */
static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
void *data)
@@ -627,6 +843,7 @@ static int sdei_device_freeze(struct device *dev)
{
int err;
+ frozen = true;
err = sdei_event_unregister_all();
if (err)
return err;
@@ -636,9 +853,13 @@ static int sdei_device_freeze(struct device *dev)
static int sdei_device_thaw(struct device *dev)
{
+ int err;
+
sdei_device_resume(dev);
- return sdei_reregister_events();
+ err = sdei_reregister_events();
+ frozen = false;
+ return err;
}
static int sdei_device_restore(struct device *dev)
@@ -670,6 +891,12 @@ static int sdei_reboot_notifier(struct notifier_block *nb, unsigned long action,
sdei_platform_reset();
+ /*
+ * There is now no point trying to unregister private events if we go on
+ * to take CPUs offline.
+ */
+ frozen = true;
+
return NOTIFY_OK;
}
@@ -760,7 +987,7 @@ static int sdei_probe(struct platform_device *pdev)
}
err = cpuhp_setup_state_nocalls(CPUHP_AP_SDEI_STARTING, "SDEI",
- &sdei_unmask_local_cpu, &sdei_mask_local_cpu);
+ &sdei_cpuhp_up, &sdei_cpuhp_down);
if (err) {
pr_warn("Failed to register CPU hotplug notifier...\n");
return err;
--
2.10.1
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