[PATCH v3 11/13] firmware: arm_sdei: add support for CPU private events

James Morse
2017-09-22T18:26:12Z

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-5wv7dgnIgG8@public.gmane.org>
---
drivers/firmware/arm_sdei.c | 242 +++++++++++++++++++++++++++++++++++++++++---
1 file changed, 228 insertions(+), 14 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index 5656830efff4..3bee2719d6f4 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>
@@ -65,12 +67,49 @@ struct sdei_event {
u8 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) {
@@ -214,6 +253,26 @@ 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->priority = event->priority;
+ reg->callback = cb;
+ reg->callback_arg = cb_arg;
+ }
+
+ event->private_registered = regs;
}

if (sdei_event_find(event_num)) {
@@ -235,6 +294,8 @@ 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);
}
@@ -265,11 +326,6 @@ static void _ipi_mask_cpu(void *ignored)
sdei_mask_local_cpu();
}

-static int sdei_cpuhp_down(unsigned int ignored)
-{
- return sdei_mask_local_cpu();
-}
-
int sdei_unmask_local_cpu(void)
{
int err;
@@ -291,11 +347,6 @@ static void _ipi_unmask_cpu(void *ignored)
sdei_unmask_local_cpu();
}

-static int sdei_cpuhp_up(unsigned int ignored)
-{
- return sdei_unmask_local_cpu();
-}
-
static void _ipi_private_reset(void *ignored)
{
int err;
@@ -346,6 +397,16 @@ static int sdei_api_event_enable(u32 event_num)
0, NULL);
}

+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;
@@ -357,6 +418,8 @@ 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;
@@ -369,6 +432,16 @@ static int sdei_api_event_disable(u32 event_num)
0, 0, NULL);
}

+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;
@@ -380,6 +453,9 @@ 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;
@@ -392,6 +468,27 @@ static int sdei_api_event_unregister(u32 event_num)
0, 0, 0, NULL);
}

+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());
+ lockdep_assert_held(&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;
@@ -412,7 +509,7 @@ 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)
@@ -471,15 +568,41 @@ static int sdei_api_event_register(u32 event_num, unsigned long entry_point,
flags, affinity, NULL);
}

+static void _local_event_register(void *data)
+{
+ int err;
+ struct sdei_registered_event *reg;
+ struct sdei_crosscall_args *arg = data;
+
+ WARN_ON(preemptible());
+ lockdep_assert_held(&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,
@@ -519,6 +642,22 @@ 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());
+ lockdep_assert_held(&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;
@@ -535,6 +674,8 @@ 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)
@@ -559,6 +700,68 @@ static int sdei_reregister_events(void)
return err;
}

+static int sdei_cpuhp_down(unsigned int cpu)
+{
+ struct sdei_event *event;
+ struct sdei_crosscall_args arg;
+
+ if (frozen) {
+ /* All events unregistered */
+ return sdei_mask_local_cpu();
+ }
+
+ /* 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);
+ if (arg.first_error)
+ pr_err("Failed to unregister event %u: %d\n",
+ event->event_num, arg.first_error);
+ }
+ spin_unlock(&sdei_events_lock);
+
+ return sdei_mask_local_cpu();
+}
+
+static int sdei_cpuhp_up(unsigned int cpu)
+{
+ struct sdei_event *event;
+ struct sdei_crosscall_args arg;
+
+ if (frozen) {
+ /* Events will be re-registered when we thaw. */
+ return sdei_unmask_local_cpu();
+ }
+
+ /* 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);
+ if (arg.first_error)
+ pr_err("Failed to re-register event %u: %d\n",
+ event->event_num, arg.first_error);
+
+ CROSSCALL_INIT(arg, event);
+ _local_event_reenable(&arg);
+ if (arg.first_error)
+ pr_err("Failed to re-enable event %u: %d\n",
+ event->event_num, arg.first_error);
+ }
+ spin_unlock(&sdei_events_lock);
+
+ return sdei_unmask_local_cpu();
+}
+
/* When entering idle, mask/unmask events for this cpu */
static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
void *data)
@@ -611,6 +814,7 @@ static int sdei_device_freeze(struct device *dev)
{
int err;

+ frozen = true;
err = sdei_event_unregister_all();
if (err)
return err;
@@ -620,9 +824,13 @@ 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)
@@ -654,6 +862,12 @@ 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;
}