--- /dev/null
+/*
+ * Virtual cpu timer based timer functions.
+ *
+ * Copyright IBM Corp. 2004, 2012
+ * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/timex.h>
+#include <linux/types.h>
+#include <linux/time.h>
+
+#include <asm/cputime.h>
+#include <asm/vtimer.h>
+#include <asm/vtime.h>
+#include <asm/cpu_mf.h>
+#include <asm/smp.h>
+
+static void virt_timer_expire(void);
+
+static LIST_HEAD(virt_timer_list);
+static DEFINE_SPINLOCK(virt_timer_lock);
+static atomic64_t virt_timer_current;
+static atomic64_t virt_timer_elapsed;
+
+static DEFINE_PER_CPU(u64, mt_cycles[32]);
+static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
+static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
+
+static inline u64 get_vtimer(void)
+{
+ u64 timer;
+
+ asm volatile("stpt %0" : "=m" (timer));
+ return timer;
+}
+
+static inline void set_vtimer(u64 expires)
+{
+ u64 timer;
+
+ asm volatile(
+ " stpt %0\n" /* Store current cpu timer value */
+ " spt %1" /* Set new value imm. afterwards */
+ : "=m" (timer) : "m" (expires));
+ S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
+ S390_lowcore.last_update_timer = expires;
+}
+
+static inline int virt_timer_forward(u64 elapsed)
+{
+ BUG_ON(!irqs_disabled());
+
+ if (list_empty(&virt_timer_list))
+ return 0;
+ elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
+ return elapsed >= atomic64_read(&virt_timer_current);
+}
+
+/*
+ * Update process times based on virtual cpu times stored by entry.S
+ * to the lowcore fields user_timer, system_timer & steal_clock.
+ */
+static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
+{
+ struct thread_info *ti = task_thread_info(tsk);
+ u64 timer, clock, user, system, steal;
+ u64 user_scaled, system_scaled;
+ int i;
+
+ timer = S390_lowcore.last_update_timer;
+ clock = S390_lowcore.last_update_clock;
+ asm volatile(
+ " stpt %0\n" /* Store current cpu timer value */
+#ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
+ " stckf %1" /* Store current tod clock value */
+#else
+ " stck %1" /* Store current tod clock value */
+#endif
+ : "=m" (S390_lowcore.last_update_timer),
+ "=m" (S390_lowcore.last_update_clock));
+ S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
+ S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
+
+ /* Do MT utilization calculation */
+ if (smp_cpu_mtid) {
+ u64 cycles_new[32], *cycles_old;
+ u64 delta, mult, div;
+
+ cycles_old = this_cpu_ptr(mt_cycles);
+ if (stcctm5(smp_cpu_mtid + 1, cycles_new) < 2) {
+ mult = div = 0;
+ for (i = 0; i <= smp_cpu_mtid; i++) {
+ delta = cycles_new[i] - cycles_old[i];
+ mult += delta;
+ div += (i + 1) * delta;
+ }
+ if (mult > 0) {
+ /* Update scaling factor */
+ __this_cpu_write(mt_scaling_mult, mult);
+ __this_cpu_write(mt_scaling_div, div);
+ memcpy(cycles_old, cycles_new,
+ sizeof(u64) * (smp_cpu_mtid + 1));
+ }
+ }
+ }
+
+ user = S390_lowcore.user_timer - ti->user_timer;
+ S390_lowcore.steal_timer -= user;
+ ti->user_timer = S390_lowcore.user_timer;
+
+ system = S390_lowcore.system_timer - ti->system_timer;
+ S390_lowcore.steal_timer -= system;
+ ti->system_timer = S390_lowcore.system_timer;
+
+ user_scaled = user;
+ system_scaled = system;
+ /* Do MT utilization scaling */
+ if (smp_cpu_mtid) {
+ u64 mult = __this_cpu_read(mt_scaling_mult);
+ u64 div = __this_cpu_read(mt_scaling_div);
+
+ user_scaled = (user_scaled * mult) / div;
+ system_scaled = (system_scaled * mult) / div;
+ }
+ account_user_time(tsk, user, user_scaled);
+ account_system_time(tsk, hardirq_offset, system, system_scaled);
+
+ steal = S390_lowcore.steal_timer;
+ if ((s64) steal > 0) {
+ S390_lowcore.steal_timer = 0;
+ account_steal_time(steal);
+ }
+
+ return virt_timer_forward(user + system);
+}
+
+void vtime_task_switch(struct task_struct *prev)
+{
+ struct thread_info *ti;
+
+ do_account_vtime(prev, 0);
+ ti = task_thread_info(prev);
+ ti->user_timer = S390_lowcore.user_timer;
+ ti->system_timer = S390_lowcore.system_timer;
+ ti = task_thread_info(current);
+ S390_lowcore.user_timer = ti->user_timer;
+ S390_lowcore.system_timer = ti->system_timer;
+}
+
+/*
+ * In s390, accounting pending user time also implies
+ * accounting system time in order to correctly compute
+ * the stolen time accounting.
+ */
+void vtime_account_user(struct task_struct *tsk)
+{
+ if (do_account_vtime(tsk, HARDIRQ_OFFSET))
+ virt_timer_expire();
+}
+
+/*
+ * Update process times based on virtual cpu times stored by entry.S
+ * to the lowcore fields user_timer, system_timer & steal_clock.
+ */
+void vtime_account_irq_enter(struct task_struct *tsk)
+{
+ struct thread_info *ti = task_thread_info(tsk);
+ u64 timer, system, system_scaled;
+
+ timer = S390_lowcore.last_update_timer;
+ S390_lowcore.last_update_timer = get_vtimer();
+ S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
+
+ system = S390_lowcore.system_timer - ti->system_timer;
+ S390_lowcore.steal_timer -= system;
+ ti->system_timer = S390_lowcore.system_timer;
+ system_scaled = system;
+ /* Do MT utilization scaling */
+ if (smp_cpu_mtid) {
+ u64 mult = __this_cpu_read(mt_scaling_mult);
+ u64 div = __this_cpu_read(mt_scaling_div);
+
+ system_scaled = (system_scaled * mult) / div;
+ }
+ account_system_time(tsk, 0, system, system_scaled);
+
+ virt_timer_forward(system);
+}
+EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
+
+void vtime_account_system(struct task_struct *tsk)
+__attribute__((alias("vtime_account_irq_enter")));
+EXPORT_SYMBOL_GPL(vtime_account_system);
+
+/*
+ * Sorted add to a list. List is linear searched until first bigger
+ * element is found.
+ */
+static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
+{
+ struct vtimer_list *tmp;
+
+ list_for_each_entry(tmp, head, entry) {
+ if (tmp->expires > timer->expires) {
+ list_add_tail(&timer->entry, &tmp->entry);
+ return;
+ }
+ }
+ list_add_tail(&timer->entry, head);
+}
+
+/*
+ * Handler for expired virtual CPU timer.
+ */
+static void virt_timer_expire(void)
+{
+ struct vtimer_list *timer, *tmp;
+ unsigned long elapsed;
+ LIST_HEAD(cb_list);
+
+ /* walk timer list, fire all expired timers */
+ spin_lock(&virt_timer_lock);
+ elapsed = atomic64_read(&virt_timer_elapsed);
+ list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
+ if (timer->expires < elapsed)
+ /* move expired timer to the callback queue */
+ list_move_tail(&timer->entry, &cb_list);
+ else
+ timer->expires -= elapsed;
+ }
+ if (!list_empty(&virt_timer_list)) {
+ timer = list_first_entry(&virt_timer_list,
+ struct vtimer_list, entry);
+ atomic64_set(&virt_timer_current, timer->expires);
+ }
+ atomic64_sub(elapsed, &virt_timer_elapsed);
+ spin_unlock(&virt_timer_lock);
+
+ /* Do callbacks and recharge periodic timers */
+ list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
+ list_del_init(&timer->entry);
+ timer->function(timer->data);
+ if (timer->interval) {
+ /* Recharge interval timer */
+ timer->expires = timer->interval +
+ atomic64_read(&virt_timer_elapsed);
+ spin_lock(&virt_timer_lock);
+ list_add_sorted(timer, &virt_timer_list);
+ spin_unlock(&virt_timer_lock);
+ }
+ }
+}
+
+void init_virt_timer(struct vtimer_list *timer)
+{
+ timer->function = NULL;
+ INIT_LIST_HEAD(&timer->entry);
+}
+EXPORT_SYMBOL(init_virt_timer);
+
+static inline int vtimer_pending(struct vtimer_list *timer)
+{
+ return !list_empty(&timer->entry);
+}
+
+static void internal_add_vtimer(struct vtimer_list *timer)
+{
+ if (list_empty(&virt_timer_list)) {
+ /* First timer, just program it. */
+ atomic64_set(&virt_timer_current, timer->expires);
+ atomic64_set(&virt_timer_elapsed, 0);
+ list_add(&timer->entry, &virt_timer_list);
+ } else {
+ /* Update timer against current base. */
+ timer->expires += atomic64_read(&virt_timer_elapsed);
+ if (likely((s64) timer->expires <
+ (s64) atomic64_read(&virt_timer_current)))
+ /* The new timer expires before the current timer. */
+ atomic64_set(&virt_timer_current, timer->expires);
+ /* Insert new timer into the list. */
+ list_add_sorted(timer, &virt_timer_list);
+ }
+}
+
+static void __add_vtimer(struct vtimer_list *timer, int periodic)
+{
+ unsigned long flags;
+
+ timer->interval = periodic ? timer->expires : 0;
+ spin_lock_irqsave(&virt_timer_lock, flags);
+ internal_add_vtimer(timer);
+ spin_unlock_irqrestore(&virt_timer_lock, flags);
+}
+
+/*
+ * add_virt_timer - add an oneshot virtual CPU timer
+ */
+void add_virt_timer(struct vtimer_list *timer)
+{
+ __add_vtimer(timer, 0);
+}
+EXPORT_SYMBOL(add_virt_timer);
+
+/*
+ * add_virt_timer_int - add an interval virtual CPU timer
+ */
+void add_virt_timer_periodic(struct vtimer_list *timer)
+{
+ __add_vtimer(timer, 1);
+}
+EXPORT_SYMBOL(add_virt_timer_periodic);
+
+static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
+{
+ unsigned long flags;
+ int rc;
+
+ BUG_ON(!timer->function);
+
+ if (timer->expires == expires && vtimer_pending(timer))
+ return 1;
+ spin_lock_irqsave(&virt_timer_lock, flags);
+ rc = vtimer_pending(timer);
+ if (rc)
+ list_del_init(&timer->entry);
+ timer->interval = periodic ? expires : 0;
+ timer->expires = expires;
+ internal_add_vtimer(timer);
+ spin_unlock_irqrestore(&virt_timer_lock, flags);
+ return rc;
+}
+
+/*
+ * returns whether it has modified a pending timer (1) or not (0)
+ */
+int mod_virt_timer(struct vtimer_list *timer, u64 expires)
+{
+ return __mod_vtimer(timer, expires, 0);
+}
+EXPORT_SYMBOL(mod_virt_timer);
+
+/*
+ * returns whether it has modified a pending timer (1) or not (0)
+ */
+int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
+{
+ return __mod_vtimer(timer, expires, 1);
+}
+EXPORT_SYMBOL(mod_virt_timer_periodic);
+
+/*
+ * Delete a virtual timer.
+ *
+ * returns whether the deleted timer was pending (1) or not (0)
+ */
+int del_virt_timer(struct vtimer_list *timer)
+{
+ unsigned long flags;
+
+ if (!vtimer_pending(timer))
+ return 0;
+ spin_lock_irqsave(&virt_timer_lock, flags);
+ list_del_init(&timer->entry);
+ spin_unlock_irqrestore(&virt_timer_lock, flags);
+ return 1;
+}
+EXPORT_SYMBOL(del_virt_timer);
+
+/*
+ * Start the virtual CPU timer on the current CPU.
+ */
+void vtime_init(void)
+{
+ /* set initial cpu timer */
+ set_vtimer(VTIMER_MAX_SLICE);
+}
Code Review / kvmfornfv.git / blobdiff