1 files changed, 454 insertions, 0 deletions
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
new file mode 100644
index 000000000..9436f3053
--- /dev/null
+++ b/arch/s390/kernel/vtime.c
@@ -0,0 +1,454 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    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/sched/cputime.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/timex.h>
+#include <linux/types.h>
+#include <linux/time.h>
+#include <asm/alternative.h>
+#include <asm/vtimer.h>
+#include <asm/vtime.h>
+#include <asm/cpu_mf.h>
+#include <asm/smp.h>
+
+#include "entry.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;
+
+DEFINE_PER_CPU(u64, mt_cycles[8]);
+static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
+static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
+static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
+
+static inline u64 get_vtimer(void)
+{
+	u64 timer;
+
+	asm volatile("stpt %0" : "=Q" (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 */
+		: "=Q" (timer) : "Q" (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);
+}
+
+static void update_mt_scaling(void)
+{
+	u64 cycles_new[8], *cycles_old;
+	u64 delta, fac, mult, div;
+	int i;
+
+	stcctm(MT_DIAG, smp_cpu_mtid + 1, cycles_new);
+	cycles_old = this_cpu_ptr(mt_cycles);
+	fac = 1;
+	mult = div = 0;
+	for (i = 0; i <= smp_cpu_mtid; i++) {
+		delta = cycles_new[i] - cycles_old[i];
+		div += delta;
+		mult *= i + 1;
+		mult += delta * fac;
+		fac *= i + 1;
+	}
+	div *= fac;
+	if (div > 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));
+	}
+	__this_cpu_write(mt_scaling_jiffies, jiffies_64);
+}
+
+static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new)
+{
+	u64 delta;
+
+	delta = new - *tsk_vtime;
+	*tsk_vtime = new;
+	return delta;
+}
+
+
+static inline u64 scale_vtime(u64 vtime)
+{
+	u64 mult = __this_cpu_read(mt_scaling_mult);
+	u64 div = __this_cpu_read(mt_scaling_div);
+
+	if (smp_cpu_mtid)
+		return vtime * mult / div;
+	return vtime;
+}
+
+static void account_system_index_scaled(struct task_struct *p, u64 cputime,
+					enum cpu_usage_stat index)
+{
+	p->stimescaled += cputime_to_nsecs(scale_vtime(cputime));
+	account_system_index_time(p, cputime_to_nsecs(cputime), index);
+}
+
+/*
+ * 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)
+{
+	u64 timer, clock, user, guest, system, hardirq, softirq;
+
+	timer = S390_lowcore.last_update_timer;
+	clock = S390_lowcore.last_update_clock;
+	asm volatile(
+		"	stpt	%0\n"	/* Store current cpu timer value */
+		"	stckf	%1"	/* Store current tod clock value */
+		: "=Q" (S390_lowcore.last_update_timer),
+		  "=Q" (S390_lowcore.last_update_clock)
+		: : "cc");
+	clock = S390_lowcore.last_update_clock - clock;
+	timer -= S390_lowcore.last_update_timer;
+
+	if (hardirq_count())
+		S390_lowcore.hardirq_timer += timer;
+	else
+		S390_lowcore.system_timer += timer;
+
+	/* Update MT utilization calculation */
+	if (smp_cpu_mtid &&
+	    time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
+		update_mt_scaling();
+
+	/* Calculate cputime delta */
+	user = update_tsk_timer(&tsk->thread.user_timer,
+				READ_ONCE(S390_lowcore.user_timer));
+	guest = update_tsk_timer(&tsk->thread.guest_timer,
+				 READ_ONCE(S390_lowcore.guest_timer));
+	system = update_tsk_timer(&tsk->thread.system_timer,
+				  READ_ONCE(S390_lowcore.system_timer));
+	hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
+				   READ_ONCE(S390_lowcore.hardirq_timer));
+	softirq = update_tsk_timer(&tsk->thread.softirq_timer,
+				   READ_ONCE(S390_lowcore.softirq_timer));
+	S390_lowcore.steal_timer +=
+		clock - user - guest - system - hardirq - softirq;
+
+	/* Push account value */
+	if (user) {
+		account_user_time(tsk, cputime_to_nsecs(user));
+		tsk->utimescaled += cputime_to_nsecs(scale_vtime(user));
+	}
+
+	if (guest) {
+		account_guest_time(tsk, cputime_to_nsecs(guest));
+		tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest));
+	}
+
+	if (system)
+		account_system_index_scaled(tsk, system, CPUTIME_SYSTEM);
+	if (hardirq)
+		account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ);
+	if (softirq)
+		account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
+
+	return virt_timer_forward(user + guest + system + hardirq + softirq);
+}
+
+void vtime_task_switch(struct task_struct *prev)
+{
+	do_account_vtime(prev);
+	prev->thread.user_timer = S390_lowcore.user_timer;
+	prev->thread.guest_timer = S390_lowcore.guest_timer;
+	prev->thread.system_timer = S390_lowcore.system_timer;
+	prev->thread.hardirq_timer = S390_lowcore.hardirq_timer;
+	prev->thread.softirq_timer = S390_lowcore.softirq_timer;
+	S390_lowcore.user_timer = current->thread.user_timer;
+	S390_lowcore.guest_timer = current->thread.guest_timer;
+	S390_lowcore.system_timer = current->thread.system_timer;
+	S390_lowcore.hardirq_timer = current->thread.hardirq_timer;
+	S390_lowcore.softirq_timer = current->thread.softirq_timer;
+}
+
+/*
+ * In s390, accounting pending user time also implies
+ * accounting system time in order to correctly compute
+ * the stolen time accounting.
+ */
+void vtime_flush(struct task_struct *tsk)
+{
+	u64 steal, avg_steal;
+
+	if (do_account_vtime(tsk))
+		virt_timer_expire();
+
+	steal = S390_lowcore.steal_timer;
+	avg_steal = S390_lowcore.avg_steal_timer / 2;
+	if ((s64) steal > 0) {
+		S390_lowcore.steal_timer = 0;
+		account_steal_time(cputime_to_nsecs(steal));
+		avg_steal += steal;
+	}
+	S390_lowcore.avg_steal_timer = avg_steal;
+}
+
+static u64 vtime_delta(void)
+{
+	u64 timer = S390_lowcore.last_update_timer;
+
+	S390_lowcore.last_update_timer = get_vtimer();
+
+	return timer - S390_lowcore.last_update_timer;
+}
+
+/*
+ * 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_kernel(struct task_struct *tsk)
+{
+	u64 delta = vtime_delta();
+
+	if (tsk->flags & PF_VCPU)
+		S390_lowcore.guest_timer += delta;
+	else
+		S390_lowcore.system_timer += delta;
+
+	virt_timer_forward(delta);
+}
+EXPORT_SYMBOL_GPL(vtime_account_kernel);
+
+void vtime_account_softirq(struct task_struct *tsk)
+{
+	u64 delta = vtime_delta();
+
+	S390_lowcore.softirq_timer += delta;
+
+	virt_timer_forward(delta);
+}
+
+void vtime_account_hardirq(struct task_struct *tsk)
+{
+	u64 delta = vtime_delta();
+
+	S390_lowcore.hardirq_timer += delta;
+
+	virt_timer_forward(delta);
+}
+
+/*
+ * 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 a 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);
+	/* Setup initial MT scaling values */
+	if (smp_cpu_mtid) {
+		__this_cpu_write(mt_scaling_jiffies, jiffies);
+		__this_cpu_write(mt_scaling_mult, 1);
+		__this_cpu_write(mt_scaling_div, 1);
+		stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
+	}
+}