[linux-2.6-block.git] / arch / x86 / xen / spinlock.c

/*
 * Split spinlock implementation out into its own file, so it can be
 * compiled in a FTRACE-compatible way.
 */
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/log2.h>
#include <linux/gfp.h>
#include <linux/slab.h>

#include <asm/paravirt.h>

#include <xen/interface/xen.h>
#include <xen/events.h>

#include "xen-ops.h"
#include "debugfs.h"

static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
static DEFINE_PER_CPU(char *, irq_name);
static bool xen_pvspin = true;

#ifdef CONFIG_QUEUED_SPINLOCKS

#include <asm/qspinlock.h>

static void xen_qlock_kick(int cpu)
{
	int irq = per_cpu(lock_kicker_irq, cpu);

	/* Don't kick if the target's kicker interrupt is not initialized. */
	if (irq == -1)
		return;

	xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
}

/*
 * Halt the current CPU & release it back to the host
 */
static void xen_qlock_wait(u8 *byte, u8 val)
{
	int irq = __this_cpu_read(lock_kicker_irq);

	/* If kicker interrupts not initialized yet, just spin */
	if (irq == -1)
		return;

	/* clear pending */
	xen_clear_irq_pending(irq);
	barrier();

	/*
	 * We check the byte value after clearing pending IRQ to make sure
	 * that we won't miss a wakeup event because of the clearing.
	 *
	 * The sync_clear_bit() call in xen_clear_irq_pending() is atomic.
	 * So it is effectively a memory barrier for x86.
	 */
	if (READ_ONCE(*byte) != val)
		return;

	/*
	 * If an interrupt happens here, it will leave the wakeup irq
	 * pending, which will cause xen_poll_irq() to return
	 * immediately.
	 */

	/* Block until irq becomes pending (or perhaps a spurious wakeup) */
	xen_poll_irq(irq);
}

#else /* CONFIG_QUEUED_SPINLOCKS */

enum xen_contention_stat {
	TAKEN_SLOW,
	TAKEN_SLOW_PICKUP,
	TAKEN_SLOW_SPURIOUS,
	RELEASED_SLOW,
	RELEASED_SLOW_KICKED,
	NR_CONTENTION_STATS
};


#ifdef CONFIG_XEN_DEBUG_FS
#define HISTO_BUCKETS	30
static struct xen_spinlock_stats
{
	u32 contention_stats[NR_CONTENTION_STATS];
	u32 histo_spin_blocked[HISTO_BUCKETS+1];
	u64 time_blocked;
} spinlock_stats;

static u8 zero_stats;

static inline void check_zero(void)
{
	u8 ret;
	u8 old = READ_ONCE(zero_stats);
	if (unlikely(old)) {
		ret = cmpxchg(&zero_stats, old, 0);
		/* This ensures only one fellow resets the stat */
		if (ret == old)
			memset(&spinlock_stats, 0, sizeof(spinlock_stats));
	}
}

static inline void add_stats(enum xen_contention_stat var, u32 val)
{
	check_zero();
	spinlock_stats.contention_stats[var] += val;
}

static inline u64 spin_time_start(void)
{
	return xen_clocksource_read();
}

static void __spin_time_accum(u64 delta, u32 *array)
{
	unsigned index = ilog2(delta);

	check_zero();

	if (index < HISTO_BUCKETS)
		array[index]++;
	else
		array[HISTO_BUCKETS]++;
}

static inline void spin_time_accum_blocked(u64 start)
{
	u32 delta = xen_clocksource_read() - start;

	__spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
	spinlock_stats.time_blocked += delta;
}
#else  /* !CONFIG_XEN_DEBUG_FS */
static inline void add_stats(enum xen_contention_stat var, u32 val)
{
}

static inline u64 spin_time_start(void)
{
	return 0;
}

static inline void spin_time_accum_blocked(u64 start)
{
}
#endif  /* CONFIG_XEN_DEBUG_FS */

struct xen_lock_waiting {
	struct arch_spinlock *lock;
	__ticket_t want;
};

static DEFINE_PER_CPU(struct xen_lock_waiting, lock_waiting);
static cpumask_t waiting_cpus;

__visible void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
{
	int irq = __this_cpu_read(lock_kicker_irq);
	struct xen_lock_waiting *w = this_cpu_ptr(&lock_waiting);
	int cpu = smp_processor_id();
	u64 start;
	__ticket_t head;
	unsigned long flags;

	/* If kicker interrupts not initialized yet, just spin */
	if (irq == -1)
		return;

	start = spin_time_start();

	/*
	 * Make sure an interrupt handler can't upset things in a
	 * partially setup state.
	 */
	local_irq_save(flags);
	/*
	 * We don't really care if we're overwriting some other
	 * (lock,want) pair, as that would mean that we're currently
	 * in an interrupt context, and the outer context had
	 * interrupts enabled.  That has already kicked the VCPU out
	 * of xen_poll_irq(), so it will just return spuriously and
	 * retry with newly setup (lock,want).
	 *
	 * The ordering protocol on this is that the "lock" pointer
	 * may only be set non-NULL if the "want" ticket is correct.
	 * If we're updating "want", we must first clear "lock".
	 */
	w->lock = NULL;
	smp_wmb();
	w->want = want;
	smp_wmb();
	w->lock = lock;

	/* This uses set_bit, which atomic and therefore a barrier */
	cpumask_set_cpu(cpu, &waiting_cpus);
	add_stats(TAKEN_SLOW, 1);

	/* clear pending */
	xen_clear_irq_pending(irq);

	/* Only check lock once pending cleared */
	barrier();

	/*
	 * Mark entry to slowpath before doing the pickup test to make
	 * sure we don't deadlock with an unlocker.
	 */
	__ticket_enter_slowpath(lock);

	/* make sure enter_slowpath, which is atomic does not cross the read */
	smp_mb__after_atomic();

	/*
	 * check again make sure it didn't become free while
	 * we weren't looking
	 */
	head = READ_ONCE(lock->tickets.head);
	if (__tickets_equal(head, want)) {
		add_stats(TAKEN_SLOW_PICKUP, 1);
		goto out;
	}

	/* Allow interrupts while blocked */
	local_irq_restore(flags);

	/*
	 * If an interrupt happens here, it will leave the wakeup irq
	 * pending, which will cause xen_poll_irq() to return
	 * immediately.
	 */

	/* Block until irq becomes pending (or perhaps a spurious wakeup) */
	xen_poll_irq(irq);
	add_stats(TAKEN_SLOW_SPURIOUS, !xen_test_irq_pending(irq));

	local_irq_save(flags);

	kstat_incr_irq_this_cpu(irq);
out:
	cpumask_clear_cpu(cpu, &waiting_cpus);
	w->lock = NULL;

	local_irq_restore(flags);

	spin_time_accum_blocked(start);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_lock_spinning);

static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
{
	int cpu;

	add_stats(RELEASED_SLOW, 1);

	for_each_cpu(cpu, &waiting_cpus) {
		const struct xen_lock_waiting *w = &per_cpu(lock_waiting, cpu);

		/* Make sure we read lock before want */
		if (READ_ONCE(w->lock) == lock &&
		    READ_ONCE(w->want) == next) {
			add_stats(RELEASED_SLOW_KICKED, 1);
			xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
			break;
		}
	}
}
#endif /* CONFIG_QUEUED_SPINLOCKS */

static irqreturn_t dummy_handler(int irq, void *dev_id)
{
	BUG();
	return IRQ_HANDLED;
}

void xen_init_lock_cpu(int cpu)
{
	int irq;
	char *name;

	if (!xen_pvspin)
		return;

	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
	     cpu, per_cpu(lock_kicker_irq, cpu));

	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
				     cpu,
				     dummy_handler,
				     IRQF_PERCPU|IRQF_NOBALANCING,
				     name,
				     NULL);

	if (irq >= 0) {
		disable_irq(irq); /* make sure it's never delivered */
		per_cpu(lock_kicker_irq, cpu) = irq;
		per_cpu(irq_name, cpu) = name;
	}

	printk("cpu %d spinlock event irq %d\n", cpu, irq);
}

void xen_uninit_lock_cpu(int cpu)
{
	if (!xen_pvspin)
		return;

	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
	per_cpu(lock_kicker_irq, cpu) = -1;
	kfree(per_cpu(irq_name, cpu));
	per_cpu(irq_name, cpu) = NULL;
}


/*
 * Our init of PV spinlocks is split in two init functions due to us
 * using paravirt patching and jump labels patching and having to do
 * all of this before SMP code is invoked.
 *
 * The paravirt patching needs to be done _before_ the alternative asm code
 * is started, otherwise we would not patch the core kernel code.
 */
void __init xen_init_spinlocks(void)
{

	if (!xen_pvspin) {
		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
		return;
	}
	printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
#ifdef CONFIG_QUEUED_SPINLOCKS
	__pv_init_lock_hash();
	pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
	pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
	pv_lock_ops.wait = xen_qlock_wait;
	pv_lock_ops.kick = xen_qlock_kick;
#else
	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
	pv_lock_ops.unlock_kick = xen_unlock_kick;
#endif
}

/*
 * While the jump_label init code needs to happend _after_ the jump labels are
 * enabled and before SMP is started. Hence we use pre-SMP initcall level
 * init. We cannot do it in xen_init_spinlocks as that is done before
 * jump labels are activated.
 */
static __init int xen_init_spinlocks_jump(void)
{
	if (!xen_pvspin)
		return 0;

	if (!xen_domain())
		return 0;

	static_key_slow_inc(&paravirt_ticketlocks_enabled);
	return 0;
}
early_initcall(xen_init_spinlocks_jump);

static __init int xen_parse_nopvspin(char *arg)
{
	xen_pvspin = false;
	return 0;
}
early_param("xen_nopvspin", xen_parse_nopvspin);

#if defined(CONFIG_XEN_DEBUG_FS) && !defined(CONFIG_QUEUED_SPINLOCKS)

static struct dentry *d_spin_debug;

static int __init xen_spinlock_debugfs(void)
{
	struct dentry *d_xen = xen_init_debugfs();

	if (d_xen == NULL)
		return -ENOMEM;

	if (!xen_pvspin)
		return 0;

	d_spin_debug = debugfs_create_dir("spinlocks", d_xen);

	debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);

	debugfs_create_u32("taken_slow", 0444, d_spin_debug,
			   &spinlock_stats.contention_stats[TAKEN_SLOW]);
	debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
			   &spinlock_stats.contention_stats[TAKEN_SLOW_PICKUP]);
	debugfs_create_u32("taken_slow_spurious", 0444, d_spin_debug,
			   &spinlock_stats.contention_stats[TAKEN_SLOW_SPURIOUS]);

	debugfs_create_u32("released_slow", 0444, d_spin_debug,
			   &spinlock_stats.contention_stats[RELEASED_SLOW]);
	debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
			   &spinlock_stats.contention_stats[RELEASED_SLOW_KICKED]);

	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
			   &spinlock_stats.time_blocked);

	debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
				spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);

	return 0;
}
fs_initcall(xen_spinlock_debugfs);

#endif	/* CONFIG_XEN_DEBUG_FS */
Commit	Line	Data
d5de8841 JF	1	/*
	2	* Split spinlock implementation out into its own file, so it can be
	3	* compiled in a FTRACE-compatible way.
	4	*/
	5	#include <linux/kernel_stat.h>
	6	#include <linux/spinlock.h>
994025ca JF	7	#include <linux/debugfs.h>
994025ca JF	8	#include <linux/log2.h>
5a0e3ad6	9	#include <linux/gfp.h>
354e7b76	10	#include <linux/slab.h>
d5de8841 JF	11
	12	#include <asm/paravirt.h>
	13
	14	#include <xen/interface/xen.h>
	15	#include <xen/events.h>
	16
	17	#include "xen-ops.h"
994025ca JF	18	#include "debugfs.h"
994025ca JF	19
e95e6f17 DV	20	static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
	21	static DEFINE_PER_CPU(char *, irq_name);
	22	static bool xen_pvspin = true;
	23
62c7a1e9	24	#ifdef CONFIG_QUEUED_SPINLOCKS
e95e6f17 DV	25
	26	#include <asm/qspinlock.h>
	27
	28	static void xen_qlock_kick(int cpu)
	29	{
707e59ba RL	30	int irq = per_cpu(lock_kicker_irq, cpu);
	31
	32	/* Don't kick if the target's kicker interrupt is not initialized. */
	33	if (irq == -1)
	34	return;
	35
e95e6f17 DV	36	xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
	37	}
	38
	39	/*
	40	* Halt the current CPU & release it back to the host
	41	*/
	42	static void xen_qlock_wait(u8 *byte, u8 val)
	43	{
	44	int irq = __this_cpu_read(lock_kicker_irq);
	45
	46	/* If kicker interrupts not initialized yet, just spin */
	47	if (irq == -1)
	48	return;
	49
	50	/* clear pending */
	51	xen_clear_irq_pending(irq);
	52	barrier();
	53
	54	/*
	55	* We check the byte value after clearing pending IRQ to make sure
	56	* that we won't miss a wakeup event because of the clearing.
	57	*
	58	* The sync_clear_bit() call in xen_clear_irq_pending() is atomic.
	59	* So it is effectively a memory barrier for x86.
	60	*/
	61	if (READ_ONCE(*byte) != val)
	62	return;
	63
	64	/*
	65	* If an interrupt happens here, it will leave the wakeup irq
	66	* pending, which will cause xen_poll_irq() to return
	67	* immediately.
	68	*/
	69
	70	/* Block until irq becomes pending (or perhaps a spurious wakeup) */
	71	xen_poll_irq(irq);
	72	}
	73
62c7a1e9	74	#else /* CONFIG_QUEUED_SPINLOCKS */
e95e6f17	75
80bd58fe JF	76	enum xen_contention_stat {
	77	TAKEN_SLOW,
	78	TAKEN_SLOW_PICKUP,
	79	TAKEN_SLOW_SPURIOUS,
	80	RELEASED_SLOW,
	81	RELEASED_SLOW_KICKED,
	82	NR_CONTENTION_STATS
	83	};
994025ca	84
994025ca	85
80bd58fe	86	#ifdef CONFIG_XEN_DEBUG_FS
f8eca41f	87	#define HISTO_BUCKETS 30
80bd58fe JF	88	static struct xen_spinlock_stats
	89	{
	90	u32 contention_stats[NR_CONTENTION_STATS];
f8eca41f	91	u32 histo_spin_blocked[HISTO_BUCKETS+1];
f8eca41f	92	u64 time_blocked;
994025ca JF	93	} spinlock_stats;
	94
	95	static u8 zero_stats;
	96
994025ca JF	97	static inline void check_zero(void)
994025ca JF	98	{
80bd58fe	99	u8 ret;
d6abfdb2	100	u8 old = READ_ONCE(zero_stats);
80bd58fe JF	101	if (unlikely(old)) {
	102	ret = cmpxchg(&zero_stats, old, 0);
	103	/* This ensures only one fellow resets the stat */
	104	if (ret == old)
	105	memset(&spinlock_stats, 0, sizeof(spinlock_stats));
994025ca JF	106	}
	107	}
	108
80bd58fe JF	109	static inline void add_stats(enum xen_contention_stat var, u32 val)
	110	{
	111	check_zero();
	112	spinlock_stats.contention_stats[var] += val;
	113	}
994025ca JF	114
	115	static inline u64 spin_time_start(void)
	116	{
	117	return xen_clocksource_read();
	118	}
	119
	120	static void __spin_time_accum(u64 delta, u32 *array)
	121	{
	122	unsigned index = ilog2(delta);
	123
	124	check_zero();
	125
	126	if (index < HISTO_BUCKETS)
	127	array[index]++;
	128	else
	129	array[HISTO_BUCKETS]++;
	130	}
	131
f8eca41f	132	static inline void spin_time_accum_blocked(u64 start)
994025ca JF	133	{
	134	u32 delta = xen_clocksource_read() - start;
	135
f8eca41f JF	136	__spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
f8eca41f JF	137	spinlock_stats.time_blocked += delta;
994025ca JF	138	}
994025ca JF	139	#else /* !CONFIG_XEN_DEBUG_FS */
80bd58fe JF	140	static inline void add_stats(enum xen_contention_stat var, u32 val)
	141	{
	142	}
994025ca JF	143
	144	static inline u64 spin_time_start(void)
	145	{
	146	return 0;
	147	}
	148
f8eca41f	149	static inline void spin_time_accum_blocked(u64 start)
994025ca JF	150	{
	151	}
	152	#endif /* CONFIG_XEN_DEBUG_FS */
d5de8841	153
80bd58fe JF	154	struct xen_lock_waiting {
	155	struct arch_spinlock *lock;
	156	__ticket_t want;
d5de8841 JF	157	};
d5de8841 JF	158
80bd58fe JF	159	static DEFINE_PER_CPU(struct xen_lock_waiting, lock_waiting);
80bd58fe JF	160	static cpumask_t waiting_cpus;
d5de8841	161
dd41f818	162	__visible void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
d5de8841	163	{
780f36d8	164	int irq = __this_cpu_read(lock_kicker_irq);
89cbc767	165	struct xen_lock_waiting *w = this_cpu_ptr(&lock_waiting);
80bd58fe	166	int cpu = smp_processor_id();
f8eca41f	167	u64 start;
d6abfdb2	168	__ticket_t head;
80bd58fe	169	unsigned long flags;
d5de8841 JF	170
	171	/* If kicker interrupts not initialized yet, just spin */
	172	if (irq == -1)
80bd58fe	173	return;
d5de8841	174
f8eca41f JF	175	start = spin_time_start();
f8eca41f JF	176
80bd58fe JF	177	/*
	178	* Make sure an interrupt handler can't upset things in a
	179	* partially setup state.
	180	*/
	181	local_irq_save(flags);
1ed7bf5f JF	182	/*
	183	* We don't really care if we're overwriting some other
	184	* (lock,want) pair, as that would mean that we're currently
	185	* in an interrupt context, and the outer context had
	186	* interrupts enabled. That has already kicked the VCPU out
	187	* of xen_poll_irq(), so it will just return spuriously and
	188	* retry with newly setup (lock,want).
	189	*
	190	* The ordering protocol on this is that the "lock" pointer
	191	* may only be set non-NULL if the "want" ticket is correct.
	192	* If we're updating "want", we must first clear "lock".
	193	*/
	194	w->lock = NULL;
	195	smp_wmb();
80bd58fe JF	196	w->want = want;
	197	smp_wmb();
	198	w->lock = lock;
4d576b57	199
80bd58fe JF	200	/* This uses set_bit, which atomic and therefore a barrier */
	201	cpumask_set_cpu(cpu, &waiting_cpus);
	202	add_stats(TAKEN_SLOW, 1);
4d576b57	203
80bd58fe JF	204	/* clear pending */
80bd58fe JF	205	xen_clear_irq_pending(irq);
4d576b57	206
80bd58fe JF	207	/* Only check lock once pending cleared */
80bd58fe JF	208	barrier();
d5de8841	209
1ed7bf5f JF	210	/*
	211	* Mark entry to slowpath before doing the pickup test to make
	212	* sure we don't deadlock with an unlocker.
	213	*/
96f853ea JF	214	__ticket_enter_slowpath(lock);
96f853ea JF	215
d6abfdb2 R	216	/* make sure enter_slowpath, which is atomic does not cross the read */
	217	smp_mb__after_atomic();
	218
1ed7bf5f JF	219	/*
	220	* check again make sure it didn't become free while
	221	* we weren't looking
	222	*/
d6abfdb2 R	223	head = READ_ONCE(lock->tickets.head);
d6abfdb2 R	224	if (__tickets_equal(head, want)) {
80bd58fe JF	225	add_stats(TAKEN_SLOW_PICKUP, 1);
	226	goto out;
	227	}
1ed7bf5f JF	228
	229	/* Allow interrupts while blocked */
	230	local_irq_restore(flags);
	231
	232	/*
	233	* If an interrupt happens here, it will leave the wakeup irq
	234	* pending, which will cause xen_poll_irq() to return
	235	* immediately.
	236	*/
	237
80bd58fe JF	238	/* Block until irq becomes pending (or perhaps a spurious wakeup) */
	239	xen_poll_irq(irq);
	240	add_stats(TAKEN_SLOW_SPURIOUS, !xen_test_irq_pending(irq));
1ed7bf5f JF	241
	242	local_irq_save(flags);
	243
770144ea	244	kstat_incr_irq_this_cpu(irq);
d5de8841	245	out:
80bd58fe JF	246	cpumask_clear_cpu(cpu, &waiting_cpus);
80bd58fe JF	247	w->lock = NULL;
1ed7bf5f	248
80bd58fe	249	local_irq_restore(flags);
1ed7bf5f	250
f8eca41f	251	spin_time_accum_blocked(start);
d5de8841	252	}
354714dd	253	PV_CALLEE_SAVE_REGS_THUNK(xen_lock_spinning);
d5de8841	254
80bd58fe	255	static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
d5de8841 JF	256	{
	257	int cpu;
	258
80bd58fe JF	259	add_stats(RELEASED_SLOW, 1);
	260
	261	for_each_cpu(cpu, &waiting_cpus) {
	262	const struct xen_lock_waiting *w = &per_cpu(lock_waiting, cpu);
994025ca	263
1ed7bf5f	264	/* Make sure we read lock before want */
d6abfdb2 R	265	if (READ_ONCE(w->lock) == lock &&
d6abfdb2 R	266	READ_ONCE(w->want) == next) {
80bd58fe	267	add_stats(RELEASED_SLOW_KICKED, 1);
d5de8841	268	xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
80bd58fe	269	break;
d5de8841 JF	270	}
	271	}
	272	}
62c7a1e9	273	#endif /* CONFIG_QUEUED_SPINLOCKS */
d5de8841	274
d5de8841 JF	275	static irqreturn_t dummy_handler(int irq, void *dev_id)
	276	{
	277	BUG();
	278	return IRQ_HANDLED;
	279	}
	280
148f9bb8	281	void xen_init_lock_cpu(int cpu)
d5de8841 JF	282	{
d5de8841 JF	283	int irq;
354e7b76	284	char *name;
d5de8841	285
3310bbed KRW	286	if (!xen_pvspin)
	287	return;
	288
cb91f8f4	289	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
cb9c6f15 KRW	290	cpu, per_cpu(lock_kicker_irq, cpu));
cb9c6f15 KRW	291
d5de8841 JF	292	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
	293	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
	294	cpu,
	295	dummy_handler,
9d71cee6	296	IRQF_PERCPU\|IRQF_NOBALANCING,
d5de8841 JF	297	name,
	298	NULL);
	299
	300	if (irq >= 0) {
	301	disable_irq(irq); /* make sure it's never delivered */
	302	per_cpu(lock_kicker_irq, cpu) = irq;
354e7b76	303	per_cpu(irq_name, cpu) = name;
d5de8841 JF	304	}
	305
	306	printk("cpu %d spinlock event irq %d\n", cpu, irq);
	307	}
	308
d68d82af AN	309	void xen_uninit_lock_cpu(int cpu)
d68d82af AN	310	{
3310bbed KRW	311	if (!xen_pvspin)
	312	return;
	313
d68d82af	314	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
cb9c6f15	315	per_cpu(lock_kicker_irq, cpu) = -1;
354e7b76 KRW	316	kfree(per_cpu(irq_name, cpu));
354e7b76 KRW	317	per_cpu(irq_name, cpu) = NULL;
d68d82af AN	318	}
d68d82af AN	319
b8fa70b5	320
a945928e KRW	321	/*
	322	* Our init of PV spinlocks is split in two init functions due to us
	323	* using paravirt patching and jump labels patching and having to do
	324	* all of this before SMP code is invoked.
	325	*
	326	* The paravirt patching needs to be done _before_ the alternative asm code
	327	* is started, otherwise we would not patch the core kernel code.
	328	*/
d5de8841 JF	329	void __init xen_init_spinlocks(void)
d5de8841 JF	330	{
70dd4998	331
b8fa70b5 JF	332	if (!xen_pvspin) {
	333	printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
	334	return;
	335	}
e0fc17a9	336	printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
62c7a1e9	337	#ifdef CONFIG_QUEUED_SPINLOCKS
e95e6f17 DV	338	__pv_init_lock_hash();
	339	pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
	340	pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
	341	pv_lock_ops.wait = xen_qlock_wait;
	342	pv_lock_ops.kick = xen_qlock_kick;
	343	#else
354714dd	344	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
80bd58fe	345	pv_lock_ops.unlock_kick = xen_unlock_kick;
e95e6f17	346	#endif
d5de8841	347	}
994025ca	348
a945928e KRW	349	/*
	350	* While the jump_label init code needs to happend _after_ the jump labels are
	351	* enabled and before SMP is started. Hence we use pre-SMP initcall level
	352	* init. We cannot do it in xen_init_spinlocks as that is done before
	353	* jump labels are activated.
	354	*/
	355	static __init int xen_init_spinlocks_jump(void)
	356	{
	357	if (!xen_pvspin)
	358	return 0;
	359
e0fc17a9 KRW	360	if (!xen_domain())
	361	return 0;
	362
a945928e KRW	363	static_key_slow_inc(&paravirt_ticketlocks_enabled);
	364	return 0;
	365	}
	366	early_initcall(xen_init_spinlocks_jump);
	367
b8fa70b5 JF	368	static __init int xen_parse_nopvspin(char *arg)
	369	{
	370	xen_pvspin = false;
	371	return 0;
	372	}
	373	early_param("xen_nopvspin", xen_parse_nopvspin);
	374
62c7a1e9	375	#if defined(CONFIG_XEN_DEBUG_FS) && !defined(CONFIG_QUEUED_SPINLOCKS)
994025ca JF	376
	377	static struct dentry *d_spin_debug;
	378
	379	static int __init xen_spinlock_debugfs(void)
	380	{
	381	struct dentry *d_xen = xen_init_debugfs();
	382
	383	if (d_xen == NULL)
	384	return -ENOMEM;
	385
3310bbed KRW	386	if (!xen_pvspin)
	387	return 0;
	388
994025ca JF	389	d_spin_debug = debugfs_create_dir("spinlocks", d_xen);
	390
	391	debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
	392
994025ca	393	debugfs_create_u32("taken_slow", 0444, d_spin_debug,
80bd58fe	394	&spinlock_stats.contention_stats[TAKEN_SLOW]);
994025ca	395	debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
80bd58fe	396	&spinlock_stats.contention_stats[TAKEN_SLOW_PICKUP]);
994025ca	397	debugfs_create_u32("taken_slow_spurious", 0444, d_spin_debug,
80bd58fe	398	&spinlock_stats.contention_stats[TAKEN_SLOW_SPURIOUS]);
994025ca	399
994025ca	400	debugfs_create_u32("released_slow", 0444, d_spin_debug,
80bd58fe	401	&spinlock_stats.contention_stats[RELEASED_SLOW]);
994025ca	402	debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
80bd58fe	403	&spinlock_stats.contention_stats[RELEASED_SLOW_KICKED]);
994025ca	404
f8eca41f JF	405	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
f8eca41f JF	406	&spinlock_stats.time_blocked);
994025ca	407
9fe2a701 SV	408	debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
9fe2a701 SV	409	spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
994025ca JF	410
	411	return 0;
	412	}
	413	fs_initcall(xen_spinlock_debugfs);
	414
	415	#endif /* CONFIG_XEN_DEBUG_FS */