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