1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_QSPINLOCK_H
3#define _ASM_X86_QSPINLOCK_H
4
5#include <linux/jump_label.h>
6#include <asm/cpufeature.h>
7#include <asm-generic/qspinlock_types.h>
8#include <asm/paravirt.h>
9
10#define _Q_PENDING_LOOPS (1 << 9)
11
12#ifdef CONFIG_PARAVIRT_SPINLOCKS
13extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
14extern void __pv_init_lock_hash(void);
15extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
16extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
17
18#define queued_spin_unlock queued_spin_unlock
19/**
20 * queued_spin_unlock - release a queued spinlock
21 * @lock : Pointer to queued spinlock structure
22 *
23 * A smp_store_release() on the least-significant byte.
24 */
25static inline void native_queued_spin_unlock(struct qspinlock *lock)
26{
27 smp_store_release(&lock->locked, 0);
28}
29
30static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
31{
32 pv_queued_spin_lock_slowpath(lock, val);
33}
34
35static inline void queued_spin_unlock(struct qspinlock *lock)
36{
37 pv_queued_spin_unlock(lock);
38}
39
40#define vcpu_is_preempted vcpu_is_preempted
41static inline bool vcpu_is_preempted(long cpu)
42{
43 return pv_vcpu_is_preempted(cpu);
44}
45#endif
46
47#ifdef CONFIG_PARAVIRT
48DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key);
49
50void native_pv_lock_init(void) __init;
51
52#define virt_spin_lock virt_spin_lock
53static inline bool virt_spin_lock(struct qspinlock *lock)
54{
55 if (!static_branch_likely(&virt_spin_lock_key))
56 return false;
57
58 /*
59 * On hypervisors without PARAVIRT_SPINLOCKS support we fall
60 * back to a Test-and-Set spinlock, because fair locks have
61 * horrible lock 'holder' preemption issues.
62 */
63
64 do {
65 while (atomic_read(&lock->val) != 0)
66 cpu_relax();
67 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);
68
69 return true;
70}
71#else
72static inline void native_pv_lock_init(void)
73{
74}
75#endif /* CONFIG_PARAVIRT */
76
77#include <asm-generic/qspinlock.h>
78
79#endif /* _ASM_X86_QSPINLOCK_H */
80