1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_QSPINLOCK_H 3 #define _ASM_X86_QSPINLOCK_H 4 5 #include <asm/cpufeature.h> 6 #include <asm-generic/qspinlock_types.h> 7 #include <asm/paravirt.h> 8 9 #define queued_spin_unlock queued_spin_unlock 10 /** 11 * queued_spin_unlock - release a queued spinlock 12 * @lock : Pointer to queued spinlock structure 13 * 14 * A smp_store_release() on the least-significant byte. 15 */ 16 static inline void native_queued_spin_unlock(struct qspinlock *lock) 17 { 18 smp_store_release((u8 *)lock, 0); 19 } 20 21 #ifdef CONFIG_PARAVIRT_SPINLOCKS 22 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 23 extern void __pv_init_lock_hash(void); 24 extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 25 extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); 26 27 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 28 { 29 pv_queued_spin_lock_slowpath(lock, val); 30 } 31 32 static inline void queued_spin_unlock(struct qspinlock *lock) 33 { 34 pv_queued_spin_unlock(lock); 35 } 36 37 #define vcpu_is_preempted vcpu_is_preempted 38 static inline bool vcpu_is_preempted(long cpu) 39 { 40 return pv_vcpu_is_preempted(cpu); 41 } 42 #else 43 static inline void queued_spin_unlock(struct qspinlock *lock) 44 { 45 native_queued_spin_unlock(lock); 46 } 47 #endif 48 49 #ifdef CONFIG_PARAVIRT 50 #define virt_spin_lock virt_spin_lock 51 static inline bool virt_spin_lock(struct qspinlock *lock) 52 { 53 if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) 54 return false; 55 56 /* 57 * On hypervisors without PARAVIRT_SPINLOCKS support we fall 58 * back to a Test-and-Set spinlock, because fair locks have 59 * horrible lock 'holder' preemption issues. 60 */ 61 62 do { 63 while (atomic_read(&lock->val) != 0) 64 cpu_relax(); 65 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0); 66 67 return true; 68 } 69 #endif /* CONFIG_PARAVIRT */ 70 71 #include <asm-generic/qspinlock.h> 72 73 #endif /* _ASM_X86_QSPINLOCK_H */ 74