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 queued_spin_unlock queued_spin_unlock 11 /** 12 * queued_spin_unlock - release a queued spinlock 13 * @lock : Pointer to queued spinlock structure 14 * 15 * A smp_store_release() on the least-significant byte. 16 */ 17 static inline void native_queued_spin_unlock(struct qspinlock *lock) 18 { 19 smp_store_release((u8 *)lock, 0); 20 } 21 22 #ifdef CONFIG_PARAVIRT_SPINLOCKS 23 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 24 extern void __pv_init_lock_hash(void); 25 extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 26 extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); 27 28 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 29 { 30 pv_queued_spin_lock_slowpath(lock, val); 31 } 32 33 static inline void queued_spin_unlock(struct qspinlock *lock) 34 { 35 pv_queued_spin_unlock(lock); 36 } 37 38 #define vcpu_is_preempted vcpu_is_preempted 39 static inline bool vcpu_is_preempted(long cpu) 40 { 41 return pv_vcpu_is_preempted(cpu); 42 } 43 #else 44 static inline void queued_spin_unlock(struct qspinlock *lock) 45 { 46 native_queued_spin_unlock(lock); 47 } 48 #endif 49 50 #ifdef CONFIG_PARAVIRT 51 DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key); 52 53 void native_pv_lock_init(void) __init; 54 55 #define virt_spin_lock virt_spin_lock 56 static inline bool virt_spin_lock(struct qspinlock *lock) 57 { 58 if (!static_branch_likely(&virt_spin_lock_key)) 59 return false; 60 61 /* 62 * On hypervisors without PARAVIRT_SPINLOCKS support we fall 63 * back to a Test-and-Set spinlock, because fair locks have 64 * horrible lock 'holder' preemption issues. 65 */ 66 67 do { 68 while (atomic_read(&lock->val) != 0) 69 cpu_relax(); 70 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0); 71 72 return true; 73 } 74 #else 75 static inline void native_pv_lock_init(void) 76 { 77 } 78 #endif /* CONFIG_PARAVIRT */ 79 80 #include <asm-generic/qspinlock.h> 81 82 #endif /* _ASM_X86_QSPINLOCK_H */ 83