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 13 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 14 extern void __pv_init_lock_hash(void); 15 extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 16 extern 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 */ 25 static inline void native_queued_spin_unlock(struct qspinlock *lock) 26 { 27 smp_store_release(&lock->locked, 0); 28 } 29 30 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 31 { 32 pv_queued_spin_lock_slowpath(lock, val); 33 } 34 35 static 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 41 static inline bool vcpu_is_preempted(long cpu) 42 { 43 return pv_vcpu_is_preempted(cpu); 44 } 45 #endif 46 47 #ifdef CONFIG_PARAVIRT 48 DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key); 49 50 void native_pv_lock_init(void) __init; 51 52 #define virt_spin_lock virt_spin_lock 53 static 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 72 static 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