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 #include <asm/rmwcc.h> 10 11 #define _Q_PENDING_LOOPS (1 << 9) 12 13 #define queued_fetch_set_pending_acquire queued_fetch_set_pending_acquire 14 static __always_inline u32 queued_fetch_set_pending_acquire(struct qspinlock *lock) 15 { 16 u32 val; 17 18 /* 19 * We can't use GEN_BINARY_RMWcc() inside an if() stmt because asm goto 20 * and CONFIG_PROFILE_ALL_BRANCHES=y results in a label inside a 21 * statement expression, which GCC doesn't like. 22 */ 23 val = GEN_BINARY_RMWcc(LOCK_PREFIX "btsl", lock->val.counter, c, 24 "I", _Q_PENDING_OFFSET) * _Q_PENDING_VAL; 25 val |= atomic_read(&lock->val) & ~_Q_PENDING_MASK; 26 27 return val; 28 } 29 30 #ifdef CONFIG_PARAVIRT_SPINLOCKS 31 extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 32 extern void __pv_init_lock_hash(void); 33 extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); 34 extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock); 35 extern bool nopvspin; 36 37 #define queued_spin_unlock queued_spin_unlock 38 /** 39 * queued_spin_unlock - release a queued spinlock 40 * @lock : Pointer to queued spinlock structure 41 * 42 * A smp_store_release() on the least-significant byte. 43 */ 44 static inline void native_queued_spin_unlock(struct qspinlock *lock) 45 { 46 smp_store_release(&lock->locked, 0); 47 } 48 49 static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 50 { 51 pv_queued_spin_lock_slowpath(lock, val); 52 } 53 54 static inline void queued_spin_unlock(struct qspinlock *lock) 55 { 56 pv_queued_spin_unlock(lock); 57 } 58 59 #define vcpu_is_preempted vcpu_is_preempted 60 static inline bool vcpu_is_preempted(long cpu) 61 { 62 return pv_vcpu_is_preempted(cpu); 63 } 64 #endif 65 66 #ifdef CONFIG_PARAVIRT 67 /* 68 * virt_spin_lock_key - enables (by default) the virt_spin_lock() hijack. 69 * 70 * Native (and PV wanting native due to vCPU pinning) should disable this key. 71 * It is done in this backwards fashion to only have a single direction change, 72 * which removes ordering between native_pv_spin_init() and HV setup. 73 */ 74 DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key); 75 76 void native_pv_lock_init(void) __init; 77 78 /* 79 * Shortcut for the queued_spin_lock_slowpath() function that allows 80 * virt to hijack it. 81 * 82 * Returns: 83 * true - lock has been negotiated, all done; 84 * false - queued_spin_lock_slowpath() will do its thing. 85 */ 86 #define virt_spin_lock virt_spin_lock 87 static inline bool virt_spin_lock(struct qspinlock *lock) 88 { 89 if (!static_branch_likely(&virt_spin_lock_key)) 90 return false; 91 92 /* 93 * On hypervisors without PARAVIRT_SPINLOCKS support we fall 94 * back to a Test-and-Set spinlock, because fair locks have 95 * horrible lock 'holder' preemption issues. 96 */ 97 98 do { 99 while (atomic_read(&lock->val) != 0) 100 cpu_relax(); 101 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0); 102 103 return true; 104 } 105 #else 106 static inline void native_pv_lock_init(void) 107 { 108 } 109 #endif /* CONFIG_PARAVIRT */ 110 111 #include <asm-generic/qspinlock.h> 112 113 #endif /* _ASM_X86_QSPINLOCK_H */ 114