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 kcsan_release(); 57 pv_queued_spin_unlock(lock); 58 } 59 60 #define vcpu_is_preempted vcpu_is_preempted 61 static inline bool vcpu_is_preempted(long cpu) 62 { 63 return pv_vcpu_is_preempted(cpu); 64 } 65 #endif 66 67 #ifdef CONFIG_PARAVIRT 68 /* 69 * virt_spin_lock_key - disables by default the virt_spin_lock() hijack. 70 * 71 * Native (and PV wanting native due to vCPU pinning) should keep this key 72 * disabled. Native does not touch the key. 73 * 74 * When in a guest then native_pv_lock_init() enables the key first and 75 * KVM/XEN might conditionally disable it later in the boot process again. 76 */ 77 DECLARE_STATIC_KEY_FALSE(virt_spin_lock_key); 78 79 /* 80 * Shortcut for the queued_spin_lock_slowpath() function that allows 81 * virt to hijack it. 82 * 83 * Returns: 84 * true - lock has been negotiated, all done; 85 * false - queued_spin_lock_slowpath() will do its thing. 86 */ 87 #define virt_spin_lock virt_spin_lock 88 static inline bool virt_spin_lock(struct qspinlock *lock) 89 { 90 if (!static_branch_likely(&virt_spin_lock_key)) 91 return false; 92 93 /* 94 * On hypervisors without PARAVIRT_SPINLOCKS support we fall 95 * back to a Test-and-Set spinlock, because fair locks have 96 * horrible lock 'holder' preemption issues. 97 */ 98 99 do { 100 while (atomic_read(&lock->val) != 0) 101 cpu_relax(); 102 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0); 103 104 return true; 105 } 106 107 #endif /* CONFIG_PARAVIRT */ 108 109 #include <asm-generic/qspinlock.h> 110 111 #endif /* _ASM_X86_QSPINLOCK_H */ 112