1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_LOONGARCH_QSPINLOCK_H 3 #define _ASM_LOONGARCH_QSPINLOCK_H 4 5 #include <asm/kvm_para.h> 6 #include <linux/jump_label.h> 7 8 #ifdef CONFIG_PARAVIRT 9 DECLARE_STATIC_KEY_FALSE(virt_preempt_key); 10 DECLARE_STATIC_KEY_FALSE(virt_spin_lock_key); 11 DECLARE_PER_CPU(struct kvm_steal_time, steal_time); 12 13 #define virt_spin_lock virt_spin_lock 14 15 static inline bool virt_spin_lock(struct qspinlock *lock) 16 { 17 int val; 18 19 if (!static_branch_unlikely(&virt_spin_lock_key)) 20 return false; 21 22 /* 23 * On hypervisors without PARAVIRT_SPINLOCKS support we fall 24 * back to a Test-and-Set spinlock, because fair locks have 25 * horrible lock 'holder' preemption issues. 26 */ 27 28 __retry: 29 val = atomic_read(&lock->val); 30 31 if (val || !atomic_try_cmpxchg(&lock->val, &val, _Q_LOCKED_VAL)) { 32 cpu_relax(); 33 goto __retry; 34 } 35 36 return true; 37 } 38 39 /* 40 * Macro is better than inline function here 41 * With macro, parameter cpu is parsed only when it is used. 42 * With inline function, parameter cpu is parsed even though it is not used. 43 * This may cause cache line thrashing across NUMA nodes. 44 */ 45 #define vcpu_is_preempted(cpu) \ 46 ({ \ 47 bool __val; \ 48 \ 49 if (!static_branch_unlikely(&virt_preempt_key)) \ 50 __val = false; \ 51 else { \ 52 struct kvm_steal_time *src; \ 53 src = &per_cpu(steal_time, cpu); \ 54 __val = !!(READ_ONCE(src->preempted) & KVM_VCPU_PREEMPTED); \ 55 } \ 56 __val; \ 57 }) 58 59 #endif /* CONFIG_PARAVIRT */ 60 61 #include <asm-generic/qspinlock.h> 62 63 #endif // _ASM_LOONGARCH_QSPINLOCK_H 64