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122 lines
3.1 KiB
122 lines
3.1 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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#ifndef _ASM_POWERPC_PARAVIRT_H |
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#define _ASM_POWERPC_PARAVIRT_H |
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#include <linux/jump_label.h> |
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#include <asm/smp.h> |
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#ifdef CONFIG_PPC64 |
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#include <asm/paca.h> |
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#include <asm/hvcall.h> |
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#endif |
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#ifdef CONFIG_PPC_SPLPAR |
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#include <linux/smp.h> |
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#include <asm/kvm_guest.h> |
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#include <asm/cputhreads.h> |
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DECLARE_STATIC_KEY_FALSE(shared_processor); |
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static inline bool is_shared_processor(void) |
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{ |
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return static_branch_unlikely(&shared_processor); |
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} |
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/* If bit 0 is set, the cpu has been preempted */ |
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static inline u32 yield_count_of(int cpu) |
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{ |
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__be32 yield_count = READ_ONCE(lppaca_of(cpu).yield_count); |
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return be32_to_cpu(yield_count); |
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} |
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/* |
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* Spinlock code confers and prods, so don't trace the hcalls because the |
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* tracing code takes spinlocks which can cause recursion deadlocks. |
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* |
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* These calls are made while the lock is not held: the lock slowpath yields if |
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* it can not acquire the lock, and unlock slow path might prod if a waiter has |
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* yielded). So this may not be a problem for simple spin locks because the |
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* tracing does not technically recurse on the lock, but we avoid it anyway. |
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* |
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* However the queued spin lock contended path is more strictly ordered: the |
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* H_CONFER hcall is made after the task has queued itself on the lock, so then |
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* recursing on that lock will cause the task to then queue up again behind the |
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* first instance (or worse: queued spinlocks use tricks that assume a context |
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* never waits on more than one spinlock, so such recursion may cause random |
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* corruption in the lock code). |
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*/ |
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static inline void yield_to_preempted(int cpu, u32 yield_count) |
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{ |
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plpar_hcall_norets_notrace(H_CONFER, get_hard_smp_processor_id(cpu), yield_count); |
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} |
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static inline void prod_cpu(int cpu) |
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{ |
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plpar_hcall_norets_notrace(H_PROD, get_hard_smp_processor_id(cpu)); |
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} |
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static inline void yield_to_any(void) |
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{ |
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plpar_hcall_norets_notrace(H_CONFER, -1, 0); |
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} |
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#else |
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static inline bool is_shared_processor(void) |
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{ |
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return false; |
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} |
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static inline u32 yield_count_of(int cpu) |
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{ |
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return 0; |
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} |
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extern void ___bad_yield_to_preempted(void); |
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static inline void yield_to_preempted(int cpu, u32 yield_count) |
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{ |
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___bad_yield_to_preempted(); /* This would be a bug */ |
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} |
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extern void ___bad_yield_to_any(void); |
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static inline void yield_to_any(void) |
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{ |
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___bad_yield_to_any(); /* This would be a bug */ |
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} |
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extern void ___bad_prod_cpu(void); |
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static inline void prod_cpu(int cpu) |
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{ |
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___bad_prod_cpu(); /* This would be a bug */ |
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} |
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#endif |
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#define vcpu_is_preempted vcpu_is_preempted |
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static inline bool vcpu_is_preempted(int cpu) |
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{ |
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if (!is_shared_processor()) |
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return false; |
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#ifdef CONFIG_PPC_SPLPAR |
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if (!is_kvm_guest()) { |
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int first_cpu = cpu_first_thread_sibling(smp_processor_id()); |
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/* |
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* Preemption can only happen at core granularity. This CPU |
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* is not preempted if one of the CPU of this core is not |
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* preempted. |
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*/ |
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if (cpu_first_thread_sibling(cpu) == first_cpu) |
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return false; |
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} |
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#endif |
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if (yield_count_of(cpu) & 1) |
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return true; |
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return false; |
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} |
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static inline bool pv_is_native_spin_unlock(void) |
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{ |
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return !is_shared_processor(); |
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} |
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#endif /* _ASM_POWERPC_PARAVIRT_H */
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