[v3,5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR

Message ID	20200706043540.1563616-6-npiggin@gmail.com (mailing list archive)
State	Changes Requested
Headers	show Return-Path: <linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org> From: Nicholas Piggin <npiggin@gmail.com> To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR Date: Mon, 6 Jul 2020 14:35:39 +1000 Message-Id: <20200706043540.1563616-6-npiggin@gmail.com> In-Reply-To: <20200706043540.1563616-1-npiggin@gmail.com> References: <20200706043540.1563616-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: list Cc: linux-arch@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, Boqun Feng <boqun.feng@gmail.com>, linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>, virtualization@lists.linux-foundation.org, Ingo Molnar <mingo@redhat.com>, kvm-ppc@vger.kernel.org, Waiman Long <longman@redhat.com>, Will Deacon <will@kernel.org> Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" <linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>
Series	powerpc: queued spinlocks and rwlocks \| expand [v3,0/6] powerpc: queued spinlocks and rwlocks [v3,1/6] powerpc/powernv: must include hvcall.h to get PAPR defines [v3,2/6] powerpc/pseries: move some PAPR paravirt functions to their own file [v3,3/6] powerpc: move spinlock implementation to simple_spinlock [v3,4/6] powerpc/64s: implement queued spinlocks and rwlocks [v3,5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR [v3,6/6] powerpc/qspinlock: optimised atomic_try_cmpxchg_lock that adds the lock hint

diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h index 7a8546660a63..f2d51f929cf5 100644 --- a/arch/powerpc/include/asm/paravirt.h +++ b/arch/powerpc/include/asm/paravirt.h @@ -29,6 +29,16 @@ static inline void yield_to_preempted(int cpu, u32 yield_count) { plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(cpu), yield_count); } + +static inline void prod_cpu(int cpu) +{ + plpar_hcall_norets(H_PROD, get_hard_smp_processor_id(cpu)); +} + +static inline void yield_to_any(void) +{ + plpar_hcall_norets(H_CONFER, -1, 0); +} #else static inline bool is_shared_processor(void) { @@ -45,6 +55,19 @@ static inline void yield_to_preempted(int cpu, u32 yield_count) { ___bad_yield_to_preempted(); /* This would be a bug */ } + +extern void ___bad_yield_to_any(void); +static inline void yield_to_any(void) +{ + ___bad_yield_to_any(); /* This would be a bug */ +} + +extern void ___bad_prod_cpu(void); +static inline void prod_cpu(int cpu) +{ + ___bad_prod_cpu(); /* This would be a bug */ +} + #endif #define vcpu_is_preempted vcpu_is_preempted @@ -57,5 +80,10 @@ static inline bool vcpu_is_preempted(int cpu) return false; } +static inline bool pv_is_native_spin_unlock(void) +{ + return !is_shared_processor(); +} + #endif /* __KERNEL__ */ #endif /* __ASM_PARAVIRT_H */ diff --git a/arch/powerpc/include/asm/qspinlock.h b/arch/powerpc/include/asm/qspinlock.h index c49e33e24edd..f5066f00a08c 100644 --- a/arch/powerpc/include/asm/qspinlock.h +++ b/arch/powerpc/include/asm/qspinlock.h @@ -3,9 +3,47 @@ #define _ASM_POWERPC_QSPINLOCK_H #include <asm-generic/qspinlock_types.h> +#include <asm/paravirt.h> #define _Q_PENDING_LOOPS (1 << 9) /* not tuned */ +#ifdef CONFIG_PARAVIRT_SPINLOCKS +extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +extern void __pv_queued_spin_unlock(struct qspinlock *lock); + +static __always_inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) +{ + if (!is_shared_processor()) + native_queued_spin_lock_slowpath(lock, val); + else + __pv_queued_spin_lock_slowpath(lock, val); +} + +#define queued_spin_unlock queued_spin_unlock +static inline void queued_spin_unlock(struct qspinlock *lock) +{ + if (!is_shared_processor()) + smp_store_release(&lock->locked, 0); + else + __pv_queued_spin_unlock(lock); +} + +#else +extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +#endif + +static __always_inline void queued_spin_lock(struct qspinlock *lock) +{ + u32 val = 0; + + if (likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL))) + return; + + queued_spin_lock_slowpath(lock, val); +} +#define queued_spin_lock queued_spin_lock + #define smp_mb__after_spinlock() smp_mb() static __always_inline int queued_spin_is_locked(struct qspinlock *lock) @@ -20,6 +58,34 @@ static __always_inline int queued_spin_is_locked(struct qspinlock *lock) } #define queued_spin_is_locked queued_spin_is_locked +#ifdef CONFIG_PARAVIRT_SPINLOCKS +#define SPIN_THRESHOLD (1<<15) /* not tuned */ + +static __always_inline void pv_wait(u8 *ptr, u8 val) +{ + if (*ptr != val) + return; + yield_to_any(); + /* + * We could pass in a CPU here if waiting in the queue and yield to + * the previous CPU in the queue. + */ +} + +static __always_inline void pv_kick(int cpu) +{ + prod_cpu(cpu); +} + +extern void __pv_init_lock_hash(void); + +static inline void pv_spinlocks_init(void) +{ + __pv_init_lock_hash(); +} + +#endif + #include <asm-generic/qspinlock.h> #endif /* _ASM_POWERPC_QSPINLOCK_H */ diff --git a/arch/powerpc/include/asm/qspinlock_paravirt.h b/arch/powerpc/include/asm/qspinlock_paravirt.h new file mode 100644 index 000000000000..750d1b5e0202 --- /dev/null +++ b/arch/powerpc/include/asm/qspinlock_paravirt.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef __ASM_QSPINLOCK_PARAVIRT_H +#define __ASM_QSPINLOCK_PARAVIRT_H + +EXPORT_SYMBOL(__pv_queued_spin_unlock); + +#endif /* __ASM_QSPINLOCK_PARAVIRT_H */ diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig index 24c18362e5ea..756e727b383f 100644 --- a/arch/powerpc/platforms/pseries/Kconfig +++ b/arch/powerpc/platforms/pseries/Kconfig @@ -25,9 +25,14 @@ config PPC_PSERIES select SWIOTLB default y +config PARAVIRT_SPINLOCKS + bool + default n + config PPC_SPLPAR depends on PPC_PSERIES bool "Support for shared-processor logical partitions" + select PARAVIRT_SPINLOCKS if PPC_QUEUED_SPINLOCKS help Enabling this option will make the kernel run more efficiently on logically-partitioned pSeries systems which use shared diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 2db8469e475f..747a203d9453 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -771,8 +771,12 @@ static void __init pSeries_setup_arch(void) if (firmware_has_feature(FW_FEATURE_LPAR)) { vpa_init(boot_cpuid); - if (lppaca_shared_proc(get_lppaca())) + if (lppaca_shared_proc(get_lppaca())) { static_branch_enable(&shared_processor); +#ifdef CONFIG_PARAVIRT_SPINLOCKS + pv_spinlocks_init(); +#endif + } ppc_md.power_save = pseries_lpar_idle; ppc_md.enable_pmcs = pseries_lpar_enable_pmcs; diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h index fb0a814d4395..38ca14e79a86 100644 --- a/include/asm-generic/qspinlock.h +++ b/include/asm-generic/qspinlock.h @@ -69,6 +69,7 @@ static __always_inline int queued_spin_trylock(struct qspinlock *lock) extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); +#ifndef queued_spin_lock /** * queued_spin_lock - acquire a queued spinlock * @lock: Pointer to queued spinlock structure @@ -82,6 +83,7 @@ static __always_inline void queued_spin_lock(struct qspinlock *lock) queued_spin_lock_slowpath(lock, val); } +#endif #ifndef queued_spin_unlock /**

[v3,5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR

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