Commit-ID: bf0c7c34adc286bec3a5a38c00c773ba1b2d0396 Gitweb: http://git.kernel.org/tip/bf0c7c34adc286bec3a5a38c00c773ba1b2d0396 Author: Waiman Long <[email protected]> AuthorDate: Fri, 24 Apr 2015 14:56:39 -0400 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 8 May 2015 12:37:17 +0200
locking/pvqspinlock, x86: Enable PV qspinlock for KVM This patch adds the necessary KVM specific code to allow KVM to support the CPU halting and kicking operations needed by the queue spinlock PV code. Signed-off-by: Waiman Long <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Daniel J Blueman <[email protected]> Cc: David Vrabel <[email protected]> Cc: Douglas Hatch <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Raghavendra K T <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Scott J Norton <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/kvm.c | 43 +++++++++++++++++++++++++++++++++++++++++++ kernel/Kconfig.locks | 2 +- 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 9435620..6c21d93 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -584,6 +584,39 @@ static void kvm_kick_cpu(int cpu) kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); } + +#ifdef CONFIG_QUEUED_SPINLOCK + +#include <asm/qspinlock.h> + +static void kvm_wait(u8 *ptr, u8 val) +{ + unsigned long flags; + + if (in_nmi()) + return; + + local_irq_save(flags); + + if (READ_ONCE(*ptr) != val) + goto out; + + /* + * halt until it's our turn and kicked. Note that we do safe halt + * for irq enabled case to avoid hang when lock info is overwritten + * in irq spinlock slowpath and no spurious interrupt occur to save us. + */ + if (arch_irqs_disabled_flags(flags)) + halt(); + else + safe_halt(); + +out: + local_irq_restore(flags); +} + +#else /* !CONFIG_QUEUED_SPINLOCK */ + enum kvm_contention_stat { TAKEN_SLOW, TAKEN_SLOW_PICKUP, @@ -817,6 +850,8 @@ static void kvm_unlock_kick(struct arch_spinlock *lock, __ticket_t ticket) } } +#endif /* !CONFIG_QUEUED_SPINLOCK */ + /* * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. */ @@ -828,8 +863,16 @@ void __init kvm_spinlock_init(void) if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) return; +#ifdef CONFIG_QUEUED_SPINLOCK + __pv_init_lock_hash(); + pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_lock_ops.wait = kvm_wait; + pv_lock_ops.kick = kvm_kick_cpu; +#else /* !CONFIG_QUEUED_SPINLOCK */ pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning); pv_lock_ops.unlock_kick = kvm_unlock_kick; +#endif } static __init int kvm_spinlock_init_jump(void) diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks index 95fdad8..4379eef 100644 --- a/kernel/Kconfig.locks +++ b/kernel/Kconfig.locks @@ -240,7 +240,7 @@ config ARCH_USE_QUEUED_SPINLOCK config QUEUED_SPINLOCK def_bool y if ARCH_USE_QUEUED_SPINLOCK - depends on SMP && !PARAVIRT_SPINLOCKS + depends on SMP && (!PARAVIRT_SPINLOCKS || !XEN) config ARCH_USE_QUEUE_RWLOCK bool -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
