From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH] KVM: x86: inline kvm_ioapic_handles_vector() Date: Thu, 19 Mar 2015 21:52:41 +0100 Message-ID: <1426798361-14982-1-git-send-email-rkrcmar@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm@vger.kernel.org, Paolo Bonzini , Marcelo Tosatti To: linux-kernel@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org An overhead from function call is not appropriate for its size and frequency of execution. Suggested-by: Paolo Bonzini Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 --- I'm not very fond of that smp_rmb(): there is no real synchronization against update_handled_vectors(), so the only point I see is to drop cached value of handled_vectors, which seems like bad use of LFENCE. Am I missing something? Thanks. arch/x86/kvm/ioapic.c | 7 ------- arch/x86/kvm/ioapic.h | 8 +++++++- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c index 1522bab6bcff..f04986e1a0b0 100644 --- a/arch/x86/kvm/ioapic.c +++ b/arch/x86/kvm/ioapic.c @@ -475,13 +475,6 @@ static void __kvm_ioapic_update_eoi(struct kvm_vcp= u *vcpu, } } =20 -bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector) -{ - struct kvm_ioapic *ioapic =3D kvm->arch.vioapic; - smp_rmb(); - return test_bit(vector, ioapic->handled_vectors); -} - void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, int trig= ger_mode) { struct kvm_ioapic *ioapic =3D vcpu->kvm->arch.vioapic; diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h index 38d8402ea65c..6e265cfcd86a 100644 --- a/arch/x86/kvm/ioapic.h +++ b/arch/x86/kvm/ioapic.h @@ -98,13 +98,19 @@ static inline struct kvm_ioapic *ioapic_irqchip(str= uct kvm *kvm) return kvm->arch.vioapic; } =20 +static inline bool kvm_ioapic_handles_vector(struct kvm *kvm, int vect= or) +{ + struct kvm_ioapic *ioapic =3D kvm->arch.vioapic; + smp_rmb(); + return test_bit(vector, ioapic->handled_vectors); +} + void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu); bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *sour= ce, int short_hand, unsigned int dest, int dest_mode); int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcp= u2); void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, int trigger_mode); -bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector); int kvm_ioapic_init(struct kvm *kvm); void kvm_ioapic_destroy(struct kvm *kvm); int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_sou= rce_id, --=20 2.3.3