From: Wanpeng Li <[email protected]> The kick after setting KVM_REQ_PENDING_TIMER is used to handle the timer fires on a different pCPU which vCPU is running on, we don't need this kick when injecting already-expired timer, this kick is expensive since memory barrier, rcu, preemption disable/enable operations. This patch reduces the overhead by don't kick vCPU which is injecting already-expired timer.
Signed-off-by: Wanpeng Li <[email protected]> --- arch/x86/kvm/lapic.c | 2 +- arch/x86/kvm/x86.c | 5 +++-- arch/x86/kvm/x86.h | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 248095a..5b5ae66 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1642,7 +1642,7 @@ static void apic_timer_expired(struct kvm_lapic *apic, bool from_timer_fn) } atomic_inc(&apic->lapic_timer.pending); - kvm_set_pending_timer(vcpu); + kvm_set_pending_timer(vcpu, from_timer_fn); } static void start_sw_tscdeadline(struct kvm_lapic *apic) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 599d732..2a45405 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1778,10 +1778,11 @@ static s64 get_kvmclock_base_ns(void) } #endif -void kvm_set_pending_timer(struct kvm_vcpu *vcpu) +void kvm_set_pending_timer(struct kvm_vcpu *vcpu, bool should_kick) { kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); - kvm_vcpu_kick(vcpu); + if (should_kick) + kvm_vcpu_kick(vcpu); } static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 995ab69..0eaae9c 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -246,7 +246,7 @@ static inline bool kvm_vcpu_latch_init(struct kvm_vcpu *vcpu) return is_smm(vcpu) || kvm_x86_ops.apic_init_signal_blocked(vcpu); } -void kvm_set_pending_timer(struct kvm_vcpu *vcpu); +void kvm_set_pending_timer(struct kvm_vcpu *vcpu, bool should_kick); void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip); void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr); -- 2.7.4
