From: Wanpeng Li <wanpengli@xxxxxxxxxxx> This patch optimizes the virtual IPI fastpath emulation sequence: write ICR2 send virtual IPI read ICR2 write ICR2 send virtual IPI ==> write ICR write ICR We can observe ~0.67% performance improvement for IPI microbenchmark (https://lore.kernel.org/kvm/20171219085010.4081-1-ynorov@xxxxxxxxxxxxxxxxxx/) on Skylake server. Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> --- arch/x86/kvm/lapic.c | 4 ++-- arch/x86/kvm/lapic.h | 1 + arch/x86/kvm/x86.c | 6 +++++- 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e3099c6..338de38 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1226,7 +1226,7 @@ void kvm_apic_set_eoi_accelerated(struct kvm_vcpu *vcpu, int vector) } EXPORT_SYMBOL_GPL(kvm_apic_set_eoi_accelerated); -static void apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high) +void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high) { struct kvm_lapic_irq irq; @@ -1940,7 +1940,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) case APIC_ICR: /* No delay here, so we always clear the pending bit */ val &= ~(1 << 12); - apic_send_ipi(apic, val, kvm_lapic_get_reg(apic, APIC_ICR2)); + kvm_apic_send_ipi(apic, val, kvm_lapic_get_reg(apic, APIC_ICR2)); kvm_lapic_set_reg(apic, APIC_ICR, val); break; diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index ec6fbfe..bc76860 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -95,6 +95,7 @@ void kvm_apic_update_apicv(struct kvm_vcpu *vcpu); bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, struct kvm_lapic_irq *irq, int *r, struct dest_map *dest_map); +void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high); u64 kvm_get_apic_base(struct kvm_vcpu *vcpu); int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 50ef1c5..c4bb7d8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1561,8 +1561,12 @@ static int handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data ((data & APIC_DEST_MASK) == APIC_DEST_PHYSICAL) && ((data & APIC_MODE_MASK) == APIC_DM_FIXED)) { + data &= ~(1 << 12); + kvm_apic_send_ipi(vcpu->arch.apic, (u32)data, (u32)(data >> 32)); kvm_lapic_set_reg(vcpu->arch.apic, APIC_ICR2, (u32)(data >> 32)); - return kvm_lapic_reg_write(vcpu->arch.apic, APIC_ICR, (u32)data); + kvm_lapic_set_reg(vcpu->arch.apic, APIC_ICR, (u32)data); + trace_kvm_apic_write(APIC_ICR, (u32)data); + return 0; } return 1; -- 2.7.4
