From 58fbbf26eb01cf6d92cf18da8d14b3a4af9c4b47 Mon Sep 17 00:00:00 2001 From: Kevin Tian Date: Tue, 30 Aug 2011 13:56:17 +0300 Subject: KVM: APIC: avoid instruction emulation for EOI writes Instruction emulation for EOI writes can be skipped, since sane guest simply uses MOV instead of string operations. This is a nice improvement when guest doesn't support x2apic or hyper-V EOI support. a single VM bandwidth is observed with ~8% bandwidth improvement (7.4Gbps->8Gbps), by saving ~5% cycles from EOI emulation. Signed-off-by: Kevin Tian : Signed-off-by: Eddie Dong Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/lapic.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/x86/kvm/lapic.c') diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 57dcbd4308fa..52645f283870 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -864,6 +864,15 @@ static int apic_mmio_write(struct kvm_io_device *this, return 0; } +void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + + if (apic) + apic_reg_write(vcpu->arch.apic, APIC_EOI, 0); +} +EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi); + void kvm_free_lapic(struct kvm_vcpu *vcpu) { if (!vcpu->arch.apic) -- cgit v1.2.3