EOI acceleration for high bandwidth IO

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

    EOI is one of key VM Exit at high bandwidth IO such as VT-d with 10Gb/s NIC.
    This patch accelerate guest EOI emulation utilizing HW VM Exit
    information.
    
    Signed-off-by: Eddie Dong <eddie.dong@xxxxxxxxx>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ccafe0d..b63138f 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -875,6 +875,15 @@ void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8)
 		     | (apic_get_reg(apic, APIC_TASKPRI) & 4));
 }
 
+void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+
+	if (apic)
+		apic_set_eoi(apic);
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_set_eoi);
+
 u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 40010b0..3a7a29a 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -27,6 +27,7 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu);
 void kvm_lapic_reset(struct kvm_vcpu *vcpu);
 u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu);
 void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8);
+void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu);
 void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value);
 u64 kvm_lapic_get_base(struct kvm_vcpu *vcpu);
 void kvm_apic_set_version(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3a75db3..6eea29d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3125,6 +3125,12 @@ static int handle_apic_access(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
 	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
 	offset = exit_qualification & 0xffful;
+	if ((exit_qualification >> 12) & 0xf == 1 &&
+		offset == APIC_EOI) {	/* EOI write */
+		kvm_lapic_set_eoi(vcpu);
+		skip_emulated_instruction(vcpu);
+		return 1;
+	}
 
 	er = emulate_instruction(vcpu, kvm_run, 0, 0, 0);

Attachment: eoi2.patch
Description: eoi2.patch