KVM: Add HYPER-V apic access MSRs

Implement HYPER-V apic MSRs. Spec defines three MSRs that speed-up
access to EOI/TPR/ICR apic registers for PV guests.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ba8c045..4b224f9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1246,3 +1246,34 @@
 
 	return 0;
 }
+
+int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 reg, u64 data)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+
+	if (!irqchip_in_kernel(vcpu->kvm))
+		return 1;
+
+	/* if this is ICR write vector before command */
+	if (reg == APIC_ICR)
+		apic_reg_write(apic, APIC_ICR2, (u32)(data >> 32));
+	return apic_reg_write(apic, reg, (u32)data);
+}
+
+int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 reg, u64 *data)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+	u32 low, high = 0;
+
+	if (!irqchip_in_kernel(vcpu->kvm))
+		return 1;
+
+	if (apic_reg_read(apic, reg, 4, &low))
+		return 1;
+	if (reg == APIC_ICR)
+		apic_reg_read(apic, APIC_ICR2, 4, &high);
+
+	*data = (((u64)high) << 32) | low;
+
+	return 0;
+}