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/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 67d19e4..a1f0b5d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -363,6 +363,8 @@
 	/* used for guest single stepping over the given code position */
 	u16 singlestep_cs;
 	unsigned long singlestep_rip;
+	/* fields used by HYPER-V emulation */
+	u64 hv_vapic;
 };
 
 struct kvm_mem_alias {