KVM: x86 emulator: add new ->halt() callback

Instead of reaching into vcpu internals.

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8af49b3..2246cf1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4351,6 +4351,11 @@
 	return kvm_set_msr(emul_to_vcpu(ctxt), msr_index, data);
 }
 
+static void emulator_halt(struct x86_emulate_ctxt *ctxt)
+{
+	emul_to_vcpu(ctxt)->arch.halt_request = 1;
+}
+
 static void emulator_get_fpu(struct x86_emulate_ctxt *ctxt)
 {
 	preempt_disable();
@@ -4400,6 +4405,7 @@
 	.set_dr              = emulator_set_dr,
 	.set_msr             = emulator_set_msr,
 	.get_msr             = emulator_get_msr,
+	.halt                = emulator_halt,
 	.get_fpu             = emulator_get_fpu,
 	.put_fpu             = emulator_put_fpu,
 	.intercept           = emulator_intercept,