KVM: Use the generic skip_emulated_instruction() in hypercall code

Instead of twiddling the rip registers directly, use the
skip_emulated_instruction() function to do that for us.

Signed-off-by: Dor Laor <dor.laor@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index fbbf9d6..a721b60 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1658,7 +1658,7 @@
 
 static int handle_vmcall(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
-	vmcs_writel(GUEST_RIP, vmcs_readl(GUEST_RIP)+3);
+	skip_emulated_instruction(vcpu);
 	return kvm_hypercall(vcpu, kvm_run);
 }