KVM: Portability: move KVM_CHECK_EXTENSION

Make KVM_CHECK_EXTENSION code into a function, all archs can define its
capability independently.

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c
index bbfa810..6097926 100644
--- a/drivers/kvm/x86.c
+++ b/drivers/kvm/x86.c
@@ -599,6 +599,26 @@
 	spin_unlock(&kvm_lock);
 }
 
+int kvm_dev_ioctl_check_extension(long ext)
+{
+	int r;
+
+	switch (ext) {
+	case KVM_CAP_IRQCHIP:
+	case KVM_CAP_HLT:
+	case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
+	case KVM_CAP_USER_MEMORY:
+	case KVM_CAP_SET_TSS_ADDR:
+		r = 1;
+		break;
+	default:
+		r = 0;
+		break;
+	}
+	return r;
+
+}
+
 long kvm_arch_dev_ioctl(struct file *filp,
 			unsigned int ioctl, unsigned long arg)
 {