KVM: Return to userspace on emulation failure

Instead of mindlessly retrying to execute the instruction, report the
failure to userspace.

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 5037e17..6710518 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -95,6 +95,10 @@
 #define KVM_EXIT_S390_RESET       14
 #define KVM_EXIT_DCR              15
 #define KVM_EXIT_NMI              16
+#define KVM_EXIT_INTERNAL_ERROR   17
+
+/* For KVM_EXIT_INTERNAL_ERROR */
+#define KVM_INTERNAL_ERROR_EMULATION 1
 
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
@@ -181,6 +185,9 @@
 			__u32 data;
 			__u8  is_write;
 		} dcr;
+		struct {
+			__u32 suberror;
+		} internal;
 		/* Fix the size of the union. */
 		char padding[256];
 	};