Index: sys/x86/x86/msi.c
===================================================================
--- sys/x86/x86/msi.c
+++ sys/x86/x86/msi.c
@@ -630,6 +630,10 @@
 	mtx_unlock(&msi_lock);
 	error = EOPNOTSUPP;
 #endif
+	if (error == EOPNOTSUPP && msi->msi_cpu > 0xff) {
+		printf("%s: invalid msi_cpu %u\n", __func__, msi->msi_cpu);
+		error = EINVAL;
+	}
 	if (error == EOPNOTSUPP) {
 		*addr = INTEL_ADDR(msi);
 		*data = INTEL_DATA(msi);