diff -Nru libvirt-4.6.0/debian/changelog libvirt-4.6.0/debian/changelog
--- libvirt-4.6.0/debian/changelog	2018-08-27 02:57:57.000000000 -0600
+++ libvirt-4.6.0/debian/changelog	2018-09-26 16:53:09.000000000 -0600
@@ -1,3 +1,11 @@
+libvirt (4.6.0-2ubuntu3+lp1771662.1) cosmic; urgency=medium
+
+  * d/p/ubuntu/cavium-thunderx-no-switchdev.patch: avoid trying
+    to form a VF-to-PF mapping on Cavium ThunderX NICs based on
+    assumptions from other devices.
+
+ -- dann frazier <dann.frazier@canonical.com>  Wed, 26 Sep 2018 16:53:09 -0600
+
 libvirt (4.6.0-2ubuntu3) cosmic; urgency=medium
 
   * d/p/ubuntu-aa/lp-1788603-fix-ptrace-rules-with-kernel-4.18.patch:
diff -Nru libvirt-4.6.0/debian/patches/series libvirt-4.6.0/debian/patches/series
--- libvirt-4.6.0/debian/patches/series	2018-08-27 02:56:53.000000000 -0600
+++ libvirt-4.6.0/debian/patches/series	2018-09-26 15:28:51.000000000 -0600
@@ -42,6 +42,7 @@
 ubuntu/dnsmasq-as-priv-user
 ubuntu/avoid-restarting-virtlog-socket.patch
 ubuntu/ovmf_paths.patch
+ubuntu/cavium-thunderx-no-switchdev.patch
 
 # Ubuntu Apparmor Changes
 ubuntu-aa/0001-apparmor-Allow-pygrub-to-run-on-Debian-Ubuntu.patch
diff -Nru libvirt-4.6.0/debian/patches/ubuntu/cavium-thunderx-no-switchdev.patch libvirt-4.6.0/debian/patches/ubuntu/cavium-thunderx-no-switchdev.patch
--- libvirt-4.6.0/debian/patches/ubuntu/cavium-thunderx-no-switchdev.patch	1969-12-31 17:00:00.000000000 -0700
+++ libvirt-4.6.0/debian/patches/ubuntu/cavium-thunderx-no-switchdev.patch	2018-09-26 16:53:09.000000000 -0600
@@ -0,0 +1,63 @@
+Description: Ignore on-chip Cavium ThunderX in switchdev check
+ libvirt assumes that the kernel will expose a VF->PF mapping
+ that is not exposed for this driver/device due to its unique 
+ architecture. Just bypass these devices until there's a proper
+ fix upstream.
+Forwarded: no
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/1771662
+Bug-Linaro: https://bugs.linaro.org/show_bug.cgi?id=3778
+Author: dann frazier <dann.frazier@canonical.com>
+Last-Updated: 2018-09-26
+
+Index: libvirt-4.6.0/src/util/virnetdev.c
+===================================================================
+--- libvirt-4.6.0.orig/src/util/virnetdev.c
++++ libvirt-4.6.0/src/util/virnetdev.c
+@@ -3242,6 +3242,37 @@ virNetDevGetFamilyId(const char *family_
+     return family_id;
+ }
+ 
++static bool
++virNetDevSwitchdevFeatureUnsupported(const char *ifname)
++{
++  int ret = false;
++  int len;
++  char *path = NULL;
++  char *id = NULL;
++  const char cavium_vendor[] = "0x177d\n";
++  const char cavium_device[] = "0xa034\n";
++
++  if (virNetDevSysfsFile(&path, ifname, "device/vendor") < 0)
++    goto cleanup;
++  if ((len = virFileReadAllQuiet(path, 1024, &id)) <= 0)
++    goto cleanup;
++  if (strcmp(cavium_vendor, id) != 0)
++    goto cleanup;
++  VIR_FREE(path);
++  if (virNetDevSysfsFile(&path, ifname, "device/device") < 0)
++    goto cleanup;
++  VIR_FREE(id);
++  if ((len = virFileReadAllQuiet(path, 1024, &id)) <= 0)
++    goto cleanup;
++  if (strcmp(cavium_device, id) != 0)
++    goto cleanup;
++  ret = true;
++
++ cleanup:
++  VIR_FREE(path);
++  VIR_FREE(id);
++  return ret;
++}
+ 
+ /**
+  * virNetDevSwitchdevFeature
+@@ -3269,6 +3300,9 @@ virNetDevSwitchdevFeature(const char *if
+     int ret = -1;
+     uint32_t family_id;
+ 
++    if (virNetDevSwitchdevFeatureUnsupported(ifname))
++        return 0;
++
+     if ((family_id = virNetDevGetFamilyId(DEVLINK_GENL_NAME)) <= 0)
+         return ret;
+