diff --git a/vtd-check-secbus-devfn.patch b/vtd-check-secbus-devfn.patch
new file mode 100644
index 0000000..7fc6d10
--- /dev/null
+++ b/vtd-check-secbus-devfn.patch
@@ -0,0 +1,43 @@
+If the device at <secbus>:00.0 is the device the mapping operation was
+initiated for, trying to map it a second time will fail, and hence
+this second mapping attempt must be prevented (as was done prior to
+said c/s).
+
+Once at it, simplify the code a little, too.
+
+Signed-off-by: Jan Beulich <jbeulich@novell.com>
+
+--- a/xen/drivers/passthrough/vtd/iommu.c
++++ b/xen/drivers/passthrough/vtd/iommu.c
+@@ -1371,23 +1371,16 @@ static int domain_context_mapping(struct
+         if ( find_upstream_bridge(&bus, &devfn, &secbus) < 1 )
+             break;
+ 
+-        /* PCIe to PCI/PCIx bridge */
+-        if ( pdev_type(bus, devfn) == DEV_TYPE_PCIe2PCI_BRIDGE )
+-        {
+-            ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
+-            if ( ret )
+-                return ret;
++        ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
+ 
+-            /*
+-             * Devices behind PCIe-to-PCI/PCIx bridge may generate
+-             * different requester-id. It may originate from devfn=0
+-             * on the secondary bus behind the bridge. Map that id
+-             * as well.
+-             */
++        /*
++         * Devices behind PCIe-to-PCI/PCIx bridge may generate different
++         * requester-id. It may originate from devfn=0 on the secondary bus
++         * behind the bridge. Map that id as well if we didn't already.
++         */
++        if ( !ret && pdev_type(bus, devfn) == DEV_TYPE_PCIe2PCI_BRIDGE &&
++             (secbus != pdev->bus || pdev->devfn != 0) )
+             ret = domain_context_mapping_one(domain, drhd->iommu, secbus, 0);
+-        }
+-        else /* Legacy PCI bridge */
+-            ret = domain_context_mapping_one(domain, drhd->iommu, bus, devfn);
+ 
+         break;
+ 
diff --git a/xen.spec b/xen.spec
index c7cabb9..8fce34d 100644
--- a/xen.spec
+++ b/xen.spec
@@ -275,6 +275,9 @@ Patch10021:     xenpaging.mem_event_check_ring-free_requests.patch
 Patch10022:     xenpaging.blacklist.patch
 Patch10023:     xenpaging.autostart_delay.patch
 Patch10040:     xenpaging.doc.patch
+
+# Other patches
+Patch11001:	vtd-check-secbus-devfn.patch
 Url:            http://www.cl.cam.ac.uk/Research/SRG/netos/xen/
 BuildRoot:      %{_tmppath}/%{name}-%{version}-build
 #%define pysite %(python -c "import distutils.sysconfig; print distutils.sysconfig.get_python_lib()")
@@ -770,6 +773,7 @@ Authors:
 %patch10022 -p1
 %patch10023 -p1
 %patch10040 -p1
+%patch11001 -p1
 
 %build
 XEN_EXTRAVERSION=%version-%release