diff --git a/vfio-Introduce-hostwin_from_range-helper.patch b/vfio-Introduce-hostwin_from_range-helper.patch
new file mode 100644
index 0000000..b9a7099
--- /dev/null
+++ b/vfio-Introduce-hostwin_from_range-helper.patch
@@ -0,0 +1,89 @@
+From 25336cd596ff551293f1be6e108ad9277d80be0f Mon Sep 17 00:00:00 2001
+From: Eric Auger <eric.auger@redhat.com>
+Date: Fri, 22 Mar 2019 18:05:23 +0100
+Subject: [PATCH] vfio: Introduce hostwin_from_range helper
+
+Let's introduce a hostwin_from_range() helper that returns the
+hostwin encapsulating an IOVA range or NULL if none is found.
+
+This improves the readibility of callers and removes the usage
+of hostwin_found.
+
+Signed-off-by: Eric Auger <eric.auger@redhat.com>
+Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
+---
+ hw/vfio/common.c | 36 +++++++++++++++++-------------------
+ 1 file changed, 17 insertions(+), 19 deletions(-)
+
+diff --git a/hw/vfio/common.c b/hw/vfio/common.c
+index c78b58d365..a8db784ac5 100644
+--- a/hw/vfio/common.c
++++ b/hw/vfio/common.c
+@@ -696,6 +696,19 @@ out:
+     rcu_read_unlock();
+ }
+ 
++static VFIOHostDMAWindow *
++hostwin_from_range(VFIOContainer *container, hwaddr iova, hwaddr end)
++{
++    VFIOHostDMAWindow *hostwin;
++
++    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
++        if (hostwin->min_iova <= iova && end <= hostwin->max_iova) {
++            return hostwin;
++        }
++    }
++    return NULL;
++}
++
+ static void vfio_listener_region_add(MemoryListener *listener,
+                                      MemoryRegionSection *section)
+ {
+@@ -705,7 +718,6 @@ static void vfio_listener_region_add(MemoryListener *listener,
+     void *vaddr;
+     int ret;
+     VFIOHostDMAWindow *hostwin;
+-    bool hostwin_found;
+ 
+     if (vfio_listener_skipped_section(section)) {
+         trace_vfio_listener_region_add_skip(
+@@ -783,15 +795,8 @@ static void vfio_listener_region_add(MemoryListener *listener,
+ #endif
+     }
+ 
+-    hostwin_found = false;
+-    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
+-        if (hostwin->min_iova <= iova && end <= hostwin->max_iova) {
+-            hostwin_found = true;
+-            break;
+-        }
+-    }
+-
+-    if (!hostwin_found) {
++    hostwin = hostwin_from_range(container, iova, end);
++    if (!hostwin) {
+         error_report("vfio: IOMMU container %p can't map guest IOVA region"
+                      " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx,
+                      container, iova, end);
+@@ -956,16 +961,9 @@ static void vfio_listener_region_del(MemoryListener *listener,
+ 
+     if (memory_region_is_ram_device(section->mr)) {
+         hwaddr pgmask;
+-        VFIOHostDMAWindow *hostwin;
+-        bool hostwin_found = false;
++        VFIOHostDMAWindow *hostwin = hostwin_from_range(container, iova, end);
+ 
+-        QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
+-            if (hostwin->min_iova <= iova && end <= hostwin->max_iova) {
+-                hostwin_found = true;
+-                break;
+-            }
+-        }
+-        assert(hostwin_found); /* or region_add() would have failed */
++        assert(hostwin); /* or region_add() would have failed */
+ 
+         pgmask = (1ULL << ctz64(hostwin->iova_pgsizes)) - 1;
+         try_unmap = !((iova & pgmask) || (int128_get64(llsize) & pgmask));
+-- 
+2.27.0
+