diff --git a/hw/arm/xen-pvh.c b/hw/arm/xen-pvh.c
index 04cb985..28af391 100644
--- a/hw/arm/xen-pvh.c
+++ b/hw/arm/xen-pvh.c
@@ -66,6 +66,9 @@
      */
     mc->max_cpus = GUEST_MAX_VCPUS;
 
+    /* Xen/ARM does not use buffered IOREQs.  */
+    xpc->handle_bufioreq = HVM_IOREQSRV_BUFIOREQ_OFF;
+
     /* List of supported features known to work on PVH ARM.  */
     xpc->has_tpm = true;
     xpc->has_virtio_mmio = true;
diff --git a/hw/i386/xen/xen-pvh.c b/hw/i386/xen/xen-pvh.c
index 4564566..f1f02d3 100644
--- a/hw/i386/xen/xen-pvh.c
+++ b/hw/i386/xen/xen-pvh.c
@@ -89,6 +89,9 @@
     /* We have an implementation specific init to create CPU objects.  */
     xpc->init = xen_pvh_init;
 
+    /* Enable buffered IOREQs.  */
+    xpc->handle_bufioreq = HVM_IOREQSRV_BUFIOREQ_ATOMIC;
+
     /*
      * PCI INTX routing.
      *
diff --git a/hw/xen/xen-pvh-common.c b/hw/xen/xen-pvh-common.c
index 08641fd..76a9b2b 100644
--- a/hw/xen/xen-pvh-common.c
+++ b/hw/xen/xen-pvh-common.c
@@ -195,7 +195,7 @@
 
     xen_pvh_init_ram(s, sysmem);
     xen_register_ioreq(&s->ioreq, ms->smp.max_cpus,
-                       HVM_IOREQSRV_BUFIOREQ_ATOMIC,
+                       xpc->handle_bufioreq,
                        &xen_memory_listener);
 
     if (s->cfg.virtio_mmio_num) {
diff --git a/include/hw/xen/xen-pvh-common.h b/include/hw/xen/xen-pvh-common.h
index bc09eea..5cdd23c 100644
--- a/include/hw/xen/xen-pvh-common.h
+++ b/include/hw/xen/xen-pvh-common.h
@@ -43,6 +43,9 @@
      */
     int (*set_pci_link_route)(uint8_t line, uint8_t irq);
 
+    /* Allow implementations to optionally enable buffered ioreqs.  */
+    uint8_t handle_bufioreq;
+
     /*
      * Each implementation can optionally enable features that it
      * supports and are known to work.