diff --git a/MAINTAINERS b/MAINTAINERS
index 2b46f3c6a8..b5c86ec494 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -101,7 +101,8 @@ F: include/hw/watchdog/wdt_diag288.h
 F: pc-bios/s390-ccw/
 F: pc-bios/s390-ccw.img
 F: target/s390x/
-F: docs/vfio-ap.txt
+F: docs/system/target-s390x.rst
+F: docs/system/s390x/
 F: tests/migration/s390x/
 K: ^Subject:.*(?i)s390x?
 T: git https://github.com/cohuck/qemu.git s390-next
@@ -1611,7 +1612,7 @@ F: hw/s390x/ap-bridge.c
 F: include/hw/s390x/ap-device.h
 F: include/hw/s390x/ap-bridge.h
 F: hw/vfio/ap.c
-F: docs/system/vfio-ap.rst
+F: docs/system/s390x/vfio-ap.rst
 L: qemu-s390x@nongnu.org
 
 vhost
diff --git a/docs/system/index.rst b/docs/system/index.rst
index 6e5f20fa13..c0f685b818 100644
--- a/docs/system/index.rst
+++ b/docs/system/index.rst
@@ -30,7 +30,6 @@ Contents:
    managed-startup
    targets
    security
-   vfio-ap
    deprecated
    build-platforms
    license
diff --git a/docs/system/vfio-ap.rst b/docs/system/s390x/vfio-ap.rst
similarity index 100%
rename from docs/system/vfio-ap.rst
rename to docs/system/s390x/vfio-ap.rst
diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst
new file mode 100644
index 0000000000..4c8b7cdd66
--- /dev/null
+++ b/docs/system/target-s390x.rst
@@ -0,0 +1,26 @@
+.. _s390x-System-emulator:
+
+s390x System emulator
+---------------------
+
+QEMU can emulate z/Architecture (in particular, 64 bit) s390x systems
+via the ``qemu-system-s390x`` binary. Only one machine type,
+``s390-ccw-virtio``, is supported (with versioning for compatibility
+handling).
+
+When using KVM as accelerator, QEMU can emulate CPUs up to the generation
+of the host. When using the default cpu model with TCG as accelerator,
+QEMU will emulate a subset of z13 cpu features that should be enough to run
+distributions built for the z13.
+
+Device support
+==============
+
+QEMU will not emulate most of the traditional devices found under LPAR or
+z/VM; virtio devices (especially using virtio-ccw) make up the bulk of
+the available devices. Passthrough of host devices via vfio-pci, vfio-ccw,
+or vfio-ap is also available.
+
+.. toctree::
+   s390x/vfio-ap
+
diff --git a/docs/system/targets.rst b/docs/system/targets.rst
index eba3111247..0d8f91580a 100644
--- a/docs/system/targets.rst
+++ b/docs/system/targets.rst
@@ -17,3 +17,4 @@ Contents:
    target-arm
    target-m68k
    target-xtensa
+   target-s390x
diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index b81942e1e6..8c3e019571 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -546,7 +546,7 @@ static void update_machine_ipl_properties(IplParameterBlock *iplb)
     /* Sync loadparm */
     if (iplb->flags & DIAG308_FLAGS_LP_VALID) {
         uint8_t *ebcdic_loadparm = iplb->loadparm;
-        char ascii_loadparm[8];
+        char ascii_loadparm[9];
         int i;
 
         for (i = 0; i < 8 && ebcdic_loadparm[i]; i++) {