diff --git a/tests/Makefile b/tests/Makefile
index 729b9694cf..c5e474455c 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -174,6 +174,8 @@ gcov-files-i386-y += hw/usb/dev-storage.c
 check-qtest-i386-y += tests/usb-hcd-xhci-test$(EXESUF)
 gcov-files-i386-y += hw/usb/hcd-xhci.c
 check-qtest-i386-y += tests/pc-cpu-test$(EXESUF)
+check-qtest-i386-y += tests/q35-test$(EXESUF)
+gcov-files-i386-y += hw/pci-host/q35.c
 check-qtest-i386-$(CONFIG_LINUX) += tests/vhost-user-test$(EXESUF)
 check-qtest-x86_64-y = $(check-qtest-i386-y)
 gcov-files-i386-y += i386-softmmu/hw/timer/mc146818rtc.c
@@ -355,6 +357,7 @@ tests/boot-order-test$(EXESUF): tests/boot-order-test.o $(libqos-obj-y)
 tests/bios-tables-test$(EXESUF): tests/bios-tables-test.o $(libqos-obj-y)
 tests/tmp105-test$(EXESUF): tests/tmp105-test.o $(libqos-omap-obj-y)
 tests/i440fx-test$(EXESUF): tests/i440fx-test.o $(libqos-pc-obj-y)
+tests/q35-test$(EXESUF): tests/q35-test.o $(libqos-pc-obj-y)
 tests/fw_cfg-test$(EXESUF): tests/fw_cfg-test.o $(libqos-pc-obj-y)
 tests/e1000-test$(EXESUF): tests/e1000-test.o
 tests/rtl8139-test$(EXESUF): tests/rtl8139-test.o $(libqos-pc-obj-y)
diff --git a/tests/q35-test.c b/tests/q35-test.c
new file mode 100644
index 0000000000..812abe5480
--- /dev/null
+++ b/tests/q35-test.c
@@ -0,0 +1,91 @@
+/*
+ * QTest testcase for Q35 northbridge
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * Author: Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <glib.h>
+#include <string.h>
+#include "libqtest.h"
+#include "libqos/pci.h"
+#include "libqos/pci-pc.h"
+#include "qemu/osdep.h"
+#include "hw/pci-host/q35.h"
+
+static void smram_set_bit(QPCIDevice *pcidev, uint8_t mask, bool enabled)
+{
+    uint8_t smram;
+
+    smram = qpci_config_readb(pcidev, MCH_HOST_BRIDGE_SMRAM);
+    if (enabled) {
+        smram |= mask;
+    } else {
+        smram &= ~mask;
+    }
+    qpci_config_writeb(pcidev, MCH_HOST_BRIDGE_SMRAM, smram);
+}
+
+static bool smram_test_bit(QPCIDevice *pcidev, uint8_t mask)
+{
+    uint8_t smram;
+
+    smram = qpci_config_readb(pcidev, MCH_HOST_BRIDGE_SMRAM);
+    return smram & mask;
+}
+
+static void test_smram_lock(void)
+{
+    QPCIBus *pcibus;
+    QPCIDevice *pcidev;
+    QDict *response;
+
+    pcibus = qpci_init_pc();
+    g_assert(pcibus != NULL);
+
+    pcidev = qpci_device_find(pcibus, 0);
+    g_assert(pcidev != NULL);
+
+    /* check open is settable */
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN, false);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == false);
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN, true);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == true);
+
+    /* lock, check open is cleared & not settable */
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_LCK, true);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == false);
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN, true);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == false);
+
+    /* reset */
+    response = qmp("{'execute': 'system_reset', 'arguments': {} }");
+    g_assert(response);
+    g_assert(!qdict_haskey(response, "error"));
+    QDECREF(response);
+
+    /* check open is settable again */
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN, false);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == false);
+    smram_set_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN, true);
+    g_assert(smram_test_bit(pcidev, MCH_HOST_BRIDGE_SMRAM_D_OPEN) == true);
+}
+
+int main(int argc, char **argv)
+{
+    int ret;
+
+    g_test_init(&argc, &argv, NULL);
+
+    qtest_add_func("/q35/smram/lock", test_smram_lock);
+
+    qtest_start("-M q35");
+    ret = g_test_run();
+    qtest_end();
+
+    return ret;
+}