[Qemu-devel] [PATCH for-4.0 v4 2/2] virtio: Provide version-specific variants of virtio PCI devices

[Eduardo Habkost <ehabkost@redhat.com>]

Many of the current virtio-*-pci device types actually represent
3 different types of devices:
* virtio 1.0 non-transitional devices
* virtio 1.0 transitional devices
* virtio 0.9 ("legacy device" in virtio 1.0 terminology)

That would be just an annoyance if it didn't break our device/bus
compatibility QMP interfaces.  With these multi-purpose device
types, there's no way to tell management software that
transitional devices and legacy devices require a Conventional
PCI bus.

The multi-purpose device types would also prevent us from telling
management software what's the PCI vendor/device ID for them,
because their PCI IDs change at runtime depending on the bus
where they were plugged.

This patch adds separate device types for each of those virtio
device flavors:

- virtio-*-pci: the existing multi-purpose device types
  - Configurable using `disable-legacy` and `disable-modern`
    properties
  - Legacy driver support is automatically enabled/disabled
    depending on the bus where it is plugged
  - Supports Conventional PCI and PCI Express buses
    (but Conventional PCI is incompatible with
    disable-legacy=off)
  - Changes PCI vendor/device IDs at runtime
- virtio-*-pci-transitional: virtio-1.0 device supporting legacy drivers
  - Supports Conventional PCI buses only, because
    it has a PIO BAR
- virtio-*-pci-non-transitional: modern-only
  - Supports both Conventional PCI and PCI Express buses

The existing TYPE_* macros for these types will point to an
abstract base type, so existing casts in the code will keep
working for all variants.

A simple test script (tests/acceptance/virtio_version.py) is
included, to check if the new device types are equivalent to
using the `disable-legacy` and `disable-modern` options.

Acked-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v3 -> v4:
* Only test code changes (Caio Carrara)
  * Rename get_interfaces() to get_pci_interfaces()
  * Use tuple instead of list at get_pci_interfaces()
  * Spaces after commas

Changes v2 -> v3:
* Split into two separate patches (type registration helper
  and introduction of new types)
* Include full type names as literals in the code instead
  of generating type names automatically

Changes v1 -> v2:
* Removed *-0.9 devices.  Nobody will want to use them, if
  transitional devices work with legacy drivers
  (Gerd Hoffmann, Michael S. Tsirkin)
* Drop virtio version from name: rename -1.0-transitional to
  -transitional (Michael S. Tsirkin)
* Renamed -1.0 to -non-transitional
* Don't add any extra variants to modern-only device types
  (they don't need it)
* Fix typo on TYPE_VIRTIO_INPUT_HOST_PCI (crash reported by
  Cornelia Huck)
* No need to change cast macros for modern-only devices
* Rename virtio_register_types() to virtio_pci_types_register()
---
 hw/virtio/virtio-pci.h             |  24 ++--
 hw/virtio/virtio-pci.c             |  60 ++++++++--
 tests/acceptance/virtio_version.py | 176 +++++++++++++++++++++++++++++
 3 files changed, 236 insertions(+), 24 deletions(-)
 create mode 100644 tests/acceptance/virtio_version.py

diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index 8cd546608e..29b4216107 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -216,7 +216,7 @@ static inline void virtio_pci_disable_modern(VirtIOPCIProxy *proxy)
 /*
  * virtio-scsi-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_SCSI_PCI "virtio-scsi-pci"
+#define TYPE_VIRTIO_SCSI_PCI "virtio-scsi-pci-base"
 #define VIRTIO_SCSI_PCI(obj) \
         OBJECT_CHECK(VirtIOSCSIPCI, (obj), TYPE_VIRTIO_SCSI_PCI)
 
@@ -229,7 +229,7 @@ struct VirtIOSCSIPCI {
 /*
  * vhost-scsi-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VHOST_SCSI_PCI "vhost-scsi-pci"
+#define TYPE_VHOST_SCSI_PCI "vhost-scsi-pci-base"
 #define VHOST_SCSI_PCI(obj) \
         OBJECT_CHECK(VHostSCSIPCI, (obj), TYPE_VHOST_SCSI_PCI)
 
@@ -239,7 +239,7 @@ struct VHostSCSIPCI {
 };
 #endif
 
-#define TYPE_VHOST_USER_SCSI_PCI "vhost-user-scsi-pci"
+#define TYPE_VHOST_USER_SCSI_PCI "vhost-user-scsi-pci-base"
 #define VHOST_USER_SCSI_PCI(obj) \
         OBJECT_CHECK(VHostUserSCSIPCI, (obj), TYPE_VHOST_USER_SCSI_PCI)
 
@@ -252,7 +252,7 @@ struct VHostUserSCSIPCI {
 /*
  * vhost-user-blk-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VHOST_USER_BLK_PCI "vhost-user-blk-pci"
+#define TYPE_VHOST_USER_BLK_PCI "vhost-user-blk-pci-base"
 #define VHOST_USER_BLK_PCI(obj) \
         OBJECT_CHECK(VHostUserBlkPCI, (obj), TYPE_VHOST_USER_BLK_PCI)
 
@@ -265,7 +265,7 @@ struct VHostUserBlkPCI {
 /*
  * virtio-blk-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_BLK_PCI "virtio-blk-pci"
+#define TYPE_VIRTIO_BLK_PCI "virtio-blk-pci-base"
 #define VIRTIO_BLK_PCI(obj) \
         OBJECT_CHECK(VirtIOBlkPCI, (obj), TYPE_VIRTIO_BLK_PCI)
 
@@ -277,7 +277,7 @@ struct VirtIOBlkPCI {
 /*
  * virtio-balloon-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_BALLOON_PCI "virtio-balloon-pci"
+#define TYPE_VIRTIO_BALLOON_PCI "virtio-balloon-pci-base"
 #define VIRTIO_BALLOON_PCI(obj) \
         OBJECT_CHECK(VirtIOBalloonPCI, (obj), TYPE_VIRTIO_BALLOON_PCI)
 
@@ -289,7 +289,7 @@ struct VirtIOBalloonPCI {
 /*
  * virtio-serial-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_SERIAL_PCI "virtio-serial-pci"
+#define TYPE_VIRTIO_SERIAL_PCI "virtio-serial-pci-base"
 #define VIRTIO_SERIAL_PCI(obj) \
         OBJECT_CHECK(VirtIOSerialPCI, (obj), TYPE_VIRTIO_SERIAL_PCI)
 
@@ -301,7 +301,7 @@ struct VirtIOSerialPCI {
 /*
  * virtio-net-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_NET_PCI "virtio-net-pci"
+#define TYPE_VIRTIO_NET_PCI "virtio-net-pci-base"
 #define VIRTIO_NET_PCI(obj) \
         OBJECT_CHECK(VirtIONetPCI, (obj), TYPE_VIRTIO_NET_PCI)
 
@@ -316,7 +316,7 @@ struct VirtIONetPCI {
 
 #ifdef CONFIG_VIRTFS
 
-#define TYPE_VIRTIO_9P_PCI "virtio-9p-pci"
+#define TYPE_VIRTIO_9P_PCI "virtio-9p-pci-base"
 #define VIRTIO_9P_PCI(obj) \
         OBJECT_CHECK(V9fsPCIState, (obj), TYPE_VIRTIO_9P_PCI)
 
@@ -330,7 +330,7 @@ typedef struct V9fsPCIState {
 /*
  * virtio-rng-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VIRTIO_RNG_PCI "virtio-rng-pci"
+#define TYPE_VIRTIO_RNG_PCI "virtio-rng-pci-base"
 #define VIRTIO_RNG_PCI(obj) \
         OBJECT_CHECK(VirtIORngPCI, (obj), TYPE_VIRTIO_RNG_PCI)
 
@@ -365,7 +365,7 @@ struct VirtIOInputHIDPCI {
 
 #ifdef CONFIG_LINUX
 
-#define TYPE_VIRTIO_INPUT_HOST_PCI "virtio-input-host-pci"
+#define TYPE_VIRTIO_INPUT_HOST_PCI "virtio-input-host-pci-base"
 #define VIRTIO_INPUT_HOST_PCI(obj) \
         OBJECT_CHECK(VirtIOInputHostPCI, (obj), TYPE_VIRTIO_INPUT_HOST_PCI)
 
@@ -392,7 +392,7 @@ struct VirtIOGPUPCI {
 /*
  * vhost-vsock-pci: This extends VirtioPCIProxy.
  */
-#define TYPE_VHOST_VSOCK_PCI "vhost-vsock-pci"
+#define TYPE_VHOST_VSOCK_PCI "vhost-vsock-pci-base"
 #define VHOST_VSOCK_PCI(obj) \
         OBJECT_CHECK(VHostVSockPCI, (obj), TYPE_VHOST_VSOCK_PCI)
 
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index f07ec55c38..d05066deb8 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1120,7 +1120,10 @@ static void virtio_9p_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_9p_pci_info = {
-    .generic_name   = TYPE_VIRTIO_9P_PCI,
+    .base_name              = TYPE_VIRTIO_9P_PCI,
+    .generic_name           = "virtio-9p-pci",
+    .transitional_name      = "virtio-9p-pci-transitional",
+    .non_transitional_name  = "virtio-9p-pci-non-transitional",
     .instance_size = sizeof(V9fsPCIState),
     .instance_init = virtio_9p_pci_instance_init,
     .class_init    = virtio_9p_pci_class_init,
@@ -2102,7 +2105,10 @@ static void virtio_blk_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_blk_pci_info = {
-    .generic_name   = TYPE_VIRTIO_BLK_PCI,
+    .base_name              = TYPE_VIRTIO_BLK_PCI,
+    .generic_name           = "virtio-blk-pci",
+    .transitional_name      = "virtio-blk-pci-transitional",
+    .non_transitional_name  = "virtio-blk-pci-non-transitional",
     .instance_size = sizeof(VirtIOBlkPCI),
     .instance_init = virtio_blk_pci_instance_init,
     .class_init    = virtio_blk_pci_class_init,
@@ -2157,7 +2163,10 @@ static void vhost_user_blk_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_user_blk_pci_info = {
-    .generic_name    = TYPE_VHOST_USER_BLK_PCI,
+    .base_name               = TYPE_VHOST_USER_BLK_PCI,
+    .generic_name            = "vhost-user-blk-pci",
+    .transitional_name       = "vhost-user-blk-pci-transitional",
+    .non_transitional_name   = "vhost-user-blk-pci-non-transitional",
     .instance_size  = sizeof(VHostUserBlkPCI),
     .instance_init  = vhost_user_blk_pci_instance_init,
     .class_init     = vhost_user_blk_pci_class_init,
@@ -2224,7 +2233,10 @@ static void virtio_scsi_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_scsi_pci_info = {
-    .generic_name   = TYPE_VIRTIO_SCSI_PCI,
+    .base_name              = TYPE_VIRTIO_SCSI_PCI,
+    .generic_name           = "virtio-scsi-pci",
+    .transitional_name      = "virtio-scsi-pci-transitional",
+    .non_transitional_name  = "virtio-scsi-pci-non-transitional",
     .instance_size = sizeof(VirtIOSCSIPCI),
     .instance_init = virtio_scsi_pci_instance_init,
     .class_init    = virtio_scsi_pci_class_init,
@@ -2278,7 +2290,10 @@ static void vhost_scsi_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_scsi_pci_info = {
-    .generic_name  = TYPE_VHOST_SCSI_PCI,
+    .base_name             = TYPE_VHOST_SCSI_PCI,
+    .generic_name          = "vhost-scsi-pci",
+    .transitional_name     = "vhost-scsi-pci-transitional",
+    .non_transitional_name = "vhost-scsi-pci-non-transitional",
     .instance_size = sizeof(VHostSCSIPCI),
     .instance_init = vhost_scsi_pci_instance_init,
     .class_init    = vhost_scsi_pci_class_init,
@@ -2332,7 +2347,10 @@ static void vhost_user_scsi_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_user_scsi_pci_info = {
-    .generic_name  = TYPE_VHOST_USER_SCSI_PCI,
+    .base_name             = TYPE_VHOST_USER_SCSI_PCI,
+    .generic_name          = "vhost-user-scsi-pci",
+    .transitional_name     = "vhost-user-scsi-pci-transitional",
+    .non_transitional_name = "vhost-user-scsi-pci-non-transitional",
     .instance_size = sizeof(VHostUserSCSIPCI),
     .instance_init = vhost_user_scsi_pci_instance_init,
     .class_init    = vhost_user_scsi_pci_class_init,
@@ -2379,7 +2397,10 @@ static void vhost_vsock_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_vsock_pci_info = {
-    .generic_name  = TYPE_VHOST_VSOCK_PCI,
+    .base_name             = TYPE_VHOST_VSOCK_PCI,
+    .generic_name          = "vhost-vsock-pci",
+    .transitional_name     = "vhost-vsock-pci-transitional",
+    .non_transitional_name = "vhost-vsock-pci-non-transitional",
     .instance_size = sizeof(VHostVSockPCI),
     .instance_init = vhost_vsock_pci_instance_init,
     .class_init    = vhost_vsock_pci_class_init,
@@ -2435,7 +2456,10 @@ static void virtio_balloon_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_balloon_pci_info = {
-    .generic_name  = TYPE_VIRTIO_BALLOON_PCI,
+    .base_name             = TYPE_VIRTIO_BALLOON_PCI,
+    .generic_name          = "virtio-balloon-pci",
+    .transitional_name     = "virtio-balloon-pci-transitional",
+    .non_transitional_name = "virtio-balloon-pci-non-transitional",
     .instance_size = sizeof(VirtIOBalloonPCI),
     .instance_init = virtio_balloon_pci_instance_init,
     .class_init    = virtio_balloon_pci_class_init,
@@ -2507,7 +2531,10 @@ static void virtio_serial_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_serial_pci_info = {
-    .generic_name  = TYPE_VIRTIO_SERIAL_PCI,
+    .base_name             = TYPE_VIRTIO_SERIAL_PCI,
+    .generic_name          = "virtio-serial-pci",
+    .transitional_name     = "virtio-serial-pci-transitional",
+    .non_transitional_name = "virtio-serial-pci-non-transitional",
     .instance_size = sizeof(VirtIOSerialPCI),
     .instance_init = virtio_serial_pci_instance_init,
     .class_init    = virtio_serial_pci_class_init,
@@ -2561,7 +2588,10 @@ static void virtio_net_pci_instance_init(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_net_pci_info = {
-    .generic_name  = TYPE_VIRTIO_NET_PCI,
+    .base_name             = TYPE_VIRTIO_NET_PCI,
+    .generic_name          = "virtio-net-pci",
+    .transitional_name     = "virtio-net-pci-transitional",
+    .non_transitional_name = "virtio-net-pci-non-transitional",
     .instance_size = sizeof(VirtIONetPCI),
     .instance_init = virtio_net_pci_instance_init,
     .class_init    = virtio_net_pci_class_init,
@@ -2611,7 +2641,10 @@ static void virtio_rng_initfn(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_rng_pci_info = {
-    .generic_name  = TYPE_VIRTIO_RNG_PCI,
+    .base_name             = TYPE_VIRTIO_RNG_PCI,
+    .generic_name          = "virtio-rng-pci",
+    .transitional_name     = "virtio-rng-pci-transitional",
+    .non_transitional_name = "virtio-rng-pci-non-transitional",
     .instance_size = sizeof(VirtIORngPCI),
     .instance_init = virtio_rng_initfn,
     .class_init    = virtio_rng_pci_class_init,
@@ -2734,7 +2767,10 @@ static void virtio_host_initfn(Object *obj)
 }
 
 static const VirtioPCIDeviceTypeInfo virtio_host_pci_info = {
-    .generic_name  = TYPE_VIRTIO_INPUT_HOST_PCI,
+    .base_name             = TYPE_VIRTIO_INPUT_HOST_PCI,
+    .generic_name          = "virtio-input-host-pci",
+    .transitional_name     = "virtio-input-host-pci-transitional",
+    .non_transitional_name = "virtio-input-host-pci-non-transitional",
     .parent        = TYPE_VIRTIO_INPUT_PCI,
     .instance_size = sizeof(VirtIOInputHostPCI),
     .instance_init = virtio_host_initfn,
diff --git a/tests/acceptance/virtio_version.py b/tests/acceptance/virtio_version.py
new file mode 100644
index 0000000000..ce990250d8
--- /dev/null
+++ b/tests/acceptance/virtio_version.py
@@ -0,0 +1,176 @@
+"""
+Check compatibility of virtio device types
+"""
+# Copyright (c) 2018 Red Hat, Inc.
+#
+# Author:
+#  Eduardo Habkost <ehabkost@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.
+import sys
+import os
+
+sys.path.append(os.path.join(os.path.dirname(__file__), "..", "..", "scripts"))
+from qemu import QEMUMachine
+from avocado_qemu import Test
+
+# Virtio Device IDs:
+VIRTIO_NET = 1
+VIRTIO_BLOCK = 2
+VIRTIO_CONSOLE = 3
+VIRTIO_RNG = 4
+VIRTIO_BALLOON = 5
+VIRTIO_RPMSG = 7
+VIRTIO_SCSI = 8
+VIRTIO_9P = 9
+VIRTIO_RPROC_SERIAL = 11
+VIRTIO_CAIF = 12
+VIRTIO_GPU = 16
+VIRTIO_INPUT = 18
+VIRTIO_VSOCK = 19
+VIRTIO_CRYPTO = 20
+
+PCI_VENDOR_ID_REDHAT_QUMRANET = 0x1af4
+
+# Device IDs for legacy/transitional devices:
+PCI_LEGACY_DEVICE_IDS = {
+    VIRTIO_NET:     0x1000,
+    VIRTIO_BLOCK:   0x1001,
+    VIRTIO_BALLOON: 0x1002,
+    VIRTIO_CONSOLE: 0x1003,
+    VIRTIO_SCSI:    0x1004,
+    VIRTIO_RNG:     0x1005,
+    VIRTIO_9P:      0x1009,
+    VIRTIO_VSOCK:   0x1012,
+}
+
+def pci_modern_device_id(virtio_devid):
+    return virtio_devid + 0x1040
+
+def devtype_implements(vm, devtype, implements):
+    return devtype in [d['name'] for d in vm.command('qom-list-types', implements=implements)]
+
+def get_pci_interfaces(vm, devtype):
+    interfaces = ('pci-express-device', 'conventional-pci-device')
+    return [i for i in interfaces if devtype_implements(vm, devtype, i)]
+
+class VirtioVersionCheck(Test):
+    """
+    Check if virtio-version-specific device types result in the
+    same device tree created by `disable-modern` and
+    `disable-legacy`.
+
+    :avocado: enable
+    :avocado: tags=x86_64
+    """
+
+    # just in case there are failures, show larger diff:
+    maxDiff = 4096
+
+    def run_device(self, devtype, opts=None, machine='pc'):
+        """
+        Run QEMU with `-device DEVTYPE`, return device info from `query-pci`
+        """
+        with QEMUMachine(self.qemu_bin) as vm:
+            vm.set_machine(machine)
+            if opts:
+                devtype += ',' + opts
+            vm.add_args('-device', '%s,id=devfortest' % (devtype))
+            vm.add_args('-S')
+            vm.launch()
+
+            pcibuses = vm.command('query-pci')
+            alldevs = [dev for bus in pcibuses for dev in bus['devices']]
+            devfortest = [dev for dev in alldevs
+                          if dev['qdev_id'] == 'devfortest']
+            return devfortest[0], get_pci_interfaces(vm, devtype)
+
+
+    def assert_devids(self, dev, devid, non_transitional=False):
+        self.assertEqual(dev['id']['vendor'], PCI_VENDOR_ID_REDHAT_QUMRANET)
+        self.assertEqual(dev['id']['device'], devid)
+        if non_transitional:
+            self.assertTrue(0x1040 <= dev['id']['device'] <= 0x107f)
+            self.assertGreaterEqual(dev['id']['subsystem'], 0x40)
+
+    def check_all_variants(self, qemu_devtype, virtio_devid):
+        """Check if a virtio device type and its variants behave as expected"""
+        # Force modern mode:
+        dev_modern, _ = self.run_device(qemu_devtype,
+                                       'disable-modern=off,disable-legacy=on')
+        self.assert_devids(dev_modern, pci_modern_device_id(virtio_devid),
+                           non_transitional=True)
+
+        # <prefix>-non-transitional device types should be 100% equivalent to
+        # <prefix>,disable-modern=off,disable-legacy=on
+        dev_1_0, nt_ifaces = self.run_device('%s-non-transitional' % (qemu_devtype))
+        self.assertEqual(dev_modern, dev_1_0)
+
+        # Force transitional mode:
+        dev_trans, _ = self.run_device(qemu_devtype,
+                                      'disable-modern=off,disable-legacy=off')
+        self.assert_devids(dev_trans, PCI_LEGACY_DEVICE_IDS[virtio_devid])
+
+        # Force legacy mode:
+        dev_legacy, _ = self.run_device(qemu_devtype,
+                                       'disable-modern=on,disable-legacy=off')
+        self.assert_devids(dev_legacy, PCI_LEGACY_DEVICE_IDS[virtio_devid])
+
+        # No options: default to transitional on PC machine-type:
+        no_opts_pc, generic_ifaces = self.run_device(qemu_devtype)
+        self.assertEqual(dev_trans, no_opts_pc)
+
+        #TODO: check if plugging on a PCI Express bus will make the
+        #      device non-transitional
+        #no_opts_q35 = self.run_device(qemu_devtype, machine='q35')
+        #self.assertEqual(dev_modern, no_opts_q35)
+
+        # <prefix>-transitional device types should be 100% equivalent to
+        # <prefix>,disable-modern=off,disable-legacy=off
+        dev_trans, trans_ifaces = self.run_device('%s-transitional' % (qemu_devtype))
+        self.assertEqual(dev_trans, dev_trans)
+
+        # ensure the interface information is correct:
+        self.assertIn('conventional-pci-device', generic_ifaces)
+        self.assertIn('pci-express-device', generic_ifaces)
+
+        self.assertIn('conventional-pci-device', nt_ifaces)
+        self.assertIn('pci-express-device', nt_ifaces)
+
+        self.assertIn('conventional-pci-device', trans_ifaces)
+        self.assertNotIn('pci-express-device', trans_ifaces)
+
+
+    def test_conventional_devs(self):
+        self.check_all_variants('virtio-net-pci', VIRTIO_NET)
+        # virtio-blk requires 'driver' parameter
+        #self.check_all_variants('virtio-blk-pci', VIRTIO_BLOCK)
+        self.check_all_variants('virtio-serial-pci', VIRTIO_CONSOLE)
+        self.check_all_variants('virtio-rng-pci', VIRTIO_RNG)
+        self.check_all_variants('virtio-balloon-pci', VIRTIO_BALLOON)
+        self.check_all_variants('virtio-scsi-pci', VIRTIO_SCSI)
+        # virtio-9p requires 'fsdev' parameter
+        #self.check_all_variants('virtio-9p-pci', VIRTIO_9P)
+
+    def check_modern_only(self, qemu_devtype, virtio_devid):
+        """Check if a modern-only virtio device type behaves as expected"""
+        # Force modern mode:
+        dev_modern, _ = self.run_device(qemu_devtype,
+                                       'disable-modern=off,disable-legacy=on')
+        self.assert_devids(dev_modern, pci_modern_device_id(virtio_devid),
+                           non_transitional=True)
+
+        # No options: should be modern anyway
+        dev_no_opts, ifaces = self.run_device(qemu_devtype)
+        self.assertEqual(dev_modern, dev_no_opts)
+
+        self.assertIn('conventional-pci-device', ifaces)
+        self.assertIn('pci-express-device', ifaces)
+
+    def test_modern_only_devs(self):
+        self.check_modern_only('virtio-vga', VIRTIO_GPU)
+        self.check_modern_only('virtio-gpu-pci', VIRTIO_GPU)
+        self.check_modern_only('virtio-mouse-pci', VIRTIO_INPUT)
+        self.check_modern_only('virtio-tablet-pci', VIRTIO_INPUT)
+        self.check_modern_only('virtio-keyboard-pci', VIRTIO_INPUT)
-- 
2.18.0.rc1.1.g3f1ff2140