[PATCH v5 2/4] vhost-vsock-pci: force virtio version 1

[Stefano Garzarella]

Commit 9b3a35ec82 ("virtio: verify that legacy support is not
accidentally on") added a safety check that requires to set
'disable-legacy=on' on vhost-vsock-pci device:

    $ ./qemu-system-x86_64 ... -device vhost-vsock-pci,guest-cid=5
        qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=5:
        device is modern-only, use disable-legacy=on

virtio-vsock was introduced after the release of VIRTIO 1.0
specifications, so it should be 'modern-only'.
In addition Cornelia verified that forcing a legacy mode on
vhost-vsock-pci device using x86-64 host and s390x guest, so with
different endianness, produces strange behaviours.

This patch forces virtio version 1 and removes the 'transitional_name'
property removing the need to specify 'disable-legacy=on' on
vhost-vsock-pci device.

To avoid migration issues, we force virtio version 1 only when
legacy check is enabled in the new machine types (>= 5.1).

As the transitional device name is not commonly used, we do not
provide compatibility handling for it.

Cc: qemu-stable@nongnu.org
Reported-by: Qian Cai <caiqian@redhat.com>
Reported-by: Qinghua Cheng <qcheng@redhat.com>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1868449
Suggested-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
v5:
 - added a phrase about transitional device in the commit message [Cornelia]
v3:
 - forced virtio version 1 only with new machine types
v2:
 - fixed commit message [Cornelia]
---
 hw/virtio/vhost-vsock-pci.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-vsock-pci.c b/hw/virtio/vhost-vsock-pci.c
index e56067b427..205da8d1f5 100644
--- a/hw/virtio/vhost-vsock-pci.c
+++ b/hw/virtio/vhost-vsock-pci.c
@@ -44,6 +44,15 @@ static void vhost_vsock_pci_realize(VirtIOPCIProxy 
*vpci_dev, Error **errp)
 {
     VHostVSockPCI *dev = VHOST_VSOCK_PCI(vpci_dev);
     DeviceState *vdev = DEVICE(&dev->vdev);
+    VirtIODevice *virtio_dev = VIRTIO_DEVICE(vdev);
+
+    /*
+     * To avoid migration issues, we force virtio version 1 only when
+     * legacy check is enabled in the new machine types (>= 5.1).
+     */
+    if (!virtio_legacy_check_disabled(virtio_dev)) {
+        virtio_pci_force_virtio_1(vpci_dev);
+    }
 
     qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
 }
@@ -73,7 +82,6 @@ static void vhost_vsock_pci_instance_init(Object *obj)
 static const VirtioPCIDeviceTypeInfo vhost_vsock_pci_info = {
     .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,
-- 
2.26.2