virtio-pci: Fix legacy device flag setting error in probe

The 'is_legacy' flag is used to differentiate between legacy vs modern
device. Currently, it is based on the value of vp_dev->ldev.ioaddr.
However, due to the shared memory of the union between struct
virtio_pci_legacy_device and struct virtio_pci_modern_device, when
virtio_pci_modern_probe modifies the content of struct
virtio_pci_modern_device, it affects the content of struct
virtio_pci_legacy_device, and ldev.ioaddr is no longer zero, causing
the 'is_legacy' flag to be set as true. To resolve issue, when legacy
device is probed, mark 'is_legacy' as true, when modern device is
probed, keep 'is_legacy' as false.

Fixes: 4f0fc22 ("virtio_pci: Optimize virtio_pci_device structure size")
Signed-off-by: Feng Liu <feliu@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Message-Id: <20230719154550.79536-1-feliu@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>

Author: Feng Liu

drivers/virtio/virtio_pci_common.c

@@ -557,8 +557,6 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
 
 	pci_set_master(pci_dev);
 
-	vp_dev->is_legacy = vp_dev->ldev.ioaddr ? true : false;
-
 	rc = register_virtio_device(&vp_dev->vdev);
 	reg_dev = vp_dev;
 	if (rc)

drivers/virtio/virtio_pci_legacy.c

@@ -223,6 +223,7 @@ int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
 	vp_dev->config_vector = vp_config_vector;
 	vp_dev->setup_vq = setup_vq;
 	vp_dev->del_vq = del_vq;
+	vp_dev->is_legacy = true;
 
 	return 0;
 }