[RFC] virtio-net: support modern-transtional devices

[Zhu Lingshan <lingshan.zhu@intel.com>]

Current virtio-net only probes a device with VIRITO_ID_NET == 1.

For a modern-transtional virtio-net device which has a transtional
device id 0x1000 and acts as a modern device, current virtio-pci
modern driver will assign the sub-device-id to its mdev->id.device,
which may not be 0x1, this sub-device-id is up to the vendor.

That means virtio-net driver doesn't probe a modern-transitonal
virtio-net with a sub-device-id other than 0x1, which is a bug.

Other types of devices also have similar issues, like virito-blk.

I propose to fix this problem of modern-transitonal device
whith this solution, all in the modern code path:
1) assign the device id to mdev->id.device
2) add transitional device ids in the virtio-net(and others) probe table.

Comments are welcome!

Thanks!

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/net/virtio_net.c               | 1 +
 drivers/virtio/virtio_pci_modern_dev.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 56ca1d270304..6b45d8602a6b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -4250,6 +4250,7 @@ static __maybe_unused int virtnet_restore(struct virtio_device *vdev)
 
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
+	{ VIRTIO_TRANS_ID_NET, VIRTIO_DEV_ANY_ID },
 	{ 0 },
 };
 
diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
index 869cb46bef96..80846e1195ce 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -229,7 +229,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 		/* Transitional devices: use the PCI subsystem device id as
 		 * virtio device id, same as legacy driver always did.
 		 */
-		mdev->id.device = pci_dev->subsystem_device;
+		mdev->id.device = pci_dev->device;
 	} else {
 		/* Modern devices: simply use PCI device id, but start from 0x1040. */
 		mdev->id.device = pci_dev->device - 0x1040;
-- 
2.39.1

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