On Thu, Dec 18, 2025 at 05:09:41PM +0800, Xiong Weimin wrote:
> From: xiongweimin <[email protected]>
>
> This commit introduces a new driver for RDMA over virtio, enabling
> RDMA capabilities in virtualized environments. The driver consists
> of the following main components:
>
> 1. Driver registration with the virtio subsystem and device discovery.
> 2. Device probe and remove handlers for managing the device lifecycle.
> 3. Initialization of the InfiniBand device attributes by reading the
> virtio configuration space, including conversion from little-endian
> to CPU byte order and capability mapping.
> 4. Setup of virtqueues for:
> - Control commands (no callback)
> - Completion queues (with callback for CQ events)
> - Send and receive queues for queue pairs (no callbacks)
> 5. Integration with the network device layer for RoCE support.
> 6. Registration with the InfiniBand core subsystem.
> 7. Comprehensive error handling during initialization and a symmetric
> teardown process.
>
> Key features:
> - Support for multiple virtqueues based on device capabilities (max_cq,
> max_qp)
> - Fast doorbell optimization when notify_offset_multiplier equals PAGE_SIZE
> - Safe resource management with rollback on failure
>
> Signed-off-by: Xiong Weimin <[email protected]>
<...>
> +/**
> + * vrdma_init_netdev - Attempt to find paired virtio-net device on same PCI
> slot
> + * @vrdev: The vRDMA device
> + *
> + * WARNING: This is a non-standard hack for development/emulation
> environments.
> + * Do not use in production or upstream drivers.
I'm impressed how much AI advanced in code generation. Please recheck
everything that was generated.
> + *
> + * Returns 0 on success, or negative errno.
> + */
> +int vrdma_init_netdev(struct vrdma_dev *vrdev)
> +{
> + struct pci_dev *pdev_net;
> + struct virtio_pci_device *vp_dev;
> + struct virtio_pci_device *vnet_pdev;
> + void *priv;
> + struct net_device *netdev;
> +
> + if (!vrdev || !vrdev->vdev) {
> + pr_err("%s: invalid vrdev or vdev\n", __func__);
> + return -EINVAL;
> + }
> +
> + vp_dev = to_vp_device(vrdev->vdev);
> +
> + /* Find the PCI device at function 0 of the same slot */
> + pdev_net = pci_get_slot(vp_dev->pci_dev->bus,
> + PCI_DEVFN(PCI_SLOT(vp_dev->pci_dev->devfn), 0));
> + if (!pdev_net) {
> + pr_err("Failed to find PCI device at fn=0 of slot %x\n",
> + PCI_SLOT(vp_dev->pci_dev->devfn));
> + return -ENODEV;
> + }
> +
> + /* Optional: Validate it's a known virtio-net device */
> + if (pdev_net->vendor != PCI_VENDOR_ID_REDHAT_QUMRANET ||
> + pdev_net->device != 0x1041) {
> + pr_warn("PCI device %04x:%04x is not expected virtio-net (1041)
> device\n",
> + pdev_net->vendor, pdev_net->device);
> + pci_dev_put(pdev_net);
> + return -ENODEV;
> + }
> +
> + /* Get the virtio_pci_device from drvdata */
> + vnet_pdev = pci_get_drvdata(pdev_net);
> + if (!vnet_pdev || !vnet_pdev->vdev.priv) {
> + pr_err("No driver data or priv for virtio-net device\n");
> + pci_dev_put(pdev_net);
> + return -ENODEV;
> + }
> +
> + priv = vnet_pdev->vdev.priv;
> + vrdev->netdev = priv - ALIGN(sizeof(struct net_device), NETDEV_ALIGN);
> + netdev = vrdev->netdev;
> +
> + if (!netdev || !netdev->netdev_ops) {
> + pr_err("Invalid net_device retrieved from virtio-net\n");
> + pci_dev_put(pdev_net);
> + return -ENODEV;
> + }
> +
> + /* Hold reference so netdev won't disappear */
> + dev_hold(netdev);
> +
> + pci_dev_put(pdev_net); /* Release reference from pci_get_slot */
> +
> + return 0;
> +}
AI was right here. It is awful hack.
Thanks
