Re: [RFC 01/10] virtio: get class_id and pci device id by the virtio id

[Cornelia Huck]

On Wed, Jan 05 2022, "Longpeng(Mike)" <longpeng2@huawei.com> wrote:

> From: Longpeng <longpeng2@huawei.com>
>
> Add helpers to get the "Transitional PCI Device ID" and "class_id" of the
> deivce which is specificed by the "Virtio Device ID".
>
> These helpers will be used to build the generic vDPA device later.
>
> Signed-off-by: Longpeng <longpeng2@huawei.com>
> ---
>  hw/virtio/virtio-pci.c | 93 ++++++++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.h |  4 ++
>  2 files changed, 97 insertions(+)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 750aa47ec1..843085c4ea 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -19,6 +19,7 @@
>  
>  #include "exec/memop.h"
>  #include "standard-headers/linux/virtio_pci.h"
> +#include "standard-headers/linux/virtio_ids.h"
>  #include "hw/boards.h"
>  #include "hw/virtio/virtio.h"
>  #include "migration/qemu-file-types.h"
> @@ -213,6 +214,95 @@ static int virtio_pci_load_queue(DeviceState *d, int n, 
> QEMUFile *f)
>      return 0;
>  }
>  
> +typedef struct VirtIOPCIIDInfo {
> +    uint16_t vdev_id; /* virtio id */
> +    uint16_t pdev_id; /* pci device id */
> +    uint16_t class_id;
> +} VirtIOPCIIDInfo;
> +
> +static const VirtIOPCIIDInfo virtio_pci_id_info[] = {
> +    {
> +        .vdev_id = VIRTIO_ID_NET,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_NET,
> +        .class_id = PCI_CLASS_NETWORK_ETHERNET,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_BLOCK,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_BLOCK,
> +        .class_id = PCI_CLASS_STORAGE_SCSI,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_CONSOLE,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_CONSOLE,
> +        .class_id = PCI_CLASS_COMMUNICATION_OTHER,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_SCSI,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_SCSI,
> +        .class_id = PCI_CLASS_STORAGE_SCSI,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_9P,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_9P,
> +        .class_id = PCI_BASE_CLASS_NETWORK,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_VSOCK,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_VSOCK,
> +        .class_id = PCI_CLASS_COMMUNICATION_OTHER,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_IOMMU,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_IOMMU,
> +        .class_id = PCI_CLASS_OTHERS,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_MEM,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_MEM,
> +        .class_id = PCI_CLASS_OTHERS,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_PMEM,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_PMEM,
> +        .class_id = PCI_CLASS_OTHERS,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_RNG,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_RNG,
> +        .class_id = PCI_CLASS_OTHERS,
> +    },
> +    {
> +        .vdev_id = VIRTIO_ID_BALLOON,
> +        .pdev_id = PCI_DEVICE_ID_VIRTIO_BALLOON,
> +        .class_id = PCI_CLASS_OTHERS,
> +    },
> +};
> +
> +static VirtIOPCIIDInfo virtio_pci_get_id_info(uint16_t vdev_id)
> +{
> +    VirtIOPCIIDInfo info = {};
> +    int i;
> +
> +    for (i = 0; i < ARRAY_SIZE(virtio_pci_id_info); i++) {
> +        if (virtio_pci_id_info[i].vdev_id == vdev_id) {
> +            info = virtio_pci_id_info[i];
> +            break;
> +        }
> +    }
> +
> +    return info;
> +}
> +
> +uint16_t virtio_pci_get_pci_devid(uint16_t device_id)
> +{
> +    return virtio_pci_get_id_info(device_id).pdev_id;
> +}
> +
> +uint16_t virtio_pci_get_class_id(uint16_t device_id)
> +{
> +    return virtio_pci_get_id_info(device_id).class_id;
> +}

What happens if these functions are called for a device_id that is not
in the array, e.g. if we forgot to add a new id to the array?

Can the array be generated in some way?