Re: [PATCH v5 2/4] virtio: get class_id and pci device id by the virtio id

[Michael S. Tsirkin]

On Thu, May 12, 2022 at 02:21:01PM +0800, Longpeng(Mike) wrote:
> From: Longpeng <longpeng2@huawei.com>
> 
> Add helpers to get the "Transitional PCI Device ID" and "class_id"
> of the device specified by the "Virtio Device ID".
> 
> These helpers will be used to build the generic vDPA device later.
> 
> Signed-off-by: Longpeng <longpeng2@huawei.com>


Except, the IDs in the current header a broken. I just fixed them
and they will be hopefully OK in the next version.

> ---
>  hw/virtio/virtio-pci.c | 77 ++++++++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.h |  5 +++
>  2 files changed, 82 insertions(+)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 7cf1231c1c..fdfa205cee 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"
> @@ -212,6 +213,79 @@ static int virtio_pci_load_queue(DeviceState *d, int n, 
> QEMUFile *f)
>      return 0;
>  }
>  
> +typedef struct VirtIOPCIIDInfo {
> +    /* virtio id */
> +    uint16_t vdev_id;
> +    /* pci device id for the transitional device */
> +    uint16_t trans_devid;
> +    uint16_t class_id;
> +} VirtIOPCIIDInfo;
> +
> +#define VIRTIO_TRANS_DEV_ID_INFO(name, class)       \
> +    {                                               \
> +        .vdev_id = VIRTIO_ID_##name,                \
> +        .trans_devid = PCI_DEVICE_ID_VIRTIO_##name, \
> +        .class_id = class,                          \
> +    }
> +
> +#define VIRTIO_MODERN_DEV_ID_NFO(name, class)       \
> +    {                                               \
> +        .vdev_id = VIRTIO_ID_##name,                \
> +        .class_id = class,                          \
> +    }
> +

No, I think I liked the original approach in the RFC better, even though
it duplicates a tiny bit of code.
This trick does not save a lot of typing and obscures the ID
use in case it's wrong (as was the case just recently).


> +static const VirtIOPCIIDInfo virtio_pci_id_info[] = {
> +    /* Non-transitional devices */
> +    VIRTIO_MODERN_DEV_ID_NFO(CRYPTO,    PCI_CLASS_OTHERS),
> +    VIRTIO_MODERN_DEV_ID_NFO(FS,        PCI_CLASS_STORAGE_OTHER),
> +    /* Transitional devices */
> +    VIRTIO_TRANS_DEV_ID_INFO(NET,       PCI_CLASS_NETWORK_ETHERNET),
> +    VIRTIO_TRANS_DEV_ID_INFO(BLOCK,     PCI_CLASS_STORAGE_SCSI),
> +    VIRTIO_TRANS_DEV_ID_INFO(CONSOLE,   PCI_CLASS_COMMUNICATION_OTHER),
> +    VIRTIO_TRANS_DEV_ID_INFO(SCSI,      PCI_CLASS_STORAGE_SCSI),
> +    VIRTIO_TRANS_DEV_ID_INFO(9P,        PCI_BASE_CLASS_NETWORK),
> +    VIRTIO_TRANS_DEV_ID_INFO(BALLOON,   PCI_CLASS_OTHERS),
> +    VIRTIO_TRANS_DEV_ID_INFO(RNG,       PCI_CLASS_OTHERS),
> +};
> +
> +static const VirtIOPCIIDInfo *virtio_pci_get_id_info(uint16_t vdev_id)
> +{
> +    const VirtIOPCIIDInfo *info = NULL;
> +    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;
> +        }
> +    }
> +
> +    if (!info) {
> +        /* The device id is invalid or not added to the id_info yet. */
> +        error_report("Invalid virtio device(id %u)", vdev_id);
> +        abort();
> +    }
> +
> +    return info;
> +}
> +
> +/*
> + * Get the Transitional Device ID for the specific device, return
> + * zero if the device is non-transitional.
> + */
> +uint16_t virtio_pci_get_trans_devid(uint16_t device_id)
> +{
> +    return virtio_pci_get_id_info(device_id)->trans_devid;
> +}
> +
> +/*
> + * Get the Class ID for the specific device.
> + */
> +uint16_t virtio_pci_get_class_id(uint16_t device_id)
> +{
> +    return virtio_pci_get_id_info(device_id)->class_id;
> +}
> +
>  static bool virtio_pci_ioeventfd_enabled(DeviceState *d)
>  {
>      VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
> @@ -1675,6 +1749,9 @@ static void virtio_pci_device_plugged(DeviceState *d, 
> Error **errp)
>           * is set to PCI_SUBVENDOR_ID_REDHAT_QUMRANET by default.
>           */
>          pci_set_word(config + PCI_SUBSYSTEM_ID, virtio_bus_get_vdev_id(bus));
> +        if (proxy->trans_devid) {
> +            pci_config_set_device_id(config, proxy->trans_devid);
> +        }
>      } else {
>          /* pure virtio-1.0 */
>          pci_set_word(config + PCI_VENDOR_ID,
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index 2446dcd9ae..f08665cd1b 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -146,6 +146,8 @@ struct VirtIOPCIProxy {
>      bool disable_modern;
>      bool ignore_backend_features;
>      OnOffAuto disable_legacy;
> +    /* Transitional device id */
> +    uint16_t trans_devid;
>      uint32_t class_code;
>      uint32_t nvectors;
>      uint32_t dfselect;
> @@ -158,6 +160,9 @@ struct VirtIOPCIProxy {
>      VirtioBusState bus;
>  };
>  
> +uint16_t virtio_pci_get_trans_devid(uint16_t device_id);
> +uint16_t virtio_pci_get_class_id(uint16_t device_id);
> +
>  static inline bool virtio_pci_modern(VirtIOPCIProxy *proxy)
>  {
>      return !proxy->disable_modern;
> -- 
> 2.23.0