Re: [PATCH 1/2] vDPA: allow userspace to query features of a vDPA device

Si-Wei Liu
2022-08-15T18:19:15Z

On 8/15/2022 2:26 AM, Zhu Lingshan wrote:
> This commit adds a new vDPA netlink attribution
> VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES. Userspace can query
> features of vDPA devices through this new attr.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
> drivers/vdpa/vdpa.c | 17 +++++++++++++----
> include/uapi/linux/vdpa.h | 3 +++
> 2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index c06c02704461..efb55a06e961 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -491,6 +491,8 @@ static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *m
> err = -EMSGSIZE;
> goto msg_err;
> }
> +
> + /* report features of a vDPA management device through VDPA_ATTR_DEV_SUPPORTED_FEATURES */
> if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
> mdev->supported_features, VDPA_ATTR_PAD)) {
> err = -EMSGSIZE;
> @@ -815,7 +817,7 @@ static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
> static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
> {
> struct virtio_net_config config = {};
> - u64 features;
> + u64 features_device, features_driver;
> u16 val_u16;
>
> vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
> @@ -832,12 +834,19 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
> if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
> return -EMSGSIZE;
>
> - features = vdev->config->get_driver_features(vdev);
> - if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features,
> + features_driver = vdev->config->get_driver_features(vdev);
> + if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
> + VDPA_ATTR_PAD))
> + return -EMSGSIZE;
> +
> + features_device = vdev->config->get_device_features(vdev);
> +
> + /* report features of a vDPA device through VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES */
> + if (nla_put_u64_64bit(msg, VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
> VDPA_ATTR_PAD))
> return -EMSGSIZE;
>
> - return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> + return vdpa_dev_net_mq_config_fill(vdev, msg, features_driver, &config);
> }
>
> static int
> diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> index 25c55cab3d7c..d171b92ef522 100644
> --- a/include/uapi/linux/vdpa.h
> +++ b/include/uapi/linux/vdpa.h
> @@ -46,7 +46,10 @@ enum vdpa_attr {
>
> VDPA_ATTR_DEV_NEGOTIATED_FEATURES, /* u64 */
> VDPA_ATTR_DEV_MGMTDEV_MAX_VQS, /* u32 */
> + /* features of a vDPA management device */
> VDPA_ATTR_DEV_SUPPORTED_FEATURES, /* u64 */
> + /* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
> + VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, /* u64 */
Append to the end, please. Otherwise it breaks userspace ABI.

-Siwei

>
> VDPA_ATTR_DEV_QUEUE_INDEX, /* u32 */
> VDPA_ATTR_DEV_VENDOR_ATTR_NAME, /* string */