Re: [PATCH 1/4] vDPA: allow userspace to query features of a vDPA device

[Jason Wang <jasowang@redhat.com>]

On Wed, Sep 21, 2022 at 2:00 PM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
>
>
>
> On 9/21/2022 10:17 AM, Jason Wang wrote:
> > On Tue, Sep 20, 2022 at 5:58 PM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
> >>
> >>
> >> On 9/20/2022 10:02 AM, Jason Wang wrote:
> >>> On Fri, Sep 9, 2022 at 5:05 PM Zhu Lingshan <lingshan.zhu@intel.com> 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.
> >>>>
> >>>> This commit invokes vdpa_config_ops.get_config() than
> >>>> vdpa_get_config_unlocked() to read the device config
> >>>> spcae, so no raeces in vdpa_set_features_unlocked()
> >>>>
> >>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> >>> It's better to share the userspace code as well.
> >> OK, will share it in V2.
> >>>> ---
> >>>>    drivers/vdpa/vdpa.c       | 19 ++++++++++++++-----
> >>>>    include/uapi/linux/vdpa.h |  4 ++++
> >>>>    2 files changed, 18 insertions(+), 5 deletions(-)
> >>>>
> >>>> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> >>>> index c06c02704461..798a02c7aa94 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 */
> >>> The code explains itself, there's no need for the comment.
> >> these comments are required in other discussions
> > I think it's more than sufficient to clarify the semantic where it is defined.
> OK, then only comments in the header file
> >
> >>>>           if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
> >>>>                                 mdev->supported_features, VDPA_ATTR_PAD)) {
> >>>>                   err = -EMSGSIZE;
> >>>> @@ -815,10 +817,10 @@ 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));
> >>>> +       vdev->config->get_config(vdev, 0, &config, sizeof(config));
> >>>>
> >>>>           if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.mac),
> >>>>                       config.mac))
> >>>> @@ -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..97531b52dcbe 100644
> >>>> --- a/include/uapi/linux/vdpa.h
> >>>> +++ b/include/uapi/linux/vdpa.h
> >>>> @@ -46,12 +46,16 @@ 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 */
> >>>>
> >>>>           VDPA_ATTR_DEV_QUEUE_INDEX,              /* u32 */
> >>>>           VDPA_ATTR_DEV_VENDOR_ATTR_NAME,         /* string */
> >>>>           VDPA_ATTR_DEV_VENDOR_ATTR_VALUE,        /* u64 */
> >>>>
> >>>> +       /* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
> >>>> +       VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,  /* u64 */
> >>> What's the difference between this and VDPA_ATTR_DEV_SUPPORTED_FEATURES?
> >> This is to report a vDPA device features, and
> >> VDPA_ATTR_DEV_SUPPORTED_FEATURES
> >> is used for reporting the management device features, we have a long
> >> discussion
> >> on this before.
> > Yes, but the comment is not clear in many ways:
> >
> > " features of a vDPA management device" sounds like features that is
> > out of the scope of the virtio.
> I think the term "vDPA device" implies that it is a virtio device.
> So how about: "virtio features of a vDPA management device"

Not a native speaker, but how about "virtio features that are
supported by the vDPA management device?"

Thanks

> >
> > And
> >
> > "/dev/vhost-vdpa0" is not a vDPA device but a vhost-vDPA device.
> will remove this example here.
>
> Thanks
> >
> > Thanks
> >
> >>> Thanks
> >>>
> >>>> +
> >>>>           /* new attributes must be added above here */
> >>>>           VDPA_ATTR_MAX,
> >>>>    };
> >>>> --
> >>>> 2.31.1
> >>>>
>

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