> From: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
> Sent: Wednesday, December 22, 2021 7:31 AM
>
> On 12/21/2021 9:20 AM, Eli Cohen wrote:
> > Add max_supported_vqs field to struct vdpa_mgmt_dev. Upstream drivers
> > need to feel this value according to the device capabilities.
> >
> > This value is reported back in a netlink message when showing
> > management devices.
> >
> > Example:
> >
> > $ vdpa dev show
> s/dev/mgmtdev/
>
> and,
> > vdpa mgmtdev show
> remove this line.
> > auxiliary/mlx5_core.sf.1:
> > supported_classes net
> > max_supported_vqs 256
It should be in same line.
Also please show the JSON output.
> Not consistent with the example in patch #11 in the series.
> >
> > Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
> > ---
> > drivers/vdpa/vdpa.c | 3 +++
> > include/linux/vdpa.h | 1 +
> > include/uapi/linux/vdpa.h | 1 +
> > 3 files changed, 5 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index
> > eb223bec5209..4b649125a038 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -507,6 +507,9 @@ static int vdpa_mgmtdev_fill(const struct
> vdpa_mgmt_dev *mdev, struct sk_buff *m
> > err = -EMSGSIZE;
> > goto msg_err;
> > }
> > + if (nla_put_u16(msg, VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,
> > + mdev->max_supported_vqs))
> It still needs a default value when the field is not explicitly filled in by the
> driver.
>
Unlikely. This can be optional field to help user decide device max limit.
When max_supported_vqs is set to zero. Vdpa should omit exposing it to user space.
> > --- a/include/linux/vdpa.h
> > +++ b/include/linux/vdpa.h
> > @@ -447,6 +447,7 @@ struct vdpa_mgmt_dev {
> > const struct vdpa_mgmtdev_ops *ops;
> > const struct virtio_device_id *id_table;
> > u64 config_attr_mask;
> > + u16 max_supported_vqs;
This breaks the natural alignment and create holes in the struct.
Please move it at the last entry in the struct after list.
There has been some talk/patches of rdma virtio device.
I anticipate such device to support more than 64K queues by nature of rdma.
It is better to keep max_supported_vqs as u32.
> > struct list_head list;
> > };
> >
> > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> > index db3738ef3beb..995257c6bf2a 100644
> > --- a/include/uapi/linux/vdpa.h
> > +++ b/include/uapi/linux/vdpa.h
> > @@ -44,6 +44,7 @@ enum vdpa_attr {
> > VDPA_ATTR_DEV_NET_CFG_MTU, /* u16 */
> >
> > VDPA_ATTR_DEV_NEGOTIATED_FEATURES, /* u64 */
> > + VDPA_ATTR_DEV_MGMTDEV_MAX_VQS, /* u16 */
> > /* new attributes must be added above here */
> > VDPA_ATTR_MAX,
> > };
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