On Tue, Dec 7, 2021 at 3:57 PM Eli Cohen <elic@xxxxxxxxxx> wrote:
>
> On Fri, Dec 03, 2021 at 10:35:30AM +0800, Jason Wang wrote:
> > On Thu, Dec 2, 2021 at 3:58 AM Eli Cohen <elic@xxxxxxxxxx> wrote:
> > >
> > > Add netlink attribute and callback function to query the control VQ
> > > index of a device.
> >
> > It's better to explain the motivation of this. Actually we can deduce
> > it from the max_virtqueue_paris if I was not wrong.
> Right, we can deduce it. But I think, let's let the kernel deduce it.
> e.g., we can avoid the new get_ctrl_vq_idx() callback, but still return
> the value to userspace with VDPA_ATTR_DEV_CTRL_VQ_IDX.
>
> > So it means the
> > value varies depending on if VIRTIO_NET_F_MQ
> I guest you meant VIRTIO_NET_F_CTRL_VQ
> > is negotiated which can
> > be changed after a query. This may probably confuse the userspace
> > sometime.
>
> No sure I follow you on this. The CVQ index is dictated after the call
> to _vdpa_register_device() and cannot change. Whether there is a CVQ or
> isn't depends on VIRTIO_NET_F_CTRL_VQ but the index doesn't change.
Looks not, according to the spec, consider we have a device with 2
queue pairs plus cvq.
When MQ is negotiated, cvq index is 4.
When MQ is not negotiated, cvq index is 2.
Thanks
>
> >
> > Thanks
> >
> > >
> > > Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
> > > ---
> > > drivers/vdpa/vdpa.c | 18 ++++++++++++++++++
> > > include/linux/vdpa.h | 1 +
> > > include/uapi/linux/vdpa.h | 1 +
> > > 3 files changed, 20 insertions(+)
> > >
> > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > > index f06f949d5fa1..ca3ab0f46188 100644
> > > --- a/drivers/vdpa/vdpa.c
> > > +++ b/drivers/vdpa/vdpa.c
> > > @@ -712,6 +712,20 @@ static int vdpa_nl_cmd_dev_get_dumpit(struct sk_buff *msg, struct netlink_callba
> > > return msg->len;
> > > }
> > >
> > > +static int vdpa_dev_net_ctrl_vq_fill(struct vdpa_device *vdev,
> > > + struct sk_buff *msg, u64 features)
> > > +{
> > > + u16 val_u16 = 0;
> > > +
> > > + if (features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ) &&
> > > + vdev->config->get_ctrl_vq_idx) {
> > > + val_u16 = vdev->config->get_ctrl_vq_idx(vdev);
> > > + return nla_put_u16(msg, VDPA_ATTR_DEV_CTRL_VQ_IDX, val_u16);
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
> > > struct sk_buff *msg, u64 features,
> > > const struct virtio_net_config *config)
> > > @@ -730,6 +744,7 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
> > > struct virtio_net_config config = {};
> > > u64 features;
> > > u16 val_u16;
> > > + int err;
> > >
> > > vdpa_get_config(vdev, 0, &config, sizeof(config));
> > >
> > > @@ -746,6 +761,9 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
> > > return -EMSGSIZE;
> > >
> > > features = vdev->config->get_features(vdev);
> > > + err = vdpa_dev_net_ctrl_vq_fill(vdev, msg, features);
> > > + if (err)
> > > + return err;
> > >
> > > return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> > > }
> > > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > > index 820621c59365..fca9bfeed9ba 100644
> > > --- a/include/linux/vdpa.h
> > > +++ b/include/linux/vdpa.h
> > > @@ -274,6 +274,7 @@ struct vdpa_config_ops {
> > > (*get_vq_notification)(struct vdpa_device *vdev, u16 idx);
> > > /* vq irq is not expected to be changed once DRIVER_OK is set */
> > > int (*get_vq_irq)(struct vdpa_device *vdev, u16 idx);
> > > + u16 (*get_ctrl_vq_idx)(struct vdpa_device *vdev);
> > >
> > > /* Device ops */
> > > u32 (*get_vq_align)(struct vdpa_device *vdev);
> > > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> > > index a252f06f9dfd..2e3a7f89f42d 100644
> > > --- a/include/uapi/linux/vdpa.h
> > > +++ b/include/uapi/linux/vdpa.h
> > > @@ -34,6 +34,7 @@ enum vdpa_attr {
> > > VDPA_ATTR_DEV_MAX_VQS, /* u32 */
> > > VDPA_ATTR_DEV_MAX_VQ_SIZE, /* u16 */
> > > VDPA_ATTR_DEV_MIN_VQ_SIZE, /* u16 */
> > > + VDPA_ATTR_DEV_CTRL_VQ_IDX, /* u16 */
> > >
> > > VDPA_ATTR_DEV_NET_CFG_MACADDR, /* binary */
> > > VDPA_ATTR_DEV_NET_STATUS, /* u8 */
> > > --
> > > 2.33.1
> > >
> >
>
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