Re: [PATCH v3 3/4] vdpa: show dev config as-is in "vdpa dev show" output

[Si-Wei Liu]

On 10/24/2022 1:40 AM, Jason Wang wrote:
> On Sat, Oct 22, 2022 at 7:49 AM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote:
> > Live migration of vdpa would typically require re-instate vdpa
> > device with an idential set of configs on the destination node,
> > same way as how source node created the device in the first
> > place. In order to save orchestration software from memorizing
> > and keeping track of vdpa config, it will be helpful if the vdpa
> > tool provides the aids for exporting the initial configs as-is,
> > the way how vdpa device was created. The "vdpa dev show" command
> > seems to be the right vehicle for that. It is unlike the "vdpa dev
> > config show" command output which usually goes with the live value
> > in the device config space, and is not quite reliable subject to
> > the dynamics of feature negotiation or possible change by the
> > driver to the config space.
> >
> > Examples:
> >
> > 1) Create vDPA by default without any config attribute
> >
> > $ vdpa dev add mgmtdev pci/0000:41:04.2 name vdpa0
> > $ vdpa dev show vdpa0
> > vdpa0: type network mgmtdev pci/0000:41:04.2 vendor_id 5555 max_vqs 9 max_vq_size 256
> > $ vdpa dev -jp show vdpa0
> > {
> >      "dev": {
> >          "vdpa0": {
> >              "type": "network",
> >              "mgmtdev": "pci/0000:41:04.2",
> >              "vendor_id": 5555,
> >              "max_vqs": 9,
> >              "max_vq_size": 256,
> >          }
> >      }
> > }
> >
> > 2) Create vDPA with config attribute(s) specified
> >
> > $ vdpa dev add mgmtdev pci/0000:41:04.2 name vdpa0 \
> >      mac e4:11:c6:d3:45:f0 max_vq_pairs 4
> > $ vdpa dev show
> > vdpa0: type network mgmtdev pci/0000:41:04.2 vendor_id 5555 max_vqs 9 max_vq_size 256
> >    initial_config: mac e4:11:c6:d3:45:f0 max_vq_pairs 4
> > $ vdpa dev -jp show
> > {
> >      "dev": {
> >          "vdpa0": {
> >              "type": "network",
> >              "mgmtdev": "pci/0000:41:04.2",
> >              "vendor_id": 5555,
> >              "max_vqs": 9,
> >              "max_vq_size": 256,
> >              "initial_config": {
> >                  "mac": "e4:11:c6:d3:45:f0",
> >                  "max_vq_pairs": 4
> >              }
> >          }
> >      }
> > }
> >
> > Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
> > ---
> >   drivers/vdpa/vdpa.c | 39 +++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 39 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > index bebded6..bfb8f54 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -677,6 +677,41 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
> >   }
> >
> >   static int
> > +vdpa_dev_initcfg_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 device_id)
> > +{
> > +       struct vdpa_dev_set_config *cfg = &vdev->init_cfg;
> > +       int err = -EMSGSIZE;
> > +
> > +       if (!cfg->mask)
> > +               return 0;
> > +
> > +       switch (device_id) {
> > +       case VIRTIO_ID_NET:
> > +               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR)) != 0 &&
> > +                   nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR,
> > +                           sizeof(cfg->net.mac), cfg->net.mac))
> > +                       return err;
> > +               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU)) != 0 &&
> > +                   nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, cfg->net.mtu))
> > +                       return err;
> > +               if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP)) != 0 &&
> > +                   nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> > +                               cfg->net.max_vq_pairs))
> > +                       return err;
> > +               break;
> > +       default:
> > +               break;
> > +       }
> > +
> > +       if ((cfg->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) != 0 &&
> > +           nla_put_u64_64bit(msg, VDPA_ATTR_DEV_FEATURES,
> > +                             cfg->device_features, VDPA_ATTR_PAD))
> > +               return err;
> A question: If any of those above attributes were not provisioned,
> should we show the ones that are inherited from the parent?
A simple answer would be yes, but the long answer is that I am not sure 
if there's any for the moment - there's no  default value for mtu, mac, 
and max_vqp that can be inherited from the parent (max_vqp by default 
being 1 is spec defined, not something inherited from the parent). And 
the device_features if inherited is displayed at 'vdpa dev config show' 
output. Can you remind me of a good example for inherited value that we 
may want to show here?


Thanks,
-Siwei


> Thanks
>
> > +
> > +       return 0;
> > +}
> > +
> > +static int
> >   vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq,
> >                int flags, struct netlink_ext_ack *extack)
> >   {
> > @@ -715,6 +750,10 @@ static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *i
> >          if (nla_put_u16(msg, VDPA_ATTR_DEV_MIN_VQ_SIZE, min_vq_size))
> >                  goto msg_err;
> >
> > +       err = vdpa_dev_initcfg_fill(vdev, msg, device_id);
> > +       if (err)
> > +               goto msg_err;
> > +
> >          genlmsg_end(msg, hdr);
> >          return 0;
> >
> > --
> > 1.8.3.1