RE: [PATCH v6 5/8] net/gve: add support for MTU setting

["Guo, Junfeng" <junfeng.guo@intel.com>]

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@amd.com>
> Sent: Thursday, October 20, 2022 22:45
> To: Guo, Junfeng <junfeng.guo@intel.com>; Zhang, Qi Z
> <qi.z.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Xing,
> Beilei <beilei.xing@intel.com>
> Cc: dev@dpdk.org; Li, Xiaoyun <xiaoyun.li@intel.com>;
> awogbemila@google.com; Richardson, Bruce
> <bruce.richardson@intel.com>; hemant.agrawal@nxp.com;
> stephen@networkplumber.org; Xia, Chenbo <chenbo.xia@intel.com>;
> Zhang, Helin <helin.zhang@intel.com>
> Subject: Re: [PATCH v6 5/8] net/gve: add support for MTU setting
> 
> On 10/20/2022 11:36 AM, Junfeng Guo wrote:
> 
> >
> > Support dev_ops mtu_set.
> >
> > Signed-off-by: Xiaoyun Li <xiaoyun.li@intel.com>
> > Signed-off-by: Junfeng Guo <junfeng.guo@intel.com>
> > ---
> >   doc/guides/nics/features/gve.ini |  1 +
> >   drivers/net/gve/gve_ethdev.c     | 27 +++++++++++++++++++++++++++
> >   2 files changed, 28 insertions(+)
> >
> > diff --git a/doc/guides/nics/features/gve.ini
> b/doc/guides/nics/features/gve.ini
> > index ae466ad677..d1703d8dab 100644
> > --- a/doc/guides/nics/features/gve.ini
> > +++ b/doc/guides/nics/features/gve.ini
> > @@ -5,6 +5,7 @@
> >   ;
> >   [Features]
> >   Link status          = Y
> > +MTU update           = Y
> >   Linux                = Y
> >   x86-32               = Y
> >   x86-64               = Y
> > diff --git a/drivers/net/gve/gve_ethdev.c
> b/drivers/net/gve/gve_ethdev.c
> > index ca4a467140..1968f38eb6 100644
> > --- a/drivers/net/gve/gve_ethdev.c
> > +++ b/drivers/net/gve/gve_ethdev.c
> > @@ -94,12 +94,39 @@ gve_dev_close(struct rte_eth_dev *dev)
> >          return err;
> >   }
> >
> > +static int
> > +gve_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> > +{
> > +       struct gve_priv *priv = dev->data->dev_private;
> > +       int err;
> > +
> > +       if (mtu < RTE_ETHER_MIN_MTU || mtu > priv->max_mtu) {
> > +               PMD_DRV_LOG(ERR, "MIN MTU is %u MAX MTU is %u",
> RTE_ETHER_MIN_MTU, priv->max_mtu);
> 
> Although this is within new 100 column limit, it is easy to break it
> without sacrificing the readability, can you break it as something like:
> 
> PMD_DRV_LOG(ERR, "MIN MTU is %u MAX MTU is %u",
> 	RTE_ETHER_MIN_MTU, priv->max_mtu);

Sure, will improve this. Thanks!

> 
> > +               return -EINVAL;
> > +       }
> > +
> > +       /* mtu setting is forbidden if port is start */
> > +       if (dev->data->dev_started) {
> > +               PMD_DRV_LOG(ERR, "Port must be stopped before
> configuration");
> > +               return -EBUSY;
> > +       }
> > +
> > +       err = gve_adminq_set_mtu(priv, mtu);
> > +       if (err) {
> > +               PMD_DRV_LOG(ERR, "Failed to set mtu as %u err = %d", mtu,
> err);
> > +               return err;
> > +       }
> > +
> > +       return 0;
> > +}
> 
> 
> configure() (gve_dev_configure()) also get 'mtu' as user config
> ('eth_conf->rxmode.mtu') which is ignored right now,
> 
> since there is 'gve_adminq_set_mtu()' command already what do you
> think
> to use it within 'gve_dev_configure()'?

Do you mean to set the mtu with the user config value like:
'gve_dev_mtu_set(dev, dev->data->dev_conf.rxmode.mtu)'
within 'gve_dev_configure()'?

The ' dev->data->dev_conf.rxmode.mtu' I get at dev configure stage
is also 1500, which is lager than priv->max_mtu (1460). And this may
still cause the testpmd launch failed...

So I'll keep this part unchanged and do more investigations to figure
out the mtu issues we met. Thanks!

> 
> > +
> >   static const struct eth_dev_ops gve_eth_dev_ops = {
> >          .dev_configure        = gve_dev_configure,
> >          .dev_start            = gve_dev_start,
> >          .dev_stop             = gve_dev_stop,
> >          .dev_close            = gve_dev_close,
> >          .link_update          = gve_link_update,
> > +       .mtu_set              = gve_dev_mtu_set,
> >   };
> >
> >   static void
> > --
> > 2.34.1
> >