Messages in this thread Patch in this message | | | Date | Mon, 30 Nov 2020 08:27:46 +0200 | From | Eli Cohen <> | Subject | Re: [PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance |
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On Sun, Nov 29, 2020 at 03:08:22PM -0500, Michael S. Tsirkin wrote: > On Sun, Nov 29, 2020 at 08:43:51AM +0200, Eli Cohen wrote: > > We should not try to use the VF MAC address as that is used by the > > regular (e.g. mlx5_core) NIC implementation. Instead, use a random > > generated MAC address. > > > > Suggested by: Cindy Lu <lulu@redhat.com> > > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") > > Signed-off-by: Eli Cohen <elic@nvidia.com> > > I didn't realise it's possible to use VF in two ways > with and without vdpa.
Using a VF you can create quite a few resources, e.g. send queues recieve queues, virtio_net queues etc. So you can possibly create several instances of vdpa net devices and nic net devices.
> Could you include a bit more description on the failure > mode?
Well, using the MAC address of the nic vport is wrong since that is the MAC of the regular NIC implementation of mlx5_core.
> Is switching to a random mac for such an unusual > configuration really justified?
Since I can't use the NIC's MAC address, I have two options: 1. To get the MAC address as was chosen by the user administering the NIC. This should invoke the set_config callback. Unfortunately this is not implemented yet.
2. Use a random MAC address. This is OK since if (1) is implemented it can always override this random configuration.
> It looks like changing a MAC could break some guests, > can it not? >
No, it will not. The current version of mlx5 VDPA does not allow regular NIC driver and VDPA to co-exist. I have patches ready that enable that from steering point of view. I will post them here once other patches on which they depend will be merged.
https://patchwork.ozlabs.org/project/netdev/patch/20201120230339.651609-12-saeedm@nvidia.com/ > > --- > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 5 +---- > > 1 file changed, 1 insertion(+), 4 deletions(-) > > > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > index 1fa6fcac8299..80d06d958b8b 100644 > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > @@ -1955,10 +1955,7 @@ void *mlx5_vdpa_add_dev(struct mlx5_core_dev *mdev) > > if (err) > > goto err_mtu; > > > > - err = mlx5_query_nic_vport_mac_address(mdev, 0, 0, config->mac); > > - if (err) > > - goto err_mtu; > > - > > + eth_random_addr(config->mac); > > mvdev->vdev.dma_dev = mdev->device; > > err = mlx5_vdpa_alloc_resources(&ndev->mvdev); > > if (err) > > -- > > 2.26.2 >
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