Re: [dpdk-dev] [PATCH v2 0/3] ethdev: configure SR-IOV VF from host

[Thomas Monjalon <thomas@monjalon.net>]

30/10/2019 16:07, Ilya Maximets:
> On 29.10.2019 19:50, Thomas Monjalon wrote:
> > In a virtual environment, the network controller may have to configure
> > some SR-IOV VF parameters for security reasons.
> > 
> > When the PF (host port) is driven by DPDK (OVS-DPDK case),
> > we face two different cases:
> >      - driver is bifurcated (Mellanox case),
> >        so the VF can be configured via the kernel.
> >      - driver is on top of UIO or VFIO, so DPDK API is required,
> >        and PMD-specific APIs were used.
> 
> So, what is wrong with setting VF mac via the representor port as
> it done now?  From our previous discussion, I thought that we concluded
> that is enough to have current API, i.e. just call set_default_mac()
> for a representor port and this will lead to setting mac for VF.
> This is how it's implemented in Linux kernel and this is how it's
> implemented in current DPDK drivers that supports setting mac for
> the representor.

I don't know what is done in the Linux kernel.
In DPDK, setting the MAC of the representor is really setting
the MAC of the representor. Is it crazy?

> The only use case for this new API is to be able to control mac of
> the representor itself, which doesn't make much sense. At least there
> are only hypothetical use cases. And once again, Linux kernel doesn't
> support this behavior.

I think it is sane to be able to set different MAC addresses
for the representor and the VF.

> > This new generic API will avoid vendors fragmentation.
> 
> I don't see the fragmentation. Right now you can set VF mac from DPDK
> by calling set_default_mac() for representor.  This API exists for all
> vendors. Not implemented for Intel, but new API is not implemented too.

No, the current situation is the following:
	- for mlx5, VF MAC can be configured with iproute2 or netlink
	- for ixgbe, rte_pmd_ixgbe_set_vf_mac_addr()
	- for i40e, rte_pmd_i40e_set_vf_mac_addr()
	- for bnxt, rte_pmd_bnxt_set_vf_mac_addr()

> The this is that this new API will produce conceptual fragmentation
> between DPDK and the Linux kernel, because to do the same thing you'll
> have to use different ways. I mean, to change mac of VF in kernel you
> need to set mac to the representor, but in DPDK changing setting mac to
> representor will lead to changing the mac of the representor itself,
> not the VF. This will be really confusing for users.

I am not responsible of the choices in Linux.
But I agree it would be interesting to check the reason of such decision.
Rony, please could you explain?