Re: [PATCH rdma-next 00/13] Elastic Fabric Adapter (EFA) driver

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On Fri, Jan 04, 2019 at 09:35:47AM -0700, Jason Gunthorpe wrote:
> On Fri, Jan 04, 2019 at 12:31:21PM +0200, Gal Pressman wrote:
> > On 04-Jan-19 06:11, Jason Gunthorpe wrote:
> > > On Thu, Jan 03, 2019 at 06:32:56PM -0500, Doug Ledford wrote:
> > >
> > >>> The original point is still un-addressed. We, as a community, have
> > >>> identified usnic as a bad idea that does not belong in
> > >>> drivers/infiniband. This has been a pretty much universal position of
> > >>> everyone who has worked on the core RDMA stack.
> > >>
> > >> I'll generally agree with this.  It turns out usnic is not so much about
> > >> access to a shared device with PD, QP, CQ, MR and AH support, but an
> > >> SRIOV network device attached to a process with minimal (but sufficient
> > >> I think) security measures to at least make sure that process can't
> > >> listen in on other traffic.  From there, it's just UDP on a private
> > >> network adapter.
> > >
> > > EFA looks the same to me, except instead of UDP it is doing a bit
> > > more, but it still just datagram processing. There are no verbs here
> > > other than SEND and RECV. There is no RMA..
> > >
> > > The functions usnic and EFA stub to EOPNOTSUPP/null look super similar
> > > to me.
> >
> > The stubs are there because of IB_MANDATORY_FUNC.
>
> Yes, because those functions are *MANDATORY* to be an actual verbs
> device :)
>
> That is another thing that should be revised for these no-kverbs
> things, I don't want to see stubs..
>
> In fact seeing null in any mandatory function pointers is a good way
> to trigger the 'clients cannot be attached' behavior in your earlier
> RFC patch.
>
> > > I've never used usnic, is this true? It sure looks like it can
> > > allocate ucontexts dynamically?? I think that is what the vnic stuff
> > > is for?? Maybe the ucontext limit is pretty small, but there sure is
> > > alot of code here if the limit is just 1.. We also don't know the EFA
> > > ucontext limit ...
> >
> > There is no ucontext limit.
>
> Oh? EFA is sharing BAR pages between user processes? You have a
> security proof that is OK?

For proprietary device with proprietary protocol in proprietary network?

Thanks

>
> Jason

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