[openib-general] mthca FMR correctness (and memory windows)

[Diego Crupnicoff]

> -----Original Message-----
> From: Talpey, Thomas [mailto:Thomas.Talpey at netapp.com]
> Sent: Monday, March 20, 2006 11:19 PM
> To: Diego Crupnicoff; Roland Dreier
> Cc: openib-general at openib.org
> Subject: RE: [openib-general] mthca FMR correctness (and memory windows)
> 
> At 08:42 PM 3/20/2006, Diego Crupnicoff wrote:
> >> If I can snoop or guess rkeys (not a huge challenge with 32 bits), and
> >> if I can use them on an arbitrary queuepair, then I can handily peek
> and
> >> poke at memory that does not belong to me.
> >
> >No. You can't get to the Window from an arbitrary QP. Only from those QPs
> that belong to the same PD.
> 
> 
> Oh yeah, I have to guess the PD too.

I do not think you can effectively guess a PD. PD is a privileged field that
gets set at QP creation time (as opposed to rkeys that are postwqe input
modifiers). The side exposing the memory has to "agree" to open a QP on a PD
in order to make windows bound to that PD accessible through it.

> 
> >> For this reason, iWARP requires its steering tags to be scoped to a
> single
> >> connection. This leverages the IP security model and provides
> correctness.
> >>
> >> It is true that IB implementations generally don't do this. They
> should.
> >
> >IB allows the 2 flavors (PD bound Windows aka type 1, and QP bound
> Windows aka type 2).
> 
> Does mthca? I thought it's all type 1.

As noted before, currently mthca does not support memory windows at all.

> 
> Tom.
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