Re: [PATCH for-next V2 02/22] IB/core: change pkey table lookups to support full and partial membership for the same pkey

On 11/09/2012 19:52, Doug Ledford wrote:

On 8/3/2012 4:40 AM, Jack Morgenstein wrote:

quoted

quoted

Enhance the cached and non-cached pkey table lookups to enable limited and full
members of the same pkey to co-exist in the pkey table.

This is necessary for SRIOV to allow for a scheme where some guests would have the full
membership pkey in their virtual pkey table, where other guests on the same hypervisor
would have the limited one. In that sense, its an extension of the IBTA model for
non virtualized nodes.

OK, maybe I'm not getting something, but I'm curious why we always pick
the full pkey in preference to the partial pkey.  Shouldn't we pick the
pkey that's appropriate for the vHCA sending the message?

Also, given the rule of least surprise, don't you think it would be best
to rename this function ib_find_cached_full_or_parital_pkey and in your
next patch instead of naming it ib_find_exact_pkey just call that one
ib_find_cached_pkey?

reply from Liran, our architect:

The physical PKey table can contain both full and partial memberships of 
the same Pkey.
This is needed to serve 2 VFs that are granted access to the same PKey, 
albeit with different membership types.

Indeed, there is no reason that the virtual PKey table of any *single* 
VF will contain both membership types.However, the PF PKey table 
certainly can because it mirrors the physical Pkey table.This patch is 
required for ULPs running on top of the PF.

--Liran
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