Re: [PATCH] RDMA/rxe: Split rxe_invalidate_mr into local and remote versions

[Bob Pearson <rpearsonhpe@gmail.com>]

On 6/28/22 12:05, haris iqbal wrote:
> On Tue, Jun 28, 2022 at 6:50 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>>
>> On Tue, Jun 28, 2022 at 06:46:39PM +0200, haris iqbal wrote:
>>> On Tue, Jun 28, 2022 at 6:34 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>>>>
>>>> On Tue, Jun 28, 2022 at 06:21:09PM +0200, haris iqbal wrote:
>>>>
>>>>>> Yes, no driver in Linux suports a disjoint key space.
>>>>>
>>>>> If disjoint key space is not supported in Linux; does this mean
>>>>> irrespective of whether an MR is registered (IB_WR_REG_MR) for LOCAL
>>>>> or REMOTE access, both rkey and lkey should be set?
>>>>
>>>> No.. It means given any key the driver can always tell if it is a rkey
>>>> or a lkey. There is never any aliasing of key values. Thus the API
>>>> often doesn't have a away to tell if the given key is an rkey or lkey.
>>>>
>>>>> PS: This discussion started in the following thread,
>>>>> https://marc.info/?l=linux-rdma&m=165390868832428&w=2
>>>>
>>>> rxe is incorrect to not accept the lkey presented on the
>>>> invalidate_rkey input. invalidate_rkey is misnamed.
>>>
>>>
>>> Understood. So a better fix for rxe (as compared to the one I sent)
>>> would be one of the following (if I understand correctly).
>>>
>>> 1) The key sent in INV, is compared with lkey or rkey based on which
>>> one is set (non-zero).
>>
>> This one seems to match the spec
>>
>> However, it requires that keys don't alias, I don't know if rxe has
>> done this.
> 
> Rxe seems to be NOT aliasing for fast reg. Unsure about other cases.
> 
> Maybe Bob or Zhu can shed some light?
> 
>>
>>> OR,
>>> 2) The key sent in INV, is compared with lkey if the MR has only LOCAL
>>> access, and rkey if the MR has REMOTE access.
>>
>> That might make more sense if rxe has aliasing keys and you need to be
>> specific about r/l
>>
>> Jason

rxe always has lkey=rkey if rkey is asked for else rkey=0 and lkey is always set.

Bob