Re: [Patch v7 21/22] CIFS: SMBD: Upper layer performs SMB read via RDMA write through memory registration

From: Stefan Metzmacher
Date: Sun Sep 23 2018 - 17:25:04 EST


Hi Tom,

>> I just tested that setting:
>>
>> mr->iova &= (PAGE_SIZE - 1);
>> mr->iova |= 0xFFFFFFFF00000000;
>>
>> after the ib_map_mr_sg() and before doing the IB_WR_REG_MR, seems to
>> work.
>
> Good! As you know, we were concerned about it after seeing that
> the ib_dma_map_sg() code was unconditionally setting it to the
> dma_mapped address. By salting those FFFF's with varying data,
> this should give your FRWR regions stronger integrity in addition
> to not leaking kernel "addresses" to the wire.

Just wondering... Isn't the thing we use called FRMR?

metze

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