Re: [PATCH v1] rxe: IB_WR_REG_MR does not capture MR's iova field

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If the subject is changed to "IB/rxe: IB_WR_REG_MR does not capture MR's iova field", it is better.

Zhu Yanjun

On 2018/11/26 6:13, Chuck Lever wrote:
FRWR memory registration is done with a series of calls and WRs.
1. ULP invokes ib_dma_map_sg()
2. ULP invokes ib_map_mr_sg()
3. ULP posts an IB_WR_REG_MR on the Send queue

Step 2 generates an iova. It is permissible for ULPs to change
this iova (with certain restrictions) between steps 2 and 3.

rxe_map_mr_sg captures the MR's iova but later when rxe processes
the REG_MR WR, it ignores the MR's iova field. If a ULP alters the
MR's iova after step 2 but before step 3, rxe never captures that
change.

When the remote sends an RDMA Read targeting that MR, rxe looks up
the R_key, but the altered iova does not match the iova stored in
the MR, causing the RDMA Read request to fail.

Reported-by: Anna Schumaker <schumaker.anna@xxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
Hi-

This seems to address the problem Anna found:

   https://marc.info/?l=linux-rdma&m=154273696218072&w=2

I imagine there is more to it than this, but NFS/RDMA seems to work
on rxe again with the XID-in-offset patch and this fix applied.


  drivers/infiniband/sw/rxe/rxe_req.c |    1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index 6c361d70d7cd..46f62f71cd28 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -643,6 +643,7 @@ int rxe_requester(void *arg)
  			rmr->access = wqe->wr.wr.reg.access;
  			rmr->lkey = wqe->wr.wr.reg.key;
  			rmr->rkey = wqe->wr.wr.reg.key;
+			rmr->iova = wqe->wr.wr.reg.mr->iova;
  			wqe->state = wqe_state_done;
  			wqe->status = IB_WC_SUCCESS;
  		} else {





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