Re: [PATCH RFC 1/2] RDMA/rxe: don't allow registering !PAGE_SIZE mr

[Zhijian Li (Fujitsu)]

On 27/10/2023 13:41, Li Zhijian wrote:
> mr->page_list only encodes *page without page offset, when
> page_size != PAGE_SIZE, we cannot restore the address with a wrong
> page_offset.
> 
> Note that this patch will break some ULPs that try to register 4K
> MR when PAGE_SIZE is not 4K.
> SRP and nvme over RXE is known to be impacted.
> 
> Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
> ---
>   drivers/infiniband/sw/rxe/rxe_mr.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> index f54042e9aeb2..61a136ea1d91 100644
> --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> @@ -234,6 +234,12 @@ int rxe_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sgl,
>   	struct rxe_mr *mr = to_rmr(ibmr);
>   	unsigned int page_size = mr_page_size(mr);
>   
> +	if (page_size != PAGE_SIZE) {

It seems this condition is too strict, it should be:
	if (!IS_ALIGNED(page_size, PAGE_SIZE))

So that, page_size with (N * PAGE_SIZE) can work as previously.
Because the offset(mr.iova & page_mask) will get lost only when !IS_ALIGNED(page_size, PAGE_SIZE)

Thanks
Zhijian



> +		rxe_info_mr(mr, "Unsupported MR with page_size %u, expect %lu\n",
> +			   page_size, PAGE_SIZE);
> +		return -EOPNOTSUPP;
> +	}
> +
>   	mr->nbuf = 0;
>   	mr->page_shift = ilog2(page_size);
>   	mr->page_mask = ~((u64)page_size - 1);