Re: [PATCH rdma-next 1/2] RDMA/irdma: Fix FRWR logic for PAGE_SIZE > 4K

[sashiko-bot@kernel.org]

> The HW only supports 1G, 2M, and 4K page sizes, but some ULPs
> pass PAGE_SIZE to ib_map_mr_sg(), and PAGE_SIZE can be some
> multiple of 4K (64K arm kernels, etc.). The HW can still support
> these scenarios, but we must force it to use 4K pages. The
> max_fast_reg_page_list_len and page_cnt during MR allocation
> must also be scaled to accommodate for the additional PBLEs
> that will be used when ib_sg_to_pages() ends up producing
> more pages than what would have otherwise been required with
> the original page size. It is worth noting that this change
> avoids this over-allocation/cracking in the off chance that
> a 1G or 2M PAGE_SIZE is ever used; it's only applicable when
> PAGE_SIZE is some power of 2 multiple of 4K that is not
> currently supported by HW.
> 
> This was discovered by encountering SMMU faults when running
> kernel NFS/RDMA on a 64K kernel, which was due to the page
> list holding PAGE_SIZE entries while the WQE was indicating
> 4K, so HW was translating every access after the first 4K
> incorrectly.
> 
> Fixes: b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")
> Tested-by: Leah Li <leahlijuan@google.com>
> Signed-off-by: Jacob Moroni <jmoroni@google.com>

Sashiko has reviewed this patch and found no issues.

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