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SubjectRe: [PATCH v2 2/2] ntb_hw_switchtec: Check for alignment of the buffer in mw_set_trans()
On Mon, Dec 18, 2017 at 11:25:06AM -0700, Logan Gunthorpe wrote:
> With Switchtec hardware, the buffer used for a memory window must be
> aligned to its size (the hardware only replaces the lower bits). In
> certain circumstances dma_alloc_coherent() will not provide a buffer
> that adheres to this requirement like when using the CMA and
> CONFIG_CMA_ALIGNMENT is set lower than the buffer size.
>
> When we get an unaligned buffer mw_set_trans() should return an error.
> We also log an error so we know the cause of the problem.
>

Applied to ntb-next.

Thanks,
Jon

> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Cc: Jon Mason <jdmason@kudzu.us>
> ---
>
> v2: Use IS_ALIGNED macro as suggested by Allen
>
> drivers/ntb/hw/mscc/ntb_hw_switchtec.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> index bcd5b6fb3800..6c6f991999b5 100644
> --- a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> +++ b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> @@ -320,6 +320,19 @@ static int switchtec_ntb_mw_set_trans(struct ntb_dev *ntb, int pidx, int widx,
> if (xlate_pos < 12)
> return -EINVAL;
>
> + if (!IS_ALIGNED(addr, BIT_ULL(xlate_pos))) {
> + /*
> + * In certain circumstances we can get a buffer that is
> + * not aligned to its size. (Most of the time
> + * dma_alloc_coherent ensures this). This can happen when
> + * using large buffers allocated by the CMA
> + * (see CMA_CONFIG_ALIGNMENT)
> + */
> + dev_err(&sndev->stdev->dev,
> + "ERROR: Memory window address is not aligned to it's size!\n");
> + return -EINVAL;
> + }
> +
> rc = switchtec_ntb_part_op(sndev, ctl, NTB_CTRL_PART_OP_LOCK,
> NTB_CTRL_PART_STATUS_LOCKED);
> if (rc)
> --
> 2.11.0
>
> --
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