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Subject[PATCH AUTOSEL for 4.15 106/189] ntb_hw_switchtec: Check for alignment of the buffer in mw_set_trans()
Date
From: Logan Gunthorpe <logang@deltatee.com>

[ Upstream commit 1e2fd202f8593985cdadca32e0c322f98e7fe7cb ]

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.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
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 ca0334a6b759..fc9ce0a31c04 100644
--- a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
+++ b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
@@ -315,6 +315,19 @@ 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)
--
2.15.1
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