From: Keith Busch <kbusch@kernel.org>
Date: Wed, 20 May 2020 19:22:53 -0700
Subject: [PATCH] nvme: set dma alignment to qword
Git-commit: 3b2a1ebceba3e03b17ef0970bb7757a3a64cdc8b
Patch-mainline: v5.8-rc1
References: jsc#SLE-15608

The default dma alignment mask is 511, which is much larger than any nvme
controller requires. NVMe controllers accept qword aligned DMA addresses,
so set the request_queue constraints to that. This can help avoid bounce
buffers on user passthrough commands.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/nvme/host/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a3a4dbc59af1..569671e264b5 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2322,6 +2322,7 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
 		blk_queue_max_segments(q, min_t(u32, max_segments, USHRT_MAX));
 	}
 	blk_queue_virt_boundary(q, ctrl->page_size - 1);
+	blk_queue_dma_alignment(q, 7);
 	if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
 		vwc = true;
 	blk_queue_write_cache(q, vwc, vwc);
-- 
2.16.4