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Commit ffa56cbd authored by Eduard Hasenleithner's avatar Eduard Hasenleithner Committed by Greg Kroah-Hartman
Browse files

nvme: Discard workaround for non-conformant devices 

[ Upstream commit 530436c45ef2e446c12538a400e465929a0b3ade ]

Users observe IOMMU related errors when performing discard on nvme from
non-compliant nvme devices reading beyond the end of the DMA mapped
ranges to discard.

Two different variants of this behavior have been observed: SM22XX
controllers round up the read size to a multiple of 512 bytes, and Phison
E12 unconditionally reads the maximum discard size allowed by the spec
(256 segments or 4kB).

Make nvme_setup_discard unconditionally allocate the maximum DSM buffer
so the driver DMA maps a memory range that will always succeed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=202665

 many
Signed-off-by: default avatarEduard Hasenleithner <eduard@hasenleithner.at>
[changelog, use existing define, kernel coding style]
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 7cc2f557

drivers/nvme/host/core.c

+9 −3
Original line number Diff line number Diff line
@@ -551,8 +551,14 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req, 
	struct nvme_dsm_range *range;

	struct bio *bio;



	range = kmalloc_array(segments, sizeof(*range),

				GFP_ATOMIC | __GFP_NOWARN);

	/*

	 * Some devices do not consider the DSM 'Number of Ranges' field when

	 * determining how much data to DMA. Always allocate memory for maximum

	 * number of segments to prevent device reading beyond end of buffer.

	 */

	static const size_t alloc_size = sizeof(*range) * NVME_DSM_MAX_RANGES;



	range = kzalloc(alloc_size, GFP_ATOMIC | __GFP_NOWARN);

	if (!range) {

		/*

		 * If we fail allocation our range, fallback to the controller
@@ -593,7 +599,7 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req, 


	req->special_vec.bv_page = virt_to_page(range);

	req->special_vec.bv_offset = offset_in_page(range);

	req->special_vec.bv_len = sizeof(*range) * segments;

	req->special_vec.bv_len = alloc_size;

	req->rq_flags |= RQF_SPECIAL_PAYLOAD;



	return BLK_STS_OK;