From: Eduard Hasenleithner <eduard@xxxxxxxxxxxxxxxx> [ 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: Eduard Hasenleithner <eduard@xxxxxxxxxxxxxxxx> [changelog, use existing define, kernel coding style] Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/nvme/host/core.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 393913e2fb233..154ce69ae2941 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -611,8 +611,14 @@ 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 @@ -652,7 +658,7 @@ 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; -- 2.20.1
