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Commit b0f2853b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
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nvme-pci: take sglist coalescing in dma_map_sg into account 



Some iommu implementations can merge physically and/or virtually
contiguous segments inside sg_map_dma.  The NVMe SGL support does not take
this into account and will warn because of falling off a loop.  Pass the
number of mapped segments to nvme_pci_setup_sgls so that the SGL setup
can take the number of mapped segments into account.

Reported-by: default avatarFangjian (Turing) <f.fangjian@huawei.com>
Fixes: a7a7cbe3 ("nvme-pci: add SGL support")
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarKeith Busch <keith.busch@intel.com>
Reviewed-by: default avatarSagi Grimberg <sagi@rimberg.me>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 20469a37

drivers/nvme/host/pci.c

+9 −12
Original line number Diff line number Diff line
@@ -725,20 +725,19 @@ static void nvme_pci_sgl_set_seg(struct nvme_sgl_desc *sge, 
}



static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,

		struct request *req, struct nvme_rw_command *cmd)

		struct request *req, struct nvme_rw_command *cmd, int entries)

{

	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);

	int length = blk_rq_payload_bytes(req);

	struct dma_pool *pool;

	struct nvme_sgl_desc *sg_list;

	struct scatterlist *sg = iod->sg;

	int entries = iod->nents, i = 0;

	dma_addr_t sgl_dma;

	int i = 0;



	/* setting the transfer type as SGL */

	cmd->flags = NVME_CMD_SGL_METABUF;



	if (length == sg_dma_len(sg)) {

	if (entries == 1) {

		nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);

		return BLK_STS_OK;

	}
@@ -778,13 +777,9 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev, 
		}



		nvme_pci_sgl_set_data(&sg_list[i++], sg);



		length -= sg_dma_len(sg);

		sg = sg_next(sg);

		entries--;

	} while (length > 0);

	} while (--entries > 0);



	WARN_ON(entries > 0);

	return BLK_STS_OK;

}
@@ -796,6 +791,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, 
	enum dma_data_direction dma_dir = rq_data_dir(req) ?

			DMA_TO_DEVICE : DMA_FROM_DEVICE;

	blk_status_t ret = BLK_STS_IOERR;

	int nr_mapped;



	sg_init_table(iod->sg, blk_rq_nr_phys_segments(req));

	iod->nents = blk_rq_map_sg(q, req, iod->sg);
@@ -803,12 +799,13 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, 
		goto out;



	ret = BLK_STS_RESOURCE;

	if (!dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,

				DMA_ATTR_NO_WARN))

	nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,

			DMA_ATTR_NO_WARN);

	if (!nr_mapped)

		goto out;



	if (iod->use_sgl)

		ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw);

		ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped);

	else

		ret = nvme_pci_setup_prps(dev, req, &cmnd->rw);