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: Fangjian (Turing) <[email protected]> Fixes: a7a7cbe3 ("nvme-pci: add SGL support") Signed-off-by: Christoph Hellwig <[email protected]> Reviewed-by: Keith Busch <[email protected]> Reviewed-by: Sagi Grimberg <[email protected]> --- drivers/nvme/host/pci.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index a7e94cc3c70e..4276ebfff22b 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -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); -- 2.14.2
