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Tue, 28 Jul 2026 14:29:57 -0700 (PDT) From: Pavel Begunkov To: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Cc: asml.silence@gmail.com, Alexander Viro , Christian Brauner , Andrew Morton , Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Jason Gunthorpe , Damien Le Moal , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , Vishal Verma , David Sterba , Ilya Dryomov , dm-devel@lists.linux.dev, nvdimm@lists.linux.dev, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org Subject: [PATCH v4 08/14] nvme-pci: implement dma_token backed requests Date: Tue, 28 Jul 2026 22:29:20 +0100 Message-ID: <19e5c945ea8114320c10f7951d19197d48b59249.1785274111.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Enable BIO_DMABUF_MAP backed requests. It creates a prp list for the dmabuf when it's mapped, which is then used to initialise requests. Suggested-by: Keith Busch Signed-off-by: Pavel Begunkov --- drivers/nvme/host/core.c | 12 ++ drivers/nvme/host/nvme.h | 2 + drivers/nvme/host/pci.c | 259 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 273 insertions(+) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 453c1f0b2dd0..ce66a1843bec 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -2676,6 +2676,17 @@ static int nvme_report_zones(struct gendisk *disk, sector_t sector, #define nvme_report_zones NULL #endif /* CONFIG_BLK_DEV_ZONED */ +static int nvme_init_dma_buf_io_ctx(struct block_device *bdev, + struct dma_buf_io_ctx *ctx) +{ + struct nvme_ns *ns = bdev->bd_disk->private_data; + struct nvme_ctrl *ctrl = ns->ctrl; + + if (!ctrl->ops->init_dma_buf_io_ctx) + return -EINVAL; + return ctrl->ops->init_dma_buf_io_ctx(ctrl, ctx); +} + const struct block_device_operations nvme_bdev_ops = { .owner = THIS_MODULE, .ioctl = nvme_ioctl, @@ -2686,6 +2697,7 @@ const struct block_device_operations nvme_bdev_ops = { .get_unique_id = nvme_get_unique_id, .report_zones = nvme_report_zones, .pr_ops = &nvme_pr_ops, + .init_dma_buf_io_ctx = nvme_init_dma_buf_io_ctx, }; static int nvme_wait_ready(struct nvme_ctrl *ctrl, u32 mask, u32 val, diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 824651cc898d..034c31af8fec 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -652,6 +652,8 @@ struct nvme_ctrl_ops { int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size); void (*print_device_info)(struct nvme_ctrl *ctrl); bool (*supports_pci_p2pdma)(struct nvme_ctrl *ctrl); + int (*init_dma_buf_io_ctx)(struct nvme_ctrl *ctrl, + struct dma_buf_io_ctx *ctx); unsigned long (*get_virt_boundary)(struct nvme_ctrl *ctrl, bool is_admin); }; diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 69932d640b53..f1b67c191892 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -27,6 +27,8 @@ #include #include #include +#include +#include #include "trace.h" #include "nvme.h" @@ -393,6 +395,13 @@ struct nvme_queue { struct completion delete_done; }; +struct nvme_dmabuf_map { + struct dma_buf_io_map base; + struct sg_table *sgt; + unsigned nr_entries; + dma_addr_t dma_list[]; +}; + /* bits for iod->flags */ enum nvme_iod_flags { /* this command has been aborted by the timeout handler */ @@ -859,6 +868,138 @@ static void nvme_free_descriptors(struct request *req) } } +static inline struct nvme_dmabuf_map * +to_nvme_dmabuf_map(struct dma_buf_io_map *map) +{ + return container_of(map, struct nvme_dmabuf_map, base); +} + +static void nvme_dmabuf_map_sync_for_cpu(struct nvme_dev *nvme_dev, + struct request *req) +{ + struct device *dev = nvme_dev->dev; + enum dma_data_direction dma_dir; + struct bio *bio = req->bio; + struct nvme_dmabuf_map *map = to_nvme_dmabuf_map(bio->bi_dmabuf_map); + dma_addr_t *dma_list = map->dma_list; + unsigned offset = bio->bi_iter.bi_offset; + unsigned map_idx = offset / NVME_CTRL_PAGE_SIZE; + int length = blk_rq_payload_bytes(req) + + (offset & (NVME_CTRL_PAGE_SIZE - 1)); + + dma_dir = rq_data_dir(req) == READ ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + while (length > 0) { + dma_sync_single_for_cpu(dev, dma_list[map_idx++], + NVME_CTRL_PAGE_SIZE, dma_dir); + length -= NVME_CTRL_PAGE_SIZE; + } +} + +static void nvme_dmabuf_map_sync_for_device(struct nvme_dev *nvme_dev, + struct request *req) +{ + struct device *dev = nvme_dev->dev; + enum dma_data_direction dma_dir; + struct bio *bio = req->bio; + struct nvme_dmabuf_map *map = to_nvme_dmabuf_map(bio->bi_dmabuf_map); + dma_addr_t *dma_list = map->dma_list; + unsigned offset = bio->bi_iter.bi_offset; + unsigned map_idx = offset / NVME_CTRL_PAGE_SIZE; + int length = blk_rq_payload_bytes(req) + + (offset & (NVME_CTRL_PAGE_SIZE - 1)); + + dma_dir = rq_data_dir(req) == READ ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + while (length > 0) { + dma_sync_single_for_device(dev, dma_list[map_idx++], + NVME_CTRL_PAGE_SIZE, dma_dir); + length -= NVME_CTRL_PAGE_SIZE; + } +} + +static void nvme_rq_clean_dmabuf_map(struct nvme_dev *dev, + struct request *req) +{ + struct nvme_iod *iod = blk_mq_rq_to_pdu(req); + + nvme_dmabuf_map_sync_for_cpu(dev, req); + + if (!(iod->flags & IOD_SINGLE_SEGMENT)) + nvme_free_descriptors(req); +} + +static blk_status_t nvme_rq_setup_dmabuf_map(struct request *req, + struct nvme_queue *nvmeq) +{ + struct nvme_iod *iod = blk_mq_rq_to_pdu(req); + struct bio *bio = req->bio; + struct nvme_dmabuf_map *map = to_nvme_dmabuf_map(bio->bi_dmabuf_map); + unsigned bvec_done = bio->bi_iter.bi_offset; + unsigned map_idx = bvec_done / NVME_CTRL_PAGE_SIZE; + unsigned offset = bvec_done & (NVME_CTRL_PAGE_SIZE - 1); + int length = blk_rq_payload_bytes(req) - (NVME_CTRL_PAGE_SIZE - offset); + dma_addr_t *dma_list = map->dma_list; + u64 prp1_dma = dma_list[map_idx++] + offset; + u64 dma_addr, prp2_dma; + dma_addr_t prp_dma; + __le64 *prp_list; + unsigned i; + + nvme_dmabuf_map_sync_for_device(nvmeq->dev, req); + + if (length <= 0) { + prp2_dma = 0; + goto done; + } + + if (length <= NVME_CTRL_PAGE_SIZE) { + prp2_dma = dma_list[map_idx]; + goto done; + } + + if (DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE) <= + NVME_SMALL_POOL_SIZE / sizeof(__le64)) + iod->flags |= IOD_SMALL_DESCRIPTOR; + + prp_list = dma_pool_alloc(nvme_dma_pool(nvmeq, iod), GFP_ATOMIC, + &prp_dma); + if (!prp_list) + return BLK_STS_RESOURCE; + + iod->descriptors[iod->nr_descriptors++] = prp_list; + prp2_dma = prp_dma; + i = 0; + for (;;) { + if (i == NVME_CTRL_PAGE_SIZE >> 3) { + __le64 *old_prp_list = prp_list; + + prp_list = dma_pool_alloc(nvmeq->descriptor_pools.large, + GFP_ATOMIC, &prp_dma); + if (!prp_list) + goto free_prps; + iod->descriptors[iod->nr_descriptors++] = prp_list; + prp_list[0] = old_prp_list[i - 1]; + old_prp_list[i - 1] = cpu_to_le64(prp_dma); + i = 1; + } + + dma_addr = dma_list[map_idx++]; + prp_list[i++] = cpu_to_le64(dma_addr); + + length -= NVME_CTRL_PAGE_SIZE; + if (length <= 0) + break; + } +done: + iod->cmd.common.dptr.prp1 = cpu_to_le64(prp1_dma); + iod->cmd.common.dptr.prp2 = cpu_to_le64(prp2_dma); + return BLK_STS_OK; +free_prps: + nvme_free_descriptors(req); + return BLK_STS_RESOURCE; +} + static void nvme_free_prps(struct request *req, unsigned int attrs) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); @@ -937,6 +1078,11 @@ static void nvme_unmap_data(struct request *req) struct device *dma_dev = nvmeq->dev->dev; unsigned int attrs = 0; + if (blk_mq_rq_is_dmabuf(req)) { + nvme_rq_clean_dmabuf_map(nvmeq->dev, req); + return; + } + if (iod->flags & IOD_SINGLE_SEGMENT) { static_assert(offsetof(union nvme_data_ptr, prp1) == offsetof(union nvme_data_ptr, sgl.addr)); @@ -1251,6 +1397,9 @@ static blk_status_t nvme_map_data(struct request *req) struct blk_dma_iter iter; blk_status_t ret; + if (blk_mq_rq_is_dmabuf(req)) + return nvme_rq_setup_dmabuf_map(req, nvmeq); + /* * Try to skip the DMA iterator for single segment requests, as that * significantly improves performances for small I/O sizes. @@ -2269,6 +2418,112 @@ static int nvme_create_queue(struct nvme_queue *nvmeq, int qid, bool polled) return result; } +#if defined(CONFIG_DMA_SHARED_BUFFER) +static void nvme_dmabuf_invalidate_mappings(struct dma_buf_attachment *attach) +{ + struct dma_buf_io_ctx *ctx = attach->importer_priv; + + dma_buf_io_invalidate_mappings(ctx); +} + +const struct dma_buf_attach_ops nvme_dmabuf_importer_ops = { + .invalidate_mappings = nvme_dmabuf_invalidate_mappings, + .allow_peer2peer = true, +}; + +static struct dma_buf_io_map *nvme_dma_buf_io_map(struct dma_buf_io_ctx *ctx) +{ + unsigned nr_entries = ctx->dmabuf->size / NVME_CTRL_PAGE_SIZE; + struct dma_buf_attachment *attach = ctx->dev_priv; + unsigned long tmp, i = 0; + struct nvme_dmabuf_map *map; + struct scatterlist *sg; + struct sg_table *sgt; + int ret; + + dma_resv_assert_held(ctx->dmabuf->resv); + + map = kmalloc_flex(*map, dma_list, nr_entries); + if (!map) + return ERR_PTR(-ENOMEM); + + sgt = dma_buf_map_attachment(attach, ctx->dir); + if (IS_ERR(sgt)) { + ret = PTR_ERR(sgt); + sgt = NULL; + goto err; + } + + for_each_sgtable_dma_sg(sgt, sg, tmp) { + dma_addr_t dma_addr = sg_dma_address(sg); + unsigned long sg_len = sg_dma_len(sg); + + if (sg_len % NVME_CTRL_PAGE_SIZE) { + ret = -EINVAL; + goto err; + } + + while (sg_len) { + map->dma_list[i++] = dma_addr; + dma_addr += NVME_CTRL_PAGE_SIZE; + sg_len -= NVME_CTRL_PAGE_SIZE; + } + } + + ret = dma_buf_io_init_map(ctx, &map->base); + if (ret) + goto err; + map->nr_entries = nr_entries; + map->sgt = sgt; + return &map->base; +err: + if (sgt) + dma_buf_unmap_attachment(attach, sgt, ctx->dir); + kfree(map); + return ERR_PTR(ret); +} + +static void nvme_dma_buf_io_unmap(struct dma_buf_io_ctx *ctx, + struct dma_buf_io_map *map_base) +{ + struct dma_buf_attachment *attach = ctx->dev_priv; + struct nvme_dmabuf_map *map = to_nvme_dmabuf_map(map_base); + + dma_resv_assert_held(ctx->dmabuf->resv); + + dma_buf_unmap_attachment(attach, map->sgt, ctx->dir); +} + +static void nvme_dma_buf_io_release(struct dma_buf_io_ctx *ctx) +{ + struct dma_buf_attachment *attach = ctx->dev_priv; + + dma_buf_detach(ctx->dmabuf, attach); +} + +const struct dma_buf_io_ops nvme_dma_buf_io_ops = { + .map = nvme_dma_buf_io_map, + .unmap = nvme_dma_buf_io_unmap, + .release = nvme_dma_buf_io_release, +}; + +static int nvme_pci_init_dma_buf_io_ctx(struct nvme_ctrl *ctrl, + struct dma_buf_io_ctx *ctx) +{ + struct dma_buf_attachment *attach; + struct nvme_dev *dev = to_nvme_dev(ctrl); + + attach = dma_buf_dynamic_attach(ctx->dmabuf, dev->dev, + &nvme_dmabuf_importer_ops, ctx); + if (IS_ERR(attach)) + return PTR_ERR(attach); + + ctx->dev_priv = attach; + ctx->dev_ops = &nvme_dma_buf_io_ops; + return 0; +} +#endif + static const struct blk_mq_ops nvme_mq_admin_ops = { .queue_rq = nvme_queue_rq, .complete = nvme_pci_complete_rq, @@ -3563,6 +3818,9 @@ static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = { .print_device_info = nvme_pci_print_device_info, .supports_pci_p2pdma = nvme_pci_supports_pci_p2pdma, .get_virt_boundary = nvme_pci_get_virt_boundary, +#if defined(CONFIG_DMA_SHARED_BUFFER) + .init_dma_buf_io_ctx = nvme_pci_init_dma_buf_io_ctx, +#endif }; static int nvme_dev_map(struct nvme_dev *dev) @@ -4327,5 +4585,6 @@ MODULE_AUTHOR("Matthew Wilcox "); MODULE_LICENSE("GPL"); MODULE_VERSION("1.0"); MODULE_DESCRIPTION("NVMe host PCIe transport driver"); +MODULE_IMPORT_NS("DMA_BUF"); module_init(nvme_init); module_exit(nvme_exit); -- 2.54.0