Enable BIO_DMABUF_MAP backed requests. On registration we map the dma-buf and store it as a prp list, which is then used to initialise requests. All attached contexts are stored in a new list dmabuf_ctxs, and additions/removals are synchronised with dmabuf_lock.
Suggested-by: Keith Busch <[email protected]> Signed-off-by: Pavel Begunkov <[email protected]> --- drivers/nvme/host/Makefile | 1 + drivers/nvme/host/core.c | 12 +++ drivers/nvme/host/nvme.h | 2 + drivers/nvme/host/pci-dmabuf.c | 165 +++++++++++++++++++++++++++++++++ drivers/nvme/host/pci-dmabuf.h | 73 +++++++++++++++ drivers/nvme/host/pci.c | 93 +++++++++++++++++++ 6 files changed, 346 insertions(+) create mode 100644 drivers/nvme/host/pci-dmabuf.c create mode 100644 drivers/nvme/host/pci-dmabuf.h diff --git a/drivers/nvme/host/Makefile b/drivers/nvme/host/Makefile index 67563a69f7dc..8288b986d713 100644 --- a/drivers/nvme/host/Makefile +++ b/drivers/nvme/host/Makefile @@ -21,6 +21,7 @@ nvme-core-$(CONFIG_NVME_HWMON) += hwmon.o nvme-core-$(CONFIG_NVME_HOST_AUTH) += auth.o nvme-y += pci.o +nvme-$(CONFIG_DMA_SHARED_BUFFER) += pci-dmabuf.o nvme-fabrics-y += fabrics.o diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 7eb0f9fe6b18..2f9b2262f77c 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -2708,6 +2708,17 @@ 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, @@ -2718,6 +2729,7 @@ 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 a643c4723a69..be32e9a5ca5a 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -668,6 +668,8 @@ 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-dmabuf.c b/drivers/nvme/host/pci-dmabuf.c new file mode 100644 index 000000000000..8dab59d93650 --- /dev/null +++ b/drivers/nvme/host/pci-dmabuf.c @@ -0,0 +1,165 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Code for supporting dma-buf I/O maps in the NVMe driver. + * Copyright (C) 2026 Pavel Begunkov <[email protected]> + */ + +#include <linux/dma-resv.h> + +#include "pci-dmabuf.h" + +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); +} + +static 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 nvme_dma_buf_io_ctx *nvme_ctx = ctx->dev_priv; + struct dma_buf_attachment *attach = nvme_ctx->attach; + 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); + + if (ctx->dmabuf->size % NVME_CTRL_PAGE_SIZE) + return ERR_PTR(-EINVAL); + + map = kvmalloc_flex(*map, dma_list, nr_entries); + if (!map) + return ERR_PTR(-ENOMEM); + map->nr_entries = nr_entries; + + 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) || + (dma_addr % 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, sgt); + if (ret) + goto err; + map->sgt = sgt; + return &map->base; +err: + if (sgt) + dma_buf_unmap_attachment(attach, sgt, ctx->dir); + kvfree(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 nvme_dma_buf_io_ctx *nvme_ctx = 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(nvme_ctx->attach, map->sgt, ctx->dir); + kvfree(map); +} + +static void nvme_dma_buf_io_release(struct dma_buf_io_ctx *base_ctx) +{ + struct nvme_dma_buf_io_ctx *ctx = base_ctx->dev_priv; + struct nvme_dma_buf_list *buf_list = ctx->buf_list; + + mutex_lock(&buf_list->lock); + if (!list_empty(&ctx->list)) { + dma_buf_detach(ctx->base->dmabuf, ctx->attach); + list_del_init(&ctx->list); + } + mutex_unlock(&buf_list->lock); + + nvme_put_ctrl(ctx->ctrl); + kfree(ctx); +} + +void __nvme_pci_remove_dmabuf(struct nvme_dma_buf_list *list) +{ + struct nvme_dma_buf_io_ctx *ctx, *tmp; + + mutex_lock(&list->lock); + list_for_each_entry_safe(ctx, tmp, &list->ctxs, list) { + dma_buf_io_detach(ctx->base); + dma_buf_detach(ctx->base->dmabuf, ctx->attach); + list_del_init(&ctx->list); + } + mutex_unlock(&list->lock); +} + +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_init_io_ctx_locked(struct nvme_ctrl *ctrl, + struct nvme_dma_buf_list *buf_list, + struct dma_buf_io_ctx *ctx) +{ + struct nvme_dma_buf_io_ctx *nvme_ctx; + struct dma_buf_attachment *attach; + + nvme_ctx = kzalloc_obj(*nvme_ctx); + if (!nvme_ctx) + return -ENOMEM; + + attach = dma_buf_dynamic_attach(ctx->dmabuf, ctrl->dev, + &nvme_dmabuf_importer_ops, ctx); + if (IS_ERR(attach)) { + kfree(nvme_ctx); + return PTR_ERR(attach); + } + + nvme_get_ctrl(ctrl); + list_add(&nvme_ctx->list, &buf_list->ctxs); + nvme_ctx->attach = attach; + nvme_ctx->base = ctx; + nvme_ctx->ctrl = ctrl; + nvme_ctx->buf_list = buf_list; + ctx->dev_priv = nvme_ctx; + ctx->dev_ops = &nvme_dma_buf_io_ops; + return 0; +} + +int __nvme_init_dma_buf_io_ctx(struct nvme_ctrl *ctrl, + struct nvme_dma_buf_list *buf_list, + struct dma_buf_io_ctx *ctx) +{ + int ret; + + mutex_lock(&buf_list->lock); + ret = nvme_init_io_ctx_locked(ctrl, buf_list, ctx); + mutex_unlock(&buf_list->lock); + return ret; +} diff --git a/drivers/nvme/host/pci-dmabuf.h b/drivers/nvme/host/pci-dmabuf.h new file mode 100644 index 000000000000..8e91f7f4ece5 --- /dev/null +++ b/drivers/nvme/host/pci-dmabuf.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2026 Pavel Begunkov <[email protected]> + */ + +#ifndef _NVME_PCI_DMABUF_H +#define _NVME_PCI_DMABUF_H + +#include <linux/dma-buf-io.h> + +#include "nvme.h" + +struct nvme_dma_buf_list { + struct list_head ctxs; + struct mutex lock; +}; + +struct nvme_dma_buf_io_ctx { + struct dma_buf_attachment *attach; + struct nvme_dma_buf_list *buf_list; + struct dma_buf_io_ctx *base; + struct nvme_ctrl *ctrl; + struct list_head list; +}; + +struct nvme_dmabuf_map { + struct dma_buf_io_map base; + struct sg_table *sgt; + unsigned nr_entries; + dma_addr_t dma_list[] __counted_by(nr_entries); +}; + +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 inline struct nvme_dmabuf_map *nvme_req_to_map(struct request *req) +{ + struct dma_buf_io_map *map = req->bio->bi_dmabuf_map; + + return to_nvme_dmabuf_map(map); +} + +void __nvme_pci_remove_dmabuf(struct nvme_dma_buf_list *list); +int __nvme_init_dma_buf_io_ctx(struct nvme_ctrl *ctrl, + struct nvme_dma_buf_list *buf_list, + struct dma_buf_io_ctx *ctx); + +static inline void nvme_pci_remove_dmabuf(struct nvme_dma_buf_list *list) +{ + if (IS_ENABLED(CONFIG_DMA_SHARED_BUFFER)) + __nvme_pci_remove_dmabuf(list); +} + +static inline int nvme_init_dma_buf_io_ctx(struct nvme_ctrl *ctrl, + struct nvme_dma_buf_list *buf_list, + struct dma_buf_io_ctx *ctx) +{ + if (!IS_ENABLED(CONFIG_DMA_SHARED_BUFFER)) + return -EOPNOTSUPP; + return __nvme_init_dma_buf_io_ctx(ctrl, buf_list, ctx); +} + +static inline void nvme_init_buf_list(struct nvme_dma_buf_list *buf_list) +{ + INIT_LIST_HEAD(&buf_list->ctxs); + mutex_init(&buf_list->lock); +} + + +#endif /* _NVME_PCI_DMABUF_H */ \ No newline at end of file diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index a65b77726e4b..a0506c93fa16 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -30,6 +30,7 @@ #include "trace.h" #include "nvme.h" +#include "pci-dmabuf.h" #define SQ_SIZE(q) ((q)->q_depth << (q)->sqes) #define CQ_SIZE(q) ((q)->q_depth * sizeof(struct nvme_completion)) @@ -318,6 +319,7 @@ struct nvme_dev { bool hmb; struct sg_table *hmb_sgt; mempool_t *dmavec_mempool; + struct nvme_dma_buf_list dmabufs; /* shadow doorbell buffer support: */ __le32 *dbbuf_dbs; @@ -865,6 +867,76 @@ static void nvme_free_descriptors(struct request *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 nvme_dmabuf_map *map = nvme_req_to_map(req); + unsigned bvec_done = req->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; + + 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: + iod->cmd.common.dptr.prp1 = cpu_to_le64(prp1_dma); + iod->cmd.common.dptr.prp2 = cpu_to_le64(prp2_dma); + 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); @@ -943,6 +1015,9 @@ 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)) + goto out_free_desc; + if (iod->flags & IOD_SINGLE_SEGMENT) { static_assert(offsetof(union nvme_data_ptr, prp1) == offsetof(union nvme_data_ptr, sgl.addr)); @@ -967,6 +1042,7 @@ static void nvme_unmap_data(struct request *req) nvme_free_prps(req, attrs); } +out_free_desc: if (iod->nr_descriptors) nvme_free_descriptors(req); } @@ -1257,6 +1333,9 @@ 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. @@ -3357,6 +3436,9 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown) nvme_unquiesce_admin_queue(&dev->ctrl); } mutex_unlock(&dev->shutdown_lock); + + if (shutdown) + nvme_pci_remove_dmabuf(&dev->dmabufs); } static int nvme_disable_prepare_reset(struct nvme_dev *dev, bool shutdown) @@ -3564,6 +3646,14 @@ static unsigned long nvme_pci_get_virt_boundary(struct nvme_ctrl *ctrl, return 0; } +static int nvme_pci_init_dma_buf_io_ctx(struct nvme_ctrl *ctrl, + struct dma_buf_io_ctx *ctx) +{ + struct nvme_dev *dev = to_nvme_dev(ctrl); + + return nvme_init_dma_buf_io_ctx(ctrl, &dev->dmabufs, ctx); +} + static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = { .name = "pcie", .module = THIS_MODULE, @@ -3579,6 +3669,7 @@ 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, + .init_dma_buf_io_ctx = nvme_pci_init_dma_buf_io_ctx, }; static int nvme_dev_map(struct nvme_dev *dev) @@ -3701,6 +3792,7 @@ static struct nvme_dev *nvme_pci_alloc_dev(struct pci_dev *pdev, return ERR_PTR(-ENOMEM); INIT_WORK(&dev->ctrl.reset_work, nvme_reset_work); mutex_init(&dev->shutdown_lock); + nvme_init_buf_list(&dev->dmabufs); dev->nr_write_queues = write_queues; dev->nr_poll_queues = poll_queues; @@ -4346,5 +4438,6 @@ MODULE_AUTHOR("Matthew Wilcox <[email protected]>"); 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
