[PATCHv3 1/3] nvme-pci: add support for sgl metadata

Keith Busch
2024-11-18T15:58:10Z

From: Keith Busch <kbusch@kernel.org>

Supporting this mode allows creating and merging multi-segment metadata
requests that wouldn't be possible otherwise. It also allows directly
using user space requests that straddle physically discontiguous pages.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
drivers/nvme/host/nvme.h | 7 ++
drivers/nvme/host/pci.c | 144 +++++++++++++++++++++++++++++++++++----
include/linux/nvme.h | 1 +
3 files changed, 137 insertions(+), 15 deletions(-)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 900719c4c70c1..5ef284a376cc7 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -1126,6 +1126,13 @@ static inline bool nvme_ctrl_sgl_supported(struct nvme_ctrl *ctrl)
return ctrl->sgls & ((1 << 0) | (1 << 1));
}

+static inline bool nvme_ctrl_meta_sgl_supported(struct nvme_ctrl *ctrl)
+{
+ if (ctrl->ops->flags & NVME_F_FABRICS)
+ return true;
+ return ctrl->sgls & NVME_CTRL_SGLS_MSDS;
+}
+
#ifdef CONFIG_NVME_HOST_AUTH
int __init nvme_init_auth(void);
void __exit nvme_exit_auth(void);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 5f2e3ad2cc521..c6c3ae3a7c434 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -43,6 +43,7 @@
*/
#define NVME_MAX_KB_SZ 8192
#define NVME_MAX_SEGS 128
+#define NVME_MAX_META_SEGS 15
#define NVME_MAX_NR_ALLOCATIONS 5

static int use_threaded_interrupts;
@@ -144,6 +145,7 @@ struct nvme_dev {
struct sg_table *hmb_sgt;

mempool_t *iod_mempool;
+ mempool_t *iod_meta_mempool;

/* shadow doorbell buffer support: */
__le32 *dbbuf_dbs;
@@ -239,6 +241,8 @@ struct nvme_iod {
dma_addr_t first_dma;
dma_addr_t meta_dma;
struct sg_table sgt;
+ struct sg_table meta_sgt;
+ union nvme_descriptor meta_list;
union nvme_descriptor list[NVME_MAX_NR_ALLOCATIONS];
};

@@ -506,6 +510,14 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx)
spin_unlock(&nvmeq->sq_lock);
}

+static inline bool nvme_pci_metadata_use_sgls(struct nvme_dev *dev,
+ struct request *req)
+{
+ if (!nvme_ctrl_meta_sgl_supported(&dev->ctrl))
+ return false;
+ return req->nr_integrity_segments > 1;
+}
+
static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
int nseg)
{
@@ -518,6 +530,8 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
return false;
if (!nvmeq->qid)
return false;
+ if (nvme_pci_metadata_use_sgls(dev, req))
+ return true;
if (!sgl_threshold || avg_seg_size < sgl_threshold)
return false;
return true;
@@ -780,7 +794,8 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
struct bio_vec bv = req_bvec(req);

if (!is_pci_p2pdma_page(bv.bv_page)) {
- if ((bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) +
+ if (!nvme_pci_metadata_use_sgls(dev, req) &&
+ (bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) +
bv.bv_len <= NVME_CTRL_PAGE_SIZE * 2)
return nvme_setup_prp_simple(dev, req,
&cmnd->rw, &bv);
@@ -824,11 +839,69 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
return ret;
}

-static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req,
- struct nvme_command *cmnd)
+static blk_status_t nvme_pci_setup_meta_sgls(struct nvme_dev *dev,
+ struct request *req)
+{
+ struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+ struct nvme_rw_command *cmnd = &iod->cmd.rw;
+ struct nvme_sgl_desc *sg_list;
+ struct scatterlist *sgl, *sg;
+ unsigned int entries;
+ dma_addr_t sgl_dma;
+ int rc, i;
+
+ iod->meta_sgt.sgl = mempool_alloc(dev->iod_meta_mempool, GFP_ATOMIC);
+ if (!iod->meta_sgt.sgl)
+ return BLK_STS_RESOURCE;
+
+ sg_init_table(iod->meta_sgt.sgl, req->nr_integrity_segments);
+ iod->meta_sgt.orig_nents = blk_rq_map_integrity_sg(req,
+ iod->meta_sgt.sgl);
+ if (!iod->meta_sgt.orig_nents)
+ goto out_free_sg;
+
+ rc = dma_map_sgtable(dev->dev, &iod->meta_sgt, rq_dma_dir(req),
+ DMA_ATTR_NO_WARN);
+ if (rc)
+ goto out_free_sg;
+
+ sg_list = dma_pool_alloc(dev->prp_small_pool, GFP_ATOMIC, &sgl_dma);
+ if (!sg_list)
+ goto out_unmap_sg;
+
+ entries = iod->meta_sgt.nents;
+ iod->meta_list.sg_list = sg_list;
+ iod->meta_dma = sgl_dma;
+
+ cmnd->flags = NVME_CMD_SGL_METASEG;
+ cmnd->metadata = cpu_to_le64(sgl_dma);
+
+ sgl = iod->meta_sgt.sgl;
+ if (entries == 1) {
+ nvme_pci_sgl_set_data(sg_list, sgl);
+ return BLK_STS_OK;
+ }
+
+ sgl_dma += sizeof(*sg_list);
+ nvme_pci_sgl_set_seg(sg_list, sgl_dma, entries);
+ for_each_sg(sgl, sg, entries, i)
+ nvme_pci_sgl_set_data(&sg_list[i + 1], sg);
+
+ return BLK_STS_OK;
+
+out_unmap_sg:
+ dma_unmap_sgtable(dev->dev, &iod->meta_sgt, rq_dma_dir(req), 0);
+out_free_sg:
+ mempool_free(iod->meta_sgt.sgl, dev->iod_meta_mempool);
+ return BLK_STS_RESOURCE;
+}
+
+static blk_status_t nvme_pci_setup_meta_mptr(struct nvme_dev *dev,
+ struct request *req)
{
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
struct bio_vec bv = rq_integrity_vec(req);
+ struct nvme_command *cmnd = &iod->cmd;

iod->meta_dma = dma_map_bvec(dev->dev, &bv, rq_dma_dir(req), 0);
if (dma_mapping_error(dev->dev, iod->meta_dma))
@@ -837,6 +910,13 @@ static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req,
return BLK_STS_OK;
}

+static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req)
+{
+ if (nvme_pci_metadata_use_sgls(dev, req))
+ return nvme_pci_setup_meta_sgls(dev, req);
+ return nvme_pci_setup_meta_mptr(dev, req);
+}
+
static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
{
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
@@ -845,6 +925,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
iod->aborted = false;
iod->nr_allocations = -1;
iod->sgt.nents = 0;
+ iod->meta_sgt.nents = 0;

ret = nvme_setup_cmd(req->q->queuedata, req);
if (ret)
@@ -857,7 +938,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
}

if (blk_integrity_rq(req)) {
- ret = nvme_map_metadata(dev, req, &iod->cmd);
+ ret = nvme_map_metadata(dev, req);
if (ret)
goto out_unmap_data;
}
@@ -955,17 +1036,31 @@ static void nvme_queue_rqs(struct rq_list *rqlist)
*rqlist = requeue_list;
}

+static __always_inline void nvme_unmap_metadata(struct nvme_dev *dev,
+ struct request *req)
+{
+ struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+
+ if (!iod->meta_sgt.nents) {
+ dma_unmap_page(dev->dev, iod->meta_dma,
+ rq_integrity_vec(req).bv_len,
+ rq_dma_dir(req));
+ return;
+ }
+
+ dma_pool_free(dev->prp_small_pool, iod->meta_list.sg_list,
+ iod->meta_dma);
+ dma_unmap_sgtable(dev->dev, &iod->meta_sgt, rq_dma_dir(req), 0);
+ mempool_free(iod->meta_sgt.sgl, dev->iod_meta_mempool);
+}
+
static __always_inline void nvme_pci_unmap_rq(struct request *req)
{
struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
struct nvme_dev *dev = nvmeq->dev;

- if (blk_integrity_rq(req)) {
- struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-
- dma_unmap_page(dev->dev, iod->meta_dma,
- rq_integrity_vec(req).bv_len, rq_dma_dir(req));
- }
+ if (blk_integrity_rq(req))
+ nvme_unmap_metadata(dev, req);

if (blk_rq_nr_phys_segments(req))
nvme_unmap_data(dev, req);
@@ -2761,6 +2856,7 @@ static void nvme_release_prp_pools(struct nvme_dev *dev)

static int nvme_pci_alloc_iod_mempool(struct nvme_dev *dev)
{
+ size_t meta_size = sizeof(struct scatterlist) * (NVME_MAX_META_SEGS + 1);
size_t alloc_size = sizeof(struct scatterlist) * NVME_MAX_SEGS;

dev->iod_mempool = mempool_create_node(1,
@@ -2769,7 +2865,18 @@ static int nvme_pci_alloc_iod_mempool(struct nvme_dev *dev)
dev_to_node(dev->dev));
if (!dev->iod_mempool)
return -ENOMEM;
+
+ dev->iod_meta_mempool = mempool_create_node(1,
+ mempool_kmalloc, mempool_kfree,
+ (void *)meta_size, GFP_KERNEL,
+ dev_to_node(dev->dev));
+ if (!dev->iod_meta_mempool)
+ goto free;
+
return 0;
+free:
+ mempool_destroy(dev->iod_mempool);
+ return -ENOMEM;
}

static void nvme_free_tagset(struct nvme_dev *dev)
@@ -2834,6 +2941,11 @@ static void nvme_reset_work(struct work_struct *work)
if (result)
goto out;

+ if (nvme_ctrl_meta_sgl_supported(&dev->ctrl))
+ dev->ctrl.max_integrity_segments = NVME_MAX_META_SEGS;
+ else
+ dev->ctrl.max_integrity_segments = 1;
+
nvme_dbbuf_dma_alloc(dev);

result = nvme_setup_host_mem(dev);
@@ -3101,11 +3213,6 @@ static struct nvme_dev *nvme_pci_alloc_dev(struct pci_dev *pdev,
dev->ctrl.max_hw_sectors = min_t(u32,
NVME_MAX_KB_SZ << 1, dma_opt_mapping_size(&pdev->dev) >> 9);
dev->ctrl.max_segments = NVME_MAX_SEGS;
-
- /*
- * There is no support for SGLs for metadata (yet), so we are limited to
- * a single integrity segment for the separate metadata pointer.
- */
dev->ctrl.max_integrity_segments = 1;
return dev;

@@ -3168,6 +3275,11 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
if (result)
goto out_disable;

+ if (nvme_ctrl_meta_sgl_supported(&dev->ctrl))
+ dev->ctrl.max_integrity_segments = NVME_MAX_META_SEGS;
+ else
+ dev->ctrl.max_integrity_segments = 1;
+
nvme_dbbuf_dma_alloc(dev);

result = nvme_setup_host_mem(dev);
@@ -3210,6 +3322,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
nvme_free_queues(dev, 0);
out_release_iod_mempool:
mempool_destroy(dev->iod_mempool);
+ mempool_destroy(dev->iod_meta_mempool);
out_release_prp_pools:
nvme_release_prp_pools(dev);
out_dev_unmap:
@@ -3275,6 +3388,7 @@ static void nvme_remove(struct pci_dev *pdev)
nvme_dbbuf_dma_free(dev);
nvme_free_queues(dev, 0);
mempool_destroy(dev->iod_mempool);
+ mempool_destroy(dev->iod_meta_mempool);
nvme_release_prp_pools(dev);
nvme_dev_unmap(dev);
nvme_uninit_ctrl(&dev->ctrl);
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 0a6e22038ce36..5873ce859cc8b 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -389,6 +389,7 @@ enum {
NVME_CTRL_CTRATT_PREDICTABLE_LAT = 1 << 5,
NVME_CTRL_CTRATT_NAMESPACE_GRANULARITY = 1 << 7,
NVME_CTRL_CTRATT_UUID_LIST = 1 << 9,
+ NVME_CTRL_SGLS_MSDS = 1 << 19,
};

struct nvme_lbaf {
--
2.43.5