From a43d304f3abea73883f99287396a6e1eb57c3637 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 12 May 2025 17:16:04 +0200 Subject: [PATCH] nvme-pci: use a better encoding for small prp pool allocations Add a separate flag to encode that the transfer is using the small page sized pool, and use a normal 0..n count for the number of descriptors. Contains improvements and suggestions from Kanchan Joshi and Leon Romanovsky . Signed-off-by: Christoph Hellwig Reviewed-by: Keith Busch Reviewed-by: Kanchan Joshi Reviewed-by: Leon Romanovsky --- drivers/nvme/host/pci.c | 82 ++++++++++++++++++++--------------------- 1 file changed, 39 insertions(+), 43 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index b880168ab520..5017d6c56519 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -229,6 +229,9 @@ struct nvme_queue { enum nvme_iod_flags { /* this command has been aborted by the timeout handler */ IOD_ABORTED = 1U << 0, + + /* uses the small descriptor pool */ + IOD_SMALL_DESCRIPTOR = 1U << 1, }; /* @@ -238,7 +241,7 @@ struct nvme_iod { struct nvme_request req; struct nvme_command cmd; u8 flags; - s8 nr_descriptors; + u8 nr_descriptors; unsigned int dma_len; /* length of single DMA segment mapping */ dma_addr_t first_dma; dma_addr_t meta_dma; @@ -589,13 +592,27 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req, return true; } -static void nvme_free_prps(struct nvme_queue *nvmeq, struct request *req) +static inline struct dma_pool *nvme_dma_pool(struct nvme_queue *nvmeq, + struct nvme_iod *iod) +{ + if (iod->flags & IOD_SMALL_DESCRIPTOR) + return nvmeq->descriptor_pools.small; + return nvmeq->descriptor_pools.large; +} + +static void nvme_free_descriptors(struct nvme_queue *nvmeq, struct request *req) { const int last_prp = NVME_CTRL_PAGE_SIZE / sizeof(__le64) - 1; struct nvme_iod *iod = blk_mq_rq_to_pdu(req); dma_addr_t dma_addr = iod->first_dma; int i; + if (iod->nr_descriptors == 1) { + dma_pool_free(nvme_dma_pool(nvmeq, iod), iod->descriptors[0], + dma_addr); + return; + } + for (i = 0; i < iod->nr_descriptors; i++) { __le64 *prp_list = iod->descriptors[i]; dma_addr_t next_dma_addr = le64_to_cpu(prp_list[last_prp]); @@ -620,15 +637,7 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_queue *nvmeq, WARN_ON_ONCE(!iod->sgt.nents); dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0); - - if (iod->nr_descriptors == 0) - dma_pool_free(nvmeq->descriptor_pools.small, - iod->descriptors[0], iod->first_dma); - else if (iod->nr_descriptors == 1) - dma_pool_free(nvmeq->descriptor_pools.large, - iod->descriptors[0], iod->first_dma); - else - nvme_free_prps(nvmeq, req); + nvme_free_descriptors(nvmeq, req); mempool_free(iod->sgt.sgl, dev->iod_mempool); } @@ -650,7 +659,6 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq, struct request *req, struct nvme_rw_command *cmnd) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); - struct dma_pool *pool; int length = blk_rq_payload_bytes(req); struct scatterlist *sg = iod->sgt.sgl; int dma_len = sg_dma_len(sg); @@ -658,7 +666,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq, int offset = dma_addr & (NVME_CTRL_PAGE_SIZE - 1); __le64 *prp_list; dma_addr_t prp_dma; - int nprps, i; + int i; length -= (NVME_CTRL_PAGE_SIZE - offset); if (length <= 0) { @@ -680,27 +688,23 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq, goto done; } - nprps = DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE); - if (nprps <= (256 / 8)) { - pool = nvmeq->descriptor_pools.small; - iod->nr_descriptors = 0; - } else { - pool = nvmeq->descriptor_pools.large; - iod->nr_descriptors = 1; - } + if (DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE) <= + 256 / sizeof(__le64)) + iod->flags |= IOD_SMALL_DESCRIPTOR; - prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma); - if (!prp_list) { - iod->nr_descriptors = -1; + prp_list = dma_pool_alloc(nvme_dma_pool(nvmeq, iod), GFP_ATOMIC, + &prp_dma); + if (!prp_list) return BLK_STS_RESOURCE; - } - iod->descriptors[0] = prp_list; + iod->descriptors[iod->nr_descriptors++] = prp_list; iod->first_dma = prp_dma; i = 0; for (;;) { if (i == NVME_CTRL_PAGE_SIZE >> 3) { __le64 *old_prp_list = prp_list; - prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma); + + 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; @@ -727,7 +731,7 @@ done: cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma); return BLK_STS_OK; free_prps: - nvme_free_prps(nvmeq, req); + nvme_free_descriptors(nvmeq, req); return BLK_STS_RESOURCE; bad_sgl: WARN(DO_ONCE(nvme_print_sgl, iod->sgt.sgl, iod->sgt.nents), @@ -756,7 +760,6 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_queue *nvmeq, struct request *req, struct nvme_rw_command *cmd) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); - struct dma_pool *pool; struct nvme_sgl_desc *sg_list; struct scatterlist *sg = iod->sgt.sgl; unsigned int entries = iod->sgt.nents; @@ -771,21 +774,14 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_queue *nvmeq, return BLK_STS_OK; } - if (entries <= (256 / sizeof(struct nvme_sgl_desc))) { - pool = nvmeq->descriptor_pools.small; - iod->nr_descriptors = 0; - } else { - pool = nvmeq->descriptor_pools.large; - iod->nr_descriptors = 1; - } + if (entries <= 256 / sizeof(*sg_list)) + iod->flags |= IOD_SMALL_DESCRIPTOR; - sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma); - if (!sg_list) { - iod->nr_descriptors = -1; + sg_list = dma_pool_alloc(nvme_dma_pool(nvmeq, iod), GFP_ATOMIC, + &sgl_dma); + if (!sg_list) return BLK_STS_RESOURCE; - } - - iod->descriptors[0] = sg_list; + iod->descriptors[iod->nr_descriptors++] = sg_list; iod->first_dma = sgl_dma; nvme_pci_sgl_set_seg(&cmd->dptr.sgl, sgl_dma, entries); @@ -982,7 +978,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req) blk_status_t ret; iod->flags = 0; - iod->nr_descriptors = -1; + iod->nr_descriptors = 0; iod->sgt.nents = 0; iod->meta_sgt.nents = 0; -- 2.25.1