// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2016 HGST, a Western Digital Company.
 */
#include <linux/memremap.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/pci-p2pdma.h>
#include <rdma/mr_pool.h>
#include <rdma/rw.h>

enum {
        RDMA_RW_SINGLE_WR,
        RDMA_RW_MULTI_WR,
        RDMA_RW_MR,
        RDMA_RW_SIG_MR,
        RDMA_RW_IOVA,
};

static bool rdma_rw_force_mr;
module_param_named(force_mr, rdma_rw_force_mr, bool, 0);
MODULE_PARM_DESC(force_mr, "Force usage of MRs for RDMA READ/WRITE operations");

/*
 * Report whether memory registration should be used. Memory registration must
 * be used for iWarp devices because of iWARP-specific limitations. Memory
 * registration is also enabled if registering memory might yield better
 * performance than using multiple SGE entries, see rdma_rw_io_needs_mr()
 */
static inline bool rdma_rw_can_use_mr(struct ib_device *dev, u32 port_num)
{
        if (rdma_protocol_iwarp(dev, port_num))
                return true;
        if (dev->attrs.max_sgl_rd)
                return true;
        if (unlikely(rdma_rw_force_mr))
                return true;
        return false;
}

/*
 * Check if the device will use memory registration for this RW operation.
 * For RDMA READs we must use MRs on iWarp and can optionally use them as an
 * optimization otherwise.  Additionally we have a debug option to force usage
 * of MRs to help testing this code path.
 */
static inline bool rdma_rw_io_needs_mr(struct ib_device *dev, u32 port_num,
                enum dma_data_direction dir, int dma_nents)
{
        if (dir == DMA_FROM_DEVICE) {
                if (rdma_protocol_iwarp(dev, port_num))
                        return true;
                if (dev->attrs.max_sgl_rd && dma_nents > dev->attrs.max_sgl_rd)
                        return true;
        }
        if (unlikely(rdma_rw_force_mr))
                return true;
        return false;
}

static inline u32 rdma_rw_fr_page_list_len(struct ib_device *dev,
                                           bool pi_support)
{
        u32 max_pages;

        if (pi_support)
                max_pages = dev->attrs.max_pi_fast_reg_page_list_len;
        else
                max_pages = dev->attrs.max_fast_reg_page_list_len;

        /* arbitrary limit to avoid allocating gigantic resources */
        return min_t(u32, max_pages, 256);
}

static inline int rdma_rw_inv_key(struct rdma_rw_reg_ctx *reg)
{
        int count = 0;

        if (reg->mr->need_inval) {
                reg->inv_wr.opcode = IB_WR_LOCAL_INV;
                reg->inv_wr.ex.invalidate_rkey = reg->mr->lkey;
                reg->inv_wr.next = &reg->reg_wr.wr;
                count++;
        } else {
                reg->inv_wr.next = NULL;
        }

        return count;
}

/* Caller must have zero-initialized *reg. */
static int rdma_rw_init_one_mr(struct ib_qp *qp, u32 port_num,
                struct rdma_rw_reg_ctx *reg, struct scatterlist *sg,
                u32 sg_cnt, u32 offset)
{
        u32 pages_per_mr = rdma_rw_fr_page_list_len(qp->pd->device,
                                                    qp->integrity_en);
        u32 nents = min(sg_cnt, pages_per_mr);
        int count = 0, ret;

        reg->mr = ib_mr_pool_get(qp, &qp->rdma_mrs);
        if (!reg->mr)
                return -EAGAIN;

        count += rdma_rw_inv_key(reg);

        ret = ib_map_mr_sg(reg->mr, sg, nents, &offset, PAGE_SIZE);
        if (ret < 0 || ret < nents) {
                ib_mr_pool_put(qp, &qp->rdma_mrs, reg->mr);
                return -EINVAL;
        }

        reg->reg_wr.wr.opcode = IB_WR_REG_MR;
        reg->reg_wr.mr = reg->mr;
        reg->reg_wr.access = IB_ACCESS_LOCAL_WRITE;
        if (rdma_protocol_iwarp(qp->device, port_num))
                reg->reg_wr.access |= IB_ACCESS_REMOTE_WRITE;
        count++;

        reg->sge.addr = reg->mr->iova;
        reg->sge.length = reg->mr->length;
        return count;
}

static int rdma_rw_init_reg_wr(struct rdma_rw_reg_ctx *reg,
                struct rdma_rw_reg_ctx *prev, struct ib_qp *qp, u32 port_num,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        if (prev) {
                if (reg->mr->need_inval)
                        prev->wr.wr.next = &reg->inv_wr;
                else
                        prev->wr.wr.next = &reg->reg_wr.wr;
        }

        reg->reg_wr.wr.next = &reg->wr.wr;

        reg->wr.wr.sg_list = &reg->sge;
        reg->wr.wr.num_sge = 1;
        reg->wr.remote_addr = remote_addr;
        reg->wr.rkey = rkey;

        if (dir == DMA_TO_DEVICE) {
                reg->wr.wr.opcode = IB_WR_RDMA_WRITE;
        } else if (!rdma_cap_read_inv(qp->device, port_num)) {
                reg->wr.wr.opcode = IB_WR_RDMA_READ;
        } else {
                reg->wr.wr.opcode = IB_WR_RDMA_READ_WITH_INV;
                reg->wr.wr.ex.invalidate_rkey = reg->mr->lkey;
        }

        return 1;
}

static int rdma_rw_init_mr_wrs(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, struct scatterlist *sg, u32 sg_cnt, u32 offset,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        struct rdma_rw_reg_ctx *prev = NULL;
        u32 pages_per_mr = rdma_rw_fr_page_list_len(qp->pd->device,
                                                    qp->integrity_en);
        int i, j, ret = 0, count = 0;

        ctx->nr_ops = DIV_ROUND_UP(sg_cnt, pages_per_mr);
        ctx->reg = kzalloc_objs(*ctx->reg, ctx->nr_ops);
        if (!ctx->reg) {
                ret = -ENOMEM;
                goto out;
        }

        for (i = 0; i < ctx->nr_ops; i++) {
                struct rdma_rw_reg_ctx *reg = &ctx->reg[i];
                u32 nents = min(sg_cnt, pages_per_mr);

                ret = rdma_rw_init_one_mr(qp, port_num, reg, sg, sg_cnt,
                                offset);
                if (ret < 0)
                        goto out_free;
                count += ret;
                count += rdma_rw_init_reg_wr(reg, prev, qp, port_num,
                                remote_addr, rkey, dir);
                remote_addr += reg->sge.length;
                sg_cnt -= nents;
                for (j = 0; j < nents; j++)
                        sg = sg_next(sg);
                prev = reg;
                offset = 0;
        }

        if (prev)
                prev->wr.wr.next = NULL;

        ctx->type = RDMA_RW_MR;
        return count;

out_free:
        while (--i >= 0)
                ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->reg[i].mr);
        kfree(ctx->reg);
out:
        return ret;
}

static int rdma_rw_init_mr_wrs_bvec(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, const struct bio_vec *bvecs, u32 nr_bvec,
                struct bvec_iter *iter, u64 remote_addr, u32 rkey,
                enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        struct rdma_rw_reg_ctx *prev = NULL;
        u32 pages_per_mr = rdma_rw_fr_page_list_len(dev, qp->integrity_en);
        struct scatterlist *sg;
        int i, ret, count = 0;
        u32 nents = 0;

        ctx->reg = kzalloc_objs(*ctx->reg, DIV_ROUND_UP(nr_bvec, pages_per_mr));
        if (!ctx->reg)
                return -ENOMEM;

        /*
         * Build scatterlist from bvecs using the iterator. This follows
         * the pattern from __blk_rq_map_sg.
         */
        ctx->reg[0].sgt.sgl = kmalloc_objs(*ctx->reg[0].sgt.sgl, nr_bvec);
        if (!ctx->reg[0].sgt.sgl) {
                ret = -ENOMEM;
                goto out_free_reg;
        }
        sg_init_table(ctx->reg[0].sgt.sgl, nr_bvec);

        for (sg = ctx->reg[0].sgt.sgl; iter->bi_size; sg = sg_next(sg)) {
                struct bio_vec bv = mp_bvec_iter_bvec(bvecs, *iter);

                if (nents >= nr_bvec) {
                        ret = -EINVAL;
                        goto out_free_sgl;
                }
                sg_set_page(sg, bv.bv_page, bv.bv_len, bv.bv_offset);
                bvec_iter_advance(bvecs, iter, bv.bv_len);
                nents++;
        }
        sg_mark_end(sg_last(ctx->reg[0].sgt.sgl, nents));
        ctx->reg[0].sgt.orig_nents = nents;

        /* DMA map the scatterlist */
        ret = ib_dma_map_sgtable_attrs(dev, &ctx->reg[0].sgt, dir, 0);
        if (ret)
                goto out_free_sgl;

        ctx->nr_ops = DIV_ROUND_UP(ctx->reg[0].sgt.nents, pages_per_mr);

        sg = ctx->reg[0].sgt.sgl;
        nents = ctx->reg[0].sgt.nents;
        for (i = 0; i < ctx->nr_ops; i++) {
                struct rdma_rw_reg_ctx *reg = &ctx->reg[i];
                u32 sge_cnt = min(nents, pages_per_mr);

                ret = rdma_rw_init_one_mr(qp, port_num, reg, sg, sge_cnt, 0);
                if (ret < 0)
                        goto out_free_mrs;
                count += ret;
                count += rdma_rw_init_reg_wr(reg, prev, qp, port_num,
                                remote_addr, rkey, dir);
                remote_addr += reg->sge.length;
                nents -= sge_cnt;
                sg += sge_cnt;
                prev = reg;
        }

        if (prev)
                prev->wr.wr.next = NULL;

        ctx->type = RDMA_RW_MR;
        return count;

out_free_mrs:
        while (--i >= 0)
                ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->reg[i].mr);
        ib_dma_unmap_sgtable_attrs(dev, &ctx->reg[0].sgt, dir, 0);
out_free_sgl:
        kfree(ctx->reg[0].sgt.sgl);
out_free_reg:
        kfree(ctx->reg);
        return ret;
}

static int rdma_rw_init_map_wrs(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                struct scatterlist *sg, u32 sg_cnt, u32 offset,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        u32 max_sge = dir == DMA_TO_DEVICE ? qp->max_write_sge :
                      qp->max_read_sge;
        struct ib_sge *sge;
        u32 total_len = 0, i, j;

        ctx->nr_ops = DIV_ROUND_UP(sg_cnt, max_sge);

        ctx->map.sges = sge = kzalloc_objs(*sge, sg_cnt);
        if (!ctx->map.sges)
                goto out;

        ctx->map.wrs = kzalloc_objs(*ctx->map.wrs, ctx->nr_ops);
        if (!ctx->map.wrs)
                goto out_free_sges;

        for (i = 0; i < ctx->nr_ops; i++) {
                struct ib_rdma_wr *rdma_wr = &ctx->map.wrs[i];
                u32 nr_sge = min(sg_cnt, max_sge);

                if (dir == DMA_TO_DEVICE)
                        rdma_wr->wr.opcode = IB_WR_RDMA_WRITE;
                else
                        rdma_wr->wr.opcode = IB_WR_RDMA_READ;
                rdma_wr->remote_addr = remote_addr + total_len;
                rdma_wr->rkey = rkey;
                rdma_wr->wr.num_sge = nr_sge;
                rdma_wr->wr.sg_list = sge;

                for (j = 0; j < nr_sge; j++, sg = sg_next(sg)) {
                        sge->addr = sg_dma_address(sg) + offset;
                        sge->length = sg_dma_len(sg) - offset;
                        sge->lkey = qp->pd->local_dma_lkey;

                        total_len += sge->length;
                        sge++;
                        sg_cnt--;
                        offset = 0;
                }

                rdma_wr->wr.next = i + 1 < ctx->nr_ops ?
                        &ctx->map.wrs[i + 1].wr : NULL;
        }

        ctx->type = RDMA_RW_MULTI_WR;
        return ctx->nr_ops;

out_free_sges:
        kfree(ctx->map.sges);
out:
        return -ENOMEM;
}

static int rdma_rw_init_single_wr(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                struct scatterlist *sg, u32 offset, u64 remote_addr, u32 rkey,
                enum dma_data_direction dir)
{
        struct ib_rdma_wr *rdma_wr = &ctx->single.wr;

        ctx->nr_ops = 1;

        ctx->single.sge.lkey = qp->pd->local_dma_lkey;
        ctx->single.sge.addr = sg_dma_address(sg) + offset;
        ctx->single.sge.length = sg_dma_len(sg) - offset;

        memset(rdma_wr, 0, sizeof(*rdma_wr));
        if (dir == DMA_TO_DEVICE)
                rdma_wr->wr.opcode = IB_WR_RDMA_WRITE;
        else
                rdma_wr->wr.opcode = IB_WR_RDMA_READ;
        rdma_wr->wr.sg_list = &ctx->single.sge;
        rdma_wr->wr.num_sge = 1;
        rdma_wr->remote_addr = remote_addr;
        rdma_wr->rkey = rkey;

        ctx->type = RDMA_RW_SINGLE_WR;
        return 1;
}

static int rdma_rw_init_single_wr_bvec(struct rdma_rw_ctx *ctx,
                struct ib_qp *qp, const struct bio_vec *bvecs,
                struct bvec_iter *iter, u64 remote_addr, u32 rkey,
                enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        struct ib_rdma_wr *rdma_wr = &ctx->single.wr;
        struct bio_vec bv = mp_bvec_iter_bvec(bvecs, *iter);
        u64 dma_addr;

        ctx->nr_ops = 1;

        dma_addr = ib_dma_map_bvec(dev, &bv, dir);
        if (ib_dma_mapping_error(dev, dma_addr))
                return -ENOMEM;

        ctx->single.sge.lkey = qp->pd->local_dma_lkey;
        ctx->single.sge.addr = dma_addr;
        ctx->single.sge.length = bv.bv_len;

        memset(rdma_wr, 0, sizeof(*rdma_wr));
        if (dir == DMA_TO_DEVICE)
                rdma_wr->wr.opcode = IB_WR_RDMA_WRITE;
        else
                rdma_wr->wr.opcode = IB_WR_RDMA_READ;
        rdma_wr->wr.sg_list = &ctx->single.sge;
        rdma_wr->wr.num_sge = 1;
        rdma_wr->remote_addr = remote_addr;
        rdma_wr->rkey = rkey;

        ctx->type = RDMA_RW_SINGLE_WR;
        return 1;
}

static int rdma_rw_init_map_wrs_bvec(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                const struct bio_vec *bvecs, u32 nr_bvec, struct bvec_iter *iter,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        u32 max_sge = dir == DMA_TO_DEVICE ? qp->max_write_sge :
                      qp->max_read_sge;
        struct ib_sge *sge;
        u32 total_len = 0, i, j;
        u32 mapped_bvecs = 0;
        u32 nr_ops = DIV_ROUND_UP(nr_bvec, max_sge);
        size_t sges_size = array_size(nr_bvec, sizeof(*ctx->map.sges));
        size_t wrs_offset = ALIGN(sges_size, __alignof__(*ctx->map.wrs));
        size_t wrs_size = array_size(nr_ops, sizeof(*ctx->map.wrs));
        void *mem;

        if (sges_size == SIZE_MAX || wrs_size == SIZE_MAX ||
            check_add_overflow(wrs_offset, wrs_size, &wrs_size))
                return -ENOMEM;

        mem = kzalloc(wrs_size, GFP_KERNEL);
        if (!mem)
                return -ENOMEM;

        ctx->map.sges = sge = mem;
        ctx->map.wrs = mem + wrs_offset;

        for (i = 0; i < nr_ops; i++) {
                struct ib_rdma_wr *rdma_wr = &ctx->map.wrs[i];
                u32 nr_sge = min(nr_bvec - mapped_bvecs, max_sge);

                if (dir == DMA_TO_DEVICE)
                        rdma_wr->wr.opcode = IB_WR_RDMA_WRITE;
                else
                        rdma_wr->wr.opcode = IB_WR_RDMA_READ;
                rdma_wr->remote_addr = remote_addr + total_len;
                rdma_wr->rkey = rkey;
                rdma_wr->wr.num_sge = nr_sge;
                rdma_wr->wr.sg_list = sge;

                for (j = 0; j < nr_sge; j++) {
                        struct bio_vec bv = mp_bvec_iter_bvec(bvecs, *iter);
                        u64 dma_addr;

                        dma_addr = ib_dma_map_bvec(dev, &bv, dir);
                        if (ib_dma_mapping_error(dev, dma_addr))
                                goto out_unmap;

                        mapped_bvecs++;
                        sge->addr = dma_addr;
                        sge->length = bv.bv_len;
                        sge->lkey = qp->pd->local_dma_lkey;

                        total_len += bv.bv_len;
                        sge++;

                        bvec_iter_advance_single(bvecs, iter, bv.bv_len);
                }

                rdma_wr->wr.next = i + 1 < nr_ops ?
                        &ctx->map.wrs[i + 1].wr : NULL;
        }

        ctx->nr_ops = nr_ops;
        ctx->type = RDMA_RW_MULTI_WR;
        return nr_ops;

out_unmap:
        for (i = 0; i < mapped_bvecs; i++)
                ib_dma_unmap_bvec(dev, ctx->map.sges[i].addr,
                                  ctx->map.sges[i].length, dir);
        kfree(ctx->map.sges);
        return -ENOMEM;
}

/*
 * Try to use the two-step IOVA API to map bvecs into a contiguous DMA range.
 * This reduces IOTLB sync overhead by doing one sync at the end instead of
 * one per bvec, and produces a contiguous DMA address range that can be
 * described by a single SGE.
 *
 * Returns the number of WQEs (always 1) on success, -EOPNOTSUPP if IOVA
 * mapping is not available, or another negative error code on failure.
 */
static int rdma_rw_init_iova_wrs_bvec(struct rdma_rw_ctx *ctx,
                struct ib_qp *qp, const struct bio_vec *bvec,
                struct bvec_iter *iter, u64 remote_addr, u32 rkey,
                enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        struct device *dma_dev = dev->dma_device;
        size_t total_len = iter->bi_size;
        struct bio_vec first_bv;
        size_t mapped_len = 0;
        int ret;

        /* Virtual DMA devices cannot support IOVA allocators */
        if (ib_uses_virt_dma(dev))
                return -EOPNOTSUPP;

        /* Try to allocate contiguous IOVA space */
        first_bv = mp_bvec_iter_bvec(bvec, *iter);
        if (!dma_iova_try_alloc(dma_dev, &ctx->iova.state,
                                bvec_phys(&first_bv), total_len))
                return -EOPNOTSUPP;

        /* Link all bvecs into the IOVA space */
        while (iter->bi_size) {
                struct bio_vec bv = mp_bvec_iter_bvec(bvec, *iter);

                ret = dma_iova_link(dma_dev, &ctx->iova.state, bvec_phys(&bv),
                                    mapped_len, bv.bv_len, dir, 0);
                if (ret)
                        goto out_destroy;

                mapped_len += bv.bv_len;
                bvec_iter_advance(bvec, iter, bv.bv_len);
        }

        /* Sync the IOTLB once for all linked pages */
        ret = dma_iova_sync(dma_dev, &ctx->iova.state, 0, mapped_len);
        if (ret)
                goto out_destroy;

        ctx->iova.mapped_len = mapped_len;

        /* Single SGE covers the entire contiguous IOVA range */
        ctx->iova.sge.addr = ctx->iova.state.addr;
        ctx->iova.sge.length = mapped_len;
        ctx->iova.sge.lkey = qp->pd->local_dma_lkey;

        /* Single WR for the whole transfer */
        memset(&ctx->iova.wr, 0, sizeof(ctx->iova.wr));
        if (dir == DMA_TO_DEVICE)
                ctx->iova.wr.wr.opcode = IB_WR_RDMA_WRITE;
        else
                ctx->iova.wr.wr.opcode = IB_WR_RDMA_READ;
        ctx->iova.wr.wr.num_sge = 1;
        ctx->iova.wr.wr.sg_list = &ctx->iova.sge;
        ctx->iova.wr.remote_addr = remote_addr;
        ctx->iova.wr.rkey = rkey;

        ctx->type = RDMA_RW_IOVA;
        ctx->nr_ops = 1;
        return 1;

out_destroy:
        /*
         * dma_iova_destroy() expects the actual mapped length, not the
         * total allocation size. It unlinks only the successfully linked
         * range and frees the entire IOVA allocation.
         */
        dma_iova_destroy(dma_dev, &ctx->iova.state, mapped_len, dir, 0);
        return ret;
}

/**
 * rdma_rw_ctx_init - initialize a RDMA READ/WRITE context
 * @ctx:        context to initialize
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @sg:         scatterlist to READ/WRITE from/to
 * @sg_cnt:     number of entries in @sg
 * @sg_offset:  current byte offset into @sg
 * @remote_addr:remote address to read/write (relative to @rkey)
 * @rkey:       remote key to operate on
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 *
 * Returns the number of WQEs that will be needed on the workqueue if
 * successful, or a negative error code.
 */
int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u32 port_num,
                struct scatterlist *sg, u32 sg_cnt, u32 sg_offset,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        struct sg_table sgt = {
                .sgl = sg,
                .orig_nents = sg_cnt,
        };
        int ret;

        ret = ib_dma_map_sgtable_attrs(dev, &sgt, dir, 0);
        if (ret)
                return ret;
        sg_cnt = sgt.nents;

        /*
         * Skip to the S/G entry that sg_offset falls into:
         */
        for (;;) {
                u32 len = sg_dma_len(sg);

                if (sg_offset < len)
                        break;

                sg = sg_next(sg);
                sg_offset -= len;
                sg_cnt--;
        }

        ret = -EIO;
        if (WARN_ON_ONCE(sg_cnt == 0))
                goto out_unmap_sg;

        if (rdma_rw_io_needs_mr(qp->device, port_num, dir, sg_cnt)) {
                ret = rdma_rw_init_mr_wrs(ctx, qp, port_num, sg, sg_cnt,
                                sg_offset, remote_addr, rkey, dir);
                /*
                 * If MR init succeeded or failed for a reason other
                 * than pool exhaustion, that result is final.
                 *
                 * Pool exhaustion (-EAGAIN) from the max_sgl_rd
                 * optimization is recoverable: fall back to
                 * direct SGE posting. iWARP and force_mr require
                 * MRs unconditionally, so -EAGAIN is terminal.
                 */
                if (ret != -EAGAIN ||
                    rdma_protocol_iwarp(qp->device, port_num) ||
                    unlikely(rdma_rw_force_mr))
                        goto out;
        }

        if (sg_cnt > 1)
                ret = rdma_rw_init_map_wrs(ctx, qp, sg, sg_cnt, sg_offset,
                                remote_addr, rkey, dir);
        else
                ret = rdma_rw_init_single_wr(ctx, qp, sg, sg_offset,
                                remote_addr, rkey, dir);

out:
        if (ret < 0)
                goto out_unmap_sg;
        return ret;

out_unmap_sg:
        ib_dma_unmap_sgtable_attrs(dev, &sgt, dir, 0);
        return ret;
}
EXPORT_SYMBOL(rdma_rw_ctx_init);

/**
 * rdma_rw_ctx_init_bvec - initialize a RDMA READ/WRITE context from bio_vec
 * @ctx:        context to initialize
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @bvecs:      bio_vec array to READ/WRITE from/to
 * @nr_bvec:    number of entries in @bvecs
 * @iter:       bvec iterator describing offset and length
 * @remote_addr: remote address to read/write (relative to @rkey)
 * @rkey:       remote key to operate on
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 *
 * Maps the bio_vec array directly, avoiding intermediate scatterlist
 * conversion. Supports MR registration for iWARP devices and force_mr mode.
 *
 * Returns the number of WQEs that will be needed on the workqueue if
 * successful, or a negative error code:
 *
 *   * -EINVAL  - @nr_bvec is zero or @iter.bi_size is zero
 *   * -ENOMEM - DMA mapping or memory allocation failed
 */
int rdma_rw_ctx_init_bvec(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, const struct bio_vec *bvecs, u32 nr_bvec,
                struct bvec_iter iter, u64 remote_addr, u32 rkey,
                enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        int ret;

        if (nr_bvec == 0 || iter.bi_size == 0)
                return -EINVAL;

        /*
         * iWARP requires MR registration for all RDMA READs. The force_mr
         * debug option also mandates MR usage.
         */
        if (dir == DMA_FROM_DEVICE && rdma_protocol_iwarp(dev, port_num))
                return rdma_rw_init_mr_wrs_bvec(ctx, qp, port_num, bvecs,
                                                nr_bvec, &iter, remote_addr,
                                                rkey, dir);
        if (unlikely(rdma_rw_force_mr))
                return rdma_rw_init_mr_wrs_bvec(ctx, qp, port_num, bvecs,
                                                nr_bvec, &iter, remote_addr,
                                                rkey, dir);

        if (nr_bvec == 1)
                return rdma_rw_init_single_wr_bvec(ctx, qp, bvecs, &iter,
                                remote_addr, rkey, dir);

        /*
         * Try IOVA-based mapping first for multi-bvec transfers.
         * IOVA coalesces bvecs into a single DMA-contiguous region,
         * reducing the number of WRs needed and avoiding MR overhead.
         */
        ret = rdma_rw_init_iova_wrs_bvec(ctx, qp, bvecs, &iter, remote_addr,
                        rkey, dir);
        if (ret != -EOPNOTSUPP)
                return ret;

        /*
         * IOVA not available; fall back to the map_wrs path, which maps
         * each bvec as a direct SGE. This is always correct: the MR path
         * is a throughput optimization, not a correctness requirement.
         * (iWARP, which does require MRs, is handled by the check above.)
         *
         * The rdma_rw_io_needs_mr() gate is not used here because nr_bvec
         * is a raw page count that overstates DMA entry demand -- the bvec
         * caller has no post-DMA-coalescing segment count, and feeding the
         * inflated count into the MR path exhausts the pool on RDMA READs.
         */
        return rdma_rw_init_map_wrs_bvec(ctx, qp, bvecs, nr_bvec, &iter,
                        remote_addr, rkey, dir);
}
EXPORT_SYMBOL(rdma_rw_ctx_init_bvec);

/**
 * rdma_rw_ctx_signature_init - initialize a RW context with signature offload
 * @ctx:        context to initialize
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @sg:         scatterlist to READ/WRITE from/to
 * @sg_cnt:     number of entries in @sg
 * @prot_sg:    scatterlist to READ/WRITE protection information from/to
 * @prot_sg_cnt: number of entries in @prot_sg
 * @sig_attrs:  signature offloading algorithms
 * @remote_addr:remote address to read/write (relative to @rkey)
 * @rkey:       remote key to operate on
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 *
 * Returns the number of WQEs that will be needed on the workqueue if
 * successful, or a negative error code.
 */
int rdma_rw_ctx_signature_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, struct scatterlist *sg, u32 sg_cnt,
                struct scatterlist *prot_sg, u32 prot_sg_cnt,
                struct ib_sig_attrs *sig_attrs,
                u64 remote_addr, u32 rkey, enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        u32 pages_per_mr = rdma_rw_fr_page_list_len(qp->pd->device,
                                                    qp->integrity_en);
        struct sg_table sgt = {
                .sgl = sg,
                .orig_nents = sg_cnt,
        };
        struct sg_table prot_sgt = {
                .sgl = prot_sg,
                .orig_nents = prot_sg_cnt,
        };
        struct ib_rdma_wr *rdma_wr;
        int count = 0, ret;

        if (sg_cnt > pages_per_mr || prot_sg_cnt > pages_per_mr) {
                pr_err("SG count too large: sg_cnt=%u, prot_sg_cnt=%u, pages_per_mr=%u\n",
                       sg_cnt, prot_sg_cnt, pages_per_mr);
                return -EINVAL;
        }

        ret = ib_dma_map_sgtable_attrs(dev, &sgt, dir, 0);
        if (ret)
                return ret;

        if (prot_sg_cnt) {
                ret = ib_dma_map_sgtable_attrs(dev, &prot_sgt, dir, 0);
                if (ret)
                        goto out_unmap_sg;
        }

        ctx->type = RDMA_RW_SIG_MR;
        ctx->nr_ops = 1;
        ctx->reg = kzalloc_obj(*ctx->reg);
        if (!ctx->reg) {
                ret = -ENOMEM;
                goto out_unmap_prot_sg;
        }

        ctx->reg->mr = ib_mr_pool_get(qp, &qp->sig_mrs);
        if (!ctx->reg->mr) {
                ret = -EAGAIN;
                goto out_free_ctx;
        }

        count += rdma_rw_inv_key(ctx->reg);

        memcpy(ctx->reg->mr->sig_attrs, sig_attrs, sizeof(struct ib_sig_attrs));

        ret = ib_map_mr_sg_pi(ctx->reg->mr, sg, sgt.nents, NULL, prot_sg,
                              prot_sgt.nents, NULL, SZ_4K);
        if (unlikely(ret)) {
                pr_err("failed to map PI sg (%u)\n",
                       sgt.nents + prot_sgt.nents);
                goto out_destroy_sig_mr;
        }

        ctx->reg->reg_wr.wr.opcode = IB_WR_REG_MR_INTEGRITY;
        ctx->reg->reg_wr.wr.wr_cqe = NULL;
        ctx->reg->reg_wr.wr.num_sge = 0;
        ctx->reg->reg_wr.wr.send_flags = 0;
        ctx->reg->reg_wr.access = IB_ACCESS_LOCAL_WRITE;
        if (rdma_protocol_iwarp(qp->device, port_num))
                ctx->reg->reg_wr.access |= IB_ACCESS_REMOTE_WRITE;
        ctx->reg->reg_wr.mr = ctx->reg->mr;
        ctx->reg->reg_wr.key = ctx->reg->mr->lkey;
        count++;

        ctx->reg->sge.addr = ctx->reg->mr->iova;
        ctx->reg->sge.length = ctx->reg->mr->length;
        if (sig_attrs->wire.sig_type == IB_SIG_TYPE_NONE)
                ctx->reg->sge.length -= ctx->reg->mr->sig_attrs->meta_length;

        rdma_wr = &ctx->reg->wr;
        rdma_wr->wr.sg_list = &ctx->reg->sge;
        rdma_wr->wr.num_sge = 1;
        rdma_wr->remote_addr = remote_addr;
        rdma_wr->rkey = rkey;
        if (dir == DMA_TO_DEVICE)
                rdma_wr->wr.opcode = IB_WR_RDMA_WRITE;
        else
                rdma_wr->wr.opcode = IB_WR_RDMA_READ;
        ctx->reg->reg_wr.wr.next = &rdma_wr->wr;
        count++;

        return count;

out_destroy_sig_mr:
        ib_mr_pool_put(qp, &qp->sig_mrs, ctx->reg->mr);
out_free_ctx:
        kfree(ctx->reg);
out_unmap_prot_sg:
        if (prot_sgt.nents)
                ib_dma_unmap_sgtable_attrs(dev, &prot_sgt, dir, 0);
out_unmap_sg:
        ib_dma_unmap_sgtable_attrs(dev, &sgt, dir, 0);
        return ret;
}
EXPORT_SYMBOL(rdma_rw_ctx_signature_init);

/*
 * Now that we are going to post the WRs we can update the lkey and need_inval
 * state on the MRs.  If we were doing this at init time, we would get double
 * or missing invalidations if a context was initialized but not actually
 * posted.
 */
static void rdma_rw_update_lkey(struct rdma_rw_reg_ctx *reg, bool need_inval)
{
        reg->mr->need_inval = need_inval;
        ib_update_fast_reg_key(reg->mr, ib_inc_rkey(reg->mr->lkey));
        reg->reg_wr.key = reg->mr->lkey;
        reg->sge.lkey = reg->mr->lkey;
}

/**
 * rdma_rw_ctx_wrs - return chain of WRs for a RDMA READ or WRITE operation
 * @ctx:        context to operate on
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @cqe:        completion queue entry for the last WR
 * @chain_wr:   WR to append to the posted chain
 *
 * Return the WR chain for the set of RDMA READ/WRITE operations described by
 * @ctx, as well as any memory registration operations needed.  If @chain_wr
 * is non-NULL the WR it points to will be appended to the chain of WRs posted.
 * If @chain_wr is not set @cqe must be set so that the caller gets a
 * completion notification.
 */
struct ib_send_wr *rdma_rw_ctx_wrs(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, struct ib_cqe *cqe, struct ib_send_wr *chain_wr)
{
        struct ib_send_wr *first_wr, *last_wr;
        int i;

        switch (ctx->type) {
        case RDMA_RW_SIG_MR:
        case RDMA_RW_MR:
                for (i = 0; i < ctx->nr_ops; i++) {
                        rdma_rw_update_lkey(&ctx->reg[i],
                                ctx->reg[i].wr.wr.opcode !=
                                        IB_WR_RDMA_READ_WITH_INV);
                }

                if (ctx->reg[0].inv_wr.next)
                        first_wr = &ctx->reg[0].inv_wr;
                else
                        first_wr = &ctx->reg[0].reg_wr.wr;
                last_wr = &ctx->reg[ctx->nr_ops - 1].wr.wr;
                break;
        case RDMA_RW_IOVA:
                first_wr = &ctx->iova.wr.wr;
                last_wr = &ctx->iova.wr.wr;
                break;
        case RDMA_RW_MULTI_WR:
                first_wr = &ctx->map.wrs[0].wr;
                last_wr = &ctx->map.wrs[ctx->nr_ops - 1].wr;
                break;
        case RDMA_RW_SINGLE_WR:
                first_wr = &ctx->single.wr.wr;
                last_wr = &ctx->single.wr.wr;
                break;
        default:
                BUG();
        }

        if (chain_wr) {
                last_wr->next = chain_wr;
        } else {
                last_wr->wr_cqe = cqe;
                last_wr->send_flags |= IB_SEND_SIGNALED;
        }

        return first_wr;
}
EXPORT_SYMBOL(rdma_rw_ctx_wrs);

/**
 * rdma_rw_ctx_post - post a RDMA READ or RDMA WRITE operation
 * @ctx:        context to operate on
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @cqe:        completion queue entry for the last WR
 * @chain_wr:   WR to append to the posted chain
 *
 * Post the set of RDMA READ/WRITE operations described by @ctx, as well as
 * any memory registration operations needed.  If @chain_wr is non-NULL the
 * WR it points to will be appended to the chain of WRs posted.  If @chain_wr
 * is not set @cqe must be set so that the caller gets a completion
 * notification.
 */
int rdma_rw_ctx_post(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u32 port_num,
                struct ib_cqe *cqe, struct ib_send_wr *chain_wr)
{
        struct ib_send_wr *first_wr;

        first_wr = rdma_rw_ctx_wrs(ctx, qp, port_num, cqe, chain_wr);
        return ib_post_send(qp, first_wr, NULL);
}
EXPORT_SYMBOL(rdma_rw_ctx_post);

/**
 * rdma_rw_ctx_destroy - release all resources allocated by rdma_rw_ctx_init
 * @ctx:        context to release
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @sg:         scatterlist that was used for the READ/WRITE
 * @sg_cnt:     number of entries in @sg
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 */
void rdma_rw_ctx_destroy(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                         u32 port_num, struct scatterlist *sg, u32 sg_cnt,
                         enum dma_data_direction dir)
{
        int i;

        switch (ctx->type) {
        case RDMA_RW_MR:
                /* Bvec MR contexts must use rdma_rw_ctx_destroy_bvec() */
                WARN_ON_ONCE(ctx->reg[0].sgt.sgl);
                for (i = 0; i < ctx->nr_ops; i++)
                        ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->reg[i].mr);
                kfree(ctx->reg);
                break;
        case RDMA_RW_MULTI_WR:
                kfree(ctx->map.wrs);
                kfree(ctx->map.sges);
                break;
        case RDMA_RW_SINGLE_WR:
                break;
        case RDMA_RW_IOVA:
                /* IOVA contexts must use rdma_rw_ctx_destroy_bvec() */
                WARN_ON_ONCE(1);
                return;
        default:
                BUG();
                break;
        }

        ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
}
EXPORT_SYMBOL(rdma_rw_ctx_destroy);

/**
 * rdma_rw_ctx_destroy_bvec - release resources from rdma_rw_ctx_init_bvec
 * @ctx:        context to release
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound (unused)
 * @bvecs:      bio_vec array that was used for the READ/WRITE (unused)
 * @nr_bvec:    number of entries in @bvecs
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 *
 * Releases all resources allocated by a successful rdma_rw_ctx_init_bvec()
 * call. Must not be called if rdma_rw_ctx_init_bvec() returned an error.
 *
 * The @port_num and @bvecs parameters are unused but present for API
 * symmetry with rdma_rw_ctx_destroy().
 */
void rdma_rw_ctx_destroy_bvec(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 __maybe_unused port_num,
                const struct bio_vec __maybe_unused *bvecs,
                u32 nr_bvec, enum dma_data_direction dir)
{
        struct ib_device *dev = qp->pd->device;
        u32 i;

        switch (ctx->type) {
        case RDMA_RW_MR:
                for (i = 0; i < ctx->nr_ops; i++)
                        ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->reg[i].mr);
                ib_dma_unmap_sgtable_attrs(dev, &ctx->reg[0].sgt, dir, 0);
                kfree(ctx->reg[0].sgt.sgl);
                kfree(ctx->reg);
                break;
        case RDMA_RW_IOVA:
                dma_iova_destroy(dev->dma_device, &ctx->iova.state,
                                 ctx->iova.mapped_len, dir, 0);
                break;
        case RDMA_RW_MULTI_WR:
                for (i = 0; i < nr_bvec; i++)
                        ib_dma_unmap_bvec(dev, ctx->map.sges[i].addr,
                                          ctx->map.sges[i].length, dir);
                kfree(ctx->map.sges);
                break;
        case RDMA_RW_SINGLE_WR:
                ib_dma_unmap_bvec(dev, ctx->single.sge.addr,
                                  ctx->single.sge.length, dir);
                break;
        default:
                WARN_ON_ONCE(1);
                return;
        }
}
EXPORT_SYMBOL(rdma_rw_ctx_destroy_bvec);

/**
 * rdma_rw_ctx_destroy_signature - release all resources allocated by
 *      rdma_rw_ctx_signature_init
 * @ctx:        context to release
 * @qp:         queue pair to operate on
 * @port_num:   port num to which the connection is bound
 * @sg:         scatterlist that was used for the READ/WRITE
 * @sg_cnt:     number of entries in @sg
 * @prot_sg:    scatterlist that was used for the READ/WRITE of the PI
 * @prot_sg_cnt: number of entries in @prot_sg
 * @dir:        %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
 */
void rdma_rw_ctx_destroy_signature(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u32 port_num, struct scatterlist *sg, u32 sg_cnt,
                struct scatterlist *prot_sg, u32 prot_sg_cnt,
                enum dma_data_direction dir)
{
        if (WARN_ON_ONCE(ctx->type != RDMA_RW_SIG_MR))
                return;

        ib_mr_pool_put(qp, &qp->sig_mrs, ctx->reg->mr);
        kfree(ctx->reg);

        if (prot_sg_cnt)
                ib_dma_unmap_sg(qp->pd->device, prot_sg, prot_sg_cnt, dir);
        ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
}
EXPORT_SYMBOL(rdma_rw_ctx_destroy_signature);

/**
 * rdma_rw_mr_factor - return number of MRs required for a payload
 * @device:     device handling the connection
 * @port_num:   port num to which the connection is bound
 * @maxpages:   maximum payload pages per rdma_rw_ctx
 *
 * Returns the number of MRs the device requires to move @maxpayload
 * bytes. The returned value is used during transport creation to
 * compute max_rdma_ctxts and the size of the transport's Send and
 * Send Completion Queues.
 */
unsigned int rdma_rw_mr_factor(struct ib_device *device, u32 port_num,
                               unsigned int maxpages)
{
        unsigned int mr_pages;

        if (rdma_rw_can_use_mr(device, port_num))
                mr_pages = rdma_rw_fr_page_list_len(device, false);
        else
                mr_pages = device->attrs.max_sge_rd;
        return DIV_ROUND_UP(maxpages, mr_pages);
}
EXPORT_SYMBOL(rdma_rw_mr_factor);

/**
 * rdma_rw_max_send_wr - compute max Send WRs needed for RDMA R/W contexts
 * @dev: RDMA device
 * @port_num: port number
 * @max_rdma_ctxs: number of rdma_rw_ctx structures
 * @create_flags: QP create flags (pass IB_QP_CREATE_INTEGRITY_EN if
 *                data integrity will be enabled on the QP)
 *
 * Returns the total number of Send Queue entries needed for
 * @max_rdma_ctxs. The result accounts for memory registration and
 * invalidation work requests when the device requires them.
 *
 * ULPs use this to size Send Queues and Send CQs before creating a
 * Queue Pair.
 */
unsigned int rdma_rw_max_send_wr(struct ib_device *dev, u32 port_num,
                                 unsigned int max_rdma_ctxs, u32 create_flags)
{
        unsigned int factor = 1;
        unsigned int result;

        if (create_flags & IB_QP_CREATE_INTEGRITY_EN ||
            rdma_rw_can_use_mr(dev, port_num))
                factor += 2;    /* reg + inv */

        if (check_mul_overflow(factor, max_rdma_ctxs, &result))
                return UINT_MAX;
        return result;
}
EXPORT_SYMBOL(rdma_rw_max_send_wr);

void rdma_rw_init_qp(struct ib_device *dev, struct ib_qp_init_attr *attr)
{
        unsigned int factor = 1;

        WARN_ON_ONCE(attr->port_num == 0);

        /*
         * If the device uses MRs to perform RDMA READ or WRITE operations,
         * or if data integrity is enabled, account for registration and
         * invalidation work requests.
         */
        if (attr->create_flags & IB_QP_CREATE_INTEGRITY_EN ||
            rdma_rw_can_use_mr(dev, attr->port_num))
                factor += 2;    /* reg + inv */

        attr->cap.max_send_wr += factor * attr->cap.max_rdma_ctxs;

        /*
         * The device might not support all we need, and we'll have to
         * live with what we get.
         */
        attr->cap.max_send_wr =
                min_t(u32, attr->cap.max_send_wr, dev->attrs.max_qp_wr);
}

int rdma_rw_init_mrs(struct ib_qp *qp, struct ib_qp_init_attr *attr)
{
        struct ib_device *dev = qp->pd->device;
        u32 nr_mrs = 0, nr_sig_mrs = 0, max_num_sg = 0;
        int ret = 0;

        if (attr->create_flags & IB_QP_CREATE_INTEGRITY_EN) {
                nr_sig_mrs = attr->cap.max_rdma_ctxs;
                nr_mrs = attr->cap.max_rdma_ctxs;
                max_num_sg = rdma_rw_fr_page_list_len(dev, true);
        } else if (rdma_rw_can_use_mr(dev, attr->port_num)) {
                nr_mrs = attr->cap.max_rdma_ctxs;
                max_num_sg = rdma_rw_fr_page_list_len(dev, false);
        }

        if (nr_mrs) {
                ret = ib_mr_pool_init(qp, &qp->rdma_mrs, nr_mrs,
                                IB_MR_TYPE_MEM_REG,
                                max_num_sg, 0);
                if (ret) {
                        pr_err("%s: failed to allocated %u MRs\n",
                                __func__, nr_mrs);
                        return ret;
                }
        }

        if (nr_sig_mrs) {
                ret = ib_mr_pool_init(qp, &qp->sig_mrs, nr_sig_mrs,
                                IB_MR_TYPE_INTEGRITY, max_num_sg, max_num_sg);
                if (ret) {
                        pr_err("%s: failed to allocated %u SIG MRs\n",
                                __func__, nr_sig_mrs);
                        goto out_free_rdma_mrs;
                }
        }

        return 0;

out_free_rdma_mrs:
        ib_mr_pool_destroy(qp, &qp->rdma_mrs);
        return ret;
}

void rdma_rw_cleanup_mrs(struct ib_qp *qp)
{
        ib_mr_pool_destroy(qp, &qp->sig_mrs);
        ib_mr_pool_destroy(qp, &qp->rdma_mrs);
}