treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288

[mirror_ubuntu-focal-kernel.git] / drivers / infiniband / core / rw.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2016 HGST, a Western Digital Company.
 */
#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,
};

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");

/*
 * Check if the device might use memory registration.  This is currently only
 * true for iWarp devices. In the future we can hopefully fine tune this based
 * on HCA driver input.
 */
static inline bool rdma_rw_can_use_mr(struct ib_device *dev, u8 port_num)
{
        if (rdma_protocol_iwarp(dev, port_num))
                return true;
        if (unlikely(rdma_rw_force_mr))
                return true;
        return false;
}

/*
 * Check if the device will use memory registration for this RW operation.
 * We currently always use memory registrations for iWarp RDMA READs, and
 * have a debug option to force usage of MRs.
 *
 * XXX: In the future we can hopefully fine tune this based on HCA driver
 * input.
 */
static inline bool rdma_rw_io_needs_mr(struct ib_device *dev, u8 port_num,
                enum dma_data_direction dir, int dma_nents)
{
        if (rdma_protocol_iwarp(dev, port_num) && dir == DMA_FROM_DEVICE)
                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)
{
        /* arbitrary limit to avoid allocating gigantic resources */
        return min_t(u32, dev->attrs.max_fast_reg_page_list_len, 256);
}

/* Caller must have zero-initialized *reg. */
static int rdma_rw_init_one_mr(struct ib_qp *qp, u8 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);
        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;

        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;
        }

        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_mr_wrs(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
                u8 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);
        int i, j, ret = 0, count = 0;

        ctx->nr_ops = (sg_cnt + pages_per_mr - 1) / pages_per_mr;
        ctx->reg = kcalloc(ctx->nr_ops, sizeof(*ctx->reg), GFP_KERNEL);
        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;

                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;
                }
                count++;

                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_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 = kcalloc(sg_cnt, sizeof(*sge), GFP_KERNEL);
        if (!ctx->map.sges)
                goto out;

        ctx->map.wrs = kcalloc(ctx->nr_ops, sizeof(*ctx->map.wrs), GFP_KERNEL);
        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;
}

/**
 * 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, u8 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;
        int ret;

        if (is_pci_p2pdma_page(sg_page(sg)))
                ret = pci_p2pdma_map_sg(dev->dma_device, sg, sg_cnt, dir);
        else
                ret = ib_dma_map_sg(dev, sg, sg_cnt, dir);

        if (!ret)
                return -ENOMEM;
        sg_cnt = ret;

        /*
         * 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);
        } else 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);
        }

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

out_unmap_sg:
        ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
        return ret;
}
EXPORT_SYMBOL(rdma_rw_ctx_init);

/**
 * 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,
                u8 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);
        struct ib_rdma_wr *rdma_wr;
        struct ib_send_wr *prev_wr = NULL;
        int count = 0, ret;

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

        ret = ib_dma_map_sg(dev, sg, sg_cnt, dir);
        if (!ret)
                return -ENOMEM;
        sg_cnt = ret;

        ret = ib_dma_map_sg(dev, prot_sg, prot_sg_cnt, dir);
        if (!ret) {
                ret = -ENOMEM;
                goto out_unmap_sg;
        }
        prot_sg_cnt = ret;

        ctx->type = RDMA_RW_SIG_MR;
        ctx->nr_ops = 1;
        ctx->sig = kcalloc(1, sizeof(*ctx->sig), GFP_KERNEL);
        if (!ctx->sig) {
                ret = -ENOMEM;
                goto out_unmap_prot_sg;
        }

        ret = rdma_rw_init_one_mr(qp, port_num, &ctx->sig->data, sg, sg_cnt, 0);
        if (ret < 0)
                goto out_free_ctx;
        count += ret;
        prev_wr = &ctx->sig->data.reg_wr.wr;

        ret = rdma_rw_init_one_mr(qp, port_num, &ctx->sig->prot,
                                  prot_sg, prot_sg_cnt, 0);
        if (ret < 0)
                goto out_destroy_data_mr;
        count += ret;

        if (ctx->sig->prot.inv_wr.next)
                prev_wr->next = &ctx->sig->prot.inv_wr;
        else
                prev_wr->next = &ctx->sig->prot.reg_wr.wr;
        prev_wr = &ctx->sig->prot.reg_wr.wr;

        ctx->sig->sig_mr = ib_mr_pool_get(qp, &qp->sig_mrs);
        if (!ctx->sig->sig_mr) {
                ret = -EAGAIN;
                goto out_destroy_prot_mr;
        }

        if (ctx->sig->sig_mr->need_inval) {
                memset(&ctx->sig->sig_inv_wr, 0, sizeof(ctx->sig->sig_inv_wr));

                ctx->sig->sig_inv_wr.opcode = IB_WR_LOCAL_INV;
                ctx->sig->sig_inv_wr.ex.invalidate_rkey = ctx->sig->sig_mr->rkey;

                prev_wr->next = &ctx->sig->sig_inv_wr;
                prev_wr = &ctx->sig->sig_inv_wr;
        }

        ctx->sig->sig_wr.wr.opcode = IB_WR_REG_SIG_MR;
        ctx->sig->sig_wr.wr.wr_cqe = NULL;
        ctx->sig->sig_wr.wr.sg_list = &ctx->sig->data.sge;
        ctx->sig->sig_wr.wr.num_sge = 1;
        ctx->sig->sig_wr.access_flags = IB_ACCESS_LOCAL_WRITE;
        ctx->sig->sig_wr.sig_attrs = sig_attrs;
        ctx->sig->sig_wr.sig_mr = ctx->sig->sig_mr;
        if (prot_sg_cnt)
                ctx->sig->sig_wr.prot = &ctx->sig->prot.sge;
        prev_wr->next = &ctx->sig->sig_wr.wr;
        prev_wr = &ctx->sig->sig_wr.wr;
        count++;

        ctx->sig->sig_sge.addr = 0;
        ctx->sig->sig_sge.length = ctx->sig->data.sge.length;
        if (sig_attrs->wire.sig_type != IB_SIG_TYPE_NONE)
                ctx->sig->sig_sge.length += ctx->sig->prot.sge.length;

        rdma_wr = &ctx->sig->data.wr;
        rdma_wr->wr.sg_list = &ctx->sig->sig_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;
        prev_wr->next = &rdma_wr->wr;
        prev_wr = &rdma_wr->wr;
        count++;

        return count;

out_destroy_prot_mr:
        if (prot_sg_cnt)
                ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->sig->prot.mr);
out_destroy_data_mr:
        ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->sig->data.mr);
out_free_ctx:
        kfree(ctx->sig);
out_unmap_prot_sg:
        ib_dma_unmap_sg(dev, prot_sg, prot_sg_cnt, dir);
out_unmap_sg:
        ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
        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,
                u8 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:
                rdma_rw_update_lkey(&ctx->sig->data, true);
                if (ctx->sig->prot.mr)
                        rdma_rw_update_lkey(&ctx->sig->prot, true);
        
                ctx->sig->sig_mr->need_inval = true;
                ib_update_fast_reg_key(ctx->sig->sig_mr,
                        ib_inc_rkey(ctx->sig->sig_mr->lkey));
                ctx->sig->sig_sge.lkey = ctx->sig->sig_mr->lkey;

                if (ctx->sig->data.inv_wr.next)
                        first_wr = &ctx->sig->data.inv_wr;
                else
                        first_wr = &ctx->sig->data.reg_wr.wr;
                last_wr = &ctx->sig->data.wr.wr;
                break;
        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_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, u8 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, u8 port_num,
                struct scatterlist *sg, u32 sg_cnt, enum dma_data_direction dir)
{
        int 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);
                kfree(ctx->reg);
                break;
        case RDMA_RW_MULTI_WR:
                kfree(ctx->map.wrs);
                kfree(ctx->map.sges);
                break;
        case RDMA_RW_SINGLE_WR:
                break;
        default:
                BUG();
                break;
        }

        /* P2PDMA contexts do not need to be unmapped */
        if (!is_pci_p2pdma_page(sg_page(sg)))
                ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
}
EXPORT_SYMBOL(rdma_rw_ctx_destroy);

/**
 * rdma_rw_ctx_destroy_signature - release all resources allocated by
 *      rdma_rw_ctx_init_signature
 * @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,
                u8 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->rdma_mrs, ctx->sig->data.mr);
        ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);

        if (ctx->sig->prot.mr) {
                ib_mr_pool_put(qp, &qp->rdma_mrs, ctx->sig->prot.mr);
                ib_dma_unmap_sg(qp->pd->device, prot_sg, prot_sg_cnt, dir);
        }

        ib_mr_pool_put(qp, &qp->sig_mrs, ctx->sig->sig_mr);
        kfree(ctx->sig);
}
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, u8 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);
        else
                mr_pages = device->attrs.max_sge_rd;
        return DIV_ROUND_UP(maxpages, mr_pages);
}
EXPORT_SYMBOL(rdma_rw_mr_factor);

void rdma_rw_init_qp(struct ib_device *dev, struct ib_qp_init_attr *attr)
{
        u32 factor;

        WARN_ON_ONCE(attr->port_num == 0);

        /*
         * Each context needs at least one RDMA READ or WRITE WR.
         *
         * For some hardware we might need more, eventually we should ask the
         * HCA driver for a multiplier here.
         */
        factor = 1;

        /*
         * If the devices needs MRs to perform RDMA READ or WRITE operations,
         * we'll need two additional MRs for the registrations and the
         * invalidation.
         */
        if (attr->create_flags & IB_QP_CREATE_SIGNATURE_EN)
                factor += 6;    /* (inv + reg) * (data + prot + sig) */
        else if (rdma_rw_can_use_mr(dev, attr->port_num))
                factor += 2;    /* inv + reg */

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

        /*
         * But maybe we were just too high in the sky and the device doesn't
         * even 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;
        int ret = 0;

        if (attr->create_flags & IB_QP_CREATE_SIGNATURE_EN) {
                nr_sig_mrs = attr->cap.max_rdma_ctxs;
                nr_mrs = attr->cap.max_rdma_ctxs * 2;
        } else if (rdma_rw_can_use_mr(dev, attr->port_num)) {
                nr_mrs = attr->cap.max_rdma_ctxs;
        }

        if (nr_mrs) {
                ret = ib_mr_pool_init(qp, &qp->rdma_mrs, nr_mrs,
                                IB_MR_TYPE_MEM_REG,
                                rdma_rw_fr_page_list_len(dev));
                if (ret) {
                        pr_err("%s: failed to allocated %d 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_SIGNATURE, 2);
                if (ret) {
                        pr_err("%s: failed to allocated %d SIG MRs\n",
                                __func__, nr_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);
}