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    Subject[RFC PATCH 3/3] RDMA/rxe: Support dma-buf as memory region
    Date
    Implement a ib device operation ‘reg_user_mr_dmabuf’. Import dma-buf
    using the IB core API and map the memory area linked the dma-buf.

    Signed-off-by: Shunsuke Mie <mie@igel.co.jp>
    ---
    drivers/infiniband/sw/rxe/rxe_loc.h | 3 +
    drivers/infiniband/sw/rxe/rxe_mr.c | 101 ++++++++++++++++++++++++++
    drivers/infiniband/sw/rxe/rxe_verbs.c | 36 +++++++++
    3 files changed, 140 insertions(+)

    diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
    index 1ddb20855dee..206d9d5f8bbf 100644
    --- a/drivers/infiniband/sw/rxe/rxe_loc.h
    +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
    @@ -75,6 +75,9 @@ u8 rxe_get_next_key(u32 last_key);
    void rxe_mr_init_dma(struct rxe_pd *pd, int access, struct rxe_mr *mr);
    int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
    int access, struct rxe_mr *mr);
    +int rxe_mr_dmabuf_init_user(struct rxe_pd *pd, int fd, u64 start, u64 length,
    + u64 iova, int access, struct rxe_mr *mr);
    +
    int rxe_mr_init_fast(struct rxe_pd *pd, int max_pages, struct rxe_mr *mr);
    int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
    enum rxe_mr_copy_dir dir, u32 *crcp);
    diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
    index 8b08705ed62a..846f52aad0de 100644
    --- a/drivers/infiniband/sw/rxe/rxe_mr.c
    +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
    @@ -4,6 +4,8 @@
    * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
    */

    +#include <linux/dma-buf.h>
    +
    #include "rxe.h"
    #include "rxe_loc.h"

    @@ -207,6 +209,105 @@ int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
    return err;
    }

    +static int rxe_map_dmabuf_mr(struct rxe_mr *mr)
    +{
    + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(mr->umem);
    + struct ib_umem *umem = mr->umem;
    + int err;
    +
    + err = ib_umem_dmabuf_map_pages(umem_dmabuf);
    + if (err)
    + goto err1;
    +
    + err = rxe_mr_gen_map(mr, umem);
    + if (err)
    + goto err2;
    +
    + return ib_umem_num_pages(umem);
    +
    +err2:
    + ib_umem_dmabuf_unmap_pages(umem_dmabuf);
    +err1:
    + return err;
    +}
    +
    +/* A function called from the dma-buf exporter when the mapped pages
    + * become invalid.
    + */
    +static void rxe_ib_dmabuf_invalidate_cb(struct dma_buf_attachment *attach)
    +{
    + int err;
    + struct ib_umem_dmabuf *umem_dmabuf = attach->importer_priv;
    + struct rxe_mr *mr = umem_dmabuf->private;
    +
    + ib_umem_dmabuf_unmap_pages(umem_dmabuf);
    +
    + /* all of memory region is immediately mapped again */
    + err = rxe_map_dmabuf_mr(mr);
    + if (err)
    + pr_err("%s: failed to map the dma-buf region", __func__);
    +}
    +
    +static struct dma_buf_attach_ops rxe_ib_dmabuf_attach_ops = {
    + .move_notify = rxe_ib_dmabuf_invalidate_cb,
    +};
    +
    +/* initialize a umem and map all the areas of dma-buf. */
    +int rxe_mr_dmabuf_init_user(struct rxe_pd *pd, int fd, u64 start, u64 length,
    + u64 iova, int access, struct rxe_mr *mr)
    +{
    + struct ib_umem_dmabuf *umem_dmabuf;
    + int num_buf;
    + int err;
    +
    + umem_dmabuf = ib_umem_dmabuf_get(pd->ibpd.device, start, length, fd,
    + access, &rxe_ib_dmabuf_attach_ops);
    + if (IS_ERR(umem_dmabuf)) {
    + err = PTR_ERR(umem_dmabuf);
    + pr_err("%s: failed to get umem_dmabuf (%d)", __func__, err);
    + goto err1;
    + }
    +
    + umem_dmabuf->private = mr;
    +
    + mr->umem = &umem_dmabuf->umem;
    + mr->umem->iova = iova;
    + num_buf = ib_umem_num_pages(mr->umem);
    +
    + rxe_mr_init(access, mr);
    +
    + err = rxe_mr_alloc(mr, num_buf);
    + if (err)
    + goto err1;
    +
    + mr->page_shift = PAGE_SHIFT;
    + mr->page_mask = PAGE_SIZE - 1;
    +
    + mr->ibmr.pd = &pd->ibpd;
    + mr->access = access;
    + mr->length = length;
    + mr->iova = iova;
    + mr->va = start;
    + mr->offset = ib_umem_offset(mr->umem);
    + mr->state = RXE_MR_STATE_VALID;
    + mr->type = RXE_MR_TYPE_MR;
    +
    + err = rxe_map_dmabuf_mr(mr);
    + if (err) {
    + pr_err("%s: failed to map the dma-buf region", __func__);
    + goto err2;
    + }
    +
    + return 0;
    +
    +err2:
    + for (i = 0; i < mr->num_map; i++)
    + kfree(mr->map[i]);
    + kfree(mr->map);
    +err1:
    + return err;
    +}
    +
    int rxe_mr_init_fast(struct rxe_pd *pd, int max_pages, struct rxe_mr *mr)
    {
    int err;
    diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
    index c223959ac174..4a38c20730b3 100644
    --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
    +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
    @@ -959,6 +959,39 @@ static struct ib_mr *rxe_reg_user_mr(struct ib_pd *ibpd,
    return ERR_PTR(err);
    }

    +static struct ib_mr *rxe_reg_user_mr_dmabuf(struct ib_pd *ibpd, u64 start,
    + u64 length, u64 iova, int fd,
    + int access, struct ib_udata *udata)
    +{
    + int err;
    + struct rxe_dev *rxe = to_rdev(ibpd->device);
    + struct rxe_pd *pd = to_rpd(ibpd);
    + struct rxe_mr *mr;
    +
    + mr = rxe_alloc(&rxe->mr_pool);
    + if (!mr) {
    + err = -ENOMEM;
    + goto err1;
    + }
    +
    + rxe_add_index(mr);
    +
    + rxe_add_ref(pd);
    +
    + err = rxe_mr_dmabuf_init_user(pd, fd, start, length, iova, access, mr);
    + if (err)
    + goto err2;
    +
    + return &mr->ibmr;
    +
    +err2:
    + rxe_drop_ref(pd);
    + rxe_drop_index(mr);
    + rxe_drop_ref(mr);
    +err1:
    + return ERR_PTR(err);
    +}
    +
    static struct ib_mr *rxe_alloc_mr(struct ib_pd *ibpd, enum ib_mr_type mr_type,
    u32 max_num_sg)
    {
    @@ -1139,6 +1172,7 @@ static const struct ib_device_ops rxe_dev_ops = {
    .query_qp = rxe_query_qp,
    .query_srq = rxe_query_srq,
    .reg_user_mr = rxe_reg_user_mr,
    + .reg_user_mr_dmabuf = rxe_reg_user_mr_dmabuf,
    .req_notify_cq = rxe_req_notify_cq,
    .resize_cq = rxe_resize_cq,

    @@ -1181,6 +1215,8 @@ int rxe_register_device(struct rxe_dev *rxe, const char *ibdev_name)
    }
    rxe->tfm = tfm;

    + dma_coerce_mask_and_coherent(&dev->dev, DMA_BIT_MASK(64));
    +
    err = ib_register_device(dev, ibdev_name, NULL);
    if (err)
    pr_warn("%s failed with error %d\n", __func__, err);
    --
    2.17.1
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