Re: [RFC PATCH v2 2/2] RDMA/rxe: Add dma-buf support

On Wed, Sep 29, 2021 at 01:19:05PM +0900, Shunsuke Mie wrote:

Implement a ib device operation ‘reg_user_mr_dmabuf’. Generate a rxe_map from the memory space linked the passed dma-buf.

Signed-off-by: Shunsuke Mie mie@igel.co.jp

drivers/infiniband/sw/rxe/rxe_loc.h | 2 + drivers/infiniband/sw/rxe/rxe_mr.c | 118 ++++++++++++++++++++++++++ drivers/infiniband/sw/rxe/rxe_verbs.c | 34 ++++++++ drivers/infiniband/sw/rxe/rxe_verbs.h | 2 + 4 files changed, 156 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h index 1ca43b859d80..8bc19ea1a376 100644 --- a/drivers/infiniband/sw/rxe/rxe_loc.h +++ b/drivers/infiniband/sw/rxe/rxe_loc.h @@ -75,6 +75,8 @@ 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); diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c index 53271df10e47..af6ef671c3a5 100644 --- a/drivers/infiniband/sw/rxe/rxe_mr.c +++ b/drivers/infiniband/sw/rxe/rxe_mr.c @@ -4,6 +4,7 @@

• Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.

*/

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

@@ -245,6 +246,120 @@ 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)
  

+{

• struct rxe_map_set *set;
• struct rxe_phys_buf *buf = NULL;
• struct rxe_map **map;
• void *vaddr, *vaddr_end;
• int num_buf = 0;
• int err;
• size_t remain;
• mr->dmabuf_map = kzalloc(sizeof &mr->dmabuf_map, GFP_KERNEL);

dmabuf_maps are just tagged pointers (and we could shrink them to actually just a tagged pointer if anyone cares about the overhead of the separate bool), allocating them seperately is overkill.

• if (!mr->dmabuf_map) {

• err = -ENOMEM;
  

• goto err_out;
  

• }
• err = dma_buf_vmap(umem_dmabuf->dmabuf, mr->dmabuf_map);
• if (err)

• goto err_free_dmabuf_map;
  

• set = mr->cur_map_set;
• set->page_shift = PAGE_SHIFT;
• set->page_mask = PAGE_SIZE - 1;
• map = set->map;
• buf = map[0]->buf;
• vaddr = mr->dmabuf_map->vaddr;

dma_buf_map can be an __iomem too, you shouldn't dig around in this, but use the dma-buf-map.h helpers instead. On x86 (and I think also on most arm) it doesn't matter, but it's kinda not very nice in a pure software driver.

If anything is missing in dma-buf-map.h wrappers just add more.

Or alternatively you need to fail the import if you can't handle __iomem.

Aside from these I think the dma-buf side here for cpu access looks reasonable now. -Daniel

• vaddr_end = vaddr + umem_dmabuf->dmabuf->size;
• remain = umem_dmabuf->dmabuf->size;
• for (; remain; vaddr += PAGE_SIZE) {

• if (num_buf >= RXE_BUF_PER_MAP) {
  

• 	map++;
  

• 	buf = map[0]->buf;
  

• 	num_buf = 0;
  

• }
  

• buf->addr = (uintptr_t)vaddr;
  

• if (remain >= PAGE_SIZE)
  

• 	buf->size = PAGE_SIZE;
  

• else
  

• 	buf->size = remain;
  

• remain -= buf->size;
  

• num_buf++;
  

• buf++;
  

• }
• return 0;

+err_free_dmabuf_map:

• kfree(mr->dmabuf_map);

+err_out:

• return err;

+}

+static void rxe_unmap_dmabuf_mr(struct rxe_mr *mr) +{

• struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(mr->umem);
• dma_buf_vunmap(umem_dmabuf->dmabuf, mr->dmabuf_map);
• kfree(mr->dmabuf_map);

+}

+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;
• struct rxe_map_set *set;
• int err;
• umem_dmabuf = ib_umem_dmabuf_get(pd->ibpd.device, start, length, fd,

• 			 access, NULL);
  

• if (IS_ERR(umem_dmabuf)) {

• err = PTR_ERR(umem_dmabuf);
  

• goto err_out;
  

• }
• rxe_mr_init(access, mr);
• err = rxe_mr_alloc(mr, ib_umem_num_pages(&umem_dmabuf->umem), 0);
• if (err) {

• pr_warn("%s: Unable to allocate memory for map\n", __func__);
  

• goto err_release_umem;
  

• }
• mr->ibmr.pd = &pd->ibpd;
• mr->umem = &umem_dmabuf->umem;
• mr->access = access;
• mr->state = RXE_MR_STATE_VALID;
• mr->type = IB_MR_TYPE_USER;
• set = mr->cur_map_set;
• set->length = length;
• set->iova = iova;
• set->va = start;
• set->offset = ib_umem_offset(mr->umem);
• err = rxe_map_dmabuf_mr(mr, umem_dmabuf);
• if (err)

• goto err_free_map_set;
  

• return 0;

+err_free_map_set:

• rxe_mr_free_map_set(mr->num_map, mr->cur_map_set);

+err_release_umem:

• ib_umem_release(&umem_dmabuf->umem);

+err_out:

• return err;

+}

int rxe_mr_init_fast(struct rxe_pd *pd, int max_pages, struct rxe_mr *mr) { int err; @@ -703,6 +818,9 @@ void rxe_mr_cleanup(struct rxe_pool_entry *arg) { struct rxe_mr *mr = container_of(arg, typeof(*mr), pelem);

• if (mr->umem && mr->umem->is_dmabuf)

• rxe_unmap_dmabuf_mr(mr);
  

• ib_umem_release(mr->umem);

  if (mr->cur_map_set)

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c index 9d0bb9aa7514..6191bb4f434d 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -916,6 +916,39 @@ 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 err2;
  

• }
• rxe_add_index(mr);
• rxe_add_ref(pd);
• err = rxe_mr_dmabuf_init_user(pd, fd, start, length, iova, access, mr);
• if (err)

• goto err3;
  

• return &mr->ibmr;

+err3:

• rxe_drop_ref(pd);
• rxe_drop_index(mr);
• rxe_drop_ref(mr);

+err2:

• 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) { @@ -1081,6 +1114,7 @@ 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,

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h index c807639435eb..0aa95ab06b6e 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.h +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h @@ -334,6 +334,8 @@ struct rxe_mr {

struct rxe_map_set *cur_map_set; struct rxe_map_set *next_map_set;

• struct dma_buf_map *dmabuf_map;

};

enum rxe_mw_state {

2.17.1