[RFC PATCH v4 2/2] RDMA/rxe: Add dma-buf support

[Shunsuke Mie <mie@igel.co.jp>]

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    | 113 ++++++++++++++++++++++++++
 drivers/infiniband/sw/rxe/rxe_verbs.c |  34 ++++++++
 3 files changed, 149 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..b954e5647f82 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 <linux/dma-buf-map.h>
 #include "rxe.h"
 #include "rxe_loc.h"
 
@@ -245,6 +247,114 @@ 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;
+	int num_buf = 0;
+	int err;
+	size_t remain;
+	struct dma_buf_map dmabuf_map;
+
+	err = dma_buf_vmap(umem_dmabuf->dmabuf, &dmabuf_map);
+	if (err || dmabuf_map.is_iomem)
+		goto err_out;
+
+	set = mr->cur_map_set;
+	set->page_shift = PAGE_SHIFT;
+	set->page_mask = PAGE_SIZE - 1;
+
+	map = set->map;
+	buf = map[0]->buf;
+
+	vaddr = dmabuf_map.vaddr;
+	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_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);
+	struct rxe_map *map = mr->cur_map_set->map[0];
+	struct dma_buf_map dma_buf_map =
+		DMA_BUF_MAP_INIT_VADDR((void *)(uintptr_t)map->buf->addr);
+
+	dma_buf_vunmap(umem_dmabuf->dmabuf, &dma_buf_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 +813,9 @@ 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 0aa0d7e52773..dc7d27b3cb90 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -940,6 +940,39 @@ 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)
 {
@@ -1105,6 +1138,7 @@ 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,
 
-- 
2.17.1