Dma-buf is a standard cross-driver buffer sharing mechanism that can be
used to support peer-to-peer access from RDMA devices.
Device memory exported via dma-buf is associated with a file descriptor.
This is passed to the user space as a property associated with the
buffer allocation. When the buffer is registered as a memory region,
the file descriptor is passed to the RDMA driver along with other
parameters.
Implement the common code for importing dma-buf object and mapping
dma-buf pages.
Signed-off-by: Jianxin Xiong <jianxin.xiong@xxxxxxxxx>
Reviewed-by: Sean Hefty <sean.hefty@xxxxxxxxx>
Acked-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Acked-by: Christian Koenig <christian.koenig@xxxxxxx>
Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/infiniband/core/Makefile | 2 +-
drivers/infiniband/core/umem.c | 4 +
drivers/infiniband/core/umem_dmabuf.c | 197 ++++++++++++++++++++++++++++++++++
drivers/infiniband/core/umem_dmabuf.h | 11 ++
include/rdma/ib_umem.h | 35 +++++-
5 files changed, 247 insertions(+), 2 deletions(-)
create mode 100644 drivers/infiniband/core/umem_dmabuf.c
create mode 100644 drivers/infiniband/core/umem_dmabuf.h
diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
index ccf2670..8ab4eea 100644
--- a/drivers/infiniband/core/Makefile
+++ b/drivers/infiniband/core/Makefile
@@ -40,5 +40,5 @@ ib_uverbs-y := uverbs_main.o uverbs_cmd.o uverbs_marshall.o \
uverbs_std_types_srq.o \
uverbs_std_types_wq.o \
uverbs_std_types_qp.o
-ib_uverbs-$(CONFIG_INFINIBAND_USER_MEM) += umem.o
+ib_uverbs-$(CONFIG_INFINIBAND_USER_MEM) += umem.o umem_dmabuf.o
ib_uverbs-$(CONFIG_INFINIBAND_ON_DEMAND_PAGING) += umem_odp.o
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index e9fecbd..2c45525 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -2,6 +2,7 @@
* Copyright (c) 2005 Topspin Communications. All rights reserved.
* Copyright (c) 2005 Cisco Systems. All rights reserved.
* Copyright (c) 2005 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2020 Intel Corporation. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
@@ -43,6 +44,7 @@
#include <rdma/ib_umem_odp.h>
#include "uverbs.h"
+#include "umem_dmabuf.h"
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
@@ -269,6 +271,8 @@ void ib_umem_release(struct ib_umem *umem)
{
if (!umem)
return;
+ if (umem->is_dmabuf)
+ return ib_umem_dmabuf_release(to_ib_umem_dmabuf(umem));
if (umem->is_odp)
return ib_umem_odp_release(to_ib_umem_odp(umem));
diff --git a/drivers/infiniband/core/umem_dmabuf.c b/drivers/infiniband/core/umem_dmabuf.c
new file mode 100644
index 0000000..66b234d
--- /dev/null
+++ b/drivers/infiniband/core/umem_dmabuf.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+/*
+ * Copyright (c) 2020 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/dma-resv.h>
+#include <linux/dma-mapping.h>
+
+#include "uverbs.h"
+#include "umem_dmabuf.h"
+
+/*
+ * Generate a new dma sg list from a sub range of an existing dma sg list.
+ * Both the input and output have their entries page aligned.
+ */
+static int ib_umem_dmabuf_sgt_slice(struct sg_table *sgt, u64 offset,
+ u64 length, struct sg_table *new_sgt)
+{
+ struct scatterlist *sg, *new_sg;
+ u64 start, end, off, addr, len;
+ unsigned int new_nents;
+ int err;
+ int i;
+
+ start = ALIGN_DOWN(offset, PAGE_SIZE);
+ end = ALIGN(offset + length, PAGE_SIZE);
+
+ offset = start;
+ length = end - start;
+ new_nents = 0;
+ for_each_sgtable_dma_sg(sgt, sg, i) {
+ len = sg_dma_len(sg);
+ off = min(len, offset);
+ len -= off;
+ len = min(len, length);
+ if (len)
+ new_nents++;
+ length -= len;
+ offset -= off;
+ }
+
+ err = sg_alloc_table(new_sgt, new_nents, GFP_KERNEL);
+ if (err)
+ return err;
+
+ offset = start;
+ length = end - start;
+ new_sg = new_sgt->sgl;
+ for_each_sgtable_dma_sg(sgt, sg, i) {
+ addr = sg_dma_address(sg);
+ len = sg_dma_len(sg);
+ off = min(len, offset);
+ addr += off;
+ len -= off;
+ len = min(len, length);
+ if (len) {
+ sg_dma_address(new_sg) = addr;
+ sg_dma_len(new_sg) = len;
+ new_sg = sg_next(new_sg);
+ }
+ length -= len;
+ offset -= off;
+ }
+
+ return 0;
+}
+
+int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf)
+{
+ struct sg_table *sgt;
+ struct dma_fence *fence;
+ int err;
+
+ dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
+
+ sgt = dma_buf_map_attachment(umem_dmabuf->attach,
+ DMA_BIDIRECTIONAL);
+
+ if (IS_ERR(sgt))
+ return PTR_ERR(sgt);
+
+ err = ib_umem_dmabuf_sgt_slice(sgt, umem_dmabuf->umem.address,
+ umem_dmabuf->umem.length,
+ &umem_dmabuf->umem.sg_head);
+ if (err) {
+ dma_buf_unmap_attachment(umem_dmabuf->attach, sgt,
+ DMA_BIDIRECTIONAL);
+ return err;
+ }
+
+ umem_dmabuf->umem.nmap = umem_dmabuf->umem.sg_head.nents;
+ umem_dmabuf->sgt = sgt;
+
+ /*
+ * Although the sg list is valid now, the content of the pages
+ * may be not up-to-date. Wait for the exporter to finish
+ * the migration.
+ */
+ fence = dma_resv_get_excl(umem_dmabuf->attach->dmabuf->resv);
+ if (fence)
+ dma_fence_wait(fence, false);
+
+ return 0;
+}
+EXPORT_SYMBOL(ib_umem_dmabuf_map_pages);
+
+void ib_umem_dmabuf_unmap_pages(struct ib_umem_dmabuf *umem_dmabuf)
+{
+ dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
+
+ if (!umem_dmabuf->sgt)
+ return;
+
+ sg_free_table(&umem_dmabuf->umem.sg_head);
+ dma_buf_unmap_attachment(umem_dmabuf->attach, umem_dmabuf->sgt,
+ DMA_BIDIRECTIONAL);
+ umem_dmabuf->sgt = NULL;
+}
+EXPORT_SYMBOL(ib_umem_dmabuf_unmap_pages);
+
+struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
+ unsigned long offset, size_t size,
+ int fd, int access,
+ const struct dma_buf_attach_ops *ops)
+{
+ struct dma_buf *dmabuf;
+ struct ib_umem_dmabuf *umem_dmabuf;
+ struct ib_umem *umem;
+ unsigned long end;
+ long ret;
+
+ if (check_add_overflow(offset, (unsigned long)size, &end))
+ return ERR_PTR(-EINVAL);
+
+ if (unlikely(PAGE_ALIGN(end) < PAGE_SIZE))
+ return ERR_PTR(-EINVAL);
+
+ if (unlikely(!ops || !ops->move_notify))
+ return ERR_PTR(-EINVAL);
+
+#ifdef CONFIG_DMA_VIRT_OPS
+ if (device->dma_device->dma_ops == &dma_virt_ops)
+ return ERR_PTR(-EINVAL);
+#endif
+
+ umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
+ if (!umem_dmabuf)
+ return ERR_PTR(-ENOMEM);
+
+ umem = &umem_dmabuf->umem;
+ umem->ibdev = device;
+ umem->length = size;
+ umem->address = offset;
+ umem->iova = offset;
+ umem->writable = ib_access_writable(access);
+ umem->is_dmabuf = 1;
+
+ dmabuf = dma_buf_get(fd);
+ if (IS_ERR(dmabuf)) {
+ ret = PTR_ERR(dmabuf);
+ goto out_free_umem;
+ }
+
+ umem_dmabuf->attach = dma_buf_dynamic_attach(
+ dmabuf,
+ device->dma_device,
+ ops,
+ umem_dmabuf);
+ if (IS_ERR(umem_dmabuf->attach)) {
+ ret = PTR_ERR(umem_dmabuf->attach);
+ goto out_release_dmabuf;
+ }
+
+ return umem;
+
+out_release_dmabuf:
+ dma_buf_put(dmabuf);
+
+out_free_umem:
+ kfree(umem_dmabuf);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(ib_umem_dmabuf_get);
+
+void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf)
+{
+ struct dma_buf *dmabuf = umem_dmabuf->attach->dmabuf;
+
+ dma_resv_lock(dmabuf->resv, NULL);
+ ib_umem_dmabuf_unmap_pages(umem_dmabuf);
+ dma_resv_unlock(dmabuf->resv);
+
+ dma_buf_detach(dmabuf, umem_dmabuf->attach);
+ dma_buf_put(dmabuf);
+ kfree(umem_dmabuf);
+}
diff --git a/drivers/infiniband/core/umem_dmabuf.h b/drivers/infiniband/core/umem_dmabuf.h
new file mode 100644
index 0000000..13acf55
--- /dev/null
+++ b/drivers/infiniband/core/umem_dmabuf.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
+/*
+ * Copyright (c) 2020 Intel Corporation. All rights reserved.
+ */
+
+#ifndef UMEM_DMABUF_H
+#define UMEM_DMABUF_H
+
+void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf);
+
+#endif /* UMEM_DMABUF_H */
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 7059750..73a7b19 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
/*
* Copyright (c) 2007 Cisco Systems. All rights reserved.
+ * Copyright (c) 2020 Intel Corporation. All rights reserved.
*/
#ifndef IB_UMEM_H
@@ -13,6 +14,7 @@
struct ib_ucontext;
struct ib_umem_odp;
+struct dma_buf_attach_ops;
struct ib_umem {
struct ib_device *ibdev;
@@ -22,12 +24,25 @@ struct ib_umem {
unsigned long address;
u32 writable : 1;
u32 is_odp : 1;
+ u32 is_dmabuf : 1;
struct work_struct work;
struct sg_table sg_head;
int nmap;
unsigned int sg_nents;
};
+struct ib_umem_dmabuf {
+ struct ib_umem umem;
+ struct dma_buf_attachment *attach;
+ struct sg_table *sgt;
+ void *device_context;
+};
+
+static inline struct ib_umem_dmabuf *to_ib_umem_dmabuf(struct ib_umem *umem)
+{
+ return container_of(umem, struct ib_umem_dmabuf, umem);
+}
+
/* Returns the offset of the umem start relative to the first page. */
static inline int ib_umem_offset(struct ib_umem *umem)
{
@@ -79,6 +94,12 @@ int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
unsigned long pgsz_bitmap,
unsigned long virt);
+struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
+ unsigned long offset, size_t size,
+ int fd, int access,
+ const struct dma_buf_attach_ops *ops);
+int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf);
+void ib_umem_dmabuf_unmap_pages(struct ib_umem_dmabuf *umem_dmabuf);
#else /* CONFIG_INFINIBAND_USER_MEM */
@@ -101,7 +122,19 @@ static inline unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
{
return 0;
}
+static inline struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
+ unsigned long offset,
+ size_t size, int fd,
+ int access,
+ struct dma_buf_attach_ops *ops)
+{
+ return ERR_PTR(-EINVAL);
+}
+static inline int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf)
+{
+ return -EINVAL;
+}
+static inline void ib_umem_dmabuf_unmap_pages(struct ib_umem_dmabuf *umem_dmabuf) { }
#endif /* CONFIG_INFINIBAND_USER_MEM */
-
#endif /* IB_UMEM_H */
--
1.8.3.1
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