Cc'd drm people.
> -----Original Message-----
> From: Xiong, Jianxin <jianxin.xiong@xxxxxxxxx>
> Sent: Monday, June 29, 2020 10:32 AM
> To: linux-rdma@xxxxxxxxxxxxxxx
> Cc: Xiong, Jianxin <jianxin.xiong@xxxxxxxxx>; Doug Ledford <dledford@xxxxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxx>; Sumit Semwal
> <sumit.semwal@xxxxxxxxxx>; Leon Romanovsky <leon@xxxxxxxxxx>; Vetter, Daniel <daniel.vetter@xxxxxxxxx>
> Subject: [RFC PATCH v2 1/3] RDMA/umem: Support importing dma-buf as user memory region
>
> 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 can be 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 pinning 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>
> ---
> drivers/infiniband/core/Makefile | 2 +-
> drivers/infiniband/core/umem.c | 4 ++
> drivers/infiniband/core/umem_dmabuf.c | 105 ++++++++++++++++++++++++++++++++++
> drivers/infiniband/core/umem_dmabuf.h | 11 ++++
> include/rdma/ib_umem.h | 14 ++++-
> 5 files changed, 134 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 d1b14887..0d4efa0 100644
> --- a/drivers/infiniband/core/Makefile
> +++ b/drivers/infiniband/core/Makefile
> @@ -37,5 +37,5 @@ ib_uverbs-y := uverbs_main.o uverbs_cmd.o uverbs_marshall.o \
> uverbs_std_types_mr.o uverbs_std_types_counters.o \
> uverbs_uapi.o uverbs_std_types_device.o \
> uverbs_std_types_async_fd.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 82455a1..bf1a6c1 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
> @@ -42,6 +43,7 @@
> #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)
> {
> @@ -317,6 +319,8 @@ void ib_umem_release(struct ib_umem *umem)
> {
> if (!umem)
> return;
> + if (umem->is_dmabuf)
> + return ib_umem_dmabuf_release(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..406ca64
> --- /dev/null
> +++ b/drivers/infiniband/core/umem_dmabuf.c
> @@ -0,0 +1,105 @@
> +// 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-mapping.h>
> +
> +#include "uverbs.h"
> +
> +struct ib_umem_dmabuf {
> + struct ib_umem umem;
> + struct dma_buf *dmabuf;
> + struct dma_buf_attachment *attach;
> + struct sg_table *sgt;
> +};
> +
> +static inline struct ib_umem_dmabuf *to_ib_umem_dmabuf(struct ib_umem *umem)
> +{
> + return container_of(umem, struct ib_umem_dmabuf, umem);
> +}
> +
> +struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
> + unsigned long addr, size_t size,
> + int dmabuf_fd, int access)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf;
> + struct sg_table *sgt;
> + enum dma_data_direction dir;
> + long ret;
> + unsigned long end;
> +
> + if (check_add_overflow(addr, size, &end))
> + return ERR_PTR(-EINVAL);
> +
> + if (unlikely(PAGE_ALIGN(end) < PAGE_SIZE))
> + return ERR_PTR(-EINVAL);
> +
> + if (access & IB_ACCESS_ON_DEMAND)
> + return ERR_PTR(-EOPNOTSUPP);
> +
> + umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> + if (!umem_dmabuf)
> + return ERR_PTR(-ENOMEM);
> +
> + umem_dmabuf->umem.ibdev = device;
> + umem_dmabuf->umem.length = size;
> + umem_dmabuf->umem.address = addr;
> + umem_dmabuf->umem.writable = ib_access_writable(access);
> + umem_dmabuf->umem.is_dmabuf = 1;
> +
> + umem_dmabuf->dmabuf = dma_buf_get(dmabuf_fd);
> + if (IS_ERR(umem_dmabuf->dmabuf)) {
> + ret = PTR_ERR(umem_dmabuf->dmabuf);
> + goto out_free_umem;
> + }
> +
> + umem_dmabuf->attach = dma_buf_attach(umem_dmabuf->dmabuf,
> + device->dma_device);
> + if (IS_ERR(umem_dmabuf->attach)) {
> + ret = PTR_ERR(umem_dmabuf->attach);
> + goto out_release_dmabuf;
> + }
> +
> + dir = umem_dmabuf->umem.writable ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
> + sgt = dma_buf_map_attachment(umem_dmabuf->attach, dir);
> + if (IS_ERR(sgt)) {
> + ret = PTR_ERR(sgt);
> + goto out_detach_dmabuf;
> + }
> +
> + umem_dmabuf->sgt = sgt;
> + umem_dmabuf->umem.sg_head = *sgt;
> + umem_dmabuf->umem.nmap = sgt->nents;
> + return &umem_dmabuf->umem;
> +
> +out_detach_dmabuf:
> + dma_buf_detach(umem_dmabuf->dmabuf, umem_dmabuf->attach);
> +
> +out_release_dmabuf:
> + dma_buf_put(umem_dmabuf->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 *umem)
> +{
> + enum dma_data_direction dir;
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(umem);
> +
> + dir = umem_dmabuf->umem.writable ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
> +
> + /*
> + * Only use the original sgt returned from dma_buf_map_attachment(),
> + * otherwise the scatterlist may be freed twice due to the map caching
> + * mechanism.
> + */
> + dma_buf_unmap_attachment(umem_dmabuf->attach, umem_dmabuf->sgt, dir);
> + dma_buf_detach(umem_dmabuf->dmabuf, umem_dmabuf->attach);
> + dma_buf_put(umem_dmabuf->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..485f653
> --- /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 *umem);
> +
> +#endif /* UMEM_DMABUF_H */
> diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
> index e3518fd..78331ce 100644
> --- a/include/rdma/ib_umem.h
> +++ b/include/rdma/ib_umem.h
> @@ -1,5 +1,6 @@
> /*
> * Copyright (c) 2007 Cisco Systems. 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
> @@ -40,6 +41,7 @@
>
> struct ib_ucontext;
> struct ib_umem_odp;
> +struct ib_umem_dmabuf;
>
> struct ib_umem {
> struct ib_device *ibdev;
> @@ -48,6 +50,7 @@ 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;
> @@ -78,6 +81,9 @@ 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 addr, size_t size,
> + int dmabuf_fd, int access);
>
> #else /* CONFIG_INFINIBAND_USER_MEM */
>
> @@ -100,7 +106,13 @@ static inline int ib_umem_find_best_pgsz(struct ib_umem *umem,
> unsigned long virt) {
> return -EINVAL;
> }
> +static inline struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
> + unsigned long addr,
> + size_t size, int dmabuf_fd,
> + int access)
> +{
> + return ERR_PTR(-EINVAL);
> +}
>
> #endif /* CONFIG_INFINIBAND_USER_MEM */
> -
> #endif /* IB_UMEM_H */
> --
> 1.8.3.1
