On Fri, Oct 23, 2020 at 09:39:58AM -0700, Jianxin Xiong wrote:
> 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
Maybe I'm confused, but should we have this check in dma_buf_attach, or at
least in dma_buf_dynamic_attach? The p2pdma functions use that too, and I
can't imagine how zerocopy should work (which is like the entire point of
dma-buf) when we have dma_virt_ops.
A similar problem exists for swiotlb bounce buffers, not sure how that's
solved.
-Daniel
> +
> + 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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> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
