[v13,1/4] RDMA/umem: Support importing dma-buf as user memory region

Commit Message

Xiong, Jianxin Dec. 7, 2020, 10:15 p.m. UTC

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 <[e-mail]>
Reviewed-by: Sean Hefty <[e-mail]>
Acked-by: Michael J. Ruhl <[e-mail]>
Acked-by: Christian Koenig <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>

Conflicts:
	include/rdma/ib_umem.h
---
 drivers/infiniband/core/Makefile      |   2 +-
 drivers/infiniband/core/umem.c        |   3 +
 drivers/infiniband/core/umem_dmabuf.c | 173 ++++++++++++++++++++++++++++++++++
 include/rdma/ib_umem.h                |  43 ++++++++-
 4 files changed, 219 insertions(+), 2 deletions(-)
 create mode 100644 drivers/infiniband/core/umem_dmabuf.c

Comments

Leon Romanovsky Dec. 8, 2020, 7:05 a.m. UTC | #1

On Mon, Dec 07, 2020 at 02:15:50PM -0800, 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 <[e-mail]>
> Reviewed-by: Sean Hefty <[e-mail]>
> Acked-by: Michael J. Ruhl <[e-mail]>
> Acked-by: Christian Koenig <[e-mail]>
> Acked-by: Daniel Vetter <[e-mail]>
>
> Conflicts:
> 	include/rdma/ib_umem.h

This probably leftover from rebase, am I right?

> ---
>  drivers/infiniband/core/Makefile      |   2 +-
>  drivers/infiniband/core/umem.c        |   3 +
>  drivers/infiniband/core/umem_dmabuf.c | 173 ++++++++++++++++++++++++++++++++++
>  include/rdma/ib_umem.h                |  43 ++++++++-
>  4 files changed, 219 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/infiniband/core/umem_dmabuf.c
>
> 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 7ca4112..cc131f8 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
> @@ -278,6 +279,8 @@ 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..e50b955
> --- /dev/null
> +++ b/drivers/infiniband/core/umem_dmabuf.c
> @@ -0,0 +1,173 @@
> +// 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"
> +
> +int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf)
> +{
> +	struct sg_table *sgt;
> +	struct scatterlist *sg;
> +	struct dma_fence *fence;
> +	unsigned long start, end, cur;
> +	unsigned int nmap;
> +	int i;
> +
> +	dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> +
> +	if (umem_dmabuf->sgt)
> +		return 0;
> +
> +	sgt = dma_buf_map_attachment(umem_dmabuf->attach, DMA_BIDIRECTIONAL);
> +	if (IS_ERR(sgt))
> +		return PTR_ERR(sgt);
> +
> +	/* modify the sg list in-place to match umem address and length */
> +
> +	start = ALIGN_DOWN(umem_dmabuf->umem.address, PAGE_SIZE);
> +	end = ALIGN(umem_dmabuf->umem.address + umem_dmabuf->umem.length,
> +		    PAGE_SIZE);
> +	cur = 0;
> +	nmap = 0;

Better to put as part of variable initialization.

> +	for_each_sgtable_dma_sg(sgt, sg, i) {
> +		if (start < cur + sg_dma_len(sg) && cur < end)
> +			nmap++;
> +		if (cur <= start && start < cur + sg_dma_len(sg)) {
> +			unsigned long offset = start - cur;
> +
> +			umem_dmabuf->first_sg = sg;
> +			umem_dmabuf->first_sg_offset = offset;
> +			sg_dma_address(sg) += offset;
> +			sg_dma_len(sg) -= offset;
> +			cur += offset;
> +		}
> +		if (cur < end && end <= cur + sg_dma_len(sg)) {
> +			unsigned long trim = cur + sg_dma_len(sg) - end;
> +
> +			umem_dmabuf->last_sg = sg;
> +			umem_dmabuf->last_sg_trim = trim;
> +			sg_dma_len(sg) -= trim;
> +			break;
> +		}
> +		cur += sg_dma_len(sg);
> +	}
> +
> +	umem_dmabuf->umem.sg_head.sgl = umem_dmabuf->first_sg;
> +	umem_dmabuf->umem.sg_head.nents = nmap;
> +	umem_dmabuf->umem.nmap = nmap;
> +	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);

Any reason do not check return result from dma_fence_wait()?

> +
> +	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;
> +
> +	/* retore the original sg list */
> +	if (umem_dmabuf->first_sg) {
> +		sg_dma_address(umem_dmabuf->first_sg) -=
> +			umem_dmabuf->first_sg_offset;
> +		sg_dma_len(umem_dmabuf->first_sg) +=
> +			umem_dmabuf->first_sg_offset;
> +		umem_dmabuf->first_sg = NULL;
> +		umem_dmabuf->first_sg_offset = 0;
> +	}
> +	if (umem_dmabuf->last_sg) {
> +		sg_dma_len(umem_dmabuf->last_sg) +=
> +			umem_dmabuf->last_sg_trim;
> +		umem_dmabuf->last_sg = NULL;
> +		umem_dmabuf->last_sg_trim = 0;
> +	}
> +
> +	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 = -EINVAL;

It is wrong type for the returned value. One of the possible options
is to declare "struct ib_umem *ret;" and set ret = ERR_PTR(-EINVAL) or
ret = ERR_CAST(dmabuf);

> +
> +	if (check_add_overflow(offset, (unsigned long)size, &end))
> +		return ERR_PTR(-EINVAL);
> +
> +	if (unlikely(!ops || !ops->move_notify))

Let's not put likely/unlikely in control paths.

> +		return ERR_PTR(-EINVAL);
> +
> +	dmabuf = dma_buf_get(fd);
> +	if (IS_ERR(dmabuf))
> +		return (void *)dmabuf;

return ERR_CAST(dmabuf);

> +
> +	if (dmabuf->size < end)
> +		goto out_release_dmabuf;
> +
> +	umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> +	if (!umem_dmabuf)
> +		return ERR_PTR(-ENOMEM);

You are leaking dmabuf here, forgot to call to dma_buf_put();

> +
> +	umem = &umem_dmabuf->umem;
> +	umem->ibdev = device;
> +	umem->length = size;
> +	umem->address = offset;
> +	umem->writable = ib_access_writable(access);
> +	umem->is_dmabuf = 1;
> +
> +	if (unlikely(!ib_umem_num_pages(umem)))

There is no advantage in "unlikely" here.

> +		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_free_umem;
> +	}
> +	return umem;
> +
> +out_free_umem:
> +	kfree(umem_dmabuf);
> +
> +out_release_dmabuf:
> +	dma_buf_put(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_buf_detach(dmabuf, umem_dmabuf->attach);
> +	dma_buf_put(dmabuf);
> +	kfree(umem_dmabuf);
> +}
> diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
> index 7752211..b49a96d 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 +24,29 @@ 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;
> +	struct scatterlist *first_sg;
> +	struct scatterlist *last_sg;
> +	unsigned long first_sg_offset;
> +	unsigned long last_sg_trim;
> +	void *private;
> +};
> +
> +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)
>  {
> @@ -86,6 +105,7 @@ 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);
> +
>  /**
>   * ib_umem_find_best_pgoff - Find best HW page size
>   *
> @@ -116,6 +136,14 @@ static inline unsigned long ib_umem_find_best_pgoff(struct ib_umem *umem,
>  				      dma_addr & pgoff_bitmask);
>  }
>
> +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);
> +void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf);
> +
>  #else /* CONFIG_INFINIBAND_USER_MEM */
>
>  #include <linux/err.h>
> @@ -143,7 +171,20 @@ static inline unsigned long ib_umem_find_best_pgoff(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);

Probably, It should be EOPNOTSUPP and not 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) { }
> +static inline void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf) { }
>
>  #endif /* CONFIG_INFINIBAND_USER_MEM */
> -
>  #endif /* IB_UMEM_H */
> --
> 1.8.3.1
>

Xiong, Jianxin Dec. 8, 2020, 7:10 a.m. UTC | #2

> -----Original Message-----
> From: Leon Romanovsky <[e-mail]>
> Sent: Monday, December 07, 2020 11:06 PM
> To: Xiong, Jianxin <[e-mail]>
> Cc: [e-mail]; [e-mail]; Doug Ledford <[e-mail]>; Jason Gunthorpe <[e-mail]>;
> Sumit Semwal <[e-mail]>; Christian Koenig <[e-mail]>; Vetter, Daniel <[e-mail]>
> Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region
> 
> On Mon, Dec 07, 2020 at 02:15:50PM -0800, 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 <[e-mail]>
> > Reviewed-by: Sean Hefty <[e-mail]>
> > Acked-by: Michael J. Ruhl <[e-mail]>
> > Acked-by: Christian Koenig <[e-mail]>
> > Acked-by: Daniel Vetter <[e-mail]>
> >
> > Conflicts:
> > 	include/rdma/ib_umem.h
> 
> This probably leftover from rebase, am I right?

Right. Should have removed it.

> 
> > ---
> >  drivers/infiniband/core/Makefile      |   2 +-
> >  drivers/infiniband/core/umem.c        |   3 +
> >  drivers/infiniband/core/umem_dmabuf.c | 173 ++++++++++++++++++++++++++++++++++
> >  include/rdma/ib_umem.h                |  43 ++++++++-
> >  4 files changed, 219 insertions(+), 2 deletions(-)  create mode
> > 100644 drivers/infiniband/core/umem_dmabuf.c
> >
> > 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 7ca4112..cc131f8 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 @@ -278,6 +279,8 @@ 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..e50b955
> > --- /dev/null
> > +++ b/drivers/infiniband/core/umem_dmabuf.c
> > @@ -0,0 +1,173 @@
> > +// 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"
> > +
> > +int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf) {
> > +	struct sg_table *sgt;
> > +	struct scatterlist *sg;
> > +	struct dma_fence *fence;
> > +	unsigned long start, end, cur;
> > +	unsigned int nmap;
> > +	int i;
> > +
> > +	dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> > +
> > +	if (umem_dmabuf->sgt)
> > +		return 0;
> > +
> > +	sgt = dma_buf_map_attachment(umem_dmabuf->attach, DMA_BIDIRECTIONAL);
> > +	if (IS_ERR(sgt))
> > +		return PTR_ERR(sgt);
> > +
> > +	/* modify the sg list in-place to match umem address and length */
> > +
> > +	start = ALIGN_DOWN(umem_dmabuf->umem.address, PAGE_SIZE);
> > +	end = ALIGN(umem_dmabuf->umem.address + umem_dmabuf->umem.length,
> > +		    PAGE_SIZE);
> > +	cur = 0;
> > +	nmap = 0;
> 
> Better to put as part of variable initialization.
> 
> > +	for_each_sgtable_dma_sg(sgt, sg, i) {
> > +		if (start < cur + sg_dma_len(sg) && cur < end)
> > +			nmap++;
> > +		if (cur <= start && start < cur + sg_dma_len(sg)) {
> > +			unsigned long offset = start - cur;
> > +
> > +			umem_dmabuf->first_sg = sg;
> > +			umem_dmabuf->first_sg_offset = offset;
> > +			sg_dma_address(sg) += offset;
> > +			sg_dma_len(sg) -= offset;
> > +			cur += offset;
> > +		}
> > +		if (cur < end && end <= cur + sg_dma_len(sg)) {
> > +			unsigned long trim = cur + sg_dma_len(sg) - end;
> > +
> > +			umem_dmabuf->last_sg = sg;
> > +			umem_dmabuf->last_sg_trim = trim;
> > +			sg_dma_len(sg) -= trim;
> > +			break;
> > +		}
> > +		cur += sg_dma_len(sg);
> > +	}
> > +
> > +	umem_dmabuf->umem.sg_head.sgl = umem_dmabuf->first_sg;
> > +	umem_dmabuf->umem.sg_head.nents = nmap;
> > +	umem_dmabuf->umem.nmap = nmap;
> > +	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);
> 
> Any reason do not check return result from dma_fence_wait()?
> 
> > +
> > +	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;
> > +
> > +	/* retore the original sg list */
> > +	if (umem_dmabuf->first_sg) {
> > +		sg_dma_address(umem_dmabuf->first_sg) -=
> > +			umem_dmabuf->first_sg_offset;
> > +		sg_dma_len(umem_dmabuf->first_sg) +=
> > +			umem_dmabuf->first_sg_offset;
> > +		umem_dmabuf->first_sg = NULL;
> > +		umem_dmabuf->first_sg_offset = 0;
> > +	}
> > +	if (umem_dmabuf->last_sg) {
> > +		sg_dma_len(umem_dmabuf->last_sg) +=
> > +			umem_dmabuf->last_sg_trim;
> > +		umem_dmabuf->last_sg = NULL;
> > +		umem_dmabuf->last_sg_trim = 0;
> > +	}
> > +
> > +	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 = -EINVAL;
> 
> It is wrong type for the returned value. One of the possible options is to declare "struct ib_umem *ret;" and set ret = ERR_PTR(-EINVAL) or
> ret = ERR_CAST(dmabuf);
> 
> > +
> > +	if (check_add_overflow(offset, (unsigned long)size, &end))
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	if (unlikely(!ops || !ops->move_notify))
> 
> Let's not put likely/unlikely in control paths.
> 
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	dmabuf = dma_buf_get(fd);
> > +	if (IS_ERR(dmabuf))
> > +		return (void *)dmabuf;
> 
> return ERR_CAST(dmabuf);
> 
> > +
> > +	if (dmabuf->size < end)
> > +		goto out_release_dmabuf;
> > +
> > +	umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> > +	if (!umem_dmabuf)
> > +		return ERR_PTR(-ENOMEM);
> 
> You are leaking dmabuf here, forgot to call to dma_buf_put();
> 
> > +
> > +	umem = &umem_dmabuf->umem;
> > +	umem->ibdev = device;
> > +	umem->length = size;
> > +	umem->address = offset;
> > +	umem->writable = ib_access_writable(access);
> > +	umem->is_dmabuf = 1;
> > +
> > +	if (unlikely(!ib_umem_num_pages(umem)))
> 
> There is no advantage in "unlikely" here.
> 
> > +		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_free_umem;
> > +	}
> > +	return umem;
> > +
> > +out_free_umem:
> > +	kfree(umem_dmabuf);
> > +
> > +out_release_dmabuf:
> > +	dma_buf_put(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_buf_detach(dmabuf, umem_dmabuf->attach);
> > +	dma_buf_put(dmabuf);
> > +	kfree(umem_dmabuf);
> > +}
> > diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h index
> > 7752211..b49a96d 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 +24,29 @@ 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;
> > +	struct scatterlist *first_sg;
> > +	struct scatterlist *last_sg;
> > +	unsigned long first_sg_offset;
> > +	unsigned long last_sg_trim;
> > +	void *private;
> > +};
> > +
> > +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)  { @@ -86,6
> > +105,7 @@ 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);
> > +
> >  /**
> >   * ib_umem_find_best_pgoff - Find best HW page size
> >   *
> > @@ -116,6 +136,14 @@ static inline unsigned long ib_umem_find_best_pgoff(struct ib_umem *umem,
> >  				      dma_addr & pgoff_bitmask);
> >  }
> >
> > +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); void
> > +ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf);
> > +
> >  #else /* CONFIG_INFINIBAND_USER_MEM */
> >
> >  #include <linux/err.h>
> > @@ -143,7 +171,20 @@ static inline unsigned long
> > ib_umem_find_best_pgoff(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);
> 
> Probably, It should be EOPNOTSUPP and not 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) { } static inline void ib_umem_dmabuf_release(struct
> > +ib_umem_dmabuf *umem_dmabuf) { }
> >
> >  #endif /* CONFIG_INFINIBAND_USER_MEM */
> > -
> >  #endif /* IB_UMEM_H */
> > --
> > 1.8.3.1
> >

Xiong, Jianxin Dec. 8, 2020, 6:13 p.m. UTC | #3

> -----Original Message-----
> From: Leon Romanovsky <[e-mail]>
> Sent: Monday, December 07, 2020 11:06 PM
> To: Xiong, Jianxin <[e-mail]>
> Cc: [e-mail]; [e-mail]; Doug Ledford <[e-mail]>; Jason Gunthorpe <[e-mail]>;
> Sumit Semwal <[e-mail]>; Christian Koenig <[e-mail]>; Vetter, Daniel <[e-mail]>
> Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region
> 
> On Mon, Dec 07, 2020 at 02:15:50PM -0800, 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 <[e-mail]>
> > Reviewed-by: Sean Hefty <[e-mail]>
> > Acked-by: Michael J. Ruhl <[e-mail]>
> > Acked-by: Christian Koenig <[e-mail]>
> > Acked-by: Daniel Vetter <[e-mail]>
> >
> > Conflicts:
> > 	include/rdma/ib_umem.h
> 
> This probably leftover from rebase, am I right?
> 
> > ---
> >  drivers/infiniband/core/Makefile      |   2 +-
> >  drivers/infiniband/core/umem.c        |   3 +
> >  drivers/infiniband/core/umem_dmabuf.c | 173 ++++++++++++++++++++++++++++++++++
> >  include/rdma/ib_umem.h                |  43 ++++++++-
> >  4 files changed, 219 insertions(+), 2 deletions(-)  create mode
> > 100644 drivers/infiniband/core/umem_dmabuf.c
> >
> > 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 7ca4112..cc131f8 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 @@ -278,6 +279,8 @@ 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..e50b955
> > --- /dev/null
> > +++ b/drivers/infiniband/core/umem_dmabuf.c
> > @@ -0,0 +1,173 @@
> > +// 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"
> > +
> > +int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf) {
> > +	struct sg_table *sgt;
> > +	struct scatterlist *sg;
> > +	struct dma_fence *fence;
> > +	unsigned long start, end, cur;
> > +	unsigned int nmap;
> > +	int i;
> > +
> > +	dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> > +
> > +	if (umem_dmabuf->sgt)
> > +		return 0;
> > +
> > +	sgt = dma_buf_map_attachment(umem_dmabuf->attach, DMA_BIDIRECTIONAL);
> > +	if (IS_ERR(sgt))
> > +		return PTR_ERR(sgt);
> > +
> > +	/* modify the sg list in-place to match umem address and length */
> > +
> > +	start = ALIGN_DOWN(umem_dmabuf->umem.address, PAGE_SIZE);
> > +	end = ALIGN(umem_dmabuf->umem.address + umem_dmabuf->umem.length,
> > +		    PAGE_SIZE);
> > +	cur = 0;
> > +	nmap = 0;
> 
> Better to put as part of variable initialization.

Sure, can change that way.

> 
> > +	for_each_sgtable_dma_sg(sgt, sg, i) {
> > +		if (start < cur + sg_dma_len(sg) && cur < end)
> > +			nmap++;
> > +		if (cur <= start && start < cur + sg_dma_len(sg)) {
> > +			unsigned long offset = start - cur;
> > +
> > +			umem_dmabuf->first_sg = sg;
> > +			umem_dmabuf->first_sg_offset = offset;
> > +			sg_dma_address(sg) += offset;
> > +			sg_dma_len(sg) -= offset;
> > +			cur += offset;
> > +		}
> > +		if (cur < end && end <= cur + sg_dma_len(sg)) {
> > +			unsigned long trim = cur + sg_dma_len(sg) - end;
> > +
> > +			umem_dmabuf->last_sg = sg;
> > +			umem_dmabuf->last_sg_trim = trim;
> > +			sg_dma_len(sg) -= trim;
> > +			break;
> > +		}
> > +		cur += sg_dma_len(sg);
> > +	}
> > +
> > +	umem_dmabuf->umem.sg_head.sgl = umem_dmabuf->first_sg;
> > +	umem_dmabuf->umem.sg_head.nents = nmap;
> > +	umem_dmabuf->umem.nmap = nmap;
> > +	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);
> 
> Any reason do not check return result from dma_fence_wait()?

This is called with interruptible flag set to false and normally should only return 0.
I do see similar usage cases that check the result and don't check the result. Maybe
we can add a WARN_ON here?   

> 
> > +
> > +	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;
> > +
> > +	/* retore the original sg list */
> > +	if (umem_dmabuf->first_sg) {
> > +		sg_dma_address(umem_dmabuf->first_sg) -=
> > +			umem_dmabuf->first_sg_offset;
> > +		sg_dma_len(umem_dmabuf->first_sg) +=
> > +			umem_dmabuf->first_sg_offset;
> > +		umem_dmabuf->first_sg = NULL;
> > +		umem_dmabuf->first_sg_offset = 0;
> > +	}
> > +	if (umem_dmabuf->last_sg) {
> > +		sg_dma_len(umem_dmabuf->last_sg) +=
> > +			umem_dmabuf->last_sg_trim;
> > +		umem_dmabuf->last_sg = NULL;
> > +		umem_dmabuf->last_sg_trim = 0;
> > +	}
> > +
> > +	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 = -EINVAL;
> 
> It is wrong type for the returned value. One of the possible options is to declare "struct ib_umem *ret;" and set ret = ERR_PTR(-EINVAL) or
> ret = ERR_CAST(dmabuf);

At the actual point the value is returned, ERR_PTR(ret) is used. I think we can change the 
variable name to "err" instead to avoid confusion.

> 
> > +
> > +	if (check_add_overflow(offset, (unsigned long)size, &end))
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	if (unlikely(!ops || !ops->move_notify))
> 
> Let's not put likely/unlikely in control paths.
> 
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	dmabuf = dma_buf_get(fd);
> > +	if (IS_ERR(dmabuf))
> > +		return (void *)dmabuf;
> 
> return ERR_CAST(dmabuf);

Will fix.

> 
> > +
> > +	if (dmabuf->size < end)
> > +		goto out_release_dmabuf;
> > +
> > +	umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> > +	if (!umem_dmabuf)
> > +		return ERR_PTR(-ENOMEM);
> 
> You are leaking dmabuf here, forgot to call to dma_buf_put();

Will fix.

> 
> > +
> > +	umem = &umem_dmabuf->umem;
> > +	umem->ibdev = device;
> > +	umem->length = size;
> > +	umem->address = offset;
> > +	umem->writable = ib_access_writable(access);
> > +	umem->is_dmabuf = 1;
> > +
> > +	if (unlikely(!ib_umem_num_pages(umem)))
> 
> There is no advantage in "unlikely" here.

Ok.

> 
> > +		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_free_umem;
> > +	}
> > +	return umem;
> > +
> > +out_free_umem:
> > +	kfree(umem_dmabuf);
> > +
> > +out_release_dmabuf:
> > +	dma_buf_put(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_buf_detach(dmabuf, umem_dmabuf->attach);
> > +	dma_buf_put(dmabuf);
> > +	kfree(umem_dmabuf);
> > +}
> > diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h index
> > 7752211..b49a96d 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 +24,29 @@ 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;
> > +	struct scatterlist *first_sg;
> > +	struct scatterlist *last_sg;
> > +	unsigned long first_sg_offset;
> > +	unsigned long last_sg_trim;
> > +	void *private;
> > +};
> > +
> > +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)  { @@ -86,6
> > +105,7 @@ 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);
> > +
> >  /**
> >   * ib_umem_find_best_pgoff - Find best HW page size
> >   *
> > @@ -116,6 +136,14 @@ static inline unsigned long ib_umem_find_best_pgoff(struct ib_umem *umem,
> >  				      dma_addr & pgoff_bitmask);
> >  }
> >
> > +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); void
> > +ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf);
> > +
> >  #else /* CONFIG_INFINIBAND_USER_MEM */
> >
> >  #include <linux/err.h>
> > @@ -143,7 +171,20 @@ static inline unsigned long
> > ib_umem_find_best_pgoff(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);
> 
> Probably, It should be EOPNOTSUPP and not EINVAL.

EINVAL is used here to be consistent with existing definitions in the same file.

> 
> > +}
> > +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) { } static inline void ib_umem_dmabuf_release(struct
> > +ib_umem_dmabuf *umem_dmabuf) { }
> >
> >  #endif /* CONFIG_INFINIBAND_USER_MEM */
> > -
> >  #endif /* IB_UMEM_H */
> > --
> > 1.8.3.1
> >

Jason Gunthorpe Dec. 8, 2020, 6:59 p.m. UTC | #4

On Tue, Dec 08, 2020 at 06:13:20PM +0000, Xiong, Jianxin wrote:

> > > +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);
> > 
> > Probably, It should be EOPNOTSUPP and not EINVAL.
> 
> EINVAL is used here to be consistent with existing definitions in the same file.

They may be wrong, EOPNOTSUPP is right for this situation

Jason

Leon Romanovsky Dec. 8, 2020, 7:02 p.m. UTC | #5

On Tue, Dec 08, 2020 at 06:13:20PM +0000, Xiong, Jianxin wrote:
> > -----Original Message-----
> > From: Leon Romanovsky <[e-mail]>
> > Sent: Monday, December 07, 2020 11:06 PM
> > To: Xiong, Jianxin <[e-mail]>
> > Cc: [e-mail]; [e-mail]; Doug Ledford <[e-mail]>; Jason Gunthorpe <[e-mail]>;
> > Sumit Semwal <[e-mail]>; Christian Koenig <[e-mail]>; Vetter, Daniel <[e-mail]>
> > Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region
> >
> > On Mon, Dec 07, 2020 at 02:15:50PM -0800, 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 <[e-mail]>
> > > Reviewed-by: Sean Hefty <[e-mail]>
> > > Acked-by: Michael J. Ruhl <[e-mail]>
> > > Acked-by: Christian Koenig <[e-mail]>
> > > Acked-by: Daniel Vetter <[e-mail]>
> > >
> > > Conflicts:
> > > 	include/rdma/ib_umem.h
> >

<...>

> > > +	/*
> > > +	 * 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);
> >
> > Any reason do not check return result from dma_fence_wait()?
>
> This is called with interruptible flag set to false and normally should only return 0.
> I do see similar usage cases that check the result and don't check the result. Maybe
> we can add a WARN_ON here?

I have no idea :), just saw that other places check returned value.

<...>

> > > +
> > > +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 = -EINVAL;
> >
> > It is wrong type for the returned value. One of the possible options is to declare "struct ib_umem *ret;" and set ret = ERR_PTR(-EINVAL) or
> > ret = ERR_CAST(dmabuf);
>
> At the actual point the value is returned, ERR_PTR(ret) is used. I think we can change the
> variable name to "err" instead to avoid confusion.

The point is that "ret" should be declared as "struct ib_umem *" and not
as "long" and ERR_CAST() should be used instead of (void *).

<...>

> > > +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);
> >
> > Probably, It should be EOPNOTSUPP and not EINVAL.
>
> EINVAL is used here to be consistent with existing definitions in the same file.

ok

Thanks

Xiong, Jianxin Dec. 8, 2020, 7:33 p.m. UTC | #6

> -----Original Message-----
> From: Jason Gunthorpe <[e-mail]>
> Sent: Tuesday, December 08, 2020 10:59 AM
> To: Xiong, Jianxin <[e-mail]>
> Cc: Leon Romanovsky <[e-mail]>; [e-mail]; [e-mail]; Doug Ledford
> <[e-mail]>; Sumit Semwal <[e-mail]>; Christian Koenig <[e-mail]>; Vetter, Daniel
> <[e-mail]>
> Subject: Re: [PATCH v13 1/4] RDMA/umem: Support importing dma-buf as user memory region
> 
> On Tue, Dec 08, 2020 at 06:13:20PM +0000, Xiong, Jianxin wrote:
> 
> > > > +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);
> > >
> > > Probably, It should be EOPNOTSUPP and not EINVAL.
> >
> > EINVAL is used here to be consistent with existing definitions in the same file.
> 
> They may be wrong, EOPNOTSUPP is right for this situation

Ok, let me change all of them to EOPNOTSUPP.

Patch

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 7ca4112..cc131f8 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
@@ -278,6 +279,8 @@  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..e50b955
--- /dev/null
+++ b/drivers/infiniband/core/umem_dmabuf.c
@@ -0,0 +1,173 @@ 
+// 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"
+
+int ib_umem_dmabuf_map_pages(struct ib_umem_dmabuf *umem_dmabuf)
+{
+	struct sg_table *sgt;
+	struct scatterlist *sg;
+	struct dma_fence *fence;
+	unsigned long start, end, cur;
+	unsigned int nmap;
+	int i;
+
+	dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
+
+	if (umem_dmabuf->sgt)
+		return 0;
+
+	sgt = dma_buf_map_attachment(umem_dmabuf->attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sgt))
+		return PTR_ERR(sgt);
+
+	/* modify the sg list in-place to match umem address and length */
+
+	start = ALIGN_DOWN(umem_dmabuf->umem.address, PAGE_SIZE);
+	end = ALIGN(umem_dmabuf->umem.address + umem_dmabuf->umem.length,
+		    PAGE_SIZE);
+	cur = 0;
+	nmap = 0;
+	for_each_sgtable_dma_sg(sgt, sg, i) {
+		if (start < cur + sg_dma_len(sg) && cur < end)
+			nmap++;
+		if (cur <= start && start < cur + sg_dma_len(sg)) {
+			unsigned long offset = start - cur;
+
+			umem_dmabuf->first_sg = sg;
+			umem_dmabuf->first_sg_offset = offset;
+			sg_dma_address(sg) += offset;
+			sg_dma_len(sg) -= offset;
+			cur += offset;
+		}
+		if (cur < end && end <= cur + sg_dma_len(sg)) {
+			unsigned long trim = cur + sg_dma_len(sg) - end;
+
+			umem_dmabuf->last_sg = sg;
+			umem_dmabuf->last_sg_trim = trim;
+			sg_dma_len(sg) -= trim;
+			break;
+		}
+		cur += sg_dma_len(sg);
+	}
+
+	umem_dmabuf->umem.sg_head.sgl = umem_dmabuf->first_sg;
+	umem_dmabuf->umem.sg_head.nents = nmap;
+	umem_dmabuf->umem.nmap = nmap;
+	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;
+
+	/* retore the original sg list */
+	if (umem_dmabuf->first_sg) {
+		sg_dma_address(umem_dmabuf->first_sg) -=
+			umem_dmabuf->first_sg_offset;
+		sg_dma_len(umem_dmabuf->first_sg) +=
+			umem_dmabuf->first_sg_offset;
+		umem_dmabuf->first_sg = NULL;
+		umem_dmabuf->first_sg_offset = 0;
+	}
+	if (umem_dmabuf->last_sg) {
+		sg_dma_len(umem_dmabuf->last_sg) +=
+			umem_dmabuf->last_sg_trim;
+		umem_dmabuf->last_sg = NULL;
+		umem_dmabuf->last_sg_trim = 0;
+	}
+
+	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 = -EINVAL;
+
+	if (check_add_overflow(offset, (unsigned long)size, &end))
+		return ERR_PTR(-EINVAL);
+
+	if (unlikely(!ops || !ops->move_notify))
+		return ERR_PTR(-EINVAL);
+
+	dmabuf = dma_buf_get(fd);
+	if (IS_ERR(dmabuf))
+		return (void *)dmabuf;
+
+	if (dmabuf->size < end)
+		goto out_release_dmabuf;
+
+	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->writable = ib_access_writable(access);
+	umem->is_dmabuf = 1;
+
+	if (unlikely(!ib_umem_num_pages(umem)))
+		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_free_umem;
+	}
+	return umem;
+
+out_free_umem:
+	kfree(umem_dmabuf);
+
+out_release_dmabuf:
+	dma_buf_put(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_buf_detach(dmabuf, umem_dmabuf->attach);
+	dma_buf_put(dmabuf);
+	kfree(umem_dmabuf);
+}
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 7752211..b49a96d 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 +24,29 @@  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;
+	struct scatterlist *first_sg;
+	struct scatterlist *last_sg;
+	unsigned long first_sg_offset;
+	unsigned long last_sg_trim;
+	void *private;
+};
+
+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)
 {
@@ -86,6 +105,7 @@  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);
+
 /**
  * ib_umem_find_best_pgoff - Find best HW page size
  *
@@ -116,6 +136,14 @@  static inline unsigned long ib_umem_find_best_pgoff(struct ib_umem *umem,
 				      dma_addr & pgoff_bitmask);
 }
 
+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);
+void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf);
+
 #else /* CONFIG_INFINIBAND_USER_MEM */
 
 #include <linux/err.h>
@@ -143,7 +171,20 @@  static inline unsigned long ib_umem_find_best_pgoff(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) { }
+static inline void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf) { }
 
 #endif /* CONFIG_INFINIBAND_USER_MEM */
-
 #endif /* IB_UMEM_H */