[RFC PATCH v3 1/4] RDMA/umem: Support importing dma-buf as user memory region
Christian König
christian.koenig at amd.com
Mon Oct 5 10:54:40 UTC 2020
Hi Jianxin,
Am 04.10.20 um 21:12 schrieb Jianxin Xiong:
> 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 at intel.com>
> Reviewed-by: Sean Hefty <sean.hefty at intel.com>
> Acked-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
well first of all really nice work you have done here.
Since I'm not an expert on RDMA or its drivers I can't really review any
of that part.
But at least from the DMA-buf side it looks like you are using the
interface correctly as intended.
So feel free to add an Acked-by: Christian König
<christian.koenig at amd.com> if it helps.
Thanks,
Christian.
> ---
> drivers/infiniband/core/Makefile | 2 +-
> drivers/infiniband/core/umem.c | 4 +
> drivers/infiniband/core/umem_dmabuf.c | 291 ++++++++++++++++++++++++++++++++++
> drivers/infiniband/core/umem_dmabuf.h | 14 ++
> drivers/infiniband/core/umem_odp.c | 12 ++
> include/rdma/ib_umem.h | 19 ++-
> 6 files changed, 340 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 24cb71a..b8d51a7 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 831bff8..59ec36c 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)
> {
> @@ -318,6 +320,8 @@ 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..10ed646
> --- /dev/null
> +++ b/drivers/infiniband/core/umem_dmabuf.c
> @@ -0,0 +1,291 @@
> +// 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 <rdma/ib_umem_odp.h>
> +
> +#include "uverbs.h"
> +
> +struct ib_umem_dmabuf {
> + struct ib_umem_odp umem_odp;
> + struct dma_buf_attachment *attach;
> + struct sg_table *sgt;
> + atomic_t notifier_seq;
> +};
> +
> +static inline struct ib_umem_dmabuf *to_ib_umem_dmabuf(struct ib_umem *umem)
> +{
> + struct ib_umem_odp *umem_odp = to_ib_umem_odp(umem);
> + return container_of(umem_odp, struct ib_umem_dmabuf, umem_odp);
> +}
> +
> +static void ib_umem_dmabuf_invalidate_cb(struct dma_buf_attachment *attach)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = attach->importer_priv;
> + struct ib_umem_odp *umem_odp = &umem_dmabuf->umem_odp;
> + struct mmu_notifier_range range = {};
> + unsigned long current_seq;
> +
> + /* no concurrent invalidation due to the dma_resv lock */
> +
> + dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> +
> + if (!umem_dmabuf->sgt)
> + return;
> +
> + range.start = ib_umem_start(umem_odp);
> + range.end = ib_umem_end(umem_odp);
> + range.flags = MMU_NOTIFIER_RANGE_BLOCKABLE;
> + current_seq = atomic_read(&umem_dmabuf->notifier_seq);
> + umem_odp->notifier.ops->invalidate(&umem_odp->notifier, &range,
> + current_seq);
> +
> + atomic_inc(&umem_dmabuf->notifier_seq);
> +}
> +
> +static struct dma_buf_attach_ops ib_umem_dmabuf_attach_ops = {
> + .allow_peer2peer = 1,
> + .move_notify = ib_umem_dmabuf_invalidate_cb,
> +};
> +
> +static inline int ib_umem_dmabuf_init_odp(struct ib_umem_odp *umem_odp)
> +{
> + size_t page_size = 1UL << umem_odp->page_shift;
> + unsigned long start;
> + unsigned long end;
> + size_t pages;
> +
> + umem_odp->umem.is_odp = 1;
> + mutex_init(&umem_odp->umem_mutex);
> +
> + start = ALIGN_DOWN(umem_odp->umem.address, page_size);
> + if (check_add_overflow(umem_odp->umem.address,
> + (unsigned long)umem_odp->umem.length,
> + &end))
> + return -EOVERFLOW;
> + end = ALIGN(end, page_size);
> + if (unlikely(end < page_size))
> + return -EOVERFLOW;
> +
> + pages = (end - start) >> umem_odp->page_shift;
> + if (!pages)
> + return -EINVAL;
> +
> + /* used for ib_umem_start() & ib_umem_end() */
> + umem_odp->notifier.interval_tree.start = start;
> + umem_odp->notifier.interval_tree.last = end - 1;
> +
> + /* umem_odp->page_list is never used for dma-buf */
> +
> + umem_odp->dma_list = kvcalloc(
> + pages, sizeof(*umem_odp->dma_list), GFP_KERNEL);
> + if (!umem_odp->dma_list)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
> + unsigned long addr, size_t size,
> + int dmabuf_fd, int access,
> + const struct mmu_interval_notifier_ops *ops)
> +{
> + struct dma_buf *dmabuf;
> + struct ib_umem_dmabuf *umem_dmabuf;
> + struct ib_umem *umem;
> + struct ib_umem_odp *umem_odp;
> + unsigned long end;
> + long ret;
> +
> + if (check_add_overflow(addr, size, &end))
> + return ERR_PTR(-EINVAL);
> +
> + if (unlikely(PAGE_ALIGN(end) < PAGE_SIZE))
> + return ERR_PTR(-EINVAL);
> +
> + umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> + if (!umem_dmabuf)
> + return ERR_PTR(-ENOMEM);
> +
> + umem = &umem_dmabuf->umem_odp.umem;
> + umem->ibdev = device;
> + umem->length = size;
> + umem->address = addr;
> + umem->writable = ib_access_writable(access);
> + umem->is_dmabuf = 1;
> +
> + dmabuf = dma_buf_get(dmabuf_fd);
> + if (IS_ERR(dmabuf)) {
> + ret = PTR_ERR(dmabuf);
> + goto out_free_umem;
> + }
> +
> + /* always attach dynamically to pass the allow_peer2peer flag */
> + umem_dmabuf->attach = dma_buf_dynamic_attach(
> + dmabuf,
> + device->dma_device,
> + &ib_umem_dmabuf_attach_ops,
> + umem_dmabuf);
> + if (IS_ERR(umem_dmabuf->attach)) {
> + ret = PTR_ERR(umem_dmabuf->attach);
> + goto out_release_dmabuf;
> + }
> +
> + umem_odp = &umem_dmabuf->umem_odp;
> + umem_odp->page_shift = PAGE_SHIFT;
> + if (access & IB_ACCESS_HUGETLB) {
> + /* don't support huge_tlb at this point */
> + ret = -EINVAL;
> + goto out_detach_dmabuf;
> + }
> +
> + ret = ib_umem_dmabuf_init_odp(umem_odp);
> + if (ret)
> + goto out_detach_dmabuf;
> +
> + umem_odp->notifier.ops = ops;
> + return umem;
> +
> +out_detach_dmabuf:
> + dma_buf_detach(dmabuf, umem_dmabuf->attach);
> +
> +out_release_dmabuf:
> + dma_buf_put(dmabuf);
> +
> +out_free_umem:
> + kfree(umem_dmabuf);
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL(ib_umem_dmabuf_get);
> +
> +unsigned long ib_umem_dmabuf_notifier_read_begin(struct ib_umem_odp *umem_odp)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(&umem_odp->umem);
> +
> + return atomic_read(&umem_dmabuf->notifier_seq);
> +}
> +EXPORT_SYMBOL(ib_umem_dmabuf_notifier_read_begin);
> +
> +int ib_umem_dmabuf_notifier_read_retry(struct ib_umem_odp *umem_odp,
> + unsigned long current_seq)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(&umem_odp->umem);
> +
> + return (atomic_read(&umem_dmabuf->notifier_seq) != current_seq);
> +}
> +EXPORT_SYMBOL(ib_umem_dmabuf_notifier_read_retry);
> +
> +int ib_umem_dmabuf_map_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
> + u64 access_mask, unsigned long current_seq)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(umem);
> + struct ib_umem_odp *umem_odp = &umem_dmabuf->umem_odp;
> + u64 start, end, addr;
> + int j, k, ret = 0, user_pages, pages, total_pages;
> + unsigned int page_shift;
> + size_t page_size;
> + struct scatterlist *sg;
> + struct sg_table *sgt;
> +
> + if (access_mask == 0)
> + return -EINVAL;
> +
> + if (user_virt < ib_umem_start(umem_odp) ||
> + user_virt + bcnt > ib_umem_end(umem_odp))
> + return -EFAULT;
> +
> + page_shift = umem_odp->page_shift;
> + page_size = 1UL << page_shift;
> + start = ALIGN_DOWN(user_virt, page_size);
> + end = ALIGN(user_virt + bcnt, page_size);
> + user_pages = (end - start) >> page_shift;
> +
> + mutex_lock(&umem_odp->umem_mutex);
> +
> + /* check for on-ongoing invalidations */
> + if (ib_umem_dmabuf_notifier_read_retry(umem_odp, current_seq)) {
> + ret = -EAGAIN;
> + goto out;
> + }
> +
> + ret = user_pages;
> + if (umem_dmabuf->sgt)
> + goto out;
> +
> + dma_resv_lock(umem_dmabuf->attach->dmabuf->resv, NULL);
> + sgt = dma_buf_map_attachment(umem_dmabuf->attach,
> + DMA_BIDIRECTIONAL);
> + dma_resv_unlock(umem_dmabuf->attach->dmabuf->resv);
> +
> + if (IS_ERR(sgt)) {
> + ret = PTR_ERR(sgt);
> + goto out;
> + }
> +
> + umem->sg_head = *sgt;
> + umem->nmap = sgt->nents;
> + umem_dmabuf->sgt = sgt;
> +
> + k = 0;
> + total_pages = ib_umem_odp_num_pages(umem_odp);
> + for_each_sg(umem->sg_head.sgl, sg, umem->sg_head.nents, j) {
> + addr = sg_dma_address(sg);
> + pages = sg_dma_len(sg) >> page_shift;
> + while (pages > 0 && k < total_pages) {
> + umem_odp->dma_list[k++] = addr | access_mask;
> + umem_odp->npages++;
> + addr += page_size;
> + pages--;
> + }
> + }
> +
> + WARN_ON(k != total_pages);
> +
> +out:
> + mutex_unlock(&umem_odp->umem_mutex);
> + return ret;
> +}
> +
> +void ib_umem_dmabuf_unmap_pages(struct ib_umem *umem)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(umem);
> + struct ib_umem_odp *umem_odp = &umem_dmabuf->umem_odp;
> + int npages = ib_umem_odp_num_pages(umem_odp);
> + int i;
> +
> + lockdep_assert_held(&umem_odp->umem_mutex);
> + dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> +
> + if (!umem_dmabuf->sgt)
> + return;
> +
> + dma_buf_unmap_attachment(umem_dmabuf->attach, umem_dmabuf->sgt,
> + DMA_BIDIRECTIONAL);
> +
> + umem_dmabuf->sgt = NULL;
> +
> + for (i = 0; i < npages; i++)
> + umem_odp->dma_list[i] = 0;
> + umem_odp->npages = 0;
> +}
> +
> +void ib_umem_dmabuf_release(struct ib_umem *umem)
> +{
> + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(umem);
> + struct ib_umem_odp *umem_odp = &umem_dmabuf->umem_odp;
> + struct dma_buf *dmabuf = umem_dmabuf->attach->dmabuf;
> +
> + mutex_lock(&umem_odp->umem_mutex);
> + dma_resv_lock(umem_dmabuf->attach->dmabuf->resv, NULL);
> + ib_umem_dmabuf_unmap_pages(umem);
> + dma_resv_unlock(umem_dmabuf->attach->dmabuf->resv);
> + mutex_unlock(&umem_odp->umem_mutex);
> + kvfree(umem_odp->dma_list);
> + 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..b9378bd
> --- /dev/null
> +++ b/drivers/infiniband/core/umem_dmabuf.h
> @@ -0,0 +1,14 @@
> +/* 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
> +
> +int ib_umem_dmabuf_map_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
> + u64 access_mask, unsigned long current_seq);
> +void ib_umem_dmabuf_unmap_pages(struct ib_umem *umem);
> +void ib_umem_dmabuf_release(struct ib_umem *umem);
> +
> +#endif /* UMEM_DMABUF_H */
> diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
> index cc6b4be..7e11619 100644
> --- a/drivers/infiniband/core/umem_odp.c
> +++ b/drivers/infiniband/core/umem_odp.c
> @@ -1,5 +1,6 @@
> /*
> * Copyright (c) 2014 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
> @@ -47,6 +48,7 @@
> #include <rdma/ib_umem_odp.h>
>
> #include "uverbs.h"
> +#include "umem_dmabuf.h"
>
> static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
> const struct mmu_interval_notifier_ops *ops)
> @@ -263,6 +265,9 @@ struct ib_umem_odp *ib_umem_odp_get(struct ib_device *device,
>
> void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
> {
> + if (umem_odp->umem.is_dmabuf)
> + return ib_umem_dmabuf_release(&umem_odp->umem);
> +
> /*
> * Ensure that no more pages are mapped in the umem.
> *
> @@ -392,6 +397,10 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> unsigned int flags = 0, page_shift;
> phys_addr_t p = 0;
>
> + if (umem_odp->umem.is_dmabuf)
> + return ib_umem_dmabuf_map_pages(&umem_odp->umem, user_virt,
> + bcnt, access_mask, current_seq);
> +
> if (access_mask == 0)
> return -EINVAL;
>
> @@ -517,6 +526,9 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
> u64 addr;
> struct ib_device *dev = umem_odp->umem.ibdev;
>
> + if (umem_odp->umem.is_dmabuf)
> + return ib_umem_dmabuf_unmap_pages(&umem_odp->umem);
> +
> lockdep_assert_held(&umem_odp->umem_mutex);
>
> virt = max_t(u64, virt, ib_umem_start(umem_odp));
> diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
> index 71f573a..b8ea693 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 ib_umem_dmabuf;
>
> struct ib_umem {
> struct ib_device *ibdev;
> @@ -21,6 +23,7 @@ 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;
> @@ -51,6 +54,13 @@ 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,
> + const struct mmu_interval_notifier_ops *ops);
> +unsigned long ib_umem_dmabuf_notifier_read_begin(struct ib_umem_odp *umem_odp);
> +int ib_umem_dmabuf_notifier_read_retry(struct ib_umem_odp *umem_odp,
> + unsigned long current_seq);
>
> #else /* CONFIG_INFINIBAND_USER_MEM */
>
> @@ -73,7 +83,14 @@ 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,
> + struct mmu_interval_notifier_ops *ops)
> +{
> + return ERR_PTR(-EINVAL);
> +}
>
> #endif /* CONFIG_INFINIBAND_USER_MEM */
> -
> #endif /* IB_UMEM_H */
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