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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 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. Link: https://lore.kernel.org/r/1608067636-98073-2-git-send-email-jianxin.xiong@intel.com Signed-off-by: Jianxin Xiong <jianxin.xiong@intel.com> Reviewed-by: Sean Hefty <sean.hefty@intel.com> Acked-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Acked-by: Christian Koenig <christian.koenig@amd.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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Jianxin Xiong
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Jason Gunthorpe
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Jan 20, 2021
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,174 @@ | ||
| // 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" | ||
|
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| 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 = 0; | ||
| unsigned int nmap = 0; | ||
| int i; | ||
|
|
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| dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv); | ||
|
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| if (umem_dmabuf->sgt) | ||
| goto wait_fence; | ||
|
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| sgt = dma_buf_map_attachment(umem_dmabuf->attach, DMA_BIDIRECTIONAL); | ||
| if (IS_ERR(sgt)) | ||
| return PTR_ERR(sgt); | ||
|
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||
| /* modify the sg list in-place to match umem address and length */ | ||
|
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| start = ALIGN_DOWN(umem_dmabuf->umem.address, PAGE_SIZE); | ||
| end = ALIGN(umem_dmabuf->umem.address + umem_dmabuf->umem.length, | ||
| PAGE_SIZE); | ||
| 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; | ||
|
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||
| 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; | ||
|
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||
| wait_fence: | ||
| /* | ||
| * 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) | ||
| return dma_fence_wait(fence, false); | ||
|
|
||
| return 0; | ||
| } | ||
| EXPORT_SYMBOL(ib_umem_dmabuf_map_pages); | ||
|
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| 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; | ||
|
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||
| /* 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; | ||
| } | ||
|
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| dma_buf_unmap_attachment(umem_dmabuf->attach, umem_dmabuf->sgt, | ||
| DMA_BIDIRECTIONAL); | ||
|
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| umem_dmabuf->sgt = NULL; | ||
| } | ||
| EXPORT_SYMBOL(ib_umem_dmabuf_unmap_pages); | ||
|
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| struct ib_umem_dmabuf *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; | ||
| struct ib_umem_dmabuf *ret = ERR_PTR(-EINVAL); | ||
|
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||
| if (check_add_overflow(offset, (unsigned long)size, &end)) | ||
| return ret; | ||
|
|
||
| if (unlikely(!ops || !ops->move_notify)) | ||
| return ret; | ||
|
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| dmabuf = dma_buf_get(fd); | ||
| if (IS_ERR(dmabuf)) | ||
| return ERR_CAST(dmabuf); | ||
|
|
||
| if (dmabuf->size < end) | ||
| goto out_release_dmabuf; | ||
|
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| umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL); | ||
| if (!umem_dmabuf) { | ||
| ret = ERR_PTR(-ENOMEM); | ||
| goto out_release_dmabuf; | ||
| } | ||
|
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| umem = &umem_dmabuf->umem; | ||
| umem->ibdev = device; | ||
| umem->length = size; | ||
| umem->address = offset; | ||
| umem->writable = ib_access_writable(access); | ||
| umem->is_dmabuf = 1; | ||
|
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| if (!ib_umem_num_pages(umem)) | ||
| goto out_free_umem; | ||
|
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| umem_dmabuf->attach = dma_buf_dynamic_attach( | ||
| dmabuf, | ||
| device->dma_device, | ||
| ops, | ||
| umem_dmabuf); | ||
| if (IS_ERR(umem_dmabuf->attach)) { | ||
| ret = ERR_CAST(umem_dmabuf->attach); | ||
| goto out_free_umem; | ||
| } | ||
| return umem_dmabuf; | ||
|
|
||
| out_free_umem: | ||
| kfree(umem_dmabuf); | ||
|
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| out_release_dmabuf: | ||
| dma_buf_put(dmabuf); | ||
| return ret; | ||
| } | ||
| EXPORT_SYMBOL(ib_umem_dmabuf_get); | ||
|
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||
| void ib_umem_dmabuf_release(struct ib_umem_dmabuf *umem_dmabuf) | ||
| { | ||
| struct dma_buf *dmabuf = umem_dmabuf->attach->dmabuf; | ||
|
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||
| dma_buf_detach(dmabuf, umem_dmabuf->attach); | ||
| dma_buf_put(dmabuf); | ||
| kfree(umem_dmabuf); | ||
| } |
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