Commit 4d674c47 authored by Boshi Yu's avatar Boshi Yu Committed by Leon Romanovsky
Browse files

RDMA/erdma: Use dma_map_page to map scatter MTT buffer 



Each high-level indirect MTT entry is assumed to point to exactly one page
of the low-level MTT buffer, but dma_map_sg may merge contiguous physical
pages when mapping. To avoid extra overhead from splitting merged regions,
use dma_map_page to map the scatter MTT buffer page by page.

Reviewed-by: default avatarCheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: default avatarBoshi Yu <boshiyu@linux.alibaba.com>
Link: https://patch.msgid.link/20250725055410.67520-2-boshiyu@linux.alibaba.com


Signed-off-by: default avatarLeon Romanovsky <leon@kernel.org>
parent a3c9d0fc

drivers/infiniband/hw/erdma/erdma_verbs.c

+69 −41
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ static int regmr_cmd(struct erdma_dev *dev, struct erdma_mr *mr) 
			req.phy_addr[0] = mr->mem.mtt->buf_dma;

			mtt_level = ERDMA_MR_MTT_1LEVEL;

		} else {

			req.phy_addr[0] = sg_dma_address(mr->mem.mtt->sglist);

			req.phy_addr[0] = mr->mem.mtt->dma_addrs[0];

			mtt_level = mr->mem.mtt->level;

		}

	} else if (mr->type != ERDMA_MR_TYPE_DMA) {
@@ -626,18 +626,27 @@ static struct erdma_mtt *erdma_create_cont_mtt(struct erdma_dev *dev, 
	return ERR_PTR(-ENOMEM);

}



static void erdma_destroy_mtt_buf_sg(struct erdma_dev *dev,

static void erdma_unmap_page_list(struct erdma_dev *dev, dma_addr_t *pg_dma,

				  u32 npages)

{

	u32 i;



	for (i = 0; i < npages; i++)

		dma_unmap_page(&dev->pdev->dev, pg_dma[i], PAGE_SIZE,

			       DMA_TO_DEVICE);

}



static void erdma_destroy_mtt_buf_dma_addrs(struct erdma_dev *dev,

					    struct erdma_mtt *mtt)

{

	dma_unmap_sg(&dev->pdev->dev, mtt->sglist,

		     DIV_ROUND_UP(mtt->size, PAGE_SIZE), DMA_TO_DEVICE);

	vfree(mtt->sglist);

	erdma_unmap_page_list(dev, mtt->dma_addrs, mtt->npages);

	vfree(mtt->dma_addrs);

}



static void erdma_destroy_scatter_mtt(struct erdma_dev *dev,

				      struct erdma_mtt *mtt)

{

	erdma_destroy_mtt_buf_sg(dev, mtt);

	erdma_destroy_mtt_buf_dma_addrs(dev, mtt);

	vfree(mtt->buf);

	kfree(mtt);

}
@@ -645,50 +654,69 @@ static void erdma_destroy_scatter_mtt(struct erdma_dev *dev, 
static void erdma_init_middle_mtt(struct erdma_mtt *mtt,

				  struct erdma_mtt *low_mtt)

{

	struct scatterlist *sg;

	u32 idx = 0, i;

	dma_addr_t *pg_addr = mtt->buf;

	u32 i;



	for_each_sg(low_mtt->sglist, sg, low_mtt->nsg, i)

		mtt->buf[idx++] = sg_dma_address(sg);

	for (i = 0; i < low_mtt->npages; i++)

		pg_addr[i] = low_mtt->dma_addrs[i];

}



static int erdma_create_mtt_buf_sg(struct erdma_dev *dev, struct erdma_mtt *mtt)

static u32 vmalloc_to_dma_addrs(struct erdma_dev *dev, dma_addr_t **dma_addrs,

				void *buf, u64 len)

{

	struct scatterlist *sglist;

	void *buf = mtt->buf;

	u32 npages, i, nsg;

	dma_addr_t *pg_dma;

	struct page *pg;

	u32 npages, i;

	void *addr;



	/* Failed if buf is not page aligned */

	if ((uintptr_t)buf & ~PAGE_MASK)

		return -EINVAL;



	npages = DIV_ROUND_UP(mtt->size, PAGE_SIZE);

	sglist = vzalloc(npages * sizeof(*sglist));

	if (!sglist)

		return -ENOMEM;

	npages = (PAGE_ALIGN((u64)buf + len) - PAGE_ALIGN_DOWN((u64)buf)) >>

		 PAGE_SHIFT;

	pg_dma = vzalloc(npages * sizeof(dma_addr_t));

	if (!pg_dma)

		return 0;



	sg_init_table(sglist, npages);

	addr = buf;

	for (i = 0; i < npages; i++) {

		pg = vmalloc_to_page(buf);

		pg = vmalloc_to_page(addr);

		if (!pg)

			goto err;

		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);

		buf += PAGE_SIZE;

	}



	nsg = dma_map_sg(&dev->pdev->dev, sglist, npages, DMA_TO_DEVICE);

	if (!nsg)

		pg_dma[i] = dma_map_page(&dev->pdev->dev, pg, 0, PAGE_SIZE,

					 DMA_TO_DEVICE);

		if (dma_mapping_error(&dev->pdev->dev, pg_dma[i]))

			goto err;



	mtt->sglist = sglist;

	mtt->nsg = nsg;

		addr += PAGE_SIZE;

	}



	return 0;

	*dma_addrs = pg_dma;



	return npages;

err:

	vfree(sglist);

	erdma_unmap_page_list(dev, pg_dma, i);

	vfree(pg_dma);



	return 0;

}



static int erdma_create_mtt_buf_dma_addrs(struct erdma_dev *dev,

					  struct erdma_mtt *mtt)

{

	dma_addr_t *addrs;

	u32 npages;



	/* Failed if buf is not page aligned */

	if ((uintptr_t)mtt->buf & ~PAGE_MASK)

		return -EINVAL;



	npages = vmalloc_to_dma_addrs(dev, &addrs, mtt->buf, mtt->size);

	if (!npages)

		return -ENOMEM;



	mtt->dma_addrs = addrs;

	mtt->npages = npages;



	return 0;

}



static struct erdma_mtt *erdma_create_scatter_mtt(struct erdma_dev *dev,
@@ -707,12 +735,12 @@ static struct erdma_mtt *erdma_create_scatter_mtt(struct erdma_dev *dev, 
	if (!mtt->buf)

		goto err_free_mtt;



	ret = erdma_create_mtt_buf_sg(dev, mtt);

	ret = erdma_create_mtt_buf_dma_addrs(dev, mtt);

	if (ret)

		goto err_free_mtt_buf;



	ibdev_dbg(&dev->ibdev, "create scatter mtt, size:%lu, nsg:%u\n",

		  mtt->size, mtt->nsg);

	ibdev_dbg(&dev->ibdev, "create scatter mtt, size:%lu, npages:%u\n",

		  mtt->size, mtt->npages);



	return mtt;
@@ -746,8 +774,8 @@ static struct erdma_mtt *erdma_create_mtt(struct erdma_dev *dev, size_t size, 
	level = 1;



	/* convergence the mtt table. */

	while (mtt->nsg != 1 && level <= 3) {

		tmp_mtt = erdma_create_scatter_mtt(dev, MTT_SIZE(mtt->nsg));

	while (mtt->npages != 1 && level <= 3) {

		tmp_mtt = erdma_create_scatter_mtt(dev, MTT_SIZE(mtt->npages));

		if (IS_ERR(tmp_mtt)) {

			ret = PTR_ERR(tmp_mtt);

			goto err_free_mtt;
@@ -765,7 +793,7 @@ static struct erdma_mtt *erdma_create_mtt(struct erdma_dev *dev, size_t size, 


	mtt->level = level;

	ibdev_dbg(&dev->ibdev, "top mtt: level:%d, dma_addr 0x%llx\n",

		  mtt->level, mtt->sglist[0].dma_address);

		  mtt->level, mtt->dma_addrs[0]);



	return mtt;

err_free_mtt:

drivers/infiniband/hw/erdma/erdma_verbs.h

+2 −2
Original line number Diff line number Diff line
@@ -99,8 +99,8 @@ struct erdma_mtt { 
	union {

		dma_addr_t buf_dma;

		struct {

			struct scatterlist *sglist;

			u32 nsg;

			dma_addr_t *dma_addrs;

			u32 npages;

			u32 level;

		};

	};