Fwd: [PATCH 1/1] RDMA/umem: add back hugepage sg list

[Zhu Yanjun <zyjzyj2000@gmail.com>]

From: Zhu Yanjun <zyjzyj2000@gmail.com>

After the commit ("RDMA/umem: Move to allocate SG table from pages"),
the sg list from ib_ume_get is like the following:
"
sg_dma_address(sg):0x4b3c1ce000
sg_dma_address(sg):0x4c3c1cd000
sg_dma_address(sg):0x4d3c1cc000
sg_dma_address(sg):0x4e3c1cb000
"

But sometimes, we need sg list like the following:
"
sg_dma_address(sg):0x203b400000
sg_dma_address(sg):0x213b200000
sg_dma_address(sg):0x223b000000
sg_dma_address(sg):0x233ae00000
sg_dma_address(sg):0x243ac00000
"
The function ib_umem_add_sg_table can provide the sg list like the
second. And this function is removed in the commit ("RDMA/umem: Move
to allocate SG table from pages"). Now I add it back.

The new function is ib_umem_get to ib_umem_hugepage_get that calls
ib_umem_add_sg_table.

This function ib_umem_huagepage_get can get 4K, 2M sg list dma address.

Fixes: 0c16d9635e3a ("RDMA/umem: Move to allocate SG table from pages")
Signed-off-by: Zhu Yanjun <zyjzyj2000@gmail.com>
---
 drivers/infiniband/core/umem.c | 197 +++++++++++++++++++++++++++++++++
 include/rdma/ib_umem.h         |   3 +
 2 files changed, 200 insertions(+)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 2dde99a9ba07..af8733788b1e 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -62,6 +62,203 @@ static void __ib_umem_release(struct ib_device
*dev, struct ib_umem *umem, int d
        sg_free_table(&umem->sg_head);
 }

+/* ib_umem_add_sg_table - Add N contiguous pages to scatter table
+ *
+ * sg: current scatterlist entry
+ * page_list: array of npage struct page pointers
+ * npages: number of pages in page_list
+ * max_seg_sz: maximum segment size in bytes
+ * nents: [out] number of entries in the scatterlist
+ *
+ * Return new end of scatterlist
+ */
+static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
+                                               struct page **page_list,
+                                               unsigned long npages,
+                                               unsigned int max_seg_sz,
+                                               int *nents)
+{
+       unsigned long first_pfn;
+       unsigned long i = 0;
+       bool update_cur_sg = false;
+       bool first = !sg_page(sg);
+
+       /* Check if new page_list is contiguous with end of previous page_list.
+        * sg->length here is a multiple of PAGE_SIZE and sg->offset is 0.
+        */
+       if (!first && (page_to_pfn(sg_page(sg)) + (sg->length >> PAGE_SHIFT) ==
+                       page_to_pfn(page_list[0])))
+               update_cur_sg = true;
+
+       while (i != npages) {
+               unsigned long len;
+               struct page *first_page = page_list[i];
+
+               first_pfn = page_to_pfn(first_page);
+
+               /* Compute the number of contiguous pages we have starting
+                * at i
+                */
+               for (len = 0; i != npages &&
+                               first_pfn + len == page_to_pfn(page_list[i]) &&
+                               len < (max_seg_sz >> PAGE_SHIFT);
+                    len++)
+                       i++;
+
+               /* Squash N contiguous pages from page_list into current sge */
+               if (update_cur_sg) {
+                       if ((max_seg_sz - sg->length) >= (len << PAGE_SHIFT)) {
+                               sg_set_page(sg, sg_page(sg),
+                               sg->length + (len << PAGE_SHIFT),
+                               0);
+                               update_cur_sg = false;
+                               continue;
+                       }
+                       update_cur_sg = false;
+               }
+
+               /* Squash N contiguous pages into next sge or first sge */
+               if (!first)
+                       sg = sg_next(sg);
+
+               (*nents)++;
+               sg_set_page(sg, first_page, len << PAGE_SHIFT, 0);
+               first = false;
+       }
+
+       return sg;
+}
+
+/**
+ * ib_umem_hugepage_get - Pin and DMA map userspace memory.
+ *
+ * @device: IB device to connect UMEM
+ * @addr: userspace virtual address to start at
+ * @size: length of region to pin
+ * @access: IB_ACCESS_xxx flags for memory being pinned
+ */
+struct ib_umem *ib_umem_hugepage_get(struct ib_device *device,
+                                    unsigned long addr,
+                                    size_t size, int access)
+{
+       struct ib_umem *umem;
+       struct page **page_list;
+       unsigned long lock_limit;
+       unsigned long new_pinned;
+       unsigned long cur_base;
+       unsigned long dma_attr = 0;
+       struct mm_struct *mm;
+       unsigned long npages;
+       int ret;
+       struct scatterlist *sg;
+       unsigned int gup_flags = FOLL_WRITE;
+
+       /*
+        * If the combination of the addr and size requested for this memory
+        * region causes an integer overflow, return error.
+        */
+       if (((addr + size) < addr) ||
+           PAGE_ALIGN(addr + size) < (addr + size))
+               return ERR_PTR(-EINVAL);
+
+       if (!can_do_mlock())
+               return ERR_PTR(-EPERM);
+
+       if (access & IB_ACCESS_ON_DEMAND)
+               return ERR_PTR(-EOPNOTSUPP);
+
+       umem = kzalloc(sizeof(*umem), GFP_KERNEL);
+       if (!umem)
+               return ERR_PTR(-ENOMEM);
+       umem->ibdev      = device;
+       umem->length     = size;
+       umem->address    = addr;
+       umem->writable   = ib_access_writable(access);
+       umem->owning_mm = mm = current->mm;
+       mmgrab(mm);
+
+       page_list = (struct page **) __get_free_page(GFP_KERNEL);
+       if (!page_list) {
+               ret = -ENOMEM;
+               goto umem_kfree;
+       }
+
+       npages = ib_umem_num_pages(umem);
+       if (npages == 0 || npages > UINT_MAX) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+       new_pinned = atomic64_add_return(npages, &mm->pinned_vm);
+       if (new_pinned > lock_limit && !capable(CAP_IPC_LOCK)) {
+               atomic64_sub(npages, &mm->pinned_vm);
+               ret = -ENOMEM;
+               goto out;
+       }
+
+       cur_base = addr & PAGE_MASK;
+
+       ret = sg_alloc_table(&umem->sg_head, npages, GFP_KERNEL);
+       if (ret)
+               goto vma;
+
+       if (!umem->writable)
+               gup_flags |= FOLL_FORCE;
+
+       sg = umem->sg_head.sgl;
+
+       while (npages) {
+               cond_resched();
+               ret = pin_user_pages_fast(cur_base,
+                                         min_t(unsigned long, npages,
+                                               PAGE_SIZE /
+                                         sizeof(struct page *)),
+                                         gup_flags | FOLL_LONGTERM, page_list);
+               if (ret < 0)
+                       goto umem_release;
+
+               cur_base += ret * PAGE_SIZE;
+               npages   -= ret;
+
+               sg = ib_umem_add_sg_table(sg, page_list, ret,
+                               dma_get_max_seg_size(device->dma_device),
+                               &umem->sg_nents);
+       }
+
+       sg_mark_end(sg);
+
+       if (access & IB_ACCESS_RELAXED_ORDERING)
+               dma_attr |= DMA_ATTR_WEAK_ORDERING;
+
+       umem->nmap =
+               ib_dma_map_sg_attrs(device, umem->sg_head.sgl, umem->sg_nents,
+                                   DMA_BIDIRECTIONAL, dma_attr);
+
+       if (!umem->nmap) {
+               ret = -ENOMEM;
+               goto umem_release;
+       }
+
+       ret = 0;
+       goto out;
+
+umem_release:
+       __ib_umem_release(device, umem, 0);
+vma:
+       atomic64_sub(ib_umem_num_pages(umem), &mm->pinned_vm);
+out:
+       free_page((unsigned long) page_list);
+umem_kfree:
+       if (ret) {
+               mmdrop(umem->owning_mm);
+               kfree(umem);
+       }
+       return ret ? ERR_PTR(ret) : umem;
+}
+EXPORT_SYMBOL(ib_umem_hugepage_get);
+
 /**
  * ib_umem_find_best_pgsz - Find best HW page size to use for this MR
  *
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 676c57f5ca80..fc6350ff21e6 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -96,6 +96,9 @@ static inline void
__rdma_umem_block_iter_start(struct ib_block_iter *biter,
             __rdma_block_iter_next(biter);)

 #ifdef CONFIG_INFINIBAND_USER_MEM
+struct ib_umem *ib_umem_hugepage_get(struct ib_device *device,
+                                    unsigned long addr,
+                                    size_t size, int access);

 struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
                            size_t size, int access);
--
2.25.1