Re: [PATCH] RDMA/rxe: Replace page_address() with kmap_local_page()

Yunsheng Lin
2022-11-11T03:35:02Z

On 2022/11/11 11:19, Xiao Yang wrote:
> 1) Use kmap_local_page() for new in-kernel memory protection schemes.
> 2) Do some cleanup(e.g. remove struct rxe_phys_buf).

As the commit log above, it seems better to spilt it to two patches:
Patch 1: Do some cleanup
Patch 2: Use kmap_local_page()

Alas, does not pin_user_pages_fast() in ib_umem_get() ensure the
user memory is accessible in the kernel space, which means we
can use page_address() safely?

>
> Signed-off-by: Xiao Yang <yangx.jy@fujitsu.com>
> ---
> drivers/infiniband/sw/rxe/rxe_loc.h | 2 +
> drivers/infiniband/sw/rxe/rxe_mr.c | 84 +++++++++++++--------------
> drivers/infiniband/sw/rxe/rxe_resp.c | 1 +
> drivers/infiniband/sw/rxe/rxe_verbs.c | 6 +-
> drivers/infiniband/sw/rxe/rxe_verbs.h | 9 +--
> 5 files changed, 45 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
> index c2a5c8814a48..a63d29156a66 100644
> --- a/drivers/infiniband/sw/rxe/rxe_loc.h
> +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
> @@ -68,6 +68,8 @@ void rxe_mr_init_dma(int access, struct rxe_mr *mr);
> int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
> int access, struct rxe_mr *mr);
> int rxe_mr_init_fast(int max_pages, struct rxe_mr *mr);
> +void *rxe_map_to_vaddr(struct rxe_mr *mr, int map_index, int addr_index, size_t offset);
> +void rxe_unmap_vaddr(struct rxe_mr *mr, void *vaddr);
> int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
> enum rxe_mr_copy_dir dir);
> int copy_data(struct rxe_pd *pd, int access, struct rxe_dma_info *dma,
> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> index bc081002bddc..4246b7f34a29 100644
> --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> @@ -115,13 +115,10 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
> int access, struct rxe_mr *mr)
> {
> struct rxe_map **map;
> - struct rxe_phys_buf *buf = NULL;
> struct ib_umem *umem;
> struct sg_page_iter sg_iter;
> int num_buf;
> - void *vaddr;
> int err;
> - int i;
>
> umem = ib_umem_get(&rxe->ib_dev, start, length, access);
> if (IS_ERR(umem)) {
> @@ -144,32 +141,19 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
>
> mr->page_shift = PAGE_SHIFT;
> mr->page_mask = PAGE_SIZE - 1;
> + mr->ibmr.page_size = PAGE_SIZE;
>
> - num_buf = 0;
> + num_buf = 0;
> map = mr->map;
> if (length > 0) {
> - buf = map[0]->buf;
> -
> for_each_sgtable_page (&umem->sgt_append.sgt, &sg_iter, 0) {
> if (num_buf >= RXE_BUF_PER_MAP) {
> map++;
> - buf = map[0]->buf;
> num_buf = 0;
> }
>
> - vaddr = page_address(sg_page_iter_page(&sg_iter));
> - if (!vaddr) {
> - pr_warn("%s: Unable to get virtual address\n",
> - __func__);
> - err = -ENOMEM;
> - goto err_cleanup_map;
> - }
> -
> - buf->addr = (uintptr_t)vaddr;
> - buf->size = PAGE_SIZE;
> + map[0]->addrs[num_buf] = (uintptr_t)sg_page_iter_page(&sg_iter);
> num_buf++;
> - buf++;
> -
> }
> }
>
> @@ -181,10 +165,6 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
>
> return 0;
>
> -err_cleanup_map:
> - for (i = 0; i < mr->num_map; i++)
> - kfree(mr->map[i]);
> - kfree(mr->map);
> err_release_umem:
> ib_umem_release(umem);
> err_out:
> @@ -216,9 +196,9 @@ static void lookup_iova(struct rxe_mr *mr, u64 iova, int *m_out, int *n_out,
> size_t *offset_out)
> {
> size_t offset = iova - mr->ibmr.iova + mr->offset;
> + u64 length = mr->ibmr.page_size;
> int map_index;
> - int buf_index;
> - u64 length;
> + int addr_index;
>
> if (likely(mr->page_shift)) {
> *offset_out = offset & mr->page_mask;
> @@ -227,27 +207,46 @@ static void lookup_iova(struct rxe_mr *mr, u64 iova, int *m_out, int *n_out,
> *m_out = offset >> mr->map_shift;
> } else {
> map_index = 0;
> - buf_index = 0;
> -
> - length = mr->map[map_index]->buf[buf_index].size;
> + addr_index = 0;
>
> while (offset >= length) {
> offset -= length;
> - buf_index++;
> + addr_index++;
>
> - if (buf_index == RXE_BUF_PER_MAP) {
> + if (addr_index == RXE_BUF_PER_MAP) {
> map_index++;
> - buf_index = 0;
> + addr_index = 0;
> }
> - length = mr->map[map_index]->buf[buf_index].size;
> }
>
> *m_out = map_index;
> - *n_out = buf_index;
> + *n_out = addr_index;
> *offset_out = offset;
> }
> }
>
> +void *rxe_map_to_vaddr(struct rxe_mr *mr, int map_index, int addr_index, size_t offset)
> +{
> + void *vaddr = NULL;
> +
> + if (mr->ibmr.type == IB_MR_TYPE_USER) {
> + vaddr = kmap_local_page((struct page *)mr->map[map_index]->addrs[addr_index]);
> + if (vaddr == NULL) {
> + pr_warn("Failed to map page");
> + return NULL;
> + }
> + } else
> + vaddr = (void *)(uintptr_t)mr->map[map_index]->addrs[addr_index];
> +
> + return vaddr + offset;
> +}
> +
> +void rxe_unmap_vaddr(struct rxe_mr *mr, void *vaddr)
> +{
> + if (mr->ibmr.type == IB_MR_TYPE_USER)
> + kunmap_local(vaddr);
> +}
> +
> void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length)
> {
> size_t offset;
> @@ -273,13 +272,13 @@ void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length)
>
> lookup_iova(mr, iova, &m, &n, &offset);
>
> - if (offset + length > mr->map[m]->buf[n].size) {
> + if (offset + length > mr->ibmr.page_size) {
> pr_warn("crosses page boundary\n");
> addr = NULL;
> goto out;
> }
>
> - addr = (void *)(uintptr_t)mr->map[m]->buf[n].addr + offset;
> + addr = rxe_map_to_vaddr(mr, m, n, offset);
>
> out:
> return addr;
> @@ -294,8 +293,6 @@ int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
> int err;
> int bytes;
> u8 *va;
> - struct rxe_map **map;
> - struct rxe_phys_buf *buf;
> int m;
> int i;
> size_t offset;
> @@ -325,17 +322,14 @@ int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
>
> lookup_iova(mr, iova, &m, &i, &offset);
>
> - map = mr->map + m;
> - buf = map[0]->buf + i;
> -
> while (length > 0) {
> u8 *src, *dest;
>
> - va = (u8 *)(uintptr_t)buf->addr + offset;
> + va = (u8 *)rxe_map_to_vaddr(mr, m, i, offset);
> src = (dir == RXE_TO_MR_OBJ) ? addr : va;
> dest = (dir == RXE_TO_MR_OBJ) ? va : addr;
>
> - bytes = buf->size - offset;
> + bytes = mr->ibmr.page_size - offset;
>
> if (bytes > length)
> bytes = length;
> @@ -346,14 +340,14 @@ int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
> addr += bytes;
>
> offset = 0;
> - buf++;
> i++;
>
> if (i == RXE_BUF_PER_MAP) {
> i = 0;
> - map++;
> - buf = map[0]->buf;
> + m++;
> }
> +
> + rxe_unmap_vaddr(mr, va);
> }
>
> return 0;
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index c32bc12cc82f..31f9ba11a921 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -652,6 +652,7 @@ static enum resp_states atomic_reply(struct rxe_qp *qp,
>
> ret = RESPST_ACKNOWLEDGE;
> out:
> + rxe_unmap_vaddr(mr, vaddr);
> return ret;
> }
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
> index bcdfdadaebbc..13e4d660cb02 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
> @@ -948,16 +948,12 @@ static int rxe_set_page(struct ib_mr *ibmr, u64 addr)
> {
> struct rxe_mr *mr = to_rmr(ibmr);
> struct rxe_map *map;
> - struct rxe_phys_buf *buf;
>
> if (unlikely(mr->nbuf == mr->num_buf))
> return -ENOMEM;
>
> map = mr->map[mr->nbuf / RXE_BUF_PER_MAP];
> - buf = &map->buf[mr->nbuf % RXE_BUF_PER_MAP];
> -
> - buf->addr = addr;
> - buf->size = ibmr->page_size;
> + map->addrs[mr->nbuf % RXE_BUF_PER_MAP] = addr;
> mr->nbuf++;
>
> return 0;
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
> index 22a299b0a9f0..d136f02d5b56 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.h
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
> @@ -277,15 +277,10 @@ enum rxe_mr_lookup_type {
> RXE_LOOKUP_REMOTE,
> };
>
> -#define RXE_BUF_PER_MAP (PAGE_SIZE / sizeof(struct rxe_phys_buf))
> -
> -struct rxe_phys_buf {
> - u64 addr;
> - u64 size;
> -};
> +#define RXE_BUF_PER_MAP (PAGE_SIZE / sizeof(u64))
>
> struct rxe_map {
> - struct rxe_phys_buf buf[RXE_BUF_PER_MAP];
> + u64 addrs[RXE_BUF_PER_MAP];
> };
>
> static inline int rkey_is_mw(u32 rkey)
>