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

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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@xxxxxxxxxxx>
> ---
>  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)
> 



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