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

Yang, Xiao/杨晓 <yangx.jy@xxxxxxxxxxx> · Fri, 11 Nov 2022 14:07:38 +0800

On 2022/11/11 11:34, Yunsheng Lin wrote:
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()

Hi Lin,

It's fine for me to split the patchset. I will send v2 soon.



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?

Now it's safe to call page_address() here but it will be broken when new 
in-kernel memory protection schemes(e.g. PKS[1]) are applied in the future.

[1]: 
https://lore.kernel.org/lkml/20220419170649.1022246-1-ira.weiny@xxxxxxxxx/

Jason suggested that we should replace page_address() with 
kmap_local_page(), please see the detailed discussion[2][3]

[2]: 
https://lore.kernel.org/linux-rdma/20220121160654.GC773547@xxxxxxxxxxxxxxxxxxxxxxxxx/
[3]: https://lore.kernel.org/linux-rdma/Y1bFG%2FOM5zSOoWcr@xxxxxxxxxx/

Best Regards,
Xiao Yang



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)







