summaryrefslogtreecommitdiff
path: root/net/xdp/xdp_umem.h
diff options
context:
space:
mode:
authorBjörn Töpel <bjorn.topel@intel.com>2018-06-04 13:57:13 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2018-06-04 17:21:02 +0200
commitbbff2f321a864ee07c9d3d1245af498023146951 (patch)
tree962414a03f749ce22e52ed553780a74216992d0a /net/xdp/xdp_umem.h
parenta509a95536a86ef84deb16c656d741437791b414 (diff)
xsk: new descriptor addressing scheme
Currently, AF_XDP only supports a fixed frame-size memory scheme where each frame is referenced via an index (idx). A user passes the frame index to the kernel, and the kernel acts upon the data. Some NICs, however, do not have a fixed frame-size model, instead they have a model where a memory window is passed to the hardware and multiple frames are filled into that window (referred to as the "type-writer" model). By changing the descriptor format from the current frame index addressing scheme, AF_XDP can in the future be extended to support these kinds of NICs. In the index-based model, an idx refers to a frame of size frame_size. Addressing a frame in the UMEM is done by offseting the UMEM starting address by a global offset, idx * frame_size + offset. Communicating via the fill- and completion-rings are done by means of idx. In this commit, the idx is removed in favor of an address (addr), which is a relative address ranging over the UMEM. To convert an idx-based address to the new addr is simply: addr = idx * frame_size + offset. We also stop referring to the UMEM "frame" as a frame. Instead it is simply called a chunk. To transfer ownership of a chunk to the kernel, the addr of the chunk is passed in the fill-ring. Note, that the kernel will mask addr to make it chunk aligned, so there is no need for userspace to do that. E.g., for a chunk size of 2k, passing an addr of 2048, 2050 or 3000 to the fill-ring will refer to the same chunk. On the completion-ring, the addr will match that of the Tx descriptor, passed to the kernel. Changing the descriptor format to use chunks/addr will allow for future changes to move to a type-writer based model, where multiple frames can reside in one chunk. In this model passing one single chunk into the fill-ring, would potentially result in multiple Rx descriptors. This commit changes the uapi of AF_XDP sockets, and updates the documentation. Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/xdp/xdp_umem.h')
-rw-r--r--net/xdp/xdp_umem.h27
1 files changed, 6 insertions, 21 deletions
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 0881cf456230..aeadd1bcb72d 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -18,35 +18,20 @@ struct xdp_umem {
struct xsk_queue *cq;
struct page **pgs;
struct xdp_umem_props props;
- u32 npgs;
- u32 frame_headroom;
- u32 nfpp_mask;
- u32 nfpplog2;
- u32 frame_size_log2;
+ u32 headroom;
+ u32 chunk_size_nohr;
struct user_struct *user;
struct pid *pid;
unsigned long address;
- size_t size;
refcount_t users;
struct work_struct work;
+ u32 npgs;
};
-static inline char *xdp_umem_get_data(struct xdp_umem *umem, u32 idx)
-{
- u64 pg, off;
- char *data;
-
- pg = idx >> umem->nfpplog2;
- off = (idx & umem->nfpp_mask) << umem->frame_size_log2;
-
- data = page_address(umem->pgs[pg]);
- return data + off;
-}
-
-static inline char *xdp_umem_get_data_with_headroom(struct xdp_umem *umem,
- u32 idx)
+static inline char *xdp_umem_get_data(struct xdp_umem *umem, u64 addr)
{
- return xdp_umem_get_data(umem, idx) + umem->frame_headroom;
+ return page_address(umem->pgs[addr >> PAGE_SHIFT]) +
+ (addr & (PAGE_SIZE - 1));
}
bool xdp_umem_validate_queues(struct xdp_umem *umem);