Commit b0d1beef authored by Björn Töpel's avatar Björn Töpel Committed by Alexei Starovoitov
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xdp: implement convert_to_xdp_frame for MEM_TYPE_ZERO_COPY 



This commit adds proper MEM_TYPE_ZERO_COPY support for
convert_to_xdp_frame. Converting a MEM_TYPE_ZERO_COPY xdp_buff to an
xdp_frame is done by transforming the MEM_TYPE_ZERO_COPY buffer into a
MEM_TYPE_PAGE_ORDER0 frame. This is costly, and in the future it might
make sense to implement a more sophisticated thread-safe alloc/free
scheme for MEM_TYPE_ZERO_COPY, so that no allocation and copy is
required in the fast-path.

Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 7d2c6cfc

include/net/xdp.h

+3 −2
Original line number Diff line number Diff line
@@ -91,6 +91,8 @@ static inline void xdp_scrub_frame(struct xdp_frame *frame) 
	frame->dev_rx = NULL;

}



struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);



/* Convert xdp_buff to xdp_frame */

static inline

struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
@@ -99,9 +101,8 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) 
	int metasize;

	int headroom;



	/* TODO: implement clone, copy, use "native" MEM_TYPE */

	if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)

		return NULL;

		return xdp_convert_zc_to_xdp_frame(xdp);



	/* Assure headroom is available for storing info */

	headroom = xdp->data - xdp->data_hard_start;

net/core/xdp.c

+39 −0
Original line number Diff line number Diff line
@@ -398,3 +398,42 @@ void xdp_attachment_setup(struct xdp_attachment_info *info, 
	info->flags = bpf->flags;

}

EXPORT_SYMBOL_GPL(xdp_attachment_setup);



struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)

{

	unsigned int metasize, headroom, totsize;

	void *addr, *data_to_copy;

	struct xdp_frame *xdpf;

	struct page *page;



	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */

	metasize = xdp_data_meta_unsupported(xdp) ? 0 :

		   xdp->data - xdp->data_meta;

	headroom = xdp->data - xdp->data_hard_start;

	totsize = xdp->data_end - xdp->data + metasize;



	if (sizeof(*xdpf) + totsize > PAGE_SIZE)

		return NULL;



	page = dev_alloc_page();

	if (!page)

		return NULL;



	addr = page_to_virt(page);

	xdpf = addr;

	memset(xdpf, 0, sizeof(*xdpf));



	addr += sizeof(*xdpf);

	data_to_copy = metasize ? xdp->data_meta : xdp->data;

	memcpy(addr, data_to_copy, totsize);



	xdpf->data = addr + metasize;

	xdpf->len = totsize - metasize;

	xdpf->headroom = 0;

	xdpf->metasize = metasize;

	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;



	xdp_return_buff(xdp);

	return xdpf;

}

EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);

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