Commit 2b43470a authored by Björn Töpel's avatar Björn Töpel Committed by Alexei Starovoitov
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xsk: Introduce AF_XDP buffer allocation API 



In order to simplify AF_XDP zero-copy enablement for NIC driver
developers, a new AF_XDP buffer allocation API is added. The
implementation is based on a single core (single producer/consumer)
buffer pool for the AF_XDP UMEM.

A buffer is allocated using the xsk_buff_alloc() function, and
returned using xsk_buff_free(). If a buffer is disassociated with the
pool, e.g. when a buffer is passed to an AF_XDP socket, a buffer is
said to be released. Currently, the release function is only used by
the AF_XDP internals and not visible to the driver.

Drivers using this API should register the XDP memory model with the
new MEM_TYPE_XSK_BUFF_POOL type.

The API is defined in net/xdp_sock_drv.h.

The buffer type is struct xdp_buff, and follows the lifetime of
regular xdp_buffs, i.e.  the lifetime of an xdp_buff is restricted to
a NAPI context. In other words, the API is not replacing xdp_frames.

In addition to introducing the API and implementations, the AF_XDP
core is migrated to use the new APIs.

rfc->v1: Fixed build errors/warnings for m68k and riscv. (kbuild test
         robot)
         Added headroom/chunk size getter. (Maxim/Björn)

v1->v2: Swapped SoBs. (Maxim)

v2->v3: Initialize struct xdp_buff member frame_sz. (Björn)
        Add API to query the DMA address of a frame. (Maxim)
        Do DMA sync for CPU till the end of the frame to handle
        possible growth (frame_sz). (Maxim)

Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200520192103.355233-6-bjorn.topel@gmail.com
parent 89e4a376

include/net/xdp.h

+3 −1
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ enum xdp_mem_type { 
	MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */

	MEM_TYPE_PAGE_POOL,

	MEM_TYPE_ZERO_COPY,

	MEM_TYPE_XSK_BUFF_POOL,

	MEM_TYPE_MAX,

};
@@ -119,7 +120,8 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) 
	int metasize;

	int headroom;



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

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

	    xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)

		return xdp_convert_zc_to_xdp_frame(xdp);



	/* Assure headroom is available for storing info */

include/net/xdp_sock.h

+2 −0
Original line number Diff line number Diff line
@@ -31,11 +31,13 @@ struct xdp_umem_fq_reuse { 
struct xdp_umem {

	struct xsk_queue *fq;

	struct xsk_queue *cq;

	struct xsk_buff_pool *pool;

	struct xdp_umem_page *pages;

	u64 chunk_mask;

	u64 size;

	u32 headroom;

	u32 chunk_size_nohr;

	u32 chunk_size;

	struct user_struct *user;

	refcount_t users;

	struct work_struct work;

include/net/xdp_sock_drv.h

+164 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#define _LINUX_XDP_SOCK_DRV_H



#include <net/xdp_sock.h>

#include <net/xsk_buff_pool.h>



#ifdef CONFIG_XDP_SOCKETS
@@ -101,6 +102,94 @@ static inline u32 xsk_umem_xdp_frame_sz(struct xdp_umem *umem) 
	return umem->chunk_size_nohr;

}



static inline u32 xsk_umem_get_headroom(struct xdp_umem *umem)

{

	return XDP_PACKET_HEADROOM + umem->headroom;

}



static inline u32 xsk_umem_get_chunk_size(struct xdp_umem *umem)

{

	return umem->chunk_size;

}



static inline u32 xsk_umem_get_rx_frame_size(struct xdp_umem *umem)

{

	return xsk_umem_get_chunk_size(umem) - xsk_umem_get_headroom(umem);

}



static inline void xsk_buff_set_rxq_info(struct xdp_umem *umem,

					 struct xdp_rxq_info *rxq)

{

	xp_set_rxq_info(umem->pool, rxq);

}



static inline void xsk_buff_dma_unmap(struct xdp_umem *umem,

				      unsigned long attrs)

{

	xp_dma_unmap(umem->pool, attrs);

}



static inline int xsk_buff_dma_map(struct xdp_umem *umem, struct device *dev,

				   unsigned long attrs)

{

	return xp_dma_map(umem->pool, dev, attrs, umem->pgs, umem->npgs);

}



static inline dma_addr_t xsk_buff_xdp_get_dma(struct xdp_buff *xdp)

{

	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);



	return xp_get_dma(xskb);

}



static inline dma_addr_t xsk_buff_xdp_get_frame_dma(struct xdp_buff *xdp)

{

	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);



	return xp_get_frame_dma(xskb);

}



static inline struct xdp_buff *xsk_buff_alloc(struct xdp_umem *umem)

{

	return xp_alloc(umem->pool);

}



static inline bool xsk_buff_can_alloc(struct xdp_umem *umem, u32 count)

{

	return xp_can_alloc(umem->pool, count);

}



static inline void xsk_buff_free(struct xdp_buff *xdp)

{

	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);



	xp_free(xskb);

}



static inline dma_addr_t xsk_buff_raw_get_dma(struct xdp_umem *umem, u64 addr)

{

	return xp_raw_get_dma(umem->pool, addr);

}



static inline void *xsk_buff_raw_get_data(struct xdp_umem *umem, u64 addr)

{

	return xp_raw_get_data(umem->pool, addr);

}



static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp)

{

	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);



	xp_dma_sync_for_cpu(xskb);

}



static inline void xsk_buff_raw_dma_sync_for_device(struct xdp_umem *umem,

						    dma_addr_t dma,

						    size_t size)

{

	xp_dma_sync_for_device(umem->pool, dma, size);

}



#else



static inline bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
@@ -212,6 +301,81 @@ static inline u32 xsk_umem_xdp_frame_sz(struct xdp_umem *umem) 
	return 0;

}



static inline u32 xsk_umem_get_headroom(struct xdp_umem *umem)

{

	return 0;

}



static inline u32 xsk_umem_get_chunk_size(struct xdp_umem *umem)

{

	return 0;

}



static inline u32 xsk_umem_get_rx_frame_size(struct xdp_umem *umem)

{

	return 0;

}



static inline void xsk_buff_set_rxq_info(struct xdp_umem *umem,

					 struct xdp_rxq_info *rxq)

{

}



static inline void xsk_buff_dma_unmap(struct xdp_umem *umem,

				      unsigned long attrs)

{

}



static inline int xsk_buff_dma_map(struct xdp_umem *umem, struct device *dev,

				   unsigned long attrs)

{

	return 0;

}



static inline dma_addr_t xsk_buff_xdp_get_dma(struct xdp_buff *xdp)

{

	return 0;

}



static inline dma_addr_t xsk_buff_xdp_get_frame_dma(struct xdp_buff *xdp)

{

	return 0;

}



static inline struct xdp_buff *xsk_buff_alloc(struct xdp_umem *umem)

{

	return NULL;

}



static inline bool xsk_buff_can_alloc(struct xdp_umem *umem, u32 count)

{

	return false;

}



static inline void xsk_buff_free(struct xdp_buff *xdp)

{

}



static inline dma_addr_t xsk_buff_raw_get_dma(struct xdp_umem *umem, u64 addr)

{

	return 0;

}



static inline void *xsk_buff_raw_get_data(struct xdp_umem *umem, u64 addr)

{

	return NULL;

}



static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp)

{

}



static inline void xsk_buff_raw_dma_sync_for_device(struct xdp_umem *umem,

						    dma_addr_t dma,

						    size_t size)

{

}



#endif /* CONFIG_XDP_SOCKETS */



#endif /* _LINUX_XDP_SOCK_DRV_H */

include/net/xsk_buff_pool.h

0 → 100644
+56 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright(c) 2020 Intel Corporation. */



#ifndef XSK_BUFF_POOL_H_

#define XSK_BUFF_POOL_H_



#include <linux/types.h>

#include <linux/dma-mapping.h>

#include <net/xdp.h>



struct xsk_buff_pool;

struct xdp_rxq_info;

struct xsk_queue;

struct xdp_desc;

struct device;

struct page;



struct xdp_buff_xsk {

	struct xdp_buff xdp;

	dma_addr_t dma;

	dma_addr_t frame_dma;

	struct xsk_buff_pool *pool;

	bool unaligned;

	u64 orig_addr;

	struct list_head free_list_node;

};



/* AF_XDP core. */

struct xsk_buff_pool *xp_create(struct page **pages, u32 nr_pages, u32 chunks,

				u32 chunk_size, u32 headroom, u64 size,

				bool unaligned);

void xp_set_fq(struct xsk_buff_pool *pool, struct xsk_queue *fq);

void xp_destroy(struct xsk_buff_pool *pool);

void xp_release(struct xdp_buff_xsk *xskb);

u64 xp_get_handle(struct xdp_buff_xsk *xskb);

bool xp_validate_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc);



/* AF_XDP, and XDP core. */

void xp_free(struct xdp_buff_xsk *xskb);



/* AF_XDP ZC drivers, via xdp_sock_buff.h */

void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq);

int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev,

	       unsigned long attrs, struct page **pages, u32 nr_pages);

void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs);

struct xdp_buff *xp_alloc(struct xsk_buff_pool *pool);

bool xp_can_alloc(struct xsk_buff_pool *pool, u32 count);

void *xp_raw_get_data(struct xsk_buff_pool *pool, u64 addr);

dma_addr_t xp_raw_get_dma(struct xsk_buff_pool *pool, u64 addr);

dma_addr_t xp_get_dma(struct xdp_buff_xsk *xskb);

dma_addr_t xp_get_frame_dma(struct xdp_buff_xsk *xskb);

void xp_dma_sync_for_cpu(struct xdp_buff_xsk *xskb);

void xp_dma_sync_for_device(struct xsk_buff_pool *pool, dma_addr_t dma,

			    size_t size);



#endif /* XSK_BUFF_POOL_H_ */

include/trace/events/xdp.h

+2 −1
Original line number Diff line number Diff line
@@ -287,7 +287,8 @@ TRACE_EVENT(xdp_devmap_xmit, 
	FN(PAGE_SHARED)		\

	FN(PAGE_ORDER0)		\

	FN(PAGE_POOL)		\

	FN(ZERO_COPY)

	FN(ZERO_COPY)		\

	FN(XSK_BUFF_POOL)



#define __MEM_TYPE_TP_FN(x)	\

	TRACE_DEFINE_ENUM(MEM_TYPE_##x);

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