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xsk: Introduce AF_XDP buffer allocation API

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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: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200520192103.355233-6-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel
2020-05-20 21:20:53 +02:00
committed by Alexei Starovoitov
parent 89e4a376e3
commit 2b43470add
12 changed files with 823 additions and 123 deletions
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56
include/net/xsk_buff_pool.h Normal file
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/* 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_ */