[linux-2.6-block.git] / net / xdp / xsk_queue.h

/* SPDX-License-Identifier: GPL-2.0 */
/* XDP user-space ring structure
 * Copyright(c) 2018 Intel Corporation.
 */

#ifndef _LINUX_XSK_QUEUE_H
#define _LINUX_XSK_QUEUE_H

#include <linux/types.h>
#include <linux/if_xdp.h>
#include <net/xdp_sock.h>

#define RX_BATCH_SIZE 16
#define LAZY_UPDATE_THRESHOLD 128

struct xdp_ring {
	u32 producer ____cacheline_aligned_in_smp;
	u32 consumer ____cacheline_aligned_in_smp;
};

/* Used for the RX and TX queues for packets */
struct xdp_rxtx_ring {
	struct xdp_ring ptrs;
	struct xdp_desc desc[0] ____cacheline_aligned_in_smp;
};

/* Used for the fill and completion queues for buffers */
struct xdp_umem_ring {
	struct xdp_ring ptrs;
	u64 desc[0] ____cacheline_aligned_in_smp;
};

struct xsk_queue {
	u64 chunk_mask;
	u64 size;
	u32 ring_mask;
	u32 nentries;
	u32 prod_head;
	u32 prod_tail;
	u32 cons_head;
	u32 cons_tail;
	struct xdp_ring *ring;
	u64 invalid_descs;
};

/* The structure of the shared state of the rings are the same as the
 * ring buffer in kernel/events/ring_buffer.c. For the Rx and completion
 * ring, the kernel is the producer and user space is the consumer. For
 * the Tx and fill rings, the kernel is the consumer and user space is
 * the producer.
 *
 * producer                         consumer
 *
 * if (LOAD ->consumer) {           LOAD ->producer
 *                    (A)           smp_rmb()       (C)
 *    STORE $data                   LOAD $data
 *    smp_wmb()       (B)           smp_mb()        (D)
 *    STORE ->producer              STORE ->consumer
 * }
 *
 * (A) pairs with (D), and (B) pairs with (C).
 *
 * Starting with (B), it protects the data from being written after
 * the producer pointer. If this barrier was missing, the consumer
 * could observe the producer pointer being set and thus load the data
 * before the producer has written the new data. The consumer would in
 * this case load the old data.
 *
 * (C) protects the consumer from speculatively loading the data before
 * the producer pointer actually has been read. If we do not have this
 * barrier, some architectures could load old data as speculative loads
 * are not discarded as the CPU does not know there is a dependency
 * between ->producer and data.
 *
 * (A) is a control dependency that separates the load of ->consumer
 * from the stores of $data. In case ->consumer indicates there is no
 * room in the buffer to store $data we do not. So no barrier is needed.
 *
 * (D) protects the load of the data to be observed to happen after the
 * store of the consumer pointer. If we did not have this memory
 * barrier, the producer could observe the consumer pointer being set
 * and overwrite the data with a new value before the consumer got the
 * chance to read the old value. The consumer would thus miss reading
 * the old entry and very likely read the new entry twice, once right
 * now and again after circling through the ring.
 */

/* Common functions operating for both RXTX and umem queues */

static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
{
	return q ? q->invalid_descs : 0;
}

static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
{
	u32 entries = q->prod_tail - q->cons_tail;

	if (entries == 0) {
		/* Refresh the local pointer */
		q->prod_tail = READ_ONCE(q->ring->producer);
		entries = q->prod_tail - q->cons_tail;
	}

	return (entries > dcnt) ? dcnt : entries;
}

static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
{
	u32 free_entries = q->nentries - (producer - q->cons_tail);

	if (free_entries >= dcnt)
		return free_entries;

	/* Refresh the local tail pointer */
	q->cons_tail = READ_ONCE(q->ring->consumer);
	return q->nentries - (producer - q->cons_tail);
}

static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
{
	u32 entries = q->prod_tail - q->cons_tail;

	if (entries >= cnt)
		return true;

	/* Refresh the local pointer. */
	q->prod_tail = READ_ONCE(q->ring->producer);
	entries = q->prod_tail - q->cons_tail;

	return entries >= cnt;
}

/* UMEM queue */

static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
{
	if (addr >= q->size) {
		q->invalid_descs++;
		return false;
	}

	return true;
}

static inline u64 *xskq_validate_addr(struct xsk_queue *q, u64 *addr)
{
	while (q->cons_tail != q->cons_head) {
		struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
		unsigned int idx = q->cons_tail & q->ring_mask;

		*addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
		if (xskq_is_valid_addr(q, *addr))
			return addr;

		q->cons_tail++;
	}

	return NULL;
}

static inline u64 *xskq_peek_addr(struct xsk_queue *q, u64 *addr)
{
	if (q->cons_tail == q->cons_head) {
		smp_mb(); /* D, matches A */
		WRITE_ONCE(q->ring->consumer, q->cons_tail);
		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);

		/* Order consumer and data */
		smp_rmb();
	}

	return xskq_validate_addr(q, addr);
}

static inline void xskq_discard_addr(struct xsk_queue *q)
{
	q->cons_tail++;
}

static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
{
	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

	if (xskq_nb_free(q, q->prod_tail, 1) == 0)
		return -ENOSPC;

	/* A, matches D */
	ring->desc[q->prod_tail++ & q->ring_mask] = addr;

	/* Order producer and data */
	smp_wmb(); /* B, matches C */

	WRITE_ONCE(q->ring->producer, q->prod_tail);
	return 0;
}

static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
{
	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

	if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
		return -ENOSPC;

	/* A, matches D */
	ring->desc[q->prod_head++ & q->ring_mask] = addr;
	return 0;
}

static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
					     u32 nb_entries)
{
	/* Order producer and data */
	smp_wmb(); /* B, matches C */

	q->prod_tail += nb_entries;
	WRITE_ONCE(q->ring->producer, q->prod_tail);
}

static inline int xskq_reserve_addr(struct xsk_queue *q)
{
	if (xskq_nb_free(q, q->prod_head, 1) == 0)
		return -ENOSPC;

	/* A, matches D */
	q->prod_head++;
	return 0;
}

/* Rx/Tx queue */

static inline bool xskq_is_valid_desc(struct xsk_queue *q, struct xdp_desc *d)
{
	if (!xskq_is_valid_addr(q, d->addr))
		return false;

	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
	    d->options) {
		q->invalid_descs++;
		return false;
	}

	return true;
}

static inline struct xdp_desc *xskq_validate_desc(struct xsk_queue *q,
						  struct xdp_desc *desc)
{
	while (q->cons_tail != q->cons_head) {
		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
		unsigned int idx = q->cons_tail & q->ring_mask;

		*desc = READ_ONCE(ring->desc[idx]);
		if (xskq_is_valid_desc(q, desc))
			return desc;

		q->cons_tail++;
	}

	return NULL;
}

static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
					      struct xdp_desc *desc)
{
	if (q->cons_tail == q->cons_head) {
		smp_mb(); /* D, matches A */
		WRITE_ONCE(q->ring->consumer, q->cons_tail);
		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);

		/* Order consumer and data */
		smp_rmb(); /* C, matches B */
	}

	return xskq_validate_desc(q, desc);
}

static inline void xskq_discard_desc(struct xsk_queue *q)
{
	q->cons_tail++;
}

static inline int xskq_produce_batch_desc(struct xsk_queue *q,
					  u64 addr, u32 len)
{
	struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
	unsigned int idx;

	if (xskq_nb_free(q, q->prod_head, 1) == 0)
		return -ENOSPC;

	/* A, matches D */
	idx = (q->prod_head++) & q->ring_mask;
	ring->desc[idx].addr = addr;
	ring->desc[idx].len = len;

	return 0;
}

static inline void xskq_produce_flush_desc(struct xsk_queue *q)
{
	/* Order producer and data */
	smp_wmb(); /* B, matches C */

	q->prod_tail = q->prod_head;
	WRITE_ONCE(q->ring->producer, q->prod_tail);
}

static inline bool xskq_full_desc(struct xsk_queue *q)
{
	return xskq_nb_avail(q, q->nentries) == q->nentries;
}

static inline bool xskq_empty_desc(struct xsk_queue *q)
{
	return xskq_nb_free(q, q->prod_tail, q->nentries) == q->nentries;
}

void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);
struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
void xskq_destroy(struct xsk_queue *q_ops);

/* Executed by the core when the entire UMEM gets freed */
void xsk_reuseq_destroy(struct xdp_umem *umem);

#endif /* _LINUX_XSK_QUEUE_H */
Commit	Line	Data
dac09149 BT	1	/* SPDX-License-Identifier: GPL-2.0 */
dac09149 BT	2	/* XDP user-space ring structure
423f3832	3	* Copyright(c) 2018 Intel Corporation.
423f3832 MK	4	*/
	5
	6	#ifndef _LINUX_XSK_QUEUE_H
	7	#define _LINUX_XSK_QUEUE_H
	8
	9	#include <linux/types.h>
	10	#include <linux/if_xdp.h>
e61e62b9	11	#include <net/xdp_sock.h>
423f3832	12
c497176c	13	#define RX_BATCH_SIZE 16
ac98d8aa	14	#define LAZY_UPDATE_THRESHOLD 128
c497176c	15
b3a9e0be BT	16	struct xdp_ring {
	17	u32 producer ____cacheline_aligned_in_smp;
	18	u32 consumer ____cacheline_aligned_in_smp;
	19	};
	20
	21	/* Used for the RX and TX queues for packets */
	22	struct xdp_rxtx_ring {
	23	struct xdp_ring ptrs;
	24	struct xdp_desc desc[0] ____cacheline_aligned_in_smp;
	25	};
	26
	27	/* Used for the fill and completion queues for buffers */
	28	struct xdp_umem_ring {
	29	struct xdp_ring ptrs;
bbff2f32	30	u64 desc[0] ____cacheline_aligned_in_smp;
b3a9e0be BT	31	};
b3a9e0be BT	32
423f3832	33	struct xsk_queue {
93ee30f3 MK	34	u64 chunk_mask;
93ee30f3 MK	35	u64 size;
423f3832 MK	36	u32 ring_mask;
	37	u32 nentries;
	38	u32 prod_head;
	39	u32 prod_tail;
	40	u32 cons_head;
	41	u32 cons_tail;
	42	struct xdp_ring *ring;
	43	u64 invalid_descs;
	44	};
	45
f63666de MK	46	/* The structure of the shared state of the rings are the same as the
	47	* ring buffer in kernel/events/ring_buffer.c. For the Rx and completion
	48	* ring, the kernel is the producer and user space is the consumer. For
	49	* the Tx and fill rings, the kernel is the consumer and user space is
	50	* the producer.
	51	*
	52	* producer consumer
	53	*
	54	* if (LOAD ->consumer) { LOAD ->producer
	55	* (A) smp_rmb() (C)
	56	* STORE $data LOAD $data
	57	* smp_wmb() (B) smp_mb() (D)
	58	* STORE ->producer STORE ->consumer
	59	* }
	60	*
	61	* (A) pairs with (D), and (B) pairs with (C).
	62	*
	63	* Starting with (B), it protects the data from being written after
	64	* the producer pointer. If this barrier was missing, the consumer
	65	* could observe the producer pointer being set and thus load the data
	66	* before the producer has written the new data. The consumer would in
	67	* this case load the old data.
	68	*
	69	* (C) protects the consumer from speculatively loading the data before
	70	* the producer pointer actually has been read. If we do not have this
	71	* barrier, some architectures could load old data as speculative loads
	72	* are not discarded as the CPU does not know there is a dependency
	73	* between ->producer and data.
	74	*
	75	* (A) is a control dependency that separates the load of ->consumer
	76	* from the stores of $data. In case ->consumer indicates there is no
	77	* room in the buffer to store $data we do not. So no barrier is needed.
	78	*
	79	* (D) protects the load of the data to be observed to happen after the
	80	* store of the consumer pointer. If we did not have this memory
	81	* barrier, the producer could observe the consumer pointer being set
	82	* and overwrite the data with a new value before the consumer got the
	83	* chance to read the old value. The consumer would thus miss reading
	84	* the old entry and very likely read the new entry twice, once right
	85	* now and again after circling through the ring.
	86	*/
	87
c497176c BT	88	/* Common functions operating for both RXTX and umem queues */
c497176c BT	89
af75d9e0 MK	90	static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
	91	{
	92	return q ? q->invalid_descs : 0;
	93	}
	94
c497176c BT	95	static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
	96	{
	97	u32 entries = q->prod_tail - q->cons_tail;
	98
	99	if (entries == 0) {
	100	/* Refresh the local pointer */
	101	q->prod_tail = READ_ONCE(q->ring->producer);
	102	entries = q->prod_tail - q->cons_tail;
	103	}
	104
	105	return (entries > dcnt) ? dcnt : entries;
	106	}
	107
	108	static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
	109	{
20b52a75	110	u32 free_entries = q->nentries - (producer - q->cons_tail);
c497176c BT	111
	112	if (free_entries >= dcnt)
	113	return free_entries;
	114
	115	/* Refresh the local tail pointer */
	116	q->cons_tail = READ_ONCE(q->ring->consumer);
	117	return q->nentries - (producer - q->cons_tail);
	118	}
	119
d57d7642 MM	120	static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
	121	{
	122	u32 entries = q->prod_tail - q->cons_tail;
	123
	124	if (entries >= cnt)
	125	return true;
	126
	127	/* Refresh the local pointer. */
	128	q->prod_tail = READ_ONCE(q->ring->producer);
	129	entries = q->prod_tail - q->cons_tail;
	130
	131	return entries >= cnt;
	132	}
	133
c497176c BT	134	/* UMEM queue */
c497176c BT	135
bbff2f32	136	static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
c497176c	137	{
93ee30f3	138	if (addr >= q->size) {
c497176c BT	139	q->invalid_descs++;
	140	return false;
	141	}
bbff2f32	142
c497176c BT	143	return true;
	144	}
	145
bbff2f32	146	static inline u64 xskq_validate_addr(struct xsk_queue q, u64 *addr)
c497176c BT	147	{
	148	while (q->cons_tail != q->cons_head) {
	149	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;
	150	unsigned int idx = q->cons_tail & q->ring_mask;
	151
93ee30f3	152	*addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
bbff2f32 BT	153	if (xskq_is_valid_addr(q, *addr))
bbff2f32 BT	154	return addr;
c497176c BT	155
	156	q->cons_tail++;
	157	}
	158
	159	return NULL;
	160	}
	161
bbff2f32	162	static inline u64 xskq_peek_addr(struct xsk_queue q, u64 *addr)
c497176c	163	{
c497176c	164	if (q->cons_tail == q->cons_head) {
f63666de	165	smp_mb(); /* D, matches A */
c497176c BT	166	WRITE_ONCE(q->ring->consumer, q->cons_tail);
	167	q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
	168
	169	/* Order consumer and data */
	170	smp_rmb();
c497176c BT	171	}
c497176c BT	172
bbff2f32	173	return xskq_validate_addr(q, addr);
c497176c BT	174	}
c497176c BT	175
bbff2f32	176	static inline void xskq_discard_addr(struct xsk_queue *q)
c497176c BT	177	{
c497176c BT	178	q->cons_tail++;
c497176c BT	179	}
c497176c BT	180
bbff2f32	181	static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
35fcde7f MK	182	{
	183	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;
	184
20b52a75	185	if (xskq_nb_free(q, q->prod_tail, 1) == 0)
ac98d8aa MK	186	return -ENOSPC;
ac98d8aa MK	187
f63666de	188	/* A, matches D */
bbff2f32	189	ring->desc[q->prod_tail++ & q->ring_mask] = addr;
35fcde7f MK	190
35fcde7f MK	191	/* Order producer and data */
f63666de	192	smp_wmb(); /* B, matches C */
35fcde7f MK	193
	194	WRITE_ONCE(q->ring->producer, q->prod_tail);
	195	return 0;
	196	}
	197
ac98d8aa MK	198	static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
	199	{
	200	struct xdp_umem_ring ring = (struct xdp_umem_ring )q->ring;
	201
	202	if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
	203	return -ENOSPC;
	204
f63666de	205	/* A, matches D */
ac98d8aa MK	206	ring->desc[q->prod_head++ & q->ring_mask] = addr;
	207	return 0;
	208	}
	209
	210	static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
	211	u32 nb_entries)
	212	{
	213	/* Order producer and data */
f63666de	214	smp_wmb(); /* B, matches C */
ac98d8aa MK	215
	216	q->prod_tail += nb_entries;
	217	WRITE_ONCE(q->ring->producer, q->prod_tail);
	218	}
	219
bbff2f32	220	static inline int xskq_reserve_addr(struct xsk_queue *q)
35fcde7f MK	221	{
	222	if (xskq_nb_free(q, q->prod_head, 1) == 0)
	223	return -ENOSPC;
	224
f63666de	225	/* A, matches D */
35fcde7f MK	226	q->prod_head++;
	227	return 0;
	228	}
	229
	230	/* Rx/Tx queue */
	231
	232	static inline bool xskq_is_valid_desc(struct xsk_queue q, struct xdp_desc d)
	233	{
bbff2f32	234	if (!xskq_is_valid_addr(q, d->addr))
35fcde7f	235	return false;
35fcde7f	236
c57b557b BT	237	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) \|\|
c57b557b BT	238	d->options) {
35fcde7f MK	239	q->invalid_descs++;
	240	return false;
	241	}
	242
	243	return true;
	244	}
	245
	246	static inline struct xdp_desc xskq_validate_desc(struct xsk_queue q,
	247	struct xdp_desc *desc)
	248	{
	249	while (q->cons_tail != q->cons_head) {
	250	struct xdp_rxtx_ring ring = (struct xdp_rxtx_ring )q->ring;
	251	unsigned int idx = q->cons_tail & q->ring_mask;
	252
4e64c835 BT	253	*desc = READ_ONCE(ring->desc[idx]);
4e64c835 BT	254	if (xskq_is_valid_desc(q, desc))
35fcde7f	255	return desc;
35fcde7f MK	256
	257	q->cons_tail++;
	258	}
	259
	260	return NULL;
	261	}
	262
	263	static inline struct xdp_desc xskq_peek_desc(struct xsk_queue q,
	264	struct xdp_desc *desc)
	265	{
35fcde7f	266	if (q->cons_tail == q->cons_head) {
f63666de	267	smp_mb(); /* D, matches A */
35fcde7f MK	268	WRITE_ONCE(q->ring->consumer, q->cons_tail);
	269	q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
	270
	271	/* Order consumer and data */
f63666de	272	smp_rmb(); /* C, matches B */
35fcde7f MK	273	}
35fcde7f MK	274
4e64c835	275	return xskq_validate_desc(q, desc);
35fcde7f MK	276	}
	277
	278	static inline void xskq_discard_desc(struct xsk_queue *q)
	279	{
	280	q->cons_tail++;
35fcde7f	281	}
c497176c BT	282
c497176c BT	283	static inline int xskq_produce_batch_desc(struct xsk_queue *q,
bbff2f32	284	u64 addr, u32 len)
c497176c BT	285	{
	286	struct xdp_rxtx_ring ring = (struct xdp_rxtx_ring )q->ring;
	287	unsigned int idx;
	288
	289	if (xskq_nb_free(q, q->prod_head, 1) == 0)
	290	return -ENOSPC;
	291
f63666de	292	/* A, matches D */
c497176c	293	idx = (q->prod_head++) & q->ring_mask;
bbff2f32	294	ring->desc[idx].addr = addr;
c497176c	295	ring->desc[idx].len = len;
c497176c BT	296
	297	return 0;
	298	}
	299
	300	static inline void xskq_produce_flush_desc(struct xsk_queue *q)
	301	{
	302	/* Order producer and data */
f63666de	303	smp_wmb(); /* B, matches C */
c497176c	304
f7019b7b	305	q->prod_tail = q->prod_head;
c497176c BT	306	WRITE_ONCE(q->ring->producer, q->prod_tail);
	307	}
	308
35fcde7f MK	309	static inline bool xskq_full_desc(struct xsk_queue *q)
35fcde7f MK	310	{
da60cf00	311	return xskq_nb_avail(q, q->nentries) == q->nentries;
35fcde7f MK	312	}
35fcde7f MK	313
c497176c BT	314	static inline bool xskq_empty_desc(struct xsk_queue *q)
c497176c BT	315	{
d24458e4	316	return xskq_nb_free(q, q->prod_tail, q->nentries) == q->nentries;
c497176c BT	317	}
c497176c BT	318
93ee30f3	319	void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);
b9b6b68e	320	struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
c497176c	321	void xskq_destroy(struct xsk_queue *q_ops);
423f3832	322
f5bd9138 JK	323	/* Executed by the core when the entire UMEM gets freed */
	324	void xsk_reuseq_destroy(struct xdp_umem *umem);
	325
423f3832	326	#endif /* _LINUX_XSK_QUEUE_H */