xref: /spdk/lib/vhost/vhost_internal.h (revision 838e61c3772fdefb17e1a0b8f9880e2bcb9c4c0d)
1 /*   SPDX-License-Identifier: BSD-3-Clause
2  *   Copyright (C) 2017 Intel Corporation.
3  *   All rights reserved.
4  */
5 
6 #ifndef SPDK_VHOST_INTERNAL_H
7 #define SPDK_VHOST_INTERNAL_H
8 #include <linux/virtio_config.h>
9 
10 #include "spdk/stdinc.h"
11 
12 #include <rte_vhost.h>
13 
14 #include "spdk_internal/vhost_user.h"
15 #include "spdk/bdev.h"
16 #include "spdk/log.h"
17 #include "spdk/util.h"
18 #include "spdk/rpc.h"
19 #include "spdk/config.h"
20 
21 #define SPDK_VHOST_MAX_VQUEUES	256
22 #define SPDK_VHOST_MAX_VQ_SIZE	1024
23 
24 #define SPDK_VHOST_SCSI_CTRLR_MAX_DEVS 8
25 
26 #define SPDK_VHOST_IOVS_MAX 129
27 
28 #define SPDK_VHOST_VQ_MAX_SUBMISSIONS	32
29 
30 /*
31  * Rate at which stats are checked for interrupt coalescing.
32  */
33 #define SPDK_VHOST_STATS_CHECK_INTERVAL_MS 10
34 /*
35  * Default threshold at which interrupts start to be coalesced.
36  */
37 #define SPDK_VHOST_VQ_IOPS_COALESCING_THRESHOLD 60000
38 
39 /*
40  * Currently coalescing is not used by default.
41  * Setting this to value > 0 here or by RPC will enable coalescing.
42  */
43 #define SPDK_VHOST_COALESCING_DELAY_BASE_US 0
44 
45 #define SPDK_VHOST_FEATURES ((1ULL << VHOST_F_LOG_ALL) | \
46 	(1ULL << VHOST_USER_F_PROTOCOL_FEATURES) | \
47 	(1ULL << VIRTIO_F_VERSION_1) | \
48 	(1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | \
49 	(1ULL << VIRTIO_RING_F_EVENT_IDX) | \
50 	(1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \
51 	(1ULL << VIRTIO_F_RING_PACKED) | \
52 	(1ULL << VIRTIO_F_ANY_LAYOUT))
53 
54 #define SPDK_VHOST_DISABLED_FEATURES ((1ULL << VIRTIO_RING_F_EVENT_IDX) | \
55 	(1ULL << VIRTIO_F_NOTIFY_ON_EMPTY))
56 
57 #define VRING_DESC_F_AVAIL	(1ULL << VRING_PACKED_DESC_F_AVAIL)
58 #define VRING_DESC_F_USED	(1ULL << VRING_PACKED_DESC_F_USED)
59 #define VRING_DESC_F_AVAIL_USED	(VRING_DESC_F_AVAIL | VRING_DESC_F_USED)
60 
61 typedef struct rte_vhost_resubmit_desc spdk_vhost_resubmit_desc;
62 typedef struct rte_vhost_resubmit_info spdk_vhost_resubmit_info;
63 typedef struct rte_vhost_inflight_desc_packed	spdk_vhost_inflight_desc;
64 
65 struct spdk_vhost_virtqueue {
66 	struct rte_vhost_vring vring;
67 	struct rte_vhost_ring_inflight vring_inflight;
68 	uint16_t last_avail_idx;
69 	uint16_t last_used_idx;
70 
71 	struct {
72 		/* To mark a descriptor as available in packed ring
73 		 * Equal to avail_wrap_counter in spec.
74 		 */
75 		uint8_t avail_phase	: 1;
76 		/* To mark a descriptor as used in packed ring
77 		 * Equal to used_wrap_counter in spec.
78 		 */
79 		uint8_t used_phase	: 1;
80 		uint8_t padding		: 5;
81 		bool packed_ring	: 1;
82 	} packed;
83 
84 	void *tasks;
85 
86 	/* Request count from last stats check */
87 	uint32_t req_cnt;
88 
89 	/* Request count from last event */
90 	uint16_t used_req_cnt;
91 
92 	/* How long interrupt is delayed */
93 	uint32_t irq_delay_time;
94 
95 	/* Next time when we need to send event */
96 	uint64_t next_event_time;
97 
98 	/* Associated vhost_virtqueue in the virtio device's virtqueue list */
99 	uint32_t vring_idx;
100 
101 	struct spdk_vhost_session *vsession;
102 
103 	struct spdk_interrupt *intr;
104 } __attribute((aligned(SPDK_CACHE_LINE_SIZE)));
105 
106 struct spdk_vhost_session {
107 	struct spdk_vhost_dev *vdev;
108 
109 	/* rte_vhost connection ID. */
110 	int vid;
111 
112 	/* Unique session ID. */
113 	uint64_t id;
114 	/* Unique session name. */
115 	char *name;
116 
117 	bool started;
118 	bool interrupt_mode;
119 
120 	struct rte_vhost_memory *mem;
121 
122 	int task_cnt;
123 
124 	uint16_t max_queues;
125 
126 	uint64_t negotiated_features;
127 
128 	/* Local copy of device coalescing settings. */
129 	uint32_t coalescing_delay_time_base;
130 	uint32_t coalescing_io_rate_threshold;
131 
132 	/* Next time when stats for event coalescing will be checked. */
133 	uint64_t next_stats_check_time;
134 
135 	/* Interval used for event coalescing checking. */
136 	uint64_t stats_check_interval;
137 
138 	/* Session's stop poller will only try limited times to destroy the session. */
139 	uint32_t stop_retry_count;
140 
141 	struct spdk_vhost_virtqueue virtqueue[SPDK_VHOST_MAX_VQUEUES];
142 
143 	TAILQ_ENTRY(spdk_vhost_session) tailq;
144 };
145 
146 struct spdk_vhost_user_dev {
147 	struct spdk_vhost_dev *vdev;
148 
149 	const struct spdk_vhost_user_dev_backend *user_backend;
150 
151 	/* Saved original values used to setup coalescing to avoid integer
152 	 * rounding issues during save/load config.
153 	 */
154 	uint32_t coalescing_delay_us;
155 	uint32_t coalescing_iops_threshold;
156 
157 	bool registered;
158 
159 	/* Use this lock to protect multiple sessions. */
160 	pthread_mutex_t lock;
161 
162 	/* Current connections to the device */
163 	TAILQ_HEAD(, spdk_vhost_session) vsessions;
164 
165 	/* Increment-only session counter */
166 	uint64_t vsessions_num;
167 
168 	/* Number of pending asynchronous operations */
169 	uint32_t pending_async_op_num;
170 };
171 
172 struct spdk_vhost_dev {
173 	char *name;
174 	char *path;
175 
176 	struct spdk_thread *thread;
177 
178 	uint64_t virtio_features;
179 	uint64_t disabled_features;
180 	uint64_t protocol_features;
181 	bool packed_ring_recovery;
182 
183 	const struct spdk_vhost_dev_backend *backend;
184 
185 	/* Context passed from transport */
186 	void *ctxt;
187 
188 	TAILQ_ENTRY(spdk_vhost_dev) tailq;
189 };
190 
191 static inline struct spdk_vhost_user_dev *
192 to_user_dev(struct spdk_vhost_dev *vdev)
193 {
194 	assert(vdev != NULL);
195 	return vdev->ctxt;
196 }
197 
198 /**
199  * \param vdev vhost device.
200  * \param vsession vhost session.
201  * \param arg user-provided parameter.
202  *
203  * \return negative values will break the foreach call, meaning
204  * the function won't be called again. Return codes zero and
205  * positive don't have any effect.
206  */
207 typedef int (*spdk_vhost_session_fn)(struct spdk_vhost_dev *vdev,
208 				     struct spdk_vhost_session *vsession,
209 				     void *arg);
210 
211 /**
212  * \param vdev vhost device.
213  * \param arg user-provided parameter.
214  */
215 typedef void (*spdk_vhost_dev_fn)(struct spdk_vhost_dev *vdev, void *arg);
216 
217 struct spdk_vhost_user_dev_backend {
218 	/**
219 	 * Size of additional per-session context data
220 	 * allocated whenever a new client connects.
221 	 */
222 	size_t session_ctx_size;
223 
224 	spdk_vhost_session_fn start_session;
225 	spdk_vhost_session_fn stop_session;
226 	int (*alloc_vq_tasks)(struct spdk_vhost_session *vsession, uint16_t qid);
227 	void (*register_vq_interrupt)(struct spdk_vhost_session *vsession, struct spdk_vhost_virtqueue *vq);
228 };
229 
230 enum vhost_backend_type {
231 	VHOST_BACKEND_BLK = 0,
232 	VHOST_BACKEND_SCSI,
233 };
234 
235 struct spdk_vhost_dev_backend {
236 	enum vhost_backend_type type;
237 
238 	int (*vhost_get_config)(struct spdk_vhost_dev *vdev, uint8_t *config, uint32_t len);
239 	int (*vhost_set_config)(struct spdk_vhost_dev *vdev, uint8_t *config,
240 				uint32_t offset, uint32_t size, uint32_t flags);
241 
242 	void (*dump_info_json)(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w);
243 	void (*write_config_json)(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w);
244 	int (*remove_device)(struct spdk_vhost_dev *vdev);
245 	int (*set_coalescing)(struct spdk_vhost_dev *vdev, uint32_t delay_base_us,
246 			      uint32_t iops_threshold);
247 	void (*get_coalescing)(struct spdk_vhost_dev *vdev, uint32_t *delay_base_us,
248 			       uint32_t *iops_threshold);
249 };
250 
251 void *vhost_gpa_to_vva(struct spdk_vhost_session *vsession, uint64_t addr, uint64_t len);
252 
253 uint16_t vhost_vq_avail_ring_get(struct spdk_vhost_virtqueue *vq, uint16_t *reqs,
254 				 uint16_t reqs_len);
255 
256 /**
257  * Get a virtio split descriptor at given index in given virtqueue.
258  * The descriptor will provide access to the entire descriptor
259  * chain. The subsequent descriptors are accessible via
260  * \c spdk_vhost_vring_desc_get_next.
261  * \param vsession vhost session
262  * \param vq virtqueue
263  * \param req_idx descriptor index
264  * \param desc pointer to be set to the descriptor
265  * \param desc_table descriptor table to be used with
266  * \c spdk_vhost_vring_desc_get_next. This might be either
267  * default virtqueue descriptor table or per-chain indirect
268  * table.
269  * \param desc_table_size size of the *desc_table*
270  * \return 0 on success, -1 if given index is invalid.
271  * If -1 is returned, the content of params is undefined.
272  */
273 int vhost_vq_get_desc(struct spdk_vhost_session *vsession, struct spdk_vhost_virtqueue *vq,
274 		      uint16_t req_idx, struct vring_desc **desc, struct vring_desc **desc_table,
275 		      uint32_t *desc_table_size);
276 
277 /**
278  * Get a virtio packed descriptor at given index in given virtqueue.
279  * The descriptor will provide access to the entire descriptor
280  * chain. The subsequent descriptors are accessible via
281  * \c vhost_vring_packed_desc_get_next.
282  * \param vsession vhost session
283  * \param vq virtqueue
284  * \param req_idx descriptor index
285  * \param desc pointer to be set to the descriptor
286  * \param desc_table descriptor table to be used with
287  * \c spdk_vhost_vring_desc_get_next. This might be either
288  * \c NULL or per-chain indirect table.
289  * \param desc_table_size size of the *desc_table*
290  * \return 0 on success, -1 if given index is invalid.
291  * If -1 is returned, the content of params is undefined.
292  */
293 int vhost_vq_get_desc_packed(struct spdk_vhost_session *vsession,
294 			     struct spdk_vhost_virtqueue *virtqueue,
295 			     uint16_t req_idx, struct vring_packed_desc **desc,
296 			     struct vring_packed_desc **desc_table, uint32_t *desc_table_size);
297 
298 int vhost_inflight_queue_get_desc(struct spdk_vhost_session *vsession,
299 				  spdk_vhost_inflight_desc *desc_array,
300 				  uint16_t req_idx, spdk_vhost_inflight_desc **desc,
301 				  struct vring_packed_desc  **desc_table, uint32_t *desc_table_size);
302 
303 /**
304  * Send IRQ/call client (if pending) for \c vq.
305  * \param vsession vhost session
306  * \param vq virtqueue
307  * \return
308  *   0 - if no interrupt was signalled
309  *   1 - if interrupt was signalled
310  */
311 int vhost_vq_used_signal(struct spdk_vhost_session *vsession, struct spdk_vhost_virtqueue *vq);
312 
313 /**
314  * Send IRQs for the queue that need to be signaled.
315  * \param vq virtqueue
316  */
317 void vhost_session_vq_used_signal(struct spdk_vhost_virtqueue *virtqueue);
318 
319 void vhost_vq_used_ring_enqueue(struct spdk_vhost_session *vsession,
320 				struct spdk_vhost_virtqueue *vq,
321 				uint16_t id, uint32_t len);
322 
323 /**
324  * Enqueue the entry to the used ring when device complete the request.
325  * \param vsession vhost session
326  * \param vq virtqueue
327  * \req_idx descriptor index. It's the first index of this descriptor chain.
328  * \num_descs descriptor count. It's the count of the number of buffers in the chain.
329  * \buffer_id descriptor buffer ID.
330  * \length device write length. Specify the length of the buffer that has been initialized
331  * (written to) by the device
332  * \inflight_head the head idx of this IO inflight desc chain.
333  */
334 void vhost_vq_packed_ring_enqueue(struct spdk_vhost_session *vsession,
335 				  struct spdk_vhost_virtqueue *virtqueue,
336 				  uint16_t num_descs, uint16_t buffer_id,
337 				  uint32_t length, uint16_t inflight_head);
338 
339 /**
340  * Get subsequent descriptor from given table.
341  * \param desc current descriptor, will be set to the
342  * next descriptor (NULL in case this is the last
343  * descriptor in the chain or the next desc is invalid)
344  * \param desc_table descriptor table
345  * \param desc_table_size size of the *desc_table*
346  * \return 0 on success, -1 if given index is invalid
347  * The *desc* param will be set regardless of the
348  * return value.
349  */
350 int vhost_vring_desc_get_next(struct vring_desc **desc,
351 			      struct vring_desc *desc_table, uint32_t desc_table_size);
352 static inline bool
353 vhost_vring_desc_is_wr(struct vring_desc *cur_desc)
354 {
355 	return !!(cur_desc->flags & VRING_DESC_F_WRITE);
356 }
357 
358 int vhost_vring_desc_to_iov(struct spdk_vhost_session *vsession, struct iovec *iov,
359 			    uint16_t *iov_index, const struct vring_desc *desc);
360 
361 bool vhost_vq_packed_ring_is_avail(struct spdk_vhost_virtqueue *virtqueue);
362 
363 /**
364  * Get subsequent descriptor from vq or desc table.
365  * \param desc current descriptor, will be set to the
366  * next descriptor (NULL in case this is the last
367  * descriptor in the chain or the next desc is invalid)
368  * \req_idx index of current desc, will be set to the next
369  * index. If desc_table != NULL the req_idx is the the vring index
370  * or the req_idx is the desc_table index.
371  * \param desc_table descriptor table
372  * \param desc_table_size size of the *desc_table*
373  * \return 0 on success, -1 if given index is invalid
374  * The *desc* param will be set regardless of the
375  * return value.
376  */
377 int vhost_vring_packed_desc_get_next(struct vring_packed_desc **desc, uint16_t *req_idx,
378 				     struct spdk_vhost_virtqueue *vq,
379 				     struct vring_packed_desc *desc_table,
380 				     uint32_t desc_table_size);
381 
382 bool vhost_vring_packed_desc_is_wr(struct vring_packed_desc *cur_desc);
383 
384 int vhost_vring_packed_desc_to_iov(struct spdk_vhost_session *vsession, struct iovec *iov,
385 				   uint16_t *iov_index, const struct vring_packed_desc *desc);
386 
387 bool vhost_vring_inflight_desc_is_wr(spdk_vhost_inflight_desc *cur_desc);
388 
389 int vhost_vring_inflight_desc_to_iov(struct spdk_vhost_session *vsession, struct iovec *iov,
390 				     uint16_t *iov_index, const spdk_vhost_inflight_desc *desc);
391 
392 uint16_t vhost_vring_packed_desc_get_buffer_id(struct spdk_vhost_virtqueue *vq, uint16_t req_idx,
393 		uint16_t *num_descs);
394 
395 static inline bool
396 __attribute__((always_inline))
397 vhost_dev_has_feature(struct spdk_vhost_session *vsession, unsigned feature_id)
398 {
399 	return vsession->negotiated_features & (1ULL << feature_id);
400 }
401 
402 int vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const char *mask_str,
403 		       const struct spdk_json_val *params,
404 		       const struct spdk_vhost_dev_backend *backend,
405 		       const struct spdk_vhost_user_dev_backend *user_backend);
406 int vhost_dev_unregister(struct spdk_vhost_dev *vdev);
407 
408 void vhost_dump_info_json(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w);
409 
410 /*
411  * Set vhost session to run in interrupt or poll mode
412  */
413 void vhost_user_session_set_interrupt_mode(struct spdk_vhost_session *vsession,
414 		bool interrupt_mode);
415 
416 /*
417  * Memory registration functions used in start/stop device callbacks
418  */
419 void vhost_session_mem_register(struct rte_vhost_memory *mem);
420 void vhost_session_mem_unregister(struct rte_vhost_memory *mem);
421 
422 /*
423  * Call a function for each session of the provided vhost device.
424  * The function will be called one-by-one on each session's thread.
425  *
426  * \param vdev vhost device
427  * \param fn function to call on each session's thread
428  * \param cpl_fn function to be called at the end of the iteration on
429  * the vhost management thread.
430  * Optional, can be NULL.
431  * \param arg additional argument to the both callbacks
432  */
433 void vhost_user_dev_foreach_session(struct spdk_vhost_dev *dev,
434 				    spdk_vhost_session_fn fn,
435 				    spdk_vhost_dev_fn cpl_fn,
436 				    void *arg);
437 
438 /**
439  * Finish a blocking vhost_user_wait_for_session_stop() call and finally
440  * stop the session. This must be called on the session's lcore which
441  * used to receive all session-related messages (e.g. from
442  * vhost_user_dev_foreach_session()). After this call, the session-
443  * related messages will be once again processed by any arbitrary thread.
444  *
445  * Must be called under the vhost user device's session access lock.
446  *
447  * \param vsession vhost session
448  * \param response return code
449  */
450 void vhost_user_session_stop_done(struct spdk_vhost_session *vsession, int response);
451 
452 struct spdk_vhost_session *vhost_session_find_by_vid(int vid);
453 void vhost_session_install_rte_compat_hooks(struct spdk_vhost_session *vsession);
454 int vhost_register_unix_socket(const char *path, const char *ctrl_name,
455 			       uint64_t virtio_features, uint64_t disabled_features, uint64_t protocol_features);
456 int vhost_driver_unregister(const char *path);
457 int vhost_get_mem_table(int vid, struct rte_vhost_memory **mem);
458 int vhost_get_negotiated_features(int vid, uint64_t *negotiated_features);
459 
460 int remove_vhost_controller(struct spdk_vhost_dev *vdev);
461 
462 struct spdk_io_channel *vhost_blk_get_io_channel(struct spdk_vhost_dev *vdev);
463 void vhost_blk_put_io_channel(struct spdk_io_channel *ch);
464 
465 /* The spdk_bdev pointer should only be used to retrieve
466  * the device properties, ex. number of blocks or I/O type supported. */
467 struct spdk_bdev *vhost_blk_get_bdev(struct spdk_vhost_dev *vdev);
468 
469 /* Function calls from vhost.c to rte_vhost_user.c,
470  * shall removed once virtio transport abstraction is complete. */
471 int vhost_user_session_set_coalescing(struct spdk_vhost_dev *dev,
472 				      struct spdk_vhost_session *vsession, void *ctx);
473 int vhost_user_dev_set_coalescing(struct spdk_vhost_user_dev *user_dev, uint32_t delay_base_us,
474 				  uint32_t iops_threshold);
475 int vhost_user_dev_register(struct spdk_vhost_dev *vdev, const char *name,
476 			    struct spdk_cpuset *cpumask, const struct spdk_vhost_user_dev_backend *user_backend);
477 int vhost_user_dev_unregister(struct spdk_vhost_dev *vdev);
478 int vhost_user_init(void);
479 void vhost_user_fini(spdk_vhost_fini_cb vhost_cb);
480 int vhost_user_set_coalescing(struct spdk_vhost_dev *vdev, uint32_t delay_base_us,
481 			      uint32_t iops_threshold);
482 void vhost_user_get_coalescing(struct spdk_vhost_dev *vdev, uint32_t *delay_base_us,
483 			       uint32_t *iops_threshold);
484 
485 int virtio_blk_construct_ctrlr(struct spdk_vhost_dev *vdev, const char *address,
486 			       struct spdk_cpuset *cpumask, const struct spdk_json_val *params,
487 			       const struct spdk_vhost_user_dev_backend *user_backend);
488 int virtio_blk_destroy_ctrlr(struct spdk_vhost_dev *vdev);
489 
490 struct spdk_vhost_blk_task;
491 
492 typedef void (*virtio_blk_request_cb)(uint8_t status, struct spdk_vhost_blk_task *task,
493 				      void *cb_arg);
494 
495 struct spdk_vhost_blk_task {
496 	struct spdk_bdev_io *bdev_io;
497 	virtio_blk_request_cb cb;
498 	void *cb_arg;
499 
500 	volatile uint8_t *status;
501 
502 	/* for io wait */
503 	struct spdk_bdev_io_wait_entry bdev_io_wait;
504 	struct spdk_io_channel *bdev_io_wait_ch;
505 	struct spdk_vhost_dev *bdev_io_wait_vdev;
506 
507 	/** Number of bytes that were written. */
508 	uint32_t used_len;
509 	uint16_t iovcnt;
510 	struct iovec iovs[SPDK_VHOST_IOVS_MAX];
511 
512 	/** Size of whole payload in bytes */
513 	uint32_t payload_size;
514 };
515 
516 int virtio_blk_process_request(struct spdk_vhost_dev *vdev, struct spdk_io_channel *ch,
517 			       struct spdk_vhost_blk_task *task, virtio_blk_request_cb cb, void *cb_arg);
518 
519 typedef void (*bdev_event_cb_complete)(struct spdk_vhost_dev *vdev, void *ctx);
520 
521 #define SPDK_VIRTIO_BLK_TRSTRING_MAX_LEN 32
522 
523 struct spdk_virtio_blk_transport_ops {
524 	/**
525 	 * Transport name
526 	 */
527 	char name[SPDK_VIRTIO_BLK_TRSTRING_MAX_LEN];
528 
529 	/**
530 	 * Create a transport for the given transport opts
531 	 */
532 	struct spdk_virtio_blk_transport *(*create)(const struct spdk_json_val *params);
533 
534 	/**
535 	 * Dump transport-specific opts into JSON
536 	 */
537 	void (*dump_opts)(struct spdk_virtio_blk_transport *transport, struct spdk_json_write_ctx *w);
538 
539 	/**
540 	 * Destroy the transport
541 	 */
542 	int (*destroy)(struct spdk_virtio_blk_transport *transport,
543 		       spdk_vhost_fini_cb cb_fn);
544 
545 	/**
546 	 * Create vhost block controller
547 	 */
548 	int (*create_ctrlr)(struct spdk_vhost_dev *vdev, struct spdk_cpuset *cpumask,
549 			    const char *address, const struct spdk_json_val *params,
550 			    void *custom_opts);
551 
552 	/**
553 	 * Destroy vhost block controller
554 	 */
555 	int (*destroy_ctrlr)(struct spdk_vhost_dev *vdev);
556 
557 	/*
558 	 * Signal removal of the bdev.
559 	 */
560 	void (*bdev_event)(enum spdk_bdev_event_type type, struct spdk_vhost_dev *vdev,
561 			   bdev_event_cb_complete cb, void *cb_arg);
562 
563 	/**
564 	 * Set coalescing parameters.
565 	 */
566 	int (*set_coalescing)(struct spdk_vhost_dev *vdev, uint32_t delay_base_us,
567 			      uint32_t iops_threshold);
568 
569 	/**
570 	 * Get coalescing parameters.
571 	 */
572 	void (*get_coalescing)(struct spdk_vhost_dev *vdev, uint32_t *delay_base_us,
573 			       uint32_t *iops_threshold);
574 };
575 
576 struct spdk_virtio_blk_transport {
577 	const struct spdk_virtio_blk_transport_ops	*ops;
578 	TAILQ_ENTRY(spdk_virtio_blk_transport)		tailq;
579 };
580 
581 struct virtio_blk_transport_ops_list_element {
582 	struct spdk_virtio_blk_transport_ops			ops;
583 	TAILQ_ENTRY(virtio_blk_transport_ops_list_element)	link;
584 };
585 
586 void virtio_blk_transport_register(const struct spdk_virtio_blk_transport_ops *ops);
587 int virtio_blk_transport_create(const char *transport_name, const struct spdk_json_val *params);
588 int virtio_blk_transport_destroy(struct spdk_virtio_blk_transport *transport,
589 				 spdk_vhost_fini_cb cb_fn);
590 struct spdk_virtio_blk_transport *virtio_blk_transport_get_first(void);
591 struct spdk_virtio_blk_transport *virtio_blk_transport_get_next(
592 	struct spdk_virtio_blk_transport *transport);
593 void virtio_blk_transport_dump_opts(struct spdk_virtio_blk_transport *transport,
594 				    struct spdk_json_write_ctx *w);
595 struct spdk_virtio_blk_transport *virtio_blk_tgt_get_transport(const char *transport_name);
596 const struct spdk_virtio_blk_transport_ops *virtio_blk_get_transport_ops(
597 	const char *transport_name);
598 
599 void vhost_session_info_json(struct spdk_vhost_dev *vdev, struct spdk_json_write_ctx *w);
600 
601 /*
602  * Macro used to register new transports.
603  */
604 #define SPDK_VIRTIO_BLK_TRANSPORT_REGISTER(name, transport_ops) \
605 static void __attribute__((constructor)) _virtio_blk_transport_register_##name(void) \
606 { \
607 	virtio_blk_transport_register(transport_ops); \
608 }
609 
610 #endif /* SPDK_VHOST_INTERNAL_H */
611