vhost.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _VHOST_H
  3#define _VHOST_H
  4
  5#include <linux/eventfd.h>
  6#include <linux/vhost.h>
  7#include <linux/mm.h>
  8#include <linux/mutex.h>
  9#include <linux/poll.h>
 10#include <linux/file.h>
 11#include <linux/uio.h>
 12#include <linux/virtio_config.h>
 13#include <linux/virtio_ring.h>
 14#include <linux/atomic.h>
 15#include <linux/vhost_iotlb.h>
 16#include <linux/irqbypass.h>
 17#include <linux/unroll.h>
 18
 19struct vhost_work;
 20struct vhost_task;
 21typedef void (*vhost_work_fn_t)(struct vhost_work *work);
 22
 23#define VHOST_WORK_QUEUED 1
 24struct vhost_work {
 25	struct llist_node	node;
 26	vhost_work_fn_t		fn;
 27	unsigned long		flags;
 28};
 29
 30struct vhost_worker;
 31struct vhost_dev;
 32
 33struct vhost_worker_ops {
 34	int (*create)(struct vhost_worker *worker, struct vhost_dev *dev,
 35		      const char *name);
 36	void (*stop)(struct vhost_worker *worker);
 37	void (*wakeup)(struct vhost_worker *worker);
 38};
 39
 40struct vhost_worker {
 41	struct task_struct *kthread_task;
 42	struct vhost_task	*vtsk;
 43	struct vhost_dev	*dev;
 44	/* Used to serialize device wide flushing with worker swapping. */
 45	struct mutex		mutex;
 46	struct llist_head	work_list;
 47	u64			kcov_handle;
 48	u32			id;
 49	int			attachment_cnt;
 50	bool			killed;
 51	const struct vhost_worker_ops *ops;
 52};
 53
 54/* Poll a file (eventfd or socket) */
 55/* Note: there's nothing vhost specific about this structure. */
 56struct vhost_poll {
 57	poll_table		table;
 58	wait_queue_head_t	*wqh;
 59	wait_queue_entry_t	wait;
 60	struct vhost_work	work;
 61	__poll_t		mask;
 62	struct vhost_dev	*dev;
 63	struct vhost_virtqueue	*vq;
 64};
 65
 66void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 67		     __poll_t mask, struct vhost_dev *dev,
 68		     struct vhost_virtqueue *vq);
 69int vhost_poll_start(struct vhost_poll *poll, struct file *file);
 70void vhost_poll_stop(struct vhost_poll *poll);
 71void vhost_poll_queue(struct vhost_poll *poll);
 72
 73void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
 74void vhost_dev_flush(struct vhost_dev *dev);
 75
 76struct vhost_log {
 77	u64 addr;
 78	u64 len;
 79};
 80
 81enum vhost_uaddr_type {
 82	VHOST_ADDR_DESC = 0,
 83	VHOST_ADDR_AVAIL = 1,
 84	VHOST_ADDR_USED = 2,
 85	VHOST_NUM_ADDRS = 3,
 86};
 87
 88struct vhost_vring_call {
 89	struct eventfd_ctx *ctx;
 90	struct irq_bypass_producer producer;
 91};
 92
 93/* The virtqueue structure describes a queue attached to a device. */
 94struct vhost_virtqueue {
 95	struct vhost_dev *dev;
 96	struct vhost_worker __rcu *worker;
 97
 98	/* The actual ring of buffers. */
 99	struct mutex mutex;
100	unsigned int num;
101	vring_desc_t __user *desc;
102	vring_avail_t __user *avail;
103	vring_used_t __user *used;
104	const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS];
105	struct file *kick;
106	struct vhost_vring_call call_ctx;
107	struct eventfd_ctx *error_ctx;
108	struct eventfd_ctx *log_ctx;
109
110	struct vhost_poll poll;
111
112	/* The routine to call when the Guest pings us, or timeout. */
113	vhost_work_fn_t handle_kick;
114
115	/* Last available index we saw.
116	 * Values are limited to 0x7fff, and the high bit is used as
117	 * a wrap counter when using VIRTIO_F_RING_PACKED. */
118	u16 last_avail_idx;
119	/* Next avail ring head when VIRTIO_F_IN_ORDER is negoitated */
120	u16 next_avail_head;
121
122	/* Caches available index value from user. */
123	u16 avail_idx;
124
125	/* Last index we used.
126	 * Values are limited to 0x7fff, and the high bit is used as
127	 * a wrap counter when using VIRTIO_F_RING_PACKED. */
128	u16 last_used_idx;
129
130	/* Used flags */
131	u16 used_flags;
132
133	/* Last used index value we have signalled on */
134	u16 signalled_used;
135
136	/* Last used index value we have signalled on */
137	bool signalled_used_valid;
138
139	/* Log writes to used structure. */
140	bool log_used;
141	u64 log_addr;
142
143	struct iovec iov[UIO_MAXIOV];
144	struct iovec iotlb_iov[64];
145	struct iovec *indirect;
146	struct vring_used_elem *heads;
147	u16 *nheads;
148	/* Protected by virtqueue mutex. */
149	struct vhost_iotlb *umem;
150	struct vhost_iotlb *iotlb;
151	void *private_data;
152	VIRTIO_DECLARE_FEATURES(acked_features);
153	u64 acked_backend_features;
154	/* Log write descriptors */
155	void __user *log_base;
156	struct vhost_log *log;
157	struct iovec log_iov[64];
158
159	/* Ring endianness. Defaults to legacy native endianness.
160	 * Set to true when starting a modern virtio device. */
161	bool is_le;
162#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
163	/* Ring endianness requested by userspace for cross-endian support. */
164	bool user_be;
165#endif
166	u32 busyloop_timeout;
167};
168
169struct vhost_msg_node {
170  union {
171	  struct vhost_msg msg;
172	  struct vhost_msg_v2 msg_v2;
173  };
174  struct vhost_virtqueue *vq;
175  struct list_head node;
176};
177
178struct vhost_dev {
179	struct mm_struct *mm;
180	struct mutex mutex;
181	struct vhost_virtqueue **vqs;
182	int nvqs;
183	struct eventfd_ctx *log_ctx;
184	struct vhost_iotlb *umem;
185	struct vhost_iotlb *iotlb;
186	spinlock_t iotlb_lock;
187	struct list_head read_list;
188	struct list_head pending_list;
189	wait_queue_head_t wait;
190	int iov_limit;
191	int weight;
192	int byte_weight;
193	struct xarray worker_xa;
194	bool use_worker;
195	/*
196	 * If fork_owner is true we use vhost_tasks to create
197	 * the worker so all settings/limits like cgroups, NPROC,
198	 * scheduler, etc are inherited from the owner. If false,
199	 * we use kthreads and only attach to the same cgroups
200	 * as the owner for compat with older kernels.
201	 * here we use true as default value.
202	 * The default value is set by fork_from_owner_default
203	 */
204	bool fork_owner;
205	int (*msg_handler)(struct vhost_dev *dev, u32 asid,
206			   struct vhost_iotlb_msg *msg);
207};
208
209bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
210void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
211		    int nvqs, int iov_limit, int weight, int byte_weight,
212		    bool use_worker,
213		    int (*msg_handler)(struct vhost_dev *dev, u32 asid,
214				       struct vhost_iotlb_msg *msg));
215long vhost_dev_set_owner(struct vhost_dev *dev);
216bool vhost_dev_has_owner(struct vhost_dev *dev);
217long vhost_dev_check_owner(struct vhost_dev *);
218struct vhost_iotlb *vhost_dev_reset_owner_prepare(void);
219void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *iotlb);
220void vhost_dev_cleanup(struct vhost_dev *);
221void vhost_dev_stop(struct vhost_dev *);
222long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
223long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp);
224long vhost_worker_ioctl(struct vhost_dev *dev, unsigned int ioctl,
225			void __user *argp);
226bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
227bool vhost_log_access_ok(struct vhost_dev *);
228void vhost_clear_msg(struct vhost_dev *dev);
229
230int vhost_get_vq_desc(struct vhost_virtqueue *,
231		      struct iovec iov[], unsigned int iov_size,
232		      unsigned int *out_num, unsigned int *in_num,
233		      struct vhost_log *log, unsigned int *log_num);
234
235int vhost_get_vq_desc_n(struct vhost_virtqueue *vq,
236			struct iovec iov[], unsigned int iov_size,
237			unsigned int *out_num, unsigned int *in_num,
238			struct vhost_log *log, unsigned int *log_num,
239			unsigned int *ndesc);
240
241void vhost_discard_vq_desc(struct vhost_virtqueue *, int nbuf,
242			   unsigned int ndesc);
243
244bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work);
245bool vhost_vq_has_work(struct vhost_virtqueue *vq);
246bool vhost_vq_is_setup(struct vhost_virtqueue *vq);
247int vhost_vq_init_access(struct vhost_virtqueue *);
248int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
249int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
250		     u16 *nheads, unsigned count);
251void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
252			       unsigned int id, int len);
253void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
254				 struct vring_used_elem *heads, u16 *nheads,
255				 unsigned count);
256void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
257void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
258bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *);
259bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
260
261int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
262		    unsigned int log_num, u64 len,
263		    struct iovec *iov, int count);
264int vq_meta_prefetch(struct vhost_virtqueue *vq);
265
266struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type);
267void vhost_enqueue_msg(struct vhost_dev *dev,
268		       struct list_head *head,
269		       struct vhost_msg_node *node);
270struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
271					 struct list_head *head);
272void vhost_set_backend_features(struct vhost_dev *dev, u64 features);
273
274__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
275			    poll_table *wait);
276ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
277			    int noblock);
278ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
279			     struct iov_iter *from);
280int vhost_init_device_iotlb(struct vhost_dev *d);
281
282void vhost_iotlb_map_free(struct vhost_iotlb *iotlb,
283			  struct vhost_iotlb_map *map);
284
285#define vq_err(vq, fmt, ...) do {                                  \
286		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
287		if ((vq)->error_ctx)                               \
288				eventfd_signal((vq)->error_ctx);\
289	} while (0)
290
291#define VHOST_FEATURES \
292	VIRTIO_F_NOTIFY_ON_EMPTY, \
293	VIRTIO_RING_F_INDIRECT_DESC, \
294	VIRTIO_RING_F_EVENT_IDX, \
295	VHOST_F_LOG_ALL, \
296	VIRTIO_F_ANY_LAYOUT, \
297	VIRTIO_F_VERSION_1
298
299static inline u64 vhost_features_u64(const int *features, int size, int idx)
300{
301	u64 res = 0;
302
303	unrolled_count(VIRTIO_FEATURES_BITS)
304	for (int i = 0; i < size; ++i) {
305		int bit = features[i];
306
307		if (virtio_features_chk_bit(bit) && VIRTIO_U64(bit) == idx)
308			res |= VIRTIO_BIT(bit);
309	}
310	return res;
311}
312
313#define VHOST_FEATURES_U64(features, idx) \
314	vhost_features_u64(features, ARRAY_SIZE(features), idx)
315
316#define DEFINE_VHOST_FEATURES_ARRAY_ENTRY(idx, features) \
317	[idx] = VHOST_FEATURES_U64(features, idx),
318
319#define DEFINE_VHOST_FEATURES_ARRAY(array, features) \
320	u64 array[VIRTIO_FEATURES_U64S] = { \
321		UNROLL(VIRTIO_FEATURES_U64S, \
322		       DEFINE_VHOST_FEATURES_ARRAY_ENTRY, features) \
323	}
324
325/**
326 * vhost_vq_set_backend - Set backend.
327 *
328 * @vq            Virtqueue.
329 * @private_data  The private data.
330 *
331 * Context: Need to call with vq->mutex acquired.
332 */
333static inline void vhost_vq_set_backend(struct vhost_virtqueue *vq,
334					void *private_data)
335{
336	vq->private_data = private_data;
337}
338
339/**
340 * vhost_vq_get_backend - Get backend.
341 *
342 * @vq            Virtqueue.
343 *
344 * Context: Need to call with vq->mutex acquired.
345 * Return: Private data previously set with vhost_vq_set_backend.
346 */
347static inline void *vhost_vq_get_backend(struct vhost_virtqueue *vq)
348{
349	return vq->private_data;
350}
351
352static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
353{
354	return virtio_features_test_bit(vq->acked_features_array, bit);
355}
356
357static inline bool vhost_backend_has_feature(struct vhost_virtqueue *vq, int bit)
358{
359	return vq->acked_backend_features & (1ULL << bit);
360}
361
362#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
363static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
364{
365	return vq->is_le;
366}
367#else
368static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
369{
370	return virtio_legacy_is_little_endian() || vq->is_le;
371}
372#endif
373
374/* Memory accessors */
375static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val)
376{
377	return __virtio16_to_cpu(vhost_is_little_endian(vq), val);
378}
379
380static inline __virtio16 cpu_to_vhost16(struct vhost_virtqueue *vq, u16 val)
381{
382	return __cpu_to_virtio16(vhost_is_little_endian(vq), val);
383}
384
385static inline u32 vhost32_to_cpu(struct vhost_virtqueue *vq, __virtio32 val)
386{
387	return __virtio32_to_cpu(vhost_is_little_endian(vq), val);
388}
389
390static inline __virtio32 cpu_to_vhost32(struct vhost_virtqueue *vq, u32 val)
391{
392	return __cpu_to_virtio32(vhost_is_little_endian(vq), val);
393}
394
395static inline u64 vhost64_to_cpu(struct vhost_virtqueue *vq, __virtio64 val)
396{
397	return __virtio64_to_cpu(vhost_is_little_endian(vq), val);
398}
399
400static inline __virtio64 cpu_to_vhost64(struct vhost_virtqueue *vq, u64 val)
401{
402	return __cpu_to_virtio64(vhost_is_little_endian(vq), val);
403}
404#endif