xref: /openbmc/linux/drivers/vhost/vhost.h (revision 05bcf503)
1 #ifndef _VHOST_H
2 #define _VHOST_H
3 
4 #include <linux/eventfd.h>
5 #include <linux/vhost.h>
6 #include <linux/mm.h>
7 #include <linux/mutex.h>
8 #include <linux/poll.h>
9 #include <linux/file.h>
10 #include <linux/skbuff.h>
11 #include <linux/uio.h>
12 #include <linux/virtio_config.h>
13 #include <linux/virtio_ring.h>
14 #include <linux/atomic.h>
15 
16 /* This is for zerocopy, used buffer len is set to 1 when lower device DMA
17  * done */
18 #define VHOST_DMA_DONE_LEN	1
19 #define VHOST_DMA_CLEAR_LEN	0
20 
21 struct vhost_device;
22 
23 struct vhost_work;
24 typedef void (*vhost_work_fn_t)(struct vhost_work *work);
25 
26 struct vhost_work {
27 	struct list_head	  node;
28 	vhost_work_fn_t		  fn;
29 	wait_queue_head_t	  done;
30 	int			  flushing;
31 	unsigned		  queue_seq;
32 	unsigned		  done_seq;
33 };
34 
35 /* Poll a file (eventfd or socket) */
36 /* Note: there's nothing vhost specific about this structure. */
37 struct vhost_poll {
38 	poll_table                table;
39 	wait_queue_head_t        *wqh;
40 	wait_queue_t              wait;
41 	struct vhost_work	  work;
42 	unsigned long		  mask;
43 	struct vhost_dev	 *dev;
44 };
45 
46 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
47 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
48 
49 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
50 		     unsigned long mask, struct vhost_dev *dev);
51 void vhost_poll_start(struct vhost_poll *poll, struct file *file);
52 void vhost_poll_stop(struct vhost_poll *poll);
53 void vhost_poll_flush(struct vhost_poll *poll);
54 void vhost_poll_queue(struct vhost_poll *poll);
55 
56 struct vhost_log {
57 	u64 addr;
58 	u64 len;
59 };
60 
61 struct vhost_virtqueue;
62 
63 struct vhost_ubuf_ref {
64 	struct kref kref;
65 	wait_queue_head_t wait;
66 	struct vhost_virtqueue *vq;
67 };
68 
69 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
70 void vhost_ubuf_put(struct vhost_ubuf_ref *);
71 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
72 
73 /* The virtqueue structure describes a queue attached to a device. */
74 struct vhost_virtqueue {
75 	struct vhost_dev *dev;
76 
77 	/* The actual ring of buffers. */
78 	struct mutex mutex;
79 	unsigned int num;
80 	struct vring_desc __user *desc;
81 	struct vring_avail __user *avail;
82 	struct vring_used __user *used;
83 	struct file *kick;
84 	struct file *call;
85 	struct file *error;
86 	struct eventfd_ctx *call_ctx;
87 	struct eventfd_ctx *error_ctx;
88 	struct eventfd_ctx *log_ctx;
89 
90 	struct vhost_poll poll;
91 
92 	/* The routine to call when the Guest pings us, or timeout. */
93 	vhost_work_fn_t handle_kick;
94 
95 	/* Last available index we saw. */
96 	u16 last_avail_idx;
97 
98 	/* Caches available index value from user. */
99 	u16 avail_idx;
100 
101 	/* Last index we used. */
102 	u16 last_used_idx;
103 
104 	/* Used flags */
105 	u16 used_flags;
106 
107 	/* Last used index value we have signalled on */
108 	u16 signalled_used;
109 
110 	/* Last used index value we have signalled on */
111 	bool signalled_used_valid;
112 
113 	/* Log writes to used structure. */
114 	bool log_used;
115 	u64 log_addr;
116 
117 	struct iovec iov[UIO_MAXIOV];
118 	/* hdr is used to store the virtio header.
119 	 * Since each iovec has >= 1 byte length, we never need more than
120 	 * header length entries to store the header. */
121 	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
122 	struct iovec *indirect;
123 	size_t vhost_hlen;
124 	size_t sock_hlen;
125 	struct vring_used_elem *heads;
126 	/* We use a kind of RCU to access private pointer.
127 	 * All readers access it from worker, which makes it possible to
128 	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
129 	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
130 	 * vhost_work execution acts instead of rcu_read_lock() and the end of
131 	 * vhost_work execution acts instead of rcu_read_unlock().
132 	 * Writers use virtqueue mutex. */
133 	void __rcu *private_data;
134 	/* Log write descriptors */
135 	void __user *log_base;
136 	struct vhost_log *log;
137 	/* vhost zerocopy support fields below: */
138 	/* last used idx for outstanding DMA zerocopy buffers */
139 	int upend_idx;
140 	/* first used idx for DMA done zerocopy buffers */
141 	int done_idx;
142 	/* an array of userspace buffers info */
143 	struct ubuf_info *ubuf_info;
144 	/* Reference counting for outstanding ubufs.
145 	 * Protected by vq mutex. Writers must also take device mutex. */
146 	struct vhost_ubuf_ref *ubufs;
147 };
148 
149 struct vhost_dev {
150 	/* Readers use RCU to access memory table pointer
151 	 * log base pointer and features.
152 	 * Writers use mutex below.*/
153 	struct vhost_memory __rcu *memory;
154 	struct mm_struct *mm;
155 	struct mutex mutex;
156 	unsigned acked_features;
157 	struct vhost_virtqueue *vqs;
158 	int nvqs;
159 	struct file *log_file;
160 	struct eventfd_ctx *log_ctx;
161 	spinlock_t work_lock;
162 	struct list_head work_list;
163 	struct task_struct *worker;
164 };
165 
166 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
167 long vhost_dev_check_owner(struct vhost_dev *);
168 long vhost_dev_reset_owner(struct vhost_dev *);
169 void vhost_dev_cleanup(struct vhost_dev *, bool locked);
170 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
171 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
172 int vhost_log_access_ok(struct vhost_dev *);
173 
174 int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
175 		      struct iovec iov[], unsigned int iov_count,
176 		      unsigned int *out_num, unsigned int *in_num,
177 		      struct vhost_log *log, unsigned int *log_num);
178 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
179 
180 int vhost_init_used(struct vhost_virtqueue *);
181 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
182 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
183 		     unsigned count);
184 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
185 			       unsigned int id, int len);
186 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
187 			       struct vring_used_elem *heads, unsigned count);
188 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
189 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
190 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
191 
192 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
193 		    unsigned int log_num, u64 len);
194 void vhost_zerocopy_callback(struct ubuf_info *);
195 int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq);
196 
197 #define vq_err(vq, fmt, ...) do {                                  \
198 		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
199 		if ((vq)->error_ctx)                               \
200 				eventfd_signal((vq)->error_ctx, 1);\
201 	} while (0)
202 
203 enum {
204 	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
205 			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
206 			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
207 			 (1ULL << VHOST_F_LOG_ALL),
208 	VHOST_NET_FEATURES = VHOST_FEATURES |
209 			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
210 			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
211 };
212 
213 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
214 {
215 	unsigned acked_features;
216 
217 	/* TODO: check that we are running from vhost_worker or dev mutex is
218 	 * held? */
219 	acked_features = rcu_dereference_index_check(dev->acked_features, 1);
220 	return acked_features & (1 << bit);
221 }
222 
223 void vhost_enable_zcopy(int vq);
224 
225 #endif
226