[linux-block.git] / include / linux / vringh.h

/*
 * Linux host-side vring helpers; for when the kernel needs to access
 * someone else's vring.
 *
 * Copyright IBM Corporation, 2013.
 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Written by: Rusty Russell <rusty@rustcorp.com.au>
 */
#ifndef _LINUX_VRINGH_H
#define _LINUX_VRINGH_H
#include <uapi/linux/virtio_ring.h>
#include <linux/uio.h>
#include <linux/slab.h>
#include <asm/barrier.h>

/* virtio_ring with information needed for host access. */
struct vringh {
	/* Guest publishes used event idx (note: we always do). */
	bool event_indices;

	/* Can we get away with weak barriers? */
	bool weak_barriers;

	/* Last available index we saw (ie. where we're up to). */
	u16 last_avail_idx;

	/* Last index we used. */
	u16 last_used_idx;

	/* How many descriptors we've completed since last need_notify(). */
	u32 completed;

	/* The vring (note: it may contain user pointers!) */
	struct vring vring;
};

/* The memory the vring can access, and what offset to apply. */
struct vringh_range {
	u64 start, end_incl;
	u64 offset;
};

/**
 * struct vringh_iov - iovec mangler.
 *
 * Mangles iovec in place, and restores it.
 * Remaining data is iov + i, of used - i elements.
 */
struct vringh_iov {
	struct iovec *iov;
	size_t consumed; /* Within iov[i] */
	unsigned i, used, max_num;
};

/**
 * struct vringh_iov - kvec mangler.
 *
 * Mangles kvec in place, and restores it.
 * Remaining data is iov + i, of used - i elements.
 */
struct vringh_kiov {
	struct kvec *iov;
	size_t consumed; /* Within iov[i] */
	unsigned i, used, max_num;
};

/* Flag on max_num to indicate we're kmalloced. */
#define VRINGH_IOV_ALLOCATED 0x8000000

/* Helpers for userspace vrings. */
int vringh_init_user(struct vringh *vrh, u32 features,
		     unsigned int num, bool weak_barriers,
		     struct vring_desc __user *desc,
		     struct vring_avail __user *avail,
		     struct vring_used __user *used);

static inline void vringh_iov_init(struct vringh_iov *iov,
				   struct iovec *iovec, unsigned num)
{
	iov->used = iov->i = 0;
	iov->consumed = 0;
	iov->max_num = num;
	iov->iov = iovec;
}

static inline void vringh_iov_reset(struct vringh_iov *iov)
{
	iov->iov[iov->i].iov_len += iov->consumed;
	iov->iov[iov->i].iov_base -= iov->consumed;
	iov->consumed = 0;
	iov->i = 0;
}

static inline void vringh_iov_cleanup(struct vringh_iov *iov)
{
	if (iov->max_num & VRINGH_IOV_ALLOCATED)
		kfree(iov->iov);
	iov->max_num = iov->used = iov->i = iov->consumed = 0;
	iov->iov = NULL;
}

/* Convert a descriptor into iovecs. */
int vringh_getdesc_user(struct vringh *vrh,
			struct vringh_iov *riov,
			struct vringh_iov *wiov,
			bool (*getrange)(struct vringh *vrh,
					 u64 addr, struct vringh_range *r),
			u16 *head);

/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);

/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
			     const void *src, size_t len);

/* Mark a descriptor as used. */
int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
int vringh_complete_multi_user(struct vringh *vrh,
			       const struct vring_used_elem used[],
			       unsigned num_used);

/* Pretend we've never seen descriptor (for easy error handling). */
void vringh_abandon_user(struct vringh *vrh, unsigned int num);

/* Do we need to fire the eventfd to notify the other side? */
int vringh_need_notify_user(struct vringh *vrh);

bool vringh_notify_enable_user(struct vringh *vrh);
void vringh_notify_disable_user(struct vringh *vrh);

/* Helpers for kernelspace vrings. */
int vringh_init_kern(struct vringh *vrh, u32 features,
		     unsigned int num, bool weak_barriers,
		     struct vring_desc *desc,
		     struct vring_avail *avail,
		     struct vring_used *used);

static inline void vringh_kiov_init(struct vringh_kiov *kiov,
				    struct kvec *kvec, unsigned num)
{
	kiov->used = kiov->i = 0;
	kiov->consumed = 0;
	kiov->max_num = num;
	kiov->iov = kvec;
}

static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
{
	kiov->iov[kiov->i].iov_len += kiov->consumed;
	kiov->iov[kiov->i].iov_base -= kiov->consumed;
	kiov->consumed = 0;
	kiov->i = 0;
}

static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
{
	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
		kfree(kiov->iov);
	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
	kiov->iov = NULL;
}

int vringh_getdesc_kern(struct vringh *vrh,
			struct vringh_kiov *riov,
			struct vringh_kiov *wiov,
			u16 *head,
			gfp_t gfp);

ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len);
ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
			     const void *src, size_t len);
void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);

bool vringh_notify_enable_kern(struct vringh *vrh);
void vringh_notify_disable_kern(struct vringh *vrh);

int vringh_need_notify_kern(struct vringh *vrh);

#endif /* _LINUX_VRINGH_H */
Commit	Line	Data
f87d0fbb RR	1	/*
	2	* Linux host-side vring helpers; for when the kernel needs to access
	3	* someone else's vring.
	4	*
	5	* Copyright IBM Corporation, 2013.
	6	* Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with this program; if not, write to the Free Software
	20	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	21	*
	22	* Written by: Rusty Russell <rusty@rustcorp.com.au>
	23	*/
	24	#ifndef _LINUX_VRINGH_H
	25	#define _LINUX_VRINGH_H
	26	#include <uapi/linux/virtio_ring.h>
	27	#include <linux/uio.h>
	28	#include <linux/slab.h>
	29	#include <asm/barrier.h>
	30
	31	/* virtio_ring with information needed for host access. */
	32	struct vringh {
	33	/* Guest publishes used event idx (note: we always do). */
	34	bool event_indices;
	35
	36	/* Can we get away with weak barriers? */
	37	bool weak_barriers;
	38
	39	/* Last available index we saw (ie. where we're up to). */
	40	u16 last_avail_idx;
	41
	42	/* Last index we used. */
	43	u16 last_used_idx;
	44
	45	/* How many descriptors we've completed since last need_notify(). */
	46	u32 completed;
	47
	48	/* The vring (note: it may contain user pointers!) */
	49	struct vring vring;
	50	};
	51
	52	/* The memory the vring can access, and what offset to apply. */
	53	struct vringh_range {
	54	u64 start, end_incl;
	55	u64 offset;
	56	};
	57
	58	/**
	59	* struct vringh_iov - iovec mangler.
	60	*
	61	* Mangles iovec in place, and restores it.
	62	* Remaining data is iov + i, of used - i elements.
	63	*/
	64	struct vringh_iov {
65	struct iovec *iov;
66	size_t consumed; /* Within iov[i] */
67	unsigned i, used, max_num;
68	};
69
70	/**
71	* struct vringh_iov - kvec mangler.
72	*
73	* Mangles kvec in place, and restores it.
74	* Remaining data is iov + i, of used - i elements.
75	*/
76	struct vringh_kiov {
77	struct kvec *iov;
78	size_t consumed; /* Within iov[i] */
79	unsigned i, used, max_num;
80	};
81
82	/* Flag on max_num to indicate we're kmalloced. */
83	#define VRINGH_IOV_ALLOCATED 0x8000000
84
85	/* Helpers for userspace vrings. */
86	int vringh_init_user(struct vringh *vrh, u32 features,
87	unsigned int num, bool weak_barriers,
88	struct vring_desc __user *desc,
89	struct vring_avail __user *avail,
90	struct vring_used __user *used);
91
92	static inline void vringh_iov_init(struct vringh_iov *iov,
93	struct iovec *iovec, unsigned num)
94	{
95	iov->used = iov->i = 0;
96	iov->consumed = 0;
97	iov->max_num = num;
98	iov->iov = iovec;
99	}
100
101	static inline void vringh_iov_reset(struct vringh_iov *iov)
102	{
103	iov->iov[iov->i].iov_len += iov->consumed;
104	iov->iov[iov->i].iov_base -= iov->consumed;
105	iov->consumed = 0;
106	iov->i = 0;
107	}
108
109	static inline void vringh_iov_cleanup(struct vringh_iov *iov)
110	{
111	if (iov->max_num & VRINGH_IOV_ALLOCATED)
112	kfree(iov->iov);
113	iov->max_num = iov->used = iov->i = iov->consumed = 0;
114	iov->iov = NULL;
115	}
116
117	/* Convert a descriptor into iovecs. */
118	int vringh_getdesc_user(struct vringh *vrh,
119	struct vringh_iov *riov,
120	struct vringh_iov *wiov,
121	bool (getrange)(struct vringh vrh,
122	u64 addr, struct vringh_range *r),
123	u16 *head);
124
125	/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
126	ssize_t vringh_iov_pull_user(struct vringh_iov riov, void dst, size_t len);
127
128	/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
129	ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
130	const void *src, size_t len);
131
132	/* Mark a descriptor as used. */
133	int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
134	int vringh_complete_multi_user(struct vringh *vrh,
135	const struct vring_used_elem used[],
136	unsigned num_used);
137
138	/* Pretend we've never seen descriptor (for easy error handling). */
139	void vringh_abandon_user(struct vringh *vrh, unsigned int num);
140
141	/* Do we need to fire the eventfd to notify the other side? */
142	int vringh_need_notify_user(struct vringh *vrh);
143
144	bool vringh_notify_enable_user(struct vringh *vrh);
145	void vringh_notify_disable_user(struct vringh *vrh);
146
147	/* Helpers for kernelspace vrings. */
148	int vringh_init_kern(struct vringh *vrh, u32 features,
149	unsigned int num, bool weak_barriers,
150	struct vring_desc *desc,
151	struct vring_avail *avail,
152	struct vring_used *used);
153
154	static inline void vringh_kiov_init(struct vringh_kiov *kiov,
155	struct kvec *kvec, unsigned num)
156	{
157	kiov->used = kiov->i = 0;
158	kiov->consumed = 0;
159	kiov->max_num = num;
160	kiov->iov = kvec;
161	}
162
163	static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
164	{
165	kiov->iov[kiov->i].iov_len += kiov->consumed;
166	kiov->iov[kiov->i].iov_base -= kiov->consumed;
167	kiov->consumed = 0;
168	kiov->i = 0;
169	}
170
171	static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
172	{
173	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
174	kfree(kiov->iov);
175	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
176	kiov->iov = NULL;
177	}
178
179	int vringh_getdesc_kern(struct vringh *vrh,
180	struct vringh_kiov *riov,
181	struct vringh_kiov *wiov,
182	u16 *head,
183	gfp_t gfp);
184
185	ssize_t vringh_iov_pull_kern(struct vringh_kiov riov, void dst, size_t len);
186	ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
187	const void *src, size_t len);
188	void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
189	int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
190
191	bool vringh_notify_enable_kern(struct vringh *vrh);
192	void vringh_notify_disable_kern(struct vringh *vrh);
193
194	int vringh_need_notify_kern(struct vringh *vrh);
195
196	#endif /* _LINUX_VRINGH_H */