[mirror_ubuntu-bionic-kernel.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 function to call to notify the guest about added buffers */
	void (*notify)(struct vringh *);
};

/**
 * struct vringh_config_ops - ops for creating a host vring from a virtio driver
 * @find_vrhs: find the host vrings and instantiate them
 *	vdev: the virtio_device
 *	nhvrs: the number of host vrings to find
 *	hvrs: on success, includes new host vrings
 *	callbacks: array of driver callbacks, for each host vring
 *		include a NULL entry for vqs that do not need a callback
 *	Returns 0 on success or error status
 * @del_vrhs: free the host vrings found by find_vrhs().
 */
struct virtio_device;
typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
struct vringh_config_ops {
	int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs,
			 struct vringh *vrhs[], vrh_callback_t *callbacks[]);
	void (*del_vrhs)(struct virtio_device *vdev);
};

/* 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);

/* Notify the guest about buffers added to the used ring */
static inline void vringh_notify(struct vringh *vrh)
{
	if (vrh->notify)
		vrh->notify(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;
3beee86a SB	50
	51	/* The function to call to notify the guest about added buffers */
	52	void (notify)(struct vringh );
	53	};
	54
	55	/**
	56	* struct vringh_config_ops - ops for creating a host vring from a virtio driver
	57	* @find_vrhs: find the host vrings and instantiate them
	58	* vdev: the virtio_device
	59	* nhvrs: the number of host vrings to find
	60	* hvrs: on success, includes new host vrings
	61	* callbacks: array of driver callbacks, for each host vring
	62	* include a NULL entry for vqs that do not need a callback
	63	* Returns 0 on success or error status
	64	* @del_vrhs: free the host vrings found by find_vrhs().
	65	*/
	66	struct virtio_device;
	67	typedef void vrh_callback_t(struct virtio_device , struct vringh );
	68	struct vringh_config_ops {
	69	int (find_vrhs)(struct virtio_device vdev, unsigned nhvrs,
	70	struct vringh vrhs[], vrh_callback_t callbacks[]);
	71	void (del_vrhs)(struct virtio_device vdev);
f87d0fbb RR	72	};
	73
	74	/* The memory the vring can access, and what offset to apply. */
	75	struct vringh_range {
	76	u64 start, end_incl;
	77	u64 offset;
	78	};
	79
	80	/**
	81	* struct vringh_iov - iovec mangler.
	82	*
	83	* Mangles iovec in place, and restores it.
	84	* Remaining data is iov + i, of used - i elements.
	85	*/
	86	struct vringh_iov {
	87	struct iovec *iov;
	88	size_t consumed; /* Within iov[i] */
	89	unsigned i, used, max_num;
	90	};
	91
	92	/**
	93	* struct vringh_iov - kvec mangler.
	94	*
	95	* Mangles kvec in place, and restores it.
	96	* Remaining data is iov + i, of used - i elements.
	97	*/
	98	struct vringh_kiov {
	99	struct kvec *iov;
	100	size_t consumed; /* Within iov[i] */
	101	unsigned i, used, max_num;
	102	};
	103
	104	/* Flag on max_num to indicate we're kmalloced. */
	105	#define VRINGH_IOV_ALLOCATED 0x8000000
	106
	107	/* Helpers for userspace vrings. */
	108	int vringh_init_user(struct vringh *vrh, u32 features,
	109	unsigned int num, bool weak_barriers,
	110	struct vring_desc __user *desc,
	111	struct vring_avail __user *avail,
	112	struct vring_used __user *used);
	113
	114	static inline void vringh_iov_init(struct vringh_iov *iov,
	115	struct iovec *iovec, unsigned num)
	116	{
	117	iov->used = iov->i = 0;
	118	iov->consumed = 0;
	119	iov->max_num = num;
	120	iov->iov = iovec;
	121	}
	122
	123	static inline void vringh_iov_reset(struct vringh_iov *iov)
	124	{
	125	iov->iov[iov->i].iov_len += iov->consumed;
	126	iov->iov[iov->i].iov_base -= iov->consumed;
	127	iov->consumed = 0;
	128	iov->i = 0;
	129	}
	130
	131	static inline void vringh_iov_cleanup(struct vringh_iov *iov)
	132	{
	133	if (iov->max_num & VRINGH_IOV_ALLOCATED)
	134	kfree(iov->iov);
	135	iov->max_num = iov->used = iov->i = iov->consumed = 0;
136	iov->iov = NULL;
137	}
138
139	/* Convert a descriptor into iovecs. */
140	int vringh_getdesc_user(struct vringh *vrh,
141	struct vringh_iov *riov,
142	struct vringh_iov *wiov,
143	bool (getrange)(struct vringh vrh,
144	u64 addr, struct vringh_range *r),
145	u16 *head);
146
147	/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
148	ssize_t vringh_iov_pull_user(struct vringh_iov riov, void dst, size_t len);
149
150	/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
151	ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
152	const void *src, size_t len);
153
154	/* Mark a descriptor as used. */
155	int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
156	int vringh_complete_multi_user(struct vringh *vrh,
157	const struct vring_used_elem used[],
158	unsigned num_used);
159
160	/* Pretend we've never seen descriptor (for easy error handling). */
161	void vringh_abandon_user(struct vringh *vrh, unsigned int num);
162
163	/* Do we need to fire the eventfd to notify the other side? */
164	int vringh_need_notify_user(struct vringh *vrh);
165
166	bool vringh_notify_enable_user(struct vringh *vrh);
167	void vringh_notify_disable_user(struct vringh *vrh);
168
169	/* Helpers for kernelspace vrings. */
170	int vringh_init_kern(struct vringh *vrh, u32 features,
171	unsigned int num, bool weak_barriers,
172	struct vring_desc *desc,
173	struct vring_avail *avail,
174	struct vring_used *used);
175
176	static inline void vringh_kiov_init(struct vringh_kiov *kiov,
177	struct kvec *kvec, unsigned num)
178	{
179	kiov->used = kiov->i = 0;
180	kiov->consumed = 0;
181	kiov->max_num = num;
182	kiov->iov = kvec;
183	}
184
185	static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
186	{
187	kiov->iov[kiov->i].iov_len += kiov->consumed;
188	kiov->iov[kiov->i].iov_base -= kiov->consumed;
189	kiov->consumed = 0;
190	kiov->i = 0;
191	}
192
193	static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
194	{
195	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
196	kfree(kiov->iov);
197	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
198	kiov->iov = NULL;
199	}
200
201	int vringh_getdesc_kern(struct vringh *vrh,
202	struct vringh_kiov *riov,
203	struct vringh_kiov *wiov,
204	u16 *head,
205	gfp_t gfp);
206
207	ssize_t vringh_iov_pull_kern(struct vringh_kiov riov, void dst, size_t len);
208	ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
209	const void *src, size_t len);
210	void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
211	int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
212
213	bool vringh_notify_enable_kern(struct vringh *vrh);
214	void vringh_notify_disable_kern(struct vringh *vrh);
215
216	int vringh_need_notify_kern(struct vringh *vrh);
217
3beee86a SB	218	/* Notify the guest about buffers added to the used ring */
	219	static inline void vringh_notify(struct vringh *vrh)
	220	{
	221	if (vrh->notify)
	222	vrh->notify(vrh);
	223	}
	224
f87d0fbb	225	#endif /* _LINUX_VRINGH_H */