[deliverable/linux.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/virtio_byteorder.h>
#include <linux/uio.h>
#include <linux/slab.h>
#include <asm/barrier.h>

/* virtio_ring with information needed for host access. */
struct vringh {
	/* Everything is little endian */
	bool little_endian;

	/* 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, u64 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, u64 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);
}

static inline bool vringh_is_little_endian(const struct vringh *vrh)
{
	return vrh->little_endian ||
		virtio_legacy_is_little_endian();
}

static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
{
	return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
}

static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
{
	return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
}

static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
{
	return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
}

static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
{
	return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
}

static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
{
	return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
}

static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
{
	return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
}
#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>
b9f7ac8c	27	#include <linux/virtio_byteorder.h>
f87d0fbb RR	28	#include <linux/uio.h>
	29	#include <linux/slab.h>
	30	#include <asm/barrier.h>
	31
	32	/* virtio_ring with information needed for host access. */
	33	struct vringh {
b9f7ac8c MT	34	/* Everything is little endian */
	35	bool little_endian;
	36
f87d0fbb RR	37	/* Guest publishes used event idx (note: we always do). */
	38	bool event_indices;
	39
	40	/* Can we get away with weak barriers? */
	41	bool weak_barriers;
	42
	43	/* Last available index we saw (ie. where we're up to). */
	44	u16 last_avail_idx;
	45
	46	/* Last index we used. */
	47	u16 last_used_idx;
	48
	49	/* How many descriptors we've completed since last need_notify(). */
	50	u32 completed;
	51
	52	/* The vring (note: it may contain user pointers!) */
	53	struct vring vring;
3beee86a SB	54
	55	/* The function to call to notify the guest about added buffers */
	56	void (notify)(struct vringh );
	57	};
	58
	59	/**
	60	* struct vringh_config_ops - ops for creating a host vring from a virtio driver
	61	* @find_vrhs: find the host vrings and instantiate them
	62	* vdev: the virtio_device
	63	* nhvrs: the number of host vrings to find
	64	* hvrs: on success, includes new host vrings
	65	* callbacks: array of driver callbacks, for each host vring
	66	* include a NULL entry for vqs that do not need a callback
	67	* Returns 0 on success or error status
	68	* @del_vrhs: free the host vrings found by find_vrhs().
	69	*/
	70	struct virtio_device;
	71	typedef void vrh_callback_t(struct virtio_device , struct vringh );
	72	struct vringh_config_ops {
	73	int (find_vrhs)(struct virtio_device vdev, unsigned nhvrs,
	74	struct vringh vrhs[], vrh_callback_t callbacks[]);
	75	void (del_vrhs)(struct virtio_device vdev);
f87d0fbb RR	76	};
	77
	78	/* The memory the vring can access, and what offset to apply. */
	79	struct vringh_range {
	80	u64 start, end_incl;
	81	u64 offset;
	82	};
	83
	84	/**
	85	* struct vringh_iov - iovec mangler.
	86	*
	87	* Mangles iovec in place, and restores it.
	88	* Remaining data is iov + i, of used - i elements.
	89	*/
	90	struct vringh_iov {
	91	struct iovec *iov;
	92	size_t consumed; /* Within iov[i] */
	93	unsigned i, used, max_num;
	94	};
	95
	96	/**
	97	* struct vringh_iov - kvec mangler.
	98	*
	99	* Mangles kvec in place, and restores it.
	100	* Remaining data is iov + i, of used - i elements.
	101	*/
	102	struct vringh_kiov {
	103	struct kvec *iov;
	104	size_t consumed; /* Within iov[i] */
	105	unsigned i, used, max_num;
	106	};
	107
	108	/* Flag on max_num to indicate we're kmalloced. */
	109	#define VRINGH_IOV_ALLOCATED 0x8000000
	110
	111	/* Helpers for userspace vrings. */
b97a8a90	112	int vringh_init_user(struct vringh *vrh, u64 features,
f87d0fbb RR	113	unsigned int num, bool weak_barriers,
	114	struct vring_desc __user *desc,
	115	struct vring_avail __user *avail,
	116	struct vring_used __user *used);
	117
	118	static inline void vringh_iov_init(struct vringh_iov *iov,
	119	struct iovec *iovec, unsigned num)
	120	{
	121	iov->used = iov->i = 0;
	122	iov->consumed = 0;
	123	iov->max_num = num;
	124	iov->iov = iovec;
	125	}
	126
	127	static inline void vringh_iov_reset(struct vringh_iov *iov)
	128	{
	129	iov->iov[iov->i].iov_len += iov->consumed;
	130	iov->iov[iov->i].iov_base -= iov->consumed;
	131	iov->consumed = 0;
	132	iov->i = 0;
	133	}
	134
	135	static inline void vringh_iov_cleanup(struct vringh_iov *iov)
	136	{
	137	if (iov->max_num & VRINGH_IOV_ALLOCATED)
	138	kfree(iov->iov);
	139	iov->max_num = iov->used = iov->i = iov->consumed = 0;
	140	iov->iov = NULL;
	141	}
	142
	143	/* Convert a descriptor into iovecs. */
	144	int vringh_getdesc_user(struct vringh *vrh,
	145	struct vringh_iov *riov,
	146	struct vringh_iov *wiov,
	147	bool (getrange)(struct vringh vrh,
	148	u64 addr, struct vringh_range *r),
	149	u16 *head);
	150
	151	/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
	152	ssize_t vringh_iov_pull_user(struct vringh_iov riov, void dst, size_t len);
	153
	154	/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
	155	ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
	156	const void *src, size_t len);
	157
	158	/* Mark a descriptor as used. */
	159	int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
	160	int vringh_complete_multi_user(struct vringh *vrh,
	161	const struct vring_used_elem used[],
	162	unsigned num_used);
	163
	164	/* Pretend we've never seen descriptor (for easy error handling). */
	165	void vringh_abandon_user(struct vringh *vrh, unsigned int num);
	166
	167	/* Do we need to fire the eventfd to notify the other side? */
	168	int vringh_need_notify_user(struct vringh *vrh);
	169
	170	bool vringh_notify_enable_user(struct vringh *vrh);
	171	void vringh_notify_disable_user(struct vringh *vrh);
	172
	173	/* Helpers for kernelspace vrings. */
b97a8a90	174	int vringh_init_kern(struct vringh *vrh, u64 features,
f87d0fbb RR	175	unsigned int num, bool weak_barriers,
	176	struct vring_desc *desc,
	177	struct vring_avail *avail,
	178	struct vring_used *used);
	179
	180	static inline void vringh_kiov_init(struct vringh_kiov *kiov,
	181	struct kvec *kvec, unsigned num)
	182	{
	183	kiov->used = kiov->i = 0;
	184	kiov->consumed = 0;
	185	kiov->max_num = num;
	186	kiov->iov = kvec;
	187	}
	188
	189	static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
	190	{
	191	kiov->iov[kiov->i].iov_len += kiov->consumed;
	192	kiov->iov[kiov->i].iov_base -= kiov->consumed;
	193	kiov->consumed = 0;
	194	kiov->i = 0;
	195	}
	196
	197	static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
	198	{
	199	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
	200	kfree(kiov->iov);
	201	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
	202	kiov->iov = NULL;
	203	}
	204
	205	int vringh_getdesc_kern(struct vringh *vrh,
	206	struct vringh_kiov *riov,
	207	struct vringh_kiov *wiov,
	208	u16 *head,
	209	gfp_t gfp);
	210
	211	ssize_t vringh_iov_pull_kern(struct vringh_kiov riov, void dst, size_t len);
	212	ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
	213	const void *src, size_t len);
	214	void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
	215	int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
	216
	217	bool vringh_notify_enable_kern(struct vringh *vrh);
	218	void vringh_notify_disable_kern(struct vringh *vrh);
	219
	220	int vringh_need_notify_kern(struct vringh *vrh);
	221
3beee86a SB	222	/* Notify the guest about buffers added to the used ring */
	223	static inline void vringh_notify(struct vringh *vrh)
	224	{
	225	if (vrh->notify)
	226	vrh->notify(vrh);
	227	}
	228
5da7b160 GK	229	static inline bool vringh_is_little_endian(const struct vringh *vrh)
5da7b160 GK	230	{
7d824109 GK	231	return vrh->little_endian \|\|
7d824109 GK	232	virtio_legacy_is_little_endian();
5da7b160 GK	233	}
5da7b160 GK	234
b9f7ac8c MT	235	static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
b9f7ac8c MT	236	{
5da7b160	237	return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	238	}
	239
	240	static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
	241	{
5da7b160	242	return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	243	}
	244
	245	static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
	246	{
5da7b160	247	return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	248	}
	249
	250	static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
	251	{
5da7b160	252	return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	253	}
	254
	255	static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
	256	{
5da7b160	257	return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	258	}
	259
	260	static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
	261	{
5da7b160	262	return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
b9f7ac8c	263	}
f87d0fbb	264	#endif /* _LINUX_VRINGH_H */