[mirror_ubuntu-eoan-kernel.git] / include / linux / vringh.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * 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.
 *
 * 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
1a59d1b8	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
f87d0fbb RR	2	/*
	3	* Linux host-side vring helpers; for when the kernel needs to access
	4	* someone else's vring.
	5	*
	6	* Copyright IBM Corporation, 2013.
	7	* Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
	8	*
f87d0fbb RR	9	* Written by: Rusty Russell <rusty@rustcorp.com.au>
	10	*/
	11	#ifndef _LINUX_VRINGH_H
	12	#define _LINUX_VRINGH_H
	13	#include <uapi/linux/virtio_ring.h>
b9f7ac8c	14	#include <linux/virtio_byteorder.h>
f87d0fbb RR	15	#include <linux/uio.h>
	16	#include <linux/slab.h>
	17	#include <asm/barrier.h>
	18
	19	/* virtio_ring with information needed for host access. */
	20	struct vringh {
b9f7ac8c MT	21	/* Everything is little endian */
	22	bool little_endian;
	23
f87d0fbb RR	24	/* Guest publishes used event idx (note: we always do). */
	25	bool event_indices;
	26
	27	/* Can we get away with weak barriers? */
	28	bool weak_barriers;
	29
	30	/* Last available index we saw (ie. where we're up to). */
	31	u16 last_avail_idx;
	32
	33	/* Last index we used. */
	34	u16 last_used_idx;
	35
	36	/* How many descriptors we've completed since last need_notify(). */
	37	u32 completed;
	38
	39	/* The vring (note: it may contain user pointers!) */
	40	struct vring vring;
3beee86a SB	41
	42	/* The function to call to notify the guest about added buffers */
	43	void (notify)(struct vringh );
	44	};
	45
	46	/**
	47	* struct vringh_config_ops - ops for creating a host vring from a virtio driver
	48	* @find_vrhs: find the host vrings and instantiate them
	49	* vdev: the virtio_device
	50	* nhvrs: the number of host vrings to find
	51	* hvrs: on success, includes new host vrings
	52	* callbacks: array of driver callbacks, for each host vring
	53	* include a NULL entry for vqs that do not need a callback
	54	* Returns 0 on success or error status
	55	* @del_vrhs: free the host vrings found by find_vrhs().
	56	*/
	57	struct virtio_device;
	58	typedef void vrh_callback_t(struct virtio_device , struct vringh );
	59	struct vringh_config_ops {
	60	int (find_vrhs)(struct virtio_device vdev, unsigned nhvrs,
	61	struct vringh vrhs[], vrh_callback_t callbacks[]);
	62	void (del_vrhs)(struct virtio_device vdev);
f87d0fbb RR	63	};
	64
	65	/* The memory the vring can access, and what offset to apply. */
	66	struct vringh_range {
	67	u64 start, end_incl;
	68	u64 offset;
	69	};
	70
	71	/**
	72	* struct vringh_iov - iovec mangler.
	73	*
	74	* Mangles iovec in place, and restores it.
	75	* Remaining data is iov + i, of used - i elements.
	76	*/
	77	struct vringh_iov {
	78	struct iovec *iov;
	79	size_t consumed; /* Within iov[i] */
	80	unsigned i, used, max_num;
	81	};
	82
	83	/**
	84	* struct vringh_iov - kvec mangler.
	85	*
	86	* Mangles kvec in place, and restores it.
	87	* Remaining data is iov + i, of used - i elements.
	88	*/
	89	struct vringh_kiov {
	90	struct kvec *iov;
	91	size_t consumed; /* Within iov[i] */
	92	unsigned i, used, max_num;
	93	};
	94
	95	/* Flag on max_num to indicate we're kmalloced. */
	96	#define VRINGH_IOV_ALLOCATED 0x8000000
	97
	98	/* Helpers for userspace vrings. */
b97a8a90	99	int vringh_init_user(struct vringh *vrh, u64 features,
f87d0fbb RR	100	unsigned int num, bool weak_barriers,
	101	struct vring_desc __user *desc,
	102	struct vring_avail __user *avail,
	103	struct vring_used __user *used);
	104
	105	static inline void vringh_iov_init(struct vringh_iov *iov,
	106	struct iovec *iovec, unsigned num)
	107	{
	108	iov->used = iov->i = 0;
	109	iov->consumed = 0;
	110	iov->max_num = num;
	111	iov->iov = iovec;
	112	}
	113
	114	static inline void vringh_iov_reset(struct vringh_iov *iov)
	115	{
	116	iov->iov[iov->i].iov_len += iov->consumed;
	117	iov->iov[iov->i].iov_base -= iov->consumed;
	118	iov->consumed = 0;
	119	iov->i = 0;
	120	}
	121
	122	static inline void vringh_iov_cleanup(struct vringh_iov *iov)
	123	{
	124	if (iov->max_num & VRINGH_IOV_ALLOCATED)
	125	kfree(iov->iov);
	126	iov->max_num = iov->used = iov->i = iov->consumed = 0;
	127	iov->iov = NULL;
	128	}
	129
	130	/* Convert a descriptor into iovecs. */
	131	int vringh_getdesc_user(struct vringh *vrh,
	132	struct vringh_iov *riov,
	133	struct vringh_iov *wiov,
	134	bool (getrange)(struct vringh vrh,
	135	u64 addr, struct vringh_range *r),
	136	u16 *head);
	137
	138	/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
	139	ssize_t vringh_iov_pull_user(struct vringh_iov riov, void dst, size_t len);
	140
	141	/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
	142	ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
	143	const void *src, size_t len);
	144
	145	/* Mark a descriptor as used. */
	146	int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
	147	int vringh_complete_multi_user(struct vringh *vrh,
	148	const struct vring_used_elem used[],
	149	unsigned num_used);
	150
	151	/* Pretend we've never seen descriptor (for easy error handling). */
	152	void vringh_abandon_user(struct vringh *vrh, unsigned int num);
	153
	154	/* Do we need to fire the eventfd to notify the other side? */
	155	int vringh_need_notify_user(struct vringh *vrh);
	156
	157	bool vringh_notify_enable_user(struct vringh *vrh);
	158	void vringh_notify_disable_user(struct vringh *vrh);
	159
	160	/* Helpers for kernelspace vrings. */
b97a8a90	161	int vringh_init_kern(struct vringh *vrh, u64 features,
f87d0fbb RR	162	unsigned int num, bool weak_barriers,
	163	struct vring_desc *desc,
	164	struct vring_avail *avail,
	165	struct vring_used *used);
	166
	167	static inline void vringh_kiov_init(struct vringh_kiov *kiov,
	168	struct kvec *kvec, unsigned num)
	169	{
	170	kiov->used = kiov->i = 0;
	171	kiov->consumed = 0;
	172	kiov->max_num = num;
	173	kiov->iov = kvec;
	174	}
	175
	176	static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
	177	{
	178	kiov->iov[kiov->i].iov_len += kiov->consumed;
	179	kiov->iov[kiov->i].iov_base -= kiov->consumed;
	180	kiov->consumed = 0;
	181	kiov->i = 0;
	182	}
	183
	184	static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
	185	{
	186	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
	187	kfree(kiov->iov);
	188	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
	189	kiov->iov = NULL;
	190	}
	191
	192	int vringh_getdesc_kern(struct vringh *vrh,
	193	struct vringh_kiov *riov,
	194	struct vringh_kiov *wiov,
	195	u16 *head,
	196	gfp_t gfp);
	197
	198	ssize_t vringh_iov_pull_kern(struct vringh_kiov riov, void dst, size_t len);
	199	ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
	200	const void *src, size_t len);
	201	void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
	202	int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
	203
	204	bool vringh_notify_enable_kern(struct vringh *vrh);
	205	void vringh_notify_disable_kern(struct vringh *vrh);
	206
	207	int vringh_need_notify_kern(struct vringh *vrh);
	208
3beee86a SB	209	/* Notify the guest about buffers added to the used ring */
	210	static inline void vringh_notify(struct vringh *vrh)
	211	{
	212	if (vrh->notify)
	213	vrh->notify(vrh);
	214	}
	215
5da7b160 GK	216	static inline bool vringh_is_little_endian(const struct vringh *vrh)
5da7b160 GK	217	{
7d824109 GK	218	return vrh->little_endian \|\|
7d824109 GK	219	virtio_legacy_is_little_endian();
5da7b160 GK	220	}
5da7b160 GK	221
b9f7ac8c MT	222	static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
b9f7ac8c MT	223	{
5da7b160	224	return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	225	}
	226
	227	static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
	228	{
5da7b160	229	return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	230	}
	231
	232	static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
	233	{
5da7b160	234	return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	235	}
	236
	237	static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
	238	{
5da7b160	239	return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	240	}
	241
	242	static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
	243	{
5da7b160	244	return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	245	}
	246
	247	static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
	248	{
5da7b160	249	return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
b9f7ac8c	250	}
f87d0fbb	251	#endif /* _LINUX_VRINGH_H */