[mirror_ubuntu-jammy-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 <linux/spinlock.h>
#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
#include <linux/dma-direction.h>
#include <linux/vhost_iotlb.h>
#endif
#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;

	/* IOTLB for this vring */
	struct vhost_iotlb *iotlb;

	/* spinlock to synchronize IOTLB accesses */
	spinlock_t *iotlb_lock;

	/* 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,
		     vring_desc_t __user *desc,
		     vring_avail_t __user *avail,
		     vring_used_t __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;
}

static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
{
	size_t len = 0;
	int i;

	for (i = kiov->i; i < kiov->used; i++)
		len += kiov->iov[i].iov_len;

	return len;
}

void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);

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);
}

#if IS_REACHABLE(CONFIG_VHOST_IOTLB)

void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
		      spinlock_t *iotlb_lock);

int vringh_init_iotlb(struct vringh *vrh, u64 features,
		      unsigned int num, bool weak_barriers,
		      struct vring_desc *desc,
		      struct vring_avail *avail,
		      struct vring_used *used);

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

ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
			      struct vringh_kiov *riov,
			      void *dst, size_t len);
ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
			      struct vringh_kiov *wiov,
			      const void *src, size_t len);

void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num);

int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);

bool vringh_notify_enable_iotlb(struct vringh *vrh);
void vringh_notify_disable_iotlb(struct vringh *vrh);

int vringh_need_notify_iotlb(struct vringh *vrh);

#endif /* CONFIG_VHOST_IOTLB */

#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>
f87d0fbb RR	16	#include <linux/slab.h>
ea2f6af1	17	#include <linux/spinlock.h>
3302363a	18	#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
9ad9c49c JW	19	#include <linux/dma-direction.h>
9ad9c49c JW	20	#include <linux/vhost_iotlb.h>
3302363a	21	#endif
f87d0fbb RR	22	#include <asm/barrier.h>
	23
	24	/* virtio_ring with information needed for host access. */
	25	struct vringh {
b9f7ac8c MT	26	/* Everything is little endian */
	27	bool little_endian;
	28
f87d0fbb RR	29	/* Guest publishes used event idx (note: we always do). */
	30	bool event_indices;
	31
	32	/* Can we get away with weak barriers? */
	33	bool weak_barriers;
	34
	35	/* Last available index we saw (ie. where we're up to). */
	36	u16 last_avail_idx;
	37
	38	/* Last index we used. */
	39	u16 last_used_idx;
	40
	41	/* How many descriptors we've completed since last need_notify(). */
	42	u32 completed;
	43
	44	/* The vring (note: it may contain user pointers!) */
	45	struct vring vring;
3beee86a	46
9ad9c49c JW	47	/* IOTLB for this vring */
	48	struct vhost_iotlb *iotlb;
	49
f53d9910 SG	50	/* spinlock to synchronize IOTLB accesses */
	51	spinlock_t *iotlb_lock;
	52
3beee86a SB	53	/* The function to call to notify the guest about added buffers */
	54	void (notify)(struct vringh );
	55	};
	56
	57	/**
	58	* struct vringh_config_ops - ops for creating a host vring from a virtio driver
	59	* @find_vrhs: find the host vrings and instantiate them
	60	* vdev: the virtio_device
	61	* nhvrs: the number of host vrings to find
	62	* hvrs: on success, includes new host vrings
	63	* callbacks: array of driver callbacks, for each host vring
	64	* include a NULL entry for vqs that do not need a callback
	65	* Returns 0 on success or error status
	66	* @del_vrhs: free the host vrings found by find_vrhs().
	67	*/
	68	struct virtio_device;
	69	typedef void vrh_callback_t(struct virtio_device , struct vringh );
	70	struct vringh_config_ops {
	71	int (find_vrhs)(struct virtio_device vdev, unsigned nhvrs,
	72	struct vringh vrhs[], vrh_callback_t callbacks[]);
	73	void (del_vrhs)(struct virtio_device vdev);
f87d0fbb RR	74	};
	75
	76	/* The memory the vring can access, and what offset to apply. */
	77	struct vringh_range {
	78	u64 start, end_incl;
	79	u64 offset;
	80	};
	81
	82	/**
	83	* struct vringh_iov - iovec mangler.
	84	*
	85	* Mangles iovec in place, and restores it.
	86	* Remaining data is iov + i, of used - i elements.
	87	*/
	88	struct vringh_iov {
	89	struct iovec *iov;
	90	size_t consumed; /* Within iov[i] */
	91	unsigned i, used, max_num;
	92	};
	93
	94	/**
	95	* struct vringh_iov - kvec mangler.
	96	*
	97	* Mangles kvec in place, and restores it.
	98	* Remaining data is iov + i, of used - i elements.
	99	*/
	100	struct vringh_kiov {
	101	struct kvec *iov;
	102	size_t consumed; /* Within iov[i] */
	103	unsigned i, used, max_num;
	104	};
	105
	106	/* Flag on max_num to indicate we're kmalloced. */
	107	#define VRINGH_IOV_ALLOCATED 0x8000000
	108
	109	/* Helpers for userspace vrings. */
b97a8a90	110	int vringh_init_user(struct vringh *vrh, u64 features,
f87d0fbb	111	unsigned int num, bool weak_barriers,
a865e420 MT	112	vring_desc_t __user *desc,
	113	vring_avail_t __user *avail,
	114	vring_used_t __user *used);
f87d0fbb RR	115
	116	static inline void vringh_iov_init(struct vringh_iov *iov,
	117	struct iovec *iovec, unsigned num)
	118	{
	119	iov->used = iov->i = 0;
	120	iov->consumed = 0;
	121	iov->max_num = num;
	122	iov->iov = iovec;
	123	}
	124
	125	static inline void vringh_iov_reset(struct vringh_iov *iov)
	126	{
	127	iov->iov[iov->i].iov_len += iov->consumed;
	128	iov->iov[iov->i].iov_base -= iov->consumed;
	129	iov->consumed = 0;
	130	iov->i = 0;
	131	}
	132
	133	static inline void vringh_iov_cleanup(struct vringh_iov *iov)
	134	{
	135	if (iov->max_num & VRINGH_IOV_ALLOCATED)
	136	kfree(iov->iov);
	137	iov->max_num = iov->used = iov->i = iov->consumed = 0;
	138	iov->iov = NULL;
	139	}
	140
	141	/* Convert a descriptor into iovecs. */
	142	int vringh_getdesc_user(struct vringh *vrh,
	143	struct vringh_iov *riov,
	144	struct vringh_iov *wiov,
	145	bool (getrange)(struct vringh vrh,
	146	u64 addr, struct vringh_range *r),
	147	u16 *head);
	148
	149	/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
	150	ssize_t vringh_iov_pull_user(struct vringh_iov riov, void dst, size_t len);
	151
	152	/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
	153	ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
	154	const void *src, size_t len);
	155
	156	/* Mark a descriptor as used. */
	157	int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
	158	int vringh_complete_multi_user(struct vringh *vrh,
	159	const struct vring_used_elem used[],
	160	unsigned num_used);
	161
	162	/* Pretend we've never seen descriptor (for easy error handling). */
	163	void vringh_abandon_user(struct vringh *vrh, unsigned int num);
	164
	165	/* Do we need to fire the eventfd to notify the other side? */
	166	int vringh_need_notify_user(struct vringh *vrh);
	167
	168	bool vringh_notify_enable_user(struct vringh *vrh);
	169	void vringh_notify_disable_user(struct vringh *vrh);
	170
	171	/* Helpers for kernelspace vrings. */
b97a8a90	172	int vringh_init_kern(struct vringh *vrh, u64 features,
f87d0fbb RR	173	unsigned int num, bool weak_barriers,
	174	struct vring_desc *desc,
	175	struct vring_avail *avail,
	176	struct vring_used *used);
	177
	178	static inline void vringh_kiov_init(struct vringh_kiov *kiov,
	179	struct kvec *kvec, unsigned num)
	180	{
	181	kiov->used = kiov->i = 0;
	182	kiov->consumed = 0;
	183	kiov->max_num = num;
	184	kiov->iov = kvec;
	185	}
	186
	187	static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
	188	{
	189	kiov->iov[kiov->i].iov_len += kiov->consumed;
	190	kiov->iov[kiov->i].iov_base -= kiov->consumed;
	191	kiov->consumed = 0;
	192	kiov->i = 0;
	193	}
	194
	195	static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
	196	{
	197	if (kiov->max_num & VRINGH_IOV_ALLOCATED)
	198	kfree(kiov->iov);
	199	kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
	200	kiov->iov = NULL;
	201	}
	202
14c9ac05 SG	203	static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
	204	{
	205	size_t len = 0;
	206	int i;
	207
	208	for (i = kiov->i; i < kiov->used; i++)
	209	len += kiov->iov[i].iov_len;
	210
	211	return len;
	212	}
	213
b8c06ad4 SG	214	void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
b8c06ad4 SG	215
f87d0fbb RR	216	int vringh_getdesc_kern(struct vringh *vrh,
	217	struct vringh_kiov *riov,
	218	struct vringh_kiov *wiov,
	219	u16 *head,
	220	gfp_t gfp);
	221
	222	ssize_t vringh_iov_pull_kern(struct vringh_kiov riov, void dst, size_t len);
	223	ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
	224	const void *src, size_t len);
	225	void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
	226	int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
	227
	228	bool vringh_notify_enable_kern(struct vringh *vrh);
	229	void vringh_notify_disable_kern(struct vringh *vrh);
	230
	231	int vringh_need_notify_kern(struct vringh *vrh);
	232
3beee86a SB	233	/* Notify the guest about buffers added to the used ring */
	234	static inline void vringh_notify(struct vringh *vrh)
	235	{
	236	if (vrh->notify)
	237	vrh->notify(vrh);
	238	}
	239
5da7b160 GK	240	static inline bool vringh_is_little_endian(const struct vringh *vrh)
5da7b160 GK	241	{
7d824109 GK	242	return vrh->little_endian \|\|
7d824109 GK	243	virtio_legacy_is_little_endian();
5da7b160 GK	244	}
5da7b160 GK	245
b9f7ac8c MT	246	static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
b9f7ac8c MT	247	{
5da7b160	248	return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	249	}
	250
	251	static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
	252	{
5da7b160	253	return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	254	}
	255
	256	static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
	257	{
5da7b160	258	return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	259	}
	260
	261	static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
	262	{
5da7b160	263	return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	264	}
	265
	266	static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
	267	{
5da7b160	268	return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
b9f7ac8c MT	269	}
	270
	271	static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
	272	{
5da7b160	273	return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
b9f7ac8c	274	}
9ad9c49c	275
3302363a MT	276	#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
3302363a MT	277
f53d9910 SG	278	void vringh_set_iotlb(struct vringh vrh, struct vhost_iotlb iotlb,
f53d9910 SG	279	spinlock_t *iotlb_lock);
9ad9c49c JW	280
	281	int vringh_init_iotlb(struct vringh *vrh, u64 features,
	282	unsigned int num, bool weak_barriers,
	283	struct vring_desc *desc,
	284	struct vring_avail *avail,
	285	struct vring_used *used);
	286
	287	int vringh_getdesc_iotlb(struct vringh *vrh,
	288	struct vringh_kiov *riov,
	289	struct vringh_kiov *wiov,
	290	u16 *head,
	291	gfp_t gfp);
	292
	293	ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
	294	struct vringh_kiov *riov,
	295	void *dst, size_t len);
	296	ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
	297	struct vringh_kiov *wiov,
	298	const void *src, size_t len);
	299
	300	void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num);
	301
	302	int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);
	303
	304	bool vringh_notify_enable_iotlb(struct vringh *vrh);
	305	void vringh_notify_disable_iotlb(struct vringh *vrh);
	306
	307	int vringh_need_notify_iotlb(struct vringh *vrh);
	308
3302363a MT	309	#endif /* CONFIG_VHOST_IOTLB */
3302363a MT	310
f87d0fbb	311	#endif /* _LINUX_VRINGH_H */