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