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/* 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 */
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