
     €ГИѓ|ЅВБЕ #b    /* 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;

	/* Use user's VA */
	bool use_va;

	/* 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 re