312 lines
8.6 KiB
C
312 lines
8.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Linux host-side vring helpers; for when the kernel needs to access
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* someone else's vring.
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*
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* Copyright IBM Corporation, 2013.
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* Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
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*
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* Written by: Rusty Russell <rusty@rustcorp.com.au>
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*/
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#ifndef _LINUX_VRINGH_H
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#define _LINUX_VRINGH_H
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#include <uapi/linux/virtio_ring.h>
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#include <linux/virtio_byteorder.h>
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#include <linux/uio.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
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#include <linux/dma-direction.h>
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#include <linux/vhost_iotlb.h>
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#endif
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#include <asm/barrier.h>
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/* virtio_ring with information needed for host access. */
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struct vringh {
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/* Everything is little endian */
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bool little_endian;
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/* Guest publishes used event idx (note: we always do). */
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bool event_indices;
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/* Can we get away with weak barriers? */
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bool weak_barriers;
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/* Last available index we saw (ie. where we're up to). */
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u16 last_avail_idx;
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/* Last index we used. */
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u16 last_used_idx;
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/* How many descriptors we've completed since last need_notify(). */
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u32 completed;
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/* The vring (note: it may contain user pointers!) */
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struct vring vring;
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/* IOTLB for this vring */
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struct vhost_iotlb *iotlb;
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/* spinlock to synchronize IOTLB accesses */
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spinlock_t *iotlb_lock;
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/* The function to call to notify the guest about added buffers */
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void (*notify)(struct vringh *);
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};
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/**
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* struct vringh_config_ops - ops for creating a host vring from a virtio driver
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* @find_vrhs: find the host vrings and instantiate them
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* vdev: the virtio_device
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* nhvrs: the number of host vrings to find
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* hvrs: on success, includes new host vrings
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* callbacks: array of driver callbacks, for each host vring
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* include a NULL entry for vqs that do not need a callback
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* Returns 0 on success or error status
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* @del_vrhs: free the host vrings found by find_vrhs().
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*/
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struct virtio_device;
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typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
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struct vringh_config_ops {
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int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs,
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struct vringh *vrhs[], vrh_callback_t *callbacks[]);
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void (*del_vrhs)(struct virtio_device *vdev);
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};
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/* The memory the vring can access, and what offset to apply. */
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struct vringh_range {
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u64 start, end_incl;
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u64 offset;
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};
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/**
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* struct vringh_iov - iovec mangler.
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*
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* Mangles iovec in place, and restores it.
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* Remaining data is iov + i, of used - i elements.
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*/
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struct vringh_iov {
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struct iovec *iov;
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size_t consumed; /* Within iov[i] */
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unsigned i, used, max_num;
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};
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/**
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* struct vringh_kiov - kvec mangler.
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*
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* Mangles kvec in place, and restores it.
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* Remaining data is iov + i, of used - i elements.
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*/
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struct vringh_kiov {
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struct kvec *iov;
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size_t consumed; /* Within iov[i] */
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unsigned i, used, max_num;
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};
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/* Flag on max_num to indicate we're kmalloced. */
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#define VRINGH_IOV_ALLOCATED 0x8000000
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/* Helpers for userspace vrings. */
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int vringh_init_user(struct vringh *vrh, u64 features,
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unsigned int num, bool weak_barriers,
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vring_desc_t __user *desc,
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vring_avail_t __user *avail,
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vring_used_t __user *used);
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static inline void vringh_iov_init(struct vringh_iov *iov,
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struct iovec *iovec, unsigned num)
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{
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iov->used = iov->i = 0;
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iov->consumed = 0;
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iov->max_num = num;
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iov->iov = iovec;
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}
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static inline void vringh_iov_reset(struct vringh_iov *iov)
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{
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iov->iov[iov->i].iov_len += iov->consumed;
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iov->iov[iov->i].iov_base -= iov->consumed;
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iov->consumed = 0;
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iov->i = 0;
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}
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static inline void vringh_iov_cleanup(struct vringh_iov *iov)
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{
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if (iov->max_num & VRINGH_IOV_ALLOCATED)
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kfree(iov->iov);
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iov->max_num = iov->used = iov->i = iov->consumed = 0;
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iov->iov = NULL;
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}
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/* Convert a descriptor into iovecs. */
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int vringh_getdesc_user(struct vringh *vrh,
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struct vringh_iov *riov,
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struct vringh_iov *wiov,
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bool (*getrange)(struct vringh *vrh,
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u64 addr, struct vringh_range *r),
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u16 *head);
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/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
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ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);
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/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
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ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
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const void *src, size_t len);
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/* Mark a descriptor as used. */
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int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
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int vringh_complete_multi_user(struct vringh *vrh,
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const struct vring_used_elem used[],
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unsigned num_used);
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/* Pretend we've never seen descriptor (for easy error handling). */
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void vringh_abandon_user(struct vringh *vrh, unsigned int num);
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/* Do we need to fire the eventfd to notify the other side? */
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int vringh_need_notify_user(struct vringh *vrh);
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bool vringh_notify_enable_user(struct vringh *vrh);
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void vringh_notify_disable_user(struct vringh *vrh);
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/* Helpers for kernelspace vrings. */
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int vringh_init_kern(struct vringh *vrh, u64 features,
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unsigned int num, bool weak_barriers,
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struct vring_desc *desc,
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struct vring_avail *avail,
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struct vring_used *used);
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static inline void vringh_kiov_init(struct vringh_kiov *kiov,
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struct kvec *kvec, unsigned num)
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{
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kiov->used = kiov->i = 0;
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kiov->consumed = 0;
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kiov->max_num = num;
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kiov->iov = kvec;
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}
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static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
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{
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kiov->iov[kiov->i].iov_len += kiov->consumed;
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kiov->iov[kiov->i].iov_base -= kiov->consumed;
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kiov->consumed = 0;
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kiov->i = 0;
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}
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static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
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{
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if (kiov->max_num & VRINGH_IOV_ALLOCATED)
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kfree(kiov->iov);
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kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
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kiov->iov = NULL;
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}
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static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
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{
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size_t len = 0;
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int i;
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for (i = kiov->i; i < kiov->used; i++)
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len += kiov->iov[i].iov_len;
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return len;
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}
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void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
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int vringh_getdesc_kern(struct vringh *vrh,
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struct vringh_kiov *riov,
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struct vringh_kiov *wiov,
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u16 *head,
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gfp_t gfp);
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ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len);
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ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
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const void *src, size_t len);
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void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
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int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
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bool vringh_notify_enable_kern(struct vringh *vrh);
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void vringh_notify_disable_kern(struct vringh *vrh);
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int vringh_need_notify_kern(struct vringh *vrh);
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/* Notify the guest about buffers added to the used ring */
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static inline void vringh_notify(struct vringh *vrh)
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{
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if (vrh->notify)
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vrh->notify(vrh);
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}
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static inline bool vringh_is_little_endian(const struct vringh *vrh)
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{
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return vrh->little_endian ||
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virtio_legacy_is_little_endian();
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}
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static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
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{
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return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
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}
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static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
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{
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return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
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}
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static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
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{
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return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
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}
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static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
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{
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return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
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}
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static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
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{
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return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
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}
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static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
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{
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return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
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}
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#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
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void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
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spinlock_t *iotlb_lock);
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int vringh_init_iotlb(struct vringh *vrh, u64 features,
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unsigned int num, bool weak_barriers,
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struct vring_desc *desc,
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struct vring_avail *avail,
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struct vring_used *used);
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int vringh_getdesc_iotlb(struct vringh *vrh,
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struct vringh_kiov *riov,
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struct vringh_kiov *wiov,
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u16 *head,
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gfp_t gfp);
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ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
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struct vringh_kiov *riov,
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void *dst, size_t len);
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ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
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struct vringh_kiov *wiov,
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const void *src, size_t len);
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void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num);
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int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);
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bool vringh_notify_enable_iotlb(struct vringh *vrh);
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void vringh_notify_disable_iotlb(struct vringh *vrh);
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int vringh_need_notify_iotlb(struct vringh *vrh);
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#endif /* CONFIG_VHOST_IOTLB */
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#endif /* _LINUX_VRINGH_H */
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