diff options
Diffstat (limited to 'include/linux/vringh.h')
| -rw-r--r-- | include/linux/vringh.h | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/include/linux/vringh.h b/include/linux/vringh.h new file mode 100644 index 000000000..c3a8117da --- /dev/null +++ b/include/linux/vringh.h @@ -0,0 +1,333 @@ +/* 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 virtio_device; +typedef void vrh_callback_t(struct virtio_device *, 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 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. + * @iov: array of iovecs to operate on + * @consumed: number of bytes consumed within iov[i] + * @i: index of current iovec + * @used: number of iovecs present in @iov + * @max_num: maximum number of iovecs. + * corresponds to allocated memory of @iov + * + * 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_kiov - kvec mangler. + * @iov: array of iovecs to operate on + * @consumed: number of bytes consumed within iov[i] + * @i: index of current iovec + * @used: number of iovecs present in @iov + * @max_num: maximum number of iovecs. + * corresponds to allocated memory of @iov + * + * 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_init_iotlb_va(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 */ |