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Diffstat (limited to 'include/linux/vringh.h')
| -rw-r--r-- | include/linux/vringh.h | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/include/linux/vringh.h b/include/linux/vringh.h new file mode 100644 index 000000000000..749cde28728b --- /dev/null +++ b/include/linux/vringh.h @@ -0,0 +1,225 @@ +/* + * 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. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Written by: Rusty Russell <rusty@rustcorp.com.au> + */ +#ifndef _LINUX_VRINGH_H +#define _LINUX_VRINGH_H +#include <uapi/linux/virtio_ring.h> +#include <linux/uio.h> +#include <linux/slab.h> +#include <asm/barrier.h> + +/* virtio_ring with information needed for host access. */ +struct vringh { + /* 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; + + /* 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, u32 features, + unsigned int num, bool weak_barriers, + struct vring_desc __user *desc, + struct vring_avail __user *avail, + struct vring_used __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, u32 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; +} + +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); +} + +#endif /* _LINUX_VRINGH_H */ |