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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; /* 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 */