1 /* 2 * Linux host-side vring helpers; for when the kernel needs to access 3 * someone else's vring. 4 * 5 * Copyright IBM Corporation, 2013. 6 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 21 * 22 * Written by: Rusty Russell <[email protected]> 23 */ 24 #ifndef _LINUX_VRINGH_H 25 #define _LINUX_VRINGH_H 26 #include <uapi/linux/virtio_ring.h> 27 #include <linux/uio.h> 28 #include <linux/slab.h> 29 #include <asm/barrier.h> 30 31 /* virtio_ring with information needed for host access. */ 32 struct vringh { 33 /* Guest publishes used event idx (note: we always do). */ 34 bool event_indices; 35 36 /* Can we get away with weak barriers? */ 37 bool weak_barriers; 38 39 /* Last available index we saw (ie. where we're up to). */ 40 u16 last_avail_idx; 41 42 /* Last index we used. */ 43 u16 last_used_idx; 44 45 /* How many descriptors we've completed since last need_notify(). */ 46 u32 completed; 47 48 /* The vring (note: it may contain user pointers!) */ 49 struct vring vring; 50 51 /* The function to call to notify the guest about added buffers */ 52 void (*notify)(struct vringh *); 53 }; 54 55 /** 56 * struct vringh_config_ops - ops for creating a host vring from a virtio driver 57 * @find_vrhs: find the host vrings and instantiate them 58 * vdev: the virtio_device 59 * nhvrs: the number of host vrings to find 60 * hvrs: on success, includes new host vrings 61 * callbacks: array of driver callbacks, for each host vring 62 * include a NULL entry for vqs that do not need a callback 63 * Returns 0 on success or error status 64 * @del_vrhs: free the host vrings found by find_vrhs(). 65 */ 66 struct virtio_device; 67 typedef void vrh_callback_t(struct virtio_device *, struct vringh *); 68 struct vringh_config_ops { 69 int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs, 70 struct vringh *vrhs[], vrh_callback_t *callbacks[]); 71 void (*del_vrhs)(struct virtio_device *vdev); 72 }; 73 74 /* The memory the vring can access, and what offset to apply. */ 75 struct vringh_range { 76 u64 start, end_incl; 77 u64 offset; 78 }; 79 80 /** 81 * struct vringh_iov - iovec mangler. 82 * 83 * Mangles iovec in place, and restores it. 84 * Remaining data is iov + i, of used - i elements. 85 */ 86 struct vringh_iov { 87 struct iovec *iov; 88 size_t consumed; /* Within iov[i] */ 89 unsigned i, used, max_num; 90 }; 91 92 /** 93 * struct vringh_iov - kvec mangler. 94 * 95 * Mangles kvec in place, and restores it. 96 * Remaining data is iov + i, of used - i elements. 97 */ 98 struct vringh_kiov { 99 struct kvec *iov; 100 size_t consumed; /* Within iov[i] */ 101 unsigned i, used, max_num; 102 }; 103 104 /* Flag on max_num to indicate we're kmalloced. */ 105 #define VRINGH_IOV_ALLOCATED 0x8000000 106 107 /* Helpers for userspace vrings. */ 108 int vringh_init_user(struct vringh *vrh, u32 features, 109 unsigned int num, bool weak_barriers, 110 struct vring_desc __user *desc, 111 struct vring_avail __user *avail, 112 struct vring_used __user *used); 113 114 static inline void vringh_iov_init(struct vringh_iov *iov, 115 struct iovec *iovec, unsigned num) 116 { 117 iov->used = iov->i = 0; 118 iov->consumed = 0; 119 iov->max_num = num; 120 iov->iov = iovec; 121 } 122 123 static inline void vringh_iov_reset(struct vringh_iov *iov) 124 { 125 iov->iov[iov->i].iov_len += iov->consumed; 126 iov->iov[iov->i].iov_base -= iov->consumed; 127 iov->consumed = 0; 128 iov->i = 0; 129 } 130 131 static inline void vringh_iov_cleanup(struct vringh_iov *iov) 132 { 133 if (iov->max_num & VRINGH_IOV_ALLOCATED) 134 kfree(iov->iov); 135 iov->max_num = iov->used = iov->i = iov->consumed = 0; 136 iov->iov = NULL; 137 } 138 139 /* Convert a descriptor into iovecs. */ 140 int vringh_getdesc_user(struct vringh *vrh, 141 struct vringh_iov *riov, 142 struct vringh_iov *wiov, 143 bool (*getrange)(struct vringh *vrh, 144 u64 addr, struct vringh_range *r), 145 u16 *head); 146 147 /* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */ 148 ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len); 149 150 /* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */ 151 ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 152 const void *src, size_t len); 153 154 /* Mark a descriptor as used. */ 155 int vringh_complete_user(struct vringh *vrh, u16 head, u32 len); 156 int vringh_complete_multi_user(struct vringh *vrh, 157 const struct vring_used_elem used[], 158 unsigned num_used); 159 160 /* Pretend we've never seen descriptor (for easy error handling). */ 161 void vringh_abandon_user(struct vringh *vrh, unsigned int num); 162 163 /* Do we need to fire the eventfd to notify the other side? */ 164 int vringh_need_notify_user(struct vringh *vrh); 165 166 bool vringh_notify_enable_user(struct vringh *vrh); 167 void vringh_notify_disable_user(struct vringh *vrh); 168 169 /* Helpers for kernelspace vrings. */ 170 int vringh_init_kern(struct vringh *vrh, u32 features, 171 unsigned int num, bool weak_barriers, 172 struct vring_desc *desc, 173 struct vring_avail *avail, 174 struct vring_used *used); 175 176 static inline void vringh_kiov_init(struct vringh_kiov *kiov, 177 struct kvec *kvec, unsigned num) 178 { 179 kiov->used = kiov->i = 0; 180 kiov->consumed = 0; 181 kiov->max_num = num; 182 kiov->iov = kvec; 183 } 184 185 static inline void vringh_kiov_reset(struct vringh_kiov *kiov) 186 { 187 kiov->iov[kiov->i].iov_len += kiov->consumed; 188 kiov->iov[kiov->i].iov_base -= kiov->consumed; 189 kiov->consumed = 0; 190 kiov->i = 0; 191 } 192 193 static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov) 194 { 195 if (kiov->max_num & VRINGH_IOV_ALLOCATED) 196 kfree(kiov->iov); 197 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0; 198 kiov->iov = NULL; 199 } 200 201 int vringh_getdesc_kern(struct vringh *vrh, 202 struct vringh_kiov *riov, 203 struct vringh_kiov *wiov, 204 u16 *head, 205 gfp_t gfp); 206 207 ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len); 208 ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 209 const void *src, size_t len); 210 void vringh_abandon_kern(struct vringh *vrh, unsigned int num); 211 int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len); 212 213 bool vringh_notify_enable_kern(struct vringh *vrh); 214 void vringh_notify_disable_kern(struct vringh *vrh); 215 216 int vringh_need_notify_kern(struct vringh *vrh); 217 218 /* Notify the guest about buffers added to the used ring */ 219 static inline void vringh_notify(struct vringh *vrh) 220 { 221 if (vrh->notify) 222 vrh->notify(vrh); 223 } 224 225 #endif /* _LINUX_VRINGH_H */ 226