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 <rusty@rustcorp.com.au> 23 */ 24 #ifndef _LINUX_VRINGH_H 25 #define _LINUX_VRINGH_H 26 #include <uapi/linux/virtio_ring.h> 27 #include <linux/virtio_byteorder.h> 28 #include <linux/uio.h> 29 #include <linux/slab.h> 30 #include <asm/barrier.h> 31 32 /* virtio_ring with information needed for host access. */ 33 struct vringh { 34 /* Everything is little endian */ 35 bool little_endian; 36 37 /* Guest publishes used event idx (note: we always do). */ 38 bool event_indices; 39 40 /* Can we get away with weak barriers? */ 41 bool weak_barriers; 42 43 /* Last available index we saw (ie. where we're up to). */ 44 u16 last_avail_idx; 45 46 /* Last index we used. */ 47 u16 last_used_idx; 48 49 /* How many descriptors we've completed since last need_notify(). */ 50 u32 completed; 51 52 /* The vring (note: it may contain user pointers!) */ 53 struct vring vring; 54 55 /* The function to call to notify the guest about added buffers */ 56 void (*notify)(struct vringh *); 57 }; 58 59 /** 60 * struct vringh_config_ops - ops for creating a host vring from a virtio driver 61 * @find_vrhs: find the host vrings and instantiate them 62 * vdev: the virtio_device 63 * nhvrs: the number of host vrings to find 64 * hvrs: on success, includes new host vrings 65 * callbacks: array of driver callbacks, for each host vring 66 * include a NULL entry for vqs that do not need a callback 67 * Returns 0 on success or error status 68 * @del_vrhs: free the host vrings found by find_vrhs(). 69 */ 70 struct virtio_device; 71 typedef void vrh_callback_t(struct virtio_device *, struct vringh *); 72 struct vringh_config_ops { 73 int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs, 74 struct vringh *vrhs[], vrh_callback_t *callbacks[]); 75 void (*del_vrhs)(struct virtio_device *vdev); 76 }; 77 78 /* The memory the vring can access, and what offset to apply. */ 79 struct vringh_range { 80 u64 start, end_incl; 81 u64 offset; 82 }; 83 84 /** 85 * struct vringh_iov - iovec mangler. 86 * 87 * Mangles iovec in place, and restores it. 88 * Remaining data is iov + i, of used - i elements. 89 */ 90 struct vringh_iov { 91 struct iovec *iov; 92 size_t consumed; /* Within iov[i] */ 93 unsigned i, used, max_num; 94 }; 95 96 /** 97 * struct vringh_iov - kvec mangler. 98 * 99 * Mangles kvec in place, and restores it. 100 * Remaining data is iov + i, of used - i elements. 101 */ 102 struct vringh_kiov { 103 struct kvec *iov; 104 size_t consumed; /* Within iov[i] */ 105 unsigned i, used, max_num; 106 }; 107 108 /* Flag on max_num to indicate we're kmalloced. */ 109 #define VRINGH_IOV_ALLOCATED 0x8000000 110 111 /* Helpers for userspace vrings. */ 112 int vringh_init_user(struct vringh *vrh, u64 features, 113 unsigned int num, bool weak_barriers, 114 struct vring_desc __user *desc, 115 struct vring_avail __user *avail, 116 struct vring_used __user *used); 117 118 static inline void vringh_iov_init(struct vringh_iov *iov, 119 struct iovec *iovec, unsigned num) 120 { 121 iov->used = iov->i = 0; 122 iov->consumed = 0; 123 iov->max_num = num; 124 iov->iov = iovec; 125 } 126 127 static inline void vringh_iov_reset(struct vringh_iov *iov) 128 { 129 iov->iov[iov->i].iov_len += iov->consumed; 130 iov->iov[iov->i].iov_base -= iov->consumed; 131 iov->consumed = 0; 132 iov->i = 0; 133 } 134 135 static inline void vringh_iov_cleanup(struct vringh_iov *iov) 136 { 137 if (iov->max_num & VRINGH_IOV_ALLOCATED) 138 kfree(iov->iov); 139 iov->max_num = iov->used = iov->i = iov->consumed = 0; 140 iov->iov = NULL; 141 } 142 143 /* Convert a descriptor into iovecs. */ 144 int vringh_getdesc_user(struct vringh *vrh, 145 struct vringh_iov *riov, 146 struct vringh_iov *wiov, 147 bool (*getrange)(struct vringh *vrh, 148 u64 addr, struct vringh_range *r), 149 u16 *head); 150 151 /* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */ 152 ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len); 153 154 /* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */ 155 ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 156 const void *src, size_t len); 157 158 /* Mark a descriptor as used. */ 159 int vringh_complete_user(struct vringh *vrh, u16 head, u32 len); 160 int vringh_complete_multi_user(struct vringh *vrh, 161 const struct vring_used_elem used[], 162 unsigned num_used); 163 164 /* Pretend we've never seen descriptor (for easy error handling). */ 165 void vringh_abandon_user(struct vringh *vrh, unsigned int num); 166 167 /* Do we need to fire the eventfd to notify the other side? */ 168 int vringh_need_notify_user(struct vringh *vrh); 169 170 bool vringh_notify_enable_user(struct vringh *vrh); 171 void vringh_notify_disable_user(struct vringh *vrh); 172 173 /* Helpers for kernelspace vrings. */ 174 int vringh_init_kern(struct vringh *vrh, u64 features, 175 unsigned int num, bool weak_barriers, 176 struct vring_desc *desc, 177 struct vring_avail *avail, 178 struct vring_used *used); 179 180 static inline void vringh_kiov_init(struct vringh_kiov *kiov, 181 struct kvec *kvec, unsigned num) 182 { 183 kiov->used = kiov->i = 0; 184 kiov->consumed = 0; 185 kiov->max_num = num; 186 kiov->iov = kvec; 187 } 188 189 static inline void vringh_kiov_reset(struct vringh_kiov *kiov) 190 { 191 kiov->iov[kiov->i].iov_len += kiov->consumed; 192 kiov->iov[kiov->i].iov_base -= kiov->consumed; 193 kiov->consumed = 0; 194 kiov->i = 0; 195 } 196 197 static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov) 198 { 199 if (kiov->max_num & VRINGH_IOV_ALLOCATED) 200 kfree(kiov->iov); 201 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0; 202 kiov->iov = NULL; 203 } 204 205 int vringh_getdesc_kern(struct vringh *vrh, 206 struct vringh_kiov *riov, 207 struct vringh_kiov *wiov, 208 u16 *head, 209 gfp_t gfp); 210 211 ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len); 212 ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 213 const void *src, size_t len); 214 void vringh_abandon_kern(struct vringh *vrh, unsigned int num); 215 int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len); 216 217 bool vringh_notify_enable_kern(struct vringh *vrh); 218 void vringh_notify_disable_kern(struct vringh *vrh); 219 220 int vringh_need_notify_kern(struct vringh *vrh); 221 222 /* Notify the guest about buffers added to the used ring */ 223 static inline void vringh_notify(struct vringh *vrh) 224 { 225 if (vrh->notify) 226 vrh->notify(vrh); 227 } 228 229 static inline bool vringh_is_little_endian(const struct vringh *vrh) 230 { 231 return vrh->little_endian || 232 virtio_legacy_is_little_endian(); 233 } 234 235 static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val) 236 { 237 return __virtio16_to_cpu(vringh_is_little_endian(vrh), val); 238 } 239 240 static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val) 241 { 242 return __cpu_to_virtio16(vringh_is_little_endian(vrh), val); 243 } 244 245 static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val) 246 { 247 return __virtio32_to_cpu(vringh_is_little_endian(vrh), val); 248 } 249 250 static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val) 251 { 252 return __cpu_to_virtio32(vringh_is_little_endian(vrh), val); 253 } 254 255 static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val) 256 { 257 return __virtio64_to_cpu(vringh_is_little_endian(vrh), val); 258 } 259 260 static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val) 261 { 262 return __cpu_to_virtio64(vringh_is_little_endian(vrh), val); 263 } 264 #endif /* _LINUX_VRINGH_H */ 265