1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Linux host-side vring helpers; for when the kernel needs to access 4 * someone else's vring. 5 * 6 * Copyright IBM Corporation, 2013. 7 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc. 8 * 9 * Written by: Rusty Russell <rusty@rustcorp.com.au> 10 */ 11 #ifndef _LINUX_VRINGH_H 12 #define _LINUX_VRINGH_H 13 #include <uapi/linux/virtio_ring.h> 14 #include <linux/virtio_byteorder.h> 15 #include <linux/uio.h> 16 #include <linux/slab.h> 17 #include <linux/spinlock.h> 18 #if IS_REACHABLE(CONFIG_VHOST_IOTLB) 19 #include <linux/dma-direction.h> 20 #include <linux/vhost_iotlb.h> 21 #endif 22 #include <asm/barrier.h> 23 24 /* virtio_ring with information needed for host access. */ 25 struct vringh { 26 /* Everything is little endian */ 27 bool little_endian; 28 29 /* Guest publishes used event idx (note: we always do). */ 30 bool event_indices; 31 32 /* Can we get away with weak barriers? */ 33 bool weak_barriers; 34 35 /* Use user's VA */ 36 bool use_va; 37 38 /* Last available index we saw (ie. where we're up to). */ 39 u16 last_avail_idx; 40 41 /* Last index we used. */ 42 u16 last_used_idx; 43 44 /* How many descriptors we've completed since last need_notify(). */ 45 u32 completed; 46 47 /* The vring (note: it may contain user pointers!) */ 48 struct vring vring; 49 50 /* IOTLB for this vring */ 51 struct vhost_iotlb *iotlb; 52 53 /* spinlock to synchronize IOTLB accesses */ 54 spinlock_t *iotlb_lock; 55 56 /* The function to call to notify the guest about added buffers */ 57 void (*notify)(struct vringh *); 58 }; 59 60 struct virtio_device; 61 typedef void vrh_callback_t(struct virtio_device *, struct vringh *); 62 63 /** 64 * struct vringh_config_ops - ops for creating a host vring from a virtio driver 65 * @find_vrhs: find the host vrings and instantiate them 66 * vdev: the virtio_device 67 * nhvrs: the number of host vrings to find 68 * hvrs: on success, includes new host vrings 69 * callbacks: array of driver callbacks, for each host vring 70 * include a NULL entry for vqs that do not need a callback 71 * Returns 0 on success or error status 72 * @del_vrhs: free the host vrings found by find_vrhs(). 73 */ 74 struct vringh_config_ops { 75 int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs, 76 struct vringh *vrhs[], vrh_callback_t *callbacks[]); 77 void (*del_vrhs)(struct virtio_device *vdev); 78 }; 79 80 /* The memory the vring can access, and what offset to apply. */ 81 struct vringh_range { 82 u64 start, end_incl; 83 u64 offset; 84 }; 85 86 /** 87 * struct vringh_iov - iovec mangler. 88 * @iov: array of iovecs to operate on 89 * @consumed: number of bytes consumed within iov[i] 90 * @i: index of current iovec 91 * @used: number of iovecs present in @iov 92 * @max_num: maximum number of iovecs. 93 * corresponds to allocated memory of @iov 94 * 95 * Mangles iovec in place, and restores it. 96 * Remaining data is iov + i, of used - i elements. 97 */ 98 struct vringh_iov { 99 struct iovec *iov; 100 size_t consumed; /* Within iov[i] */ 101 unsigned i, used, max_num; 102 }; 103 104 /** 105 * struct vringh_kiov - kvec mangler. 106 * @iov: array of iovecs to operate on 107 * @consumed: number of bytes consumed within iov[i] 108 * @i: index of current iovec 109 * @used: number of iovecs present in @iov 110 * @max_num: maximum number of iovecs. 111 * corresponds to allocated memory of @iov 112 * 113 * Mangles kvec in place, and restores it. 114 * Remaining data is iov + i, of used - i elements. 115 */ 116 struct vringh_kiov { 117 struct kvec *iov; 118 size_t consumed; /* Within iov[i] */ 119 unsigned i, used, max_num; 120 }; 121 122 /* Flag on max_num to indicate we're kmalloced. */ 123 #define VRINGH_IOV_ALLOCATED 0x8000000 124 125 /* Helpers for userspace vrings. */ 126 int vringh_init_user(struct vringh *vrh, u64 features, 127 unsigned int num, bool weak_barriers, 128 vring_desc_t __user *desc, 129 vring_avail_t __user *avail, 130 vring_used_t __user *used); 131 vringh_iov_init(struct vringh_iov * iov,struct iovec * iovec,unsigned num)132 static inline void vringh_iov_init(struct vringh_iov *iov, 133 struct iovec *iovec, unsigned num) 134 { 135 iov->used = iov->i = 0; 136 iov->consumed = 0; 137 iov->max_num = num; 138 iov->iov = iovec; 139 } 140 vringh_iov_reset(struct vringh_iov * iov)141 static inline void vringh_iov_reset(struct vringh_iov *iov) 142 { 143 iov->iov[iov->i].iov_len += iov->consumed; 144 iov->iov[iov->i].iov_base -= iov->consumed; 145 iov->consumed = 0; 146 iov->i = 0; 147 } 148 vringh_iov_cleanup(struct vringh_iov * iov)149 static inline void vringh_iov_cleanup(struct vringh_iov *iov) 150 { 151 if (iov->max_num & VRINGH_IOV_ALLOCATED) 152 kfree(iov->iov); 153 iov->max_num = iov->used = iov->i = iov->consumed = 0; 154 iov->iov = NULL; 155 } 156 157 /* Convert a descriptor into iovecs. */ 158 int vringh_getdesc_user(struct vringh *vrh, 159 struct vringh_iov *riov, 160 struct vringh_iov *wiov, 161 bool (*getrange)(struct vringh *vrh, 162 u64 addr, struct vringh_range *r), 163 u16 *head); 164 165 /* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */ 166 ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len); 167 168 /* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */ 169 ssize_t vringh_iov_push_user(struct vringh_iov *wiov, 170 const void *src, size_t len); 171 172 /* Mark a descriptor as used. */ 173 int vringh_complete_user(struct vringh *vrh, u16 head, u32 len); 174 int vringh_complete_multi_user(struct vringh *vrh, 175 const struct vring_used_elem used[], 176 unsigned num_used); 177 178 /* Pretend we've never seen descriptor (for easy error handling). */ 179 void vringh_abandon_user(struct vringh *vrh, unsigned int num); 180 181 /* Do we need to fire the eventfd to notify the other side? */ 182 int vringh_need_notify_user(struct vringh *vrh); 183 184 bool vringh_notify_enable_user(struct vringh *vrh); 185 void vringh_notify_disable_user(struct vringh *vrh); 186 187 /* Helpers for kernelspace vrings. */ 188 int vringh_init_kern(struct vringh *vrh, u64 features, 189 unsigned int num, bool weak_barriers, 190 struct vring_desc *desc, 191 struct vring_avail *avail, 192 struct vring_used *used); 193 vringh_kiov_init(struct vringh_kiov * kiov,struct kvec * kvec,unsigned num)194 static inline void vringh_kiov_init(struct vringh_kiov *kiov, 195 struct kvec *kvec, unsigned num) 196 { 197 kiov->used = kiov->i = 0; 198 kiov->consumed = 0; 199 kiov->max_num = num; 200 kiov->iov = kvec; 201 } 202 vringh_kiov_reset(struct vringh_kiov * kiov)203 static inline void vringh_kiov_reset(struct vringh_kiov *kiov) 204 { 205 kiov->iov[kiov->i].iov_len += kiov->consumed; 206 kiov->iov[kiov->i].iov_base -= kiov->consumed; 207 kiov->consumed = 0; 208 kiov->i = 0; 209 } 210 vringh_kiov_cleanup(struct vringh_kiov * kiov)211 static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov) 212 { 213 if (kiov->max_num & VRINGH_IOV_ALLOCATED) 214 kfree(kiov->iov); 215 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0; 216 kiov->iov = NULL; 217 } 218 vringh_kiov_length(struct vringh_kiov * kiov)219 static inline size_t vringh_kiov_length(struct vringh_kiov *kiov) 220 { 221 size_t len = 0; 222 int i; 223 224 for (i = kiov->i; i < kiov->used; i++) 225 len += kiov->iov[i].iov_len; 226 227 return len; 228 } 229 230 void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len); 231 232 int vringh_getdesc_kern(struct vringh *vrh, 233 struct vringh_kiov *riov, 234 struct vringh_kiov *wiov, 235 u16 *head, 236 gfp_t gfp); 237 238 ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len); 239 ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov, 240 const void *src, size_t len); 241 void vringh_abandon_kern(struct vringh *vrh, unsigned int num); 242 int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len); 243 244 bool vringh_notify_enable_kern(struct vringh *vrh); 245 void vringh_notify_disable_kern(struct vringh *vrh); 246 247 int vringh_need_notify_kern(struct vringh *vrh); 248 249 /* Notify the guest about buffers added to the used ring */ vringh_notify(struct vringh * vrh)250 static inline void vringh_notify(struct vringh *vrh) 251 { 252 if (vrh->notify) 253 vrh->notify(vrh); 254 } 255 vringh_is_little_endian(const struct vringh * vrh)256 static inline bool vringh_is_little_endian(const struct vringh *vrh) 257 { 258 return vrh->little_endian || 259 virtio_legacy_is_little_endian(); 260 } 261 vringh16_to_cpu(const struct vringh * vrh,__virtio16 val)262 static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val) 263 { 264 return __virtio16_to_cpu(vringh_is_little_endian(vrh), val); 265 } 266 cpu_to_vringh16(const struct vringh * vrh,u16 val)267 static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val) 268 { 269 return __cpu_to_virtio16(vringh_is_little_endian(vrh), val); 270 } 271 vringh32_to_cpu(const struct vringh * vrh,__virtio32 val)272 static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val) 273 { 274 return __virtio32_to_cpu(vringh_is_little_endian(vrh), val); 275 } 276 cpu_to_vringh32(const struct vringh * vrh,u32 val)277 static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val) 278 { 279 return __cpu_to_virtio32(vringh_is_little_endian(vrh), val); 280 } 281 vringh64_to_cpu(const struct vringh * vrh,__virtio64 val)282 static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val) 283 { 284 return __virtio64_to_cpu(vringh_is_little_endian(vrh), val); 285 } 286 cpu_to_vringh64(const struct vringh * vrh,u64 val)287 static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val) 288 { 289 return __cpu_to_virtio64(vringh_is_little_endian(vrh), val); 290 } 291 292 #if IS_REACHABLE(CONFIG_VHOST_IOTLB) 293 294 void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb, 295 spinlock_t *iotlb_lock); 296 297 int vringh_init_iotlb(struct vringh *vrh, u64 features, 298 unsigned int num, bool weak_barriers, 299 struct vring_desc *desc, 300 struct vring_avail *avail, 301 struct vring_used *used); 302 303 int vringh_init_iotlb_va(struct vringh *vrh, u64 features, 304 unsigned int num, bool weak_barriers, 305 struct vring_desc *desc, 306 struct vring_avail *avail, 307 struct vring_used *used); 308 309 int vringh_getdesc_iotlb(struct vringh *vrh, 310 struct vringh_kiov *riov, 311 struct vringh_kiov *wiov, 312 u16 *head, 313 gfp_t gfp); 314 315 ssize_t vringh_iov_pull_iotlb(struct vringh *vrh, 316 struct vringh_kiov *riov, 317 void *dst, size_t len); 318 ssize_t vringh_iov_push_iotlb(struct vringh *vrh, 319 struct vringh_kiov *wiov, 320 const void *src, size_t len); 321 322 void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num); 323 324 int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len); 325 326 bool vringh_notify_enable_iotlb(struct vringh *vrh); 327 void vringh_notify_disable_iotlb(struct vringh *vrh); 328 329 int vringh_need_notify_iotlb(struct vringh *vrh); 330 331 #endif /* CONFIG_VHOST_IOTLB */ 332 333 #endif /* _LINUX_VRINGH_H */ 334