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