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