1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2013 Chris Torek <torek @ torek net> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #ifndef _BHYVE_VIRTIO_H_ 30 #define _BHYVE_VIRTIO_H_ 31 32 #include <machine/atomic.h> 33 34 #include <dev/virtio/virtio.h> 35 #include <dev/virtio/virtio_ring.h> 36 #include <dev/virtio/pci/virtio_pci_var.h> 37 38 /* 39 * These are derived from several virtio specifications. 40 * 41 * Some useful links: 42 * https://github.com/rustyrussell/virtio-spec 43 * http://people.redhat.com/pbonzini/virtio-spec.pdf 44 */ 45 46 /* 47 * A virtual device has zero or more "virtual queues" (virtqueue). 48 * Each virtqueue uses at least two 4096-byte pages, laid out thus: 49 * 50 * +-----------------------------------------------+ 51 * | "desc": <N> descriptors, 16 bytes each | 52 * | ----------------------------------------- | 53 * | "avail": 2 uint16; <N> uint16; 1 uint16 | 54 * | ----------------------------------------- | 55 * | pad to 4k boundary | 56 * +-----------------------------------------------+ 57 * | "used": 2 x uint16; <N> elems; 1 uint16 | 58 * | ----------------------------------------- | 59 * | pad to 4k boundary | 60 * +-----------------------------------------------+ 61 * 62 * The number <N> that appears here is always a power of two and is 63 * limited to no more than 32768 (as it must fit in a 16-bit field). 64 * If <N> is sufficiently large, the above will occupy more than 65 * two pages. In any case, all pages must be physically contiguous 66 * within the guest's physical address space. 67 * 68 * The <N> 16-byte "desc" descriptors consist of a 64-bit guest 69 * physical address <addr>, a 32-bit length <len>, a 16-bit 70 * <flags>, and a 16-bit <next> field (all in guest byte order). 71 * 72 * There are three flags that may be set : 73 * NEXT descriptor is chained, so use its "next" field 74 * WRITE descriptor is for host to write into guest RAM 75 * (else host is to read from guest RAM) 76 * INDIRECT descriptor address field is (guest physical) 77 * address of a linear array of descriptors 78 * 79 * Unless INDIRECT is set, <len> is the number of bytes that may 80 * be read/written from guest physical address <addr>. If 81 * INDIRECT is set, WRITE is ignored and <len> provides the length 82 * of the indirect descriptors (and <len> must be a multiple of 83 * 16). Note that NEXT may still be set in the main descriptor 84 * pointing to the indirect, and should be set in each indirect 85 * descriptor that uses the next descriptor (these should generally 86 * be numbered sequentially). However, INDIRECT must not be set 87 * in the indirect descriptors. Upon reaching an indirect descriptor 88 * without a NEXT bit, control returns to the direct descriptors. 89 * 90 * Except inside an indirect, each <next> value must be in the 91 * range [0 .. N) (i.e., the half-open interval). (Inside an 92 * indirect, each <next> must be in the range [0 .. <len>/16).) 93 * 94 * The "avail" data structures reside in the same pages as the 95 * "desc" structures since both together are used by the device to 96 * pass information to the hypervisor's virtual driver. These 97 * begin with a 16-bit <flags> field and 16-bit index <idx>, then 98 * have <N> 16-bit <ring> values, followed by one final 16-bit 99 * field <used_event>. The <N> <ring> entries are simply indices 100 * indices into the descriptor ring (and thus must meet the same 101 * constraints as each <next> value). However, <idx> is counted 102 * up from 0 (initially) and simply wraps around after 65535; it 103 * is taken mod <N> to find the next available entry. 104 * 105 * The "used" ring occupies a separate page or pages, and contains 106 * values written from the virtual driver back to the guest OS. 107 * This begins with a 16-bit <flags> and 16-bit <idx>, then there 108 * are <N> "vring_used" elements, followed by a 16-bit <avail_event>. 109 * The <N> "vring_used" elements consist of a 32-bit <id> and a 110 * 32-bit <len> (vu_tlen below). The <id> is simply the index of 111 * the head of a descriptor chain the guest made available 112 * earlier, and the <len> is the number of bytes actually written, 113 * e.g., in the case of a network driver that provided a large 114 * receive buffer but received only a small amount of data. 115 * 116 * The two event fields, <used_event> and <avail_event>, in the 117 * avail and used rings (respectively -- note the reversal!), are 118 * always provided, but are used only if the virtual device 119 * negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature 120 * negotiation. Similarly, both rings provide a flag -- 121 * VRING_AVAIL_F_NO_INTERRUPT and VRING_USED_F_NO_NOTIFY -- in 122 * their <flags> field, indicating that the guest does not need an 123 * interrupt, or that the hypervisor driver does not need a 124 * notify, when descriptors are added to the corresponding ring. 125 * (These are provided only for interrupt optimization and need 126 * not be implemented.) 127 */ 128 #define VRING_ALIGN 4096 129 130 /* 131 * The address of any given virtual queue is determined by a single 132 * Page Frame Number register. The guest writes the PFN into the 133 * PCI config space. However, a device that has two or more 134 * virtqueues can have a different PFN, and size, for each queue. 135 * The number of queues is determinable via the PCI config space 136 * VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means 137 * queue #0, 1 means queue#1, etc. Once a queue is selected, the 138 * remaining PFN and QNUM registers refer to that queue. 139 * 140 * QNUM is a read-only register containing a nonzero power of two 141 * that indicates the (hypervisor's) queue size. Or, if reading it 142 * produces zero, the hypervisor does not have a corresponding 143 * queue. (The number of possible queues depends on the virtual 144 * device. The block device has just one; the network device 145 * provides either two -- 0 = receive, 1 = transmit -- or three, 146 * with 2 = control.) 147 * 148 * PFN is a read/write register giving the physical page address of 149 * the virtqueue in guest memory (the guest must allocate enough space 150 * based on the hypervisor's provided QNUM). 151 * 152 * QNOTIFY is effectively write-only: when the guest writes a queue 153 * number to the register, the hypervisor should scan the specified 154 * virtqueue. (Reading QNOTIFY currently always gets 0). 155 */ 156 157 /* 158 * PFN register shift amount 159 */ 160 #define VRING_PFN 12 161 162 /* 163 * PCI vendor/device IDs 164 */ 165 #define VIRTIO_VENDOR 0x1AF4 166 #define VIRTIO_DEV_NET 0x1000 167 #define VIRTIO_DEV_BLOCK 0x1001 168 #define VIRTIO_DEV_CONSOLE 0x1003 169 #define VIRTIO_DEV_SCSI 0x1004 170 #define VIRTIO_DEV_RANDOM 0x1005 171 #define VIRTIO_DEV_9P 0x1009 172 #define VIRTIO_DEV_INPUT 0x1052 173 174 /* 175 * PCI revision IDs 176 */ 177 #define VIRTIO_REV_INPUT 1 178 179 /* 180 * PCI subvendor IDs 181 */ 182 #define VIRTIO_SUBVEN_INPUT 0x108E 183 184 /* 185 * PCI subdevice IDs 186 */ 187 #define VIRTIO_SUBDEV_INPUT 0x1100 188 189 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 190 static inline int 191 vring_size_aligned(u_int qsz) 192 { 193 return (roundup2(vring_size(qsz, VRING_ALIGN), VRING_ALIGN)); 194 } 195 196 struct pci_devinst; 197 struct vqueue_info; 198 struct vm_snapshot_meta; 199 200 /* 201 * A virtual device, with some number (possibly 0) of virtual 202 * queues and some size (possibly 0) of configuration-space 203 * registers private to the device. The virtio_softc should come 204 * at the front of each "derived class", so that a pointer to the 205 * virtio_softc is also a pointer to the more specific, derived- 206 * from-virtio driver's softc. 207 * 208 * Note: inside each hypervisor virtio driver, changes to these 209 * data structures must be locked against other threads, if any. 210 * Except for PCI config space register read/write, we assume each 211 * driver does the required locking, but we need a pointer to the 212 * lock (if there is one) for PCI config space read/write ops. 213 * 214 * When the guest reads or writes the device's config space, the 215 * generic layer checks for operations on the special registers 216 * described above. If the offset of the register(s) being read 217 * or written is past the CFG area (CFG0 or CFG1), the request is 218 * passed on to the virtual device, after subtracting off the 219 * generic-layer size. (So, drivers can just use the offset as 220 * an offset into "struct config", for instance.) 221 * 222 * (The virtio layer also makes sure that the read or write is to/ 223 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 224 * However, the driver must verify the read or write size and offset 225 * and that no one is writing a readonly register.) 226 * 227 * The BROKED flag ("this thing done gone and broked") is for future 228 * use. 229 */ 230 #define VIRTIO_USE_MSIX 0x01 231 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 232 #define VIRTIO_BROKED 0x08 /* ??? */ 233 234 struct virtio_softc { 235 struct virtio_consts *vs_vc; /* constants (see below) */ 236 int vs_flags; /* VIRTIO_* flags from above */ 237 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 238 struct pci_devinst *vs_pi; /* PCI device instance */ 239 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 240 struct vqueue_info *vs_queues; /* one per vc_nvq */ 241 int vs_curq; /* current queue */ 242 uint8_t vs_status; /* value from last status write */ 243 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 244 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 245 }; 246 247 #define VS_LOCK(vs) \ 248 do { \ 249 if (vs->vs_mtx) \ 250 pthread_mutex_lock(vs->vs_mtx); \ 251 } while (0) 252 253 #define VS_UNLOCK(vs) \ 254 do { \ 255 if (vs->vs_mtx) \ 256 pthread_mutex_unlock(vs->vs_mtx); \ 257 } while (0) 258 259 struct virtio_consts { 260 const char *vc_name; /* name of driver (for diagnostics) */ 261 int vc_nvq; /* number of virtual queues */ 262 size_t vc_cfgsize; /* size of dev-specific config regs */ 263 void (*vc_reset)(void *); /* called on virtual device reset */ 264 void (*vc_qnotify)(void *, struct vqueue_info *); 265 /* called on QNOTIFY if no VQ notify */ 266 int (*vc_cfgread)(void *, int, int, uint32_t *); 267 /* called to read config regs */ 268 int (*vc_cfgwrite)(void *, int, int, uint32_t); 269 /* called to write config regs */ 270 void (*vc_apply_features)(void *, uint64_t); 271 /* called to apply negotiated features */ 272 uint64_t vc_hv_caps; /* hypervisor-provided capabilities */ 273 void (*vc_pause)(void *); /* called to pause device activity */ 274 void (*vc_resume)(void *); /* called to resume device activity */ 275 int (*vc_snapshot)(void *, struct vm_snapshot_meta *); 276 /* called to save / restore device state */ 277 }; 278 279 /* 280 * Data structure allocated (statically) per virtual queue. 281 * 282 * Drivers may change vq_qsize after a reset. When the guest OS 283 * requests a device reset, the hypervisor first calls 284 * vs->vs_vc->vc_reset(); then the data structure below is 285 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 286 * 287 * The remaining fields should only be fussed-with by the generic 288 * code. 289 * 290 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 291 * computable from each other, but it's a lot simpler if we just 292 * keep a pointer to each one. The event indices are similarly 293 * (but more easily) computable, and this time we'll compute them: 294 * they're just XX_ring[N]. 295 */ 296 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 297 #define VQ_BROKED 0x02 /* ??? */ 298 struct vqueue_info { 299 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 300 void (*vq_notify)(void *, struct vqueue_info *); 301 /* called instead of vc_notify, if not NULL */ 302 303 struct virtio_softc *vq_vs; /* backpointer to softc */ 304 uint16_t vq_num; /* we're the num'th queue in the softc */ 305 306 uint16_t vq_flags; /* flags (see above) */ 307 uint16_t vq_last_avail; /* a recent value of vq_avail->idx */ 308 uint16_t vq_next_used; /* index of the next used slot to be filled */ 309 uint16_t vq_save_used; /* saved vq_used->idx; see vq_endchains */ 310 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 311 312 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 313 314 struct vring_desc *vq_desc; /* descriptor array */ 315 struct vring_avail *vq_avail; /* the "avail" ring */ 316 struct vring_used *vq_used; /* the "used" ring */ 317 318 }; 319 /* as noted above, these are sort of backwards, name-wise */ 320 #define VQ_AVAIL_EVENT_IDX(vq) \ 321 (*(uint16_t *)&(vq)->vq_used->ring[(vq)->vq_qsize]) 322 #define VQ_USED_EVENT_IDX(vq) \ 323 ((vq)->vq_avail->ring[(vq)->vq_qsize]) 324 325 /* 326 * Is this ring ready for I/O? 327 */ 328 static inline int 329 vq_ring_ready(struct vqueue_info *vq) 330 { 331 332 return (vq->vq_flags & VQ_ALLOC); 333 } 334 335 /* 336 * Are there "available" descriptors? (This does not count 337 * how many, just returns True if there are some.) 338 */ 339 static inline int 340 vq_has_descs(struct vqueue_info *vq) 341 { 342 343 return (vq_ring_ready(vq) && vq->vq_last_avail != 344 vq->vq_avail->idx); 345 } 346 347 /* 348 * Deliver an interrupt to the guest for a specific MSI-X queue or 349 * event. 350 */ 351 static inline void 352 vi_interrupt(struct virtio_softc *vs, uint8_t isr, uint16_t msix_idx) 353 { 354 355 if (pci_msix_enabled(vs->vs_pi)) 356 pci_generate_msix(vs->vs_pi, msix_idx); 357 else { 358 VS_LOCK(vs); 359 vs->vs_isr |= isr; 360 pci_generate_msi(vs->vs_pi, 0); 361 pci_lintr_assert(vs->vs_pi); 362 VS_UNLOCK(vs); 363 } 364 } 365 366 /* 367 * Deliver an interrupt to the guest on the given virtual queue (if 368 * possible, or a generic MSI interrupt if not using MSI-X). 369 */ 370 static inline void 371 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 372 { 373 374 vi_interrupt(vs, VIRTIO_PCI_ISR_INTR, vq->vq_msix_idx); 375 } 376 377 static inline void 378 vq_kick_enable(struct vqueue_info *vq) 379 { 380 381 vq->vq_used->flags &= ~VRING_USED_F_NO_NOTIFY; 382 /* 383 * Full memory barrier to make sure the store to vq_used->flags 384 * happens before the load from vq_avail->idx, which results from a 385 * subsequent call to vq_has_descs(). 386 */ 387 atomic_thread_fence_seq_cst(); 388 } 389 390 static inline void 391 vq_kick_disable(struct vqueue_info *vq) 392 { 393 394 vq->vq_used->flags |= VRING_USED_F_NO_NOTIFY; 395 } 396 397 struct iovec; 398 399 /* 400 * Request description returned by vq_getchain. 401 * 402 * Writable iovecs start at iov[req.readable]. 403 */ 404 struct vi_req { 405 int readable; /* num of readable iovecs */ 406 int writable; /* num of writable iovecs */ 407 unsigned int idx; /* ring index */ 408 }; 409 410 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 411 void *dev_softc, struct pci_devinst *pi, 412 struct vqueue_info *queues); 413 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 414 void vi_reset_dev(struct virtio_softc *); 415 void vi_set_io_bar(struct virtio_softc *, int); 416 417 int vq_getchain(struct vqueue_info *vq, struct iovec *iov, int niov, 418 struct vi_req *reqp); 419 void vq_retchains(struct vqueue_info *vq, uint16_t n_chains); 420 void vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx, 421 uint32_t iolen); 422 void vq_relchain_publish(struct vqueue_info *vq); 423 void vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen); 424 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 425 426 uint64_t vi_pci_read(struct pci_devinst *pi, int baridx, uint64_t offset, 427 int size); 428 void vi_pci_write(struct pci_devinst *pi, int baridx, uint64_t offset, 429 int size, uint64_t value); 430 #ifdef BHYVE_SNAPSHOT 431 int vi_pci_snapshot(struct vm_snapshot_meta *meta); 432 int vi_pci_pause(struct pci_devinst *pi); 433 int vi_pci_resume(struct pci_devinst *pi); 434 #endif 435 #endif /* _BHYVE_VIRTIO_H_ */ 436