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 <pthread_np.h> 33 #include <machine/atomic.h> 34 35 #include <dev/virtio/virtio.h> 36 #ifdef __FreeBSD__ 37 #include <dev/virtio/virtio_ring.h> 38 #include <dev/virtio/pci/virtio_pci_var.h> 39 #endif 40 41 /* 42 * These are derived from several virtio specifications. 43 * 44 * Some useful links: 45 * https://github.com/rustyrussell/virtio-spec 46 * http://people.redhat.com/pbonzini/virtio-spec.pdf 47 */ 48 49 /* 50 * A virtual device has zero or more "virtual queues" (virtqueue). 51 * Each virtqueue uses at least two 4096-byte pages, laid out thus: 52 * 53 * +-----------------------------------------------+ 54 * | "desc": <N> descriptors, 16 bytes each | 55 * | ----------------------------------------- | 56 * | "avail": 2 uint16; <N> uint16; 1 uint16 | 57 * | ----------------------------------------- | 58 * | pad to 4k boundary | 59 * +-----------------------------------------------+ 60 * | "used": 2 x uint16; <N> elems; 1 uint16 | 61 * | ----------------------------------------- | 62 * | pad to 4k boundary | 63 * +-----------------------------------------------+ 64 * 65 * The number <N> that appears here is always a power of two and is 66 * limited to no more than 32768 (as it must fit in a 16-bit field). 67 * If <N> is sufficiently large, the above will occupy more than 68 * two pages. In any case, all pages must be physically contiguous 69 * within the guest's physical address space. 70 * 71 * The <N> 16-byte "desc" descriptors consist of a 64-bit guest 72 * physical address <addr>, a 32-bit length <len>, a 16-bit 73 * <flags>, and a 16-bit <next> field (all in guest byte order). 74 * 75 * There are three flags that may be set : 76 * NEXT descriptor is chained, so use its "next" field 77 * WRITE descriptor is for host to write into guest RAM 78 * (else host is to read from guest RAM) 79 * INDIRECT descriptor address field is (guest physical) 80 * address of a linear array of descriptors 81 * 82 * Unless INDIRECT is set, <len> is the number of bytes that may 83 * be read/written from guest physical address <addr>. If 84 * INDIRECT is set, WRITE is ignored and <len> provides the length 85 * of the indirect descriptors (and <len> must be a multiple of 86 * 16). Note that NEXT may still be set in the main descriptor 87 * pointing to the indirect, and should be set in each indirect 88 * descriptor that uses the next descriptor (these should generally 89 * be numbered sequentially). However, INDIRECT must not be set 90 * in the indirect descriptors. Upon reaching an indirect descriptor 91 * without a NEXT bit, control returns to the direct descriptors. 92 * 93 * Except inside an indirect, each <next> value must be in the 94 * range [0 .. N) (i.e., the half-open interval). (Inside an 95 * indirect, each <next> must be in the range [0 .. <len>/16).) 96 * 97 * The "avail" data structures reside in the same pages as the 98 * "desc" structures since both together are used by the device to 99 * pass information to the hypervisor's virtual driver. These 100 * begin with a 16-bit <flags> field and 16-bit index <idx>, then 101 * have <N> 16-bit <ring> values, followed by one final 16-bit 102 * field <used_event>. The <N> <ring> entries are simply indices 103 * into the descriptor ring (and thus must meet the same 104 * constraints as each <next> value). However, <idx> is counted 105 * up from 0 (initially) and simply wraps around after 65535; it 106 * is taken mod <N> to find the next available entry. 107 * 108 * The "used" ring occupies a separate page or pages, and contains 109 * values written from the virtual driver back to the guest OS. 110 * This begins with a 16-bit <flags> and 16-bit <idx>, then there 111 * are <N> "vring_used" elements, followed by a 16-bit <avail_event>. 112 * The <N> "vring_used" elements consist of a 32-bit <id> and a 113 * 32-bit <len> (vu_tlen below). The <id> is simply the index of 114 * the head of a descriptor chain the guest made available 115 * earlier, and the <len> is the number of bytes actually written, 116 * e.g., in the case of a network driver that provided a large 117 * receive buffer but received only a small amount of data. 118 * 119 * The two event fields, <used_event> and <avail_event>, in the 120 * avail and used rings (respectively -- note the reversal!), are 121 * always provided, but are used only if the virtual device 122 * negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature 123 * negotiation. Similarly, both rings provide a flag -- 124 * VRING_AVAIL_F_NO_INTERRUPT and VRING_USED_F_NO_NOTIFY -- in 125 * their <flags> field, indicating that the guest does not need an 126 * interrupt, or that the hypervisor driver does not need a 127 * notify, when descriptors are added to the corresponding ring. 128 * (These are provided only for interrupt optimization and need 129 * not be implemented.) 130 */ 131 #define VRING_ALIGN 4096 132 133 /* 134 * The address of any given virtual queue is determined by a single 135 * Page Frame Number register. The guest writes the PFN into the 136 * PCI config space. However, a device that has two or more 137 * virtqueues can have a different PFN, and size, for each queue. 138 * The number of queues is determinable via the PCI config space 139 * VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means 140 * queue #0, 1 means queue#1, etc. Once a queue is selected, the 141 * remaining PFN and QNUM registers refer to that queue. 142 * 143 * QNUM is a read-only register containing a nonzero power of two 144 * that indicates the (hypervisor's) queue size. Or, if reading it 145 * produces zero, the hypervisor does not have a corresponding 146 * queue. (The number of possible queues depends on the virtual 147 * device. The block device has just one; the network device 148 * provides either two -- 0 = receive, 1 = transmit -- or three, 149 * with 2 = control.) 150 * 151 * PFN is a read/write register giving the physical page address of 152 * the virtqueue in guest memory (the guest must allocate enough space 153 * based on the hypervisor's provided QNUM). 154 * 155 * QNOTIFY is effectively write-only: when the guest writes a queue 156 * number to the register, the hypervisor should scan the specified 157 * virtqueue. (Reading QNOTIFY currently always gets 0). 158 */ 159 160 /* 161 * PFN register shift amount 162 */ 163 #define VRING_PFN 12 164 165 /* 166 * PCI vendor/device IDs 167 */ 168 #define VIRTIO_VENDOR 0x1AF4 169 #define VIRTIO_DEV_NET 0x1000 170 #define VIRTIO_DEV_BLOCK 0x1001 171 #define VIRTIO_DEV_CONSOLE 0x1003 172 #define VIRTIO_DEV_SCSI 0x1004 173 #define VIRTIO_DEV_RANDOM 0x1005 174 #define VIRTIO_DEV_9P 0x1009 175 #define VIRTIO_DEV_INPUT 0x1052 176 177 /* 178 * PCI revision IDs 179 */ 180 #define VIRTIO_REV_INPUT 1 181 182 /* 183 * PCI subvendor IDs 184 */ 185 #define VIRTIO_SUBVEN_INPUT 0x108E 186 187 /* 188 * PCI subdevice IDs 189 */ 190 #define VIRTIO_SUBDEV_INPUT 0x1100 191 192 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 193 static inline int 194 vring_size_aligned(u_int qsz) 195 { 196 return (roundup2(vring_size(qsz, VRING_ALIGN), VRING_ALIGN)); 197 } 198 199 struct pci_devinst; 200 struct vqueue_info; 201 202 /* 203 * A virtual device, with some number (possibly 0) of virtual 204 * queues and some size (possibly 0) of configuration-space 205 * registers private to the device. The virtio_softc should come 206 * at the front of each "derived class", so that a pointer to the 207 * virtio_softc is also a pointer to the more specific, derived- 208 * from-virtio driver's softc. 209 * 210 * Note: inside each hypervisor virtio driver, changes to these 211 * data structures must be locked against other threads, if any. 212 * Except for PCI config space register read/write, we assume each 213 * driver does the required locking, but we need a pointer to the 214 * lock (if there is one) for PCI config space read/write ops. 215 * 216 * When the guest reads or writes the device's config space, the 217 * generic layer checks for operations on the special registers 218 * described above. If the offset of the register(s) being read 219 * or written is past the CFG area (CFG0 or CFG1), the request is 220 * passed on to the virtual device, after subtracting off the 221 * generic-layer size. (So, drivers can just use the offset as 222 * an offset into "struct config", for instance.) 223 * 224 * (The virtio layer also makes sure that the read or write is to/ 225 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 226 * However, the driver must verify the read or write size and offset 227 * and that no one is writing a readonly register.) 228 * 229 * The BROKED flag ("this thing done gone and broked") is for future 230 * use. 231 */ 232 #define VIRTIO_USE_MSIX 0x01 233 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 234 #define VIRTIO_BROKED 0x08 /* ??? */ 235 236 struct virtio_softc { 237 struct virtio_consts *vs_vc; /* constants (see below) */ 238 int vs_flags; /* VIRTIO_* flags from above */ 239 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 240 struct pci_devinst *vs_pi; /* PCI device instance */ 241 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 242 struct vqueue_info *vs_queues; /* one per vc_nvq */ 243 int vs_curq; /* current queue */ 244 uint8_t vs_status; /* value from last status write */ 245 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 246 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 247 }; 248 249 #define VS_LOCK(vs) \ 250 do { \ 251 if (vs->vs_mtx) \ 252 pthread_mutex_lock(vs->vs_mtx); \ 253 } while (0) 254 255 #define VS_UNLOCK(vs) \ 256 do { \ 257 if (vs->vs_mtx) \ 258 pthread_mutex_unlock(vs->vs_mtx); \ 259 } while (0) 260 261 struct virtio_consts { 262 const char *vc_name; /* name of driver (for diagnostics) */ 263 int vc_nvq; /* number of virtual queues */ 264 size_t vc_cfgsize; /* size of dev-specific config regs */ 265 void (*vc_reset)(void *); /* called on virtual device reset */ 266 void (*vc_qnotify)(void *, struct vqueue_info *); 267 /* called on QNOTIFY if no VQ notify */ 268 int (*vc_cfgread)(void *, int, int, uint32_t *); 269 /* called to read config regs */ 270 int (*vc_cfgwrite)(void *, int, int, uint32_t); 271 /* called to write config regs */ 272 void (*vc_apply_features)(void *, uint64_t); 273 /* called to apply negotiated features */ 274 uint64_t vc_hv_caps; /* hypervisor-provided capabilities */ 275 }; 276 277 /* 278 * Data structure allocated (statically) per virtual queue. 279 * 280 * Drivers may change vq_qsize after a reset. When the guest OS 281 * requests a device reset, the hypervisor first calls 282 * vs->vs_vc->vc_reset(); then the data structure below is 283 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 284 * 285 * The remaining fields should only be fussed-with by the generic 286 * code. 287 * 288 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 289 * computable from each other, but it's a lot simpler if we just 290 * keep a pointer to each one. The event indices are similarly 291 * (but more easily) computable, and this time we'll compute them: 292 * they're just XX_ring[N]. 293 */ 294 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 295 #define VQ_BROKED 0x02 /* ??? */ 296 struct vqueue_info { 297 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 298 void (*vq_notify)(void *, struct vqueue_info *); 299 /* called instead of vc_notify, if not NULL */ 300 301 struct virtio_softc *vq_vs; /* backpointer to softc */ 302 uint16_t vq_num; /* we're the num'th queue in the softc */ 303 304 uint16_t vq_flags; /* flags (see above) */ 305 uint16_t vq_last_avail; /* a recent value of vq_avail->idx */ 306 uint16_t vq_next_used; /* index of the next used slot to be filled */ 307 uint16_t vq_save_used; /* saved vq_used->idx; see vq_endchains */ 308 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 309 310 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 311 312 struct vring_desc *vq_desc; /* descriptor array */ 313 struct vring_avail *vq_avail; /* the "avail" ring */ 314 struct vring_used *vq_used; /* the "used" ring */ 315 316 }; 317 /* as noted above, these are sort of backwards, name-wise */ 318 #define VQ_AVAIL_EVENT_IDX(vq) \ 319 (*(uint16_t *)&(vq)->vq_used->ring[(vq)->vq_qsize]) 320 #define VQ_USED_EVENT_IDX(vq) \ 321 ((vq)->vq_avail->ring[(vq)->vq_qsize]) 322 323 /* 324 * Is this ring ready for I/O? 325 */ 326 static inline int 327 vq_ring_ready(struct vqueue_info *vq) 328 { 329 330 return (vq->vq_flags & VQ_ALLOC); 331 } 332 333 /* 334 * Are there "available" descriptors? (This does not count 335 * how many, just returns True if there are some.) 336 */ 337 static inline int 338 vq_has_descs(struct vqueue_info *vq) 339 { 340 341 return (vq_ring_ready(vq) && vq->vq_last_avail != 342 vq->vq_avail->idx); 343 } 344 345 /* 346 * Deliver an interrupt to the guest for a specific MSI-X queue or 347 * event. 348 */ 349 static inline void 350 vi_interrupt(struct virtio_softc *vs, uint8_t isr, uint16_t msix_idx) 351 { 352 353 if (pci_msix_enabled(vs->vs_pi)) 354 pci_generate_msix(vs->vs_pi, msix_idx); 355 else { 356 #ifndef __FreeBSD__ 357 boolean_t unlock = B_FALSE; 358 359 if (vs->vs_mtx && !pthread_mutex_isowned_np(vs->vs_mtx)) { 360 unlock = B_TRUE; 361 pthread_mutex_lock(vs->vs_mtx); 362 } 363 #else 364 VS_LOCK(vs); 365 #endif 366 vs->vs_isr |= isr; 367 pci_generate_msi(vs->vs_pi, 0); 368 pci_lintr_assert(vs->vs_pi); 369 #ifndef __FreeBSD__ 370 if (unlock) 371 pthread_mutex_unlock(vs->vs_mtx); 372 #else 373 VS_UNLOCK(vs); 374 #endif 375 } 376 } 377 378 /* 379 * Deliver an interrupt to the guest on the given virtual queue (if 380 * possible, or a generic MSI interrupt if not using MSI-X). 381 */ 382 static inline void 383 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 384 { 385 386 vi_interrupt(vs, VIRTIO_PCI_ISR_INTR, vq->vq_msix_idx); 387 } 388 389 static inline void 390 vq_kick_enable(struct vqueue_info *vq) 391 { 392 393 vq->vq_used->flags &= ~VRING_USED_F_NO_NOTIFY; 394 /* 395 * Full memory barrier to make sure the store to vq_used->flags 396 * happens before the load from vq_avail->idx, which results from a 397 * subsequent call to vq_has_descs(). 398 */ 399 atomic_thread_fence_seq_cst(); 400 } 401 402 static inline void 403 vq_kick_disable(struct vqueue_info *vq) 404 { 405 406 vq->vq_used->flags |= VRING_USED_F_NO_NOTIFY; 407 } 408 409 struct iovec; 410 411 /* 412 * Request description returned by vq_getchain. 413 * 414 * Writable iovecs start at iov[req.readable]. 415 */ 416 struct vi_req { 417 int readable; /* num of readable iovecs */ 418 int writable; /* num of writable iovecs */ 419 unsigned int idx; /* ring index */ 420 }; 421 422 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 423 void *dev_softc, struct pci_devinst *pi, 424 struct vqueue_info *queues); 425 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 426 void vi_reset_dev(struct virtio_softc *); 427 void vi_set_io_bar(struct virtio_softc *, int); 428 429 int vq_getchain(struct vqueue_info *vq, struct iovec *iov, int niov, 430 struct vi_req *reqp); 431 void vq_retchains(struct vqueue_info *vq, uint16_t n_chains); 432 void vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx, 433 uint32_t iolen); 434 void vq_relchain_publish(struct vqueue_info *vq); 435 void vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen); 436 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 437 438 uint64_t vi_pci_read(struct pci_devinst *pi, int baridx, uint64_t offset, 439 int size); 440 void vi_pci_write(struct pci_devinst *pi, int baridx, uint64_t offset, 441 int size, uint64_t value); 442 443 #ifndef __FreeBSD__ 444 void vi_vq_init(struct virtio_softc *, uint32_t); 445 #endif 446 447 #endif /* _BHYVE_VIRTIO_H_ */ 448