1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 * $FreeBSD$ 29 */ 30 31 #ifndef _BHYVE_VIRTIO_H_ 32 #define _BHYVE_VIRTIO_H_ 33 34 #include <pthread_np.h> 35 #include <machine/atomic.h> 36 37 #include <dev/virtio/virtio.h> 38 #ifdef __FreeBSD__ 39 #include <dev/virtio/virtio_ring.h> 40 #include <dev/virtio/pci/virtio_pci_var.h> 41 #endif 42 43 /* 44 * These are derived from several virtio specifications. 45 * 46 * Some useful links: 47 * https://github.com/rustyrussell/virtio-spec 48 * http://people.redhat.com/pbonzini/virtio-spec.pdf 49 */ 50 51 /* 52 * A virtual device has zero or more "virtual queues" (virtqueue). 53 * Each virtqueue uses at least two 4096-byte pages, laid out thus: 54 * 55 * +-----------------------------------------------+ 56 * | "desc": <N> descriptors, 16 bytes each | 57 * | ----------------------------------------- | 58 * | "avail": 2 uint16; <N> uint16; 1 uint16 | 59 * | ----------------------------------------- | 60 * | pad to 4k boundary | 61 * +-----------------------------------------------+ 62 * | "used": 2 x uint16; <N> elems; 1 uint16 | 63 * | ----------------------------------------- | 64 * | pad to 4k boundary | 65 * +-----------------------------------------------+ 66 * 67 * The number <N> that appears here is always a power of two and is 68 * limited to no more than 32768 (as it must fit in a 16-bit field). 69 * If <N> is sufficiently large, the above will occupy more than 70 * two pages. In any case, all pages must be physically contiguous 71 * within the guest's physical address space. 72 * 73 * The <N> 16-byte "desc" descriptors consist of a 64-bit guest 74 * physical address <addr>, a 32-bit length <len>, a 16-bit 75 * <flags>, and a 16-bit <next> field (all in guest byte order). 76 * 77 * There are three flags that may be set : 78 * NEXT descriptor is chained, so use its "next" field 79 * WRITE descriptor is for host to write into guest RAM 80 * (else host is to read from guest RAM) 81 * INDIRECT descriptor address field is (guest physical) 82 * address of a linear array of descriptors 83 * 84 * Unless INDIRECT is set, <len> is the number of bytes that may 85 * be read/written from guest physical address <addr>. If 86 * INDIRECT is set, WRITE is ignored and <len> provides the length 87 * of the indirect descriptors (and <len> must be a multiple of 88 * 16). Note that NEXT may still be set in the main descriptor 89 * pointing to the indirect, and should be set in each indirect 90 * descriptor that uses the next descriptor (these should generally 91 * be numbered sequentially). However, INDIRECT must not be set 92 * in the indirect descriptors. Upon reaching an indirect descriptor 93 * without a NEXT bit, control returns to the direct descriptors. 94 * 95 * Except inside an indirect, each <next> value must be in the 96 * range [0 .. N) (i.e., the half-open interval). (Inside an 97 * indirect, each <next> must be in the range [0 .. <len>/16).) 98 * 99 * The "avail" data structures reside in the same pages as the 100 * "desc" structures since both together are used by the device to 101 * pass information to the hypervisor's virtual driver. These 102 * begin with a 16-bit <flags> field and 16-bit index <idx>, then 103 * have <N> 16-bit <ring> values, followed by one final 16-bit 104 * field <used_event>. The <N> <ring> entries are simply indices 105 * indices into the descriptor ring (and thus must meet the same 106 * constraints as each <next> value). However, <idx> is counted 107 * up from 0 (initially) and simply wraps around after 65535; it 108 * is taken mod <N> to find the next available entry. 109 * 110 * The "used" ring occupies a separate page or pages, and contains 111 * values written from the virtual driver back to the guest OS. 112 * This begins with a 16-bit <flags> and 16-bit <idx>, then there 113 * are <N> "vring_used" elements, followed by a 16-bit <avail_event>. 114 * The <N> "vring_used" elements consist of a 32-bit <id> and a 115 * 32-bit <len> (vu_tlen below). The <id> is simply the index of 116 * the head of a descriptor chain the guest made available 117 * earlier, and the <len> is the number of bytes actually written, 118 * e.g., in the case of a network driver that provided a large 119 * receive buffer but received only a small amount of data. 120 * 121 * The two event fields, <used_event> and <avail_event>, in the 122 * avail and used rings (respectively -- note the reversal!), are 123 * always provided, but are used only if the virtual device 124 * negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature 125 * negotiation. Similarly, both rings provide a flag -- 126 * VRING_AVAIL_F_NO_INTERRUPT and VRING_USED_F_NO_NOTIFY -- in 127 * their <flags> field, indicating that the guest does not need an 128 * interrupt, or that the hypervisor driver does not need a 129 * notify, when descriptors are added to the corresponding ring. 130 * (These are provided only for interrupt optimization and need 131 * not be implemented.) 132 */ 133 #define VRING_ALIGN 4096 134 135 /* 136 * The address of any given virtual queue is determined by a single 137 * Page Frame Number register. The guest writes the PFN into the 138 * PCI config space. However, a device that has two or more 139 * virtqueues can have a different PFN, and size, for each queue. 140 * The number of queues is determinable via the PCI config space 141 * VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means 142 * queue #0, 1 means queue#1, etc. Once a queue is selected, the 143 * remaining PFN and QNUM registers refer to that queue. 144 * 145 * QNUM is a read-only register containing a nonzero power of two 146 * that indicates the (hypervisor's) queue size. Or, if reading it 147 * produces zero, the hypervisor does not have a corresponding 148 * queue. (The number of possible queues depends on the virtual 149 * device. The block device has just one; the network device 150 * provides either two -- 0 = receive, 1 = transmit -- or three, 151 * with 2 = control.) 152 * 153 * PFN is a read/write register giving the physical page address of 154 * the virtqueue in guest memory (the guest must allocate enough space 155 * based on the hypervisor's provided QNUM). 156 * 157 * QNOTIFY is effectively write-only: when the guest writes a queue 158 * number to the register, the hypervisor should scan the specified 159 * virtqueue. (Reading QNOTIFY currently always gets 0). 160 */ 161 162 /* 163 * PFN register shift amount 164 */ 165 #define VRING_PFN 12 166 167 /* 168 * PCI vendor/device IDs 169 */ 170 #define VIRTIO_VENDOR 0x1AF4 171 #define VIRTIO_DEV_NET 0x1000 172 #define VIRTIO_DEV_BLOCK 0x1001 173 #define VIRTIO_DEV_CONSOLE 0x1003 174 #define VIRTIO_DEV_SCSI 0x1004 175 #define VIRTIO_DEV_RANDOM 0x1005 176 #define VIRTIO_DEV_9P 0x1009 177 #define VIRTIO_DEV_INPUT 0x1052 178 179 /* 180 * PCI revision IDs 181 */ 182 #define VIRTIO_REV_INPUT 1 183 184 /* 185 * PCI subvendor IDs 186 */ 187 #define VIRTIO_SUBVEN_INPUT 0x108E 188 189 /* 190 * PCI subdevice IDs 191 */ 192 #define VIRTIO_SUBDEV_INPUT 0x1100 193 194 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 195 static inline int 196 vring_size_aligned(u_int qsz) 197 { 198 return (roundup2(vring_size(qsz, VRING_ALIGN), VRING_ALIGN)); 199 } 200 201 struct vmctx; 202 struct pci_devinst; 203 struct vqueue_info; 204 205 /* 206 * A virtual device, with some number (possibly 0) of virtual 207 * queues and some size (possibly 0) of configuration-space 208 * registers private to the device. The virtio_softc should come 209 * at the front of each "derived class", so that a pointer to the 210 * virtio_softc is also a pointer to the more specific, derived- 211 * from-virtio driver's softc. 212 * 213 * Note: inside each hypervisor virtio driver, changes to these 214 * data structures must be locked against other threads, if any. 215 * Except for PCI config space register read/write, we assume each 216 * driver does the required locking, but we need a pointer to the 217 * lock (if there is one) for PCI config space read/write ops. 218 * 219 * When the guest reads or writes the device's config space, the 220 * generic layer checks for operations on the special registers 221 * described above. If the offset of the register(s) being read 222 * or written is past the CFG area (CFG0 or CFG1), the request is 223 * passed on to the virtual device, after subtracting off the 224 * generic-layer size. (So, drivers can just use the offset as 225 * an offset into "struct config", for instance.) 226 * 227 * (The virtio layer also makes sure that the read or write is to/ 228 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 229 * However, the driver must verify the read or write size and offset 230 * and that no one is writing a readonly register.) 231 * 232 * The BROKED flag ("this thing done gone and broked") is for future 233 * use. 234 */ 235 #define VIRTIO_USE_MSIX 0x01 236 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 237 #define VIRTIO_BROKED 0x08 /* ??? */ 238 239 struct virtio_softc { 240 struct virtio_consts *vs_vc; /* constants (see below) */ 241 int vs_flags; /* VIRTIO_* flags from above */ 242 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 243 struct pci_devinst *vs_pi; /* PCI device instance */ 244 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 245 struct vqueue_info *vs_queues; /* one per vc_nvq */ 246 int vs_curq; /* current queue */ 247 uint8_t vs_status; /* value from last status write */ 248 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 249 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 250 }; 251 252 #define VS_LOCK(vs) \ 253 do { \ 254 if (vs->vs_mtx) \ 255 pthread_mutex_lock(vs->vs_mtx); \ 256 } while (0) 257 258 #define VS_UNLOCK(vs) \ 259 do { \ 260 if (vs->vs_mtx) \ 261 pthread_mutex_unlock(vs->vs_mtx); \ 262 } while (0) 263 264 struct virtio_consts { 265 const char *vc_name; /* name of driver (for diagnostics) */ 266 int vc_nvq; /* number of virtual queues */ 267 size_t vc_cfgsize; /* size of dev-specific config regs */ 268 void (*vc_reset)(void *); /* called on virtual device reset */ 269 void (*vc_qnotify)(void *, struct vqueue_info *); 270 /* called on QNOTIFY if no VQ notify */ 271 int (*vc_cfgread)(void *, int, int, uint32_t *); 272 /* called to read config regs */ 273 int (*vc_cfgwrite)(void *, int, int, uint32_t); 274 /* called to write config regs */ 275 void (*vc_apply_features)(void *, uint64_t); 276 /* called to apply negotiated features */ 277 uint64_t vc_hv_caps; /* hypervisor-provided capabilities */ 278 }; 279 280 /* 281 * Data structure allocated (statically) per virtual queue. 282 * 283 * Drivers may change vq_qsize after a reset. When the guest OS 284 * requests a device reset, the hypervisor first calls 285 * vs->vs_vc->vc_reset(); then the data structure below is 286 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 287 * 288 * The remaining fields should only be fussed-with by the generic 289 * code. 290 * 291 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 292 * computable from each other, but it's a lot simpler if we just 293 * keep a pointer to each one. The event indices are similarly 294 * (but more easily) computable, and this time we'll compute them: 295 * they're just XX_ring[N]. 296 */ 297 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 298 #define VQ_BROKED 0x02 /* ??? */ 299 struct vqueue_info { 300 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 301 void (*vq_notify)(void *, struct vqueue_info *); 302 /* called instead of vc_notify, if not NULL */ 303 304 struct virtio_softc *vq_vs; /* backpointer to softc */ 305 uint16_t vq_num; /* we're the num'th queue in the softc */ 306 307 uint16_t vq_flags; /* flags (see above) */ 308 uint16_t vq_last_avail; /* a recent value of vq_avail->idx */ 309 uint16_t vq_next_used; /* index of the next used slot to be filled */ 310 uint16_t vq_save_used; /* saved vq_used->idx; see vq_endchains */ 311 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 312 313 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 314 315 struct vring_desc *vq_desc; /* descriptor array */ 316 struct vring_avail *vq_avail; /* the "avail" ring */ 317 struct vring_used *vq_used; /* the "used" ring */ 318 319 }; 320 /* as noted above, these are sort of backwards, name-wise */ 321 #define VQ_AVAIL_EVENT_IDX(vq) \ 322 (*(uint16_t *)&(vq)->vq_used->ring[(vq)->vq_qsize]) 323 #define VQ_USED_EVENT_IDX(vq) \ 324 ((vq)->vq_avail->ring[(vq)->vq_qsize]) 325 326 /* 327 * Is this ring ready for I/O? 328 */ 329 static inline int 330 vq_ring_ready(struct vqueue_info *vq) 331 { 332 333 return (vq->vq_flags & VQ_ALLOC); 334 } 335 336 /* 337 * Are there "available" descriptors? (This does not count 338 * how many, just returns True if there are some.) 339 */ 340 static inline int 341 vq_has_descs(struct vqueue_info *vq) 342 { 343 344 return (vq_ring_ready(vq) && vq->vq_last_avail != 345 vq->vq_avail->idx); 346 } 347 348 /* 349 * Deliver an interrupt to the guest for a specific MSI-X queue or 350 * event. 351 */ 352 static inline void 353 vi_interrupt(struct virtio_softc *vs, uint8_t isr, uint16_t msix_idx) 354 { 355 356 if (pci_msix_enabled(vs->vs_pi)) 357 pci_generate_msix(vs->vs_pi, msix_idx); 358 else { 359 #ifndef __FreeBSD__ 360 boolean_t unlock = B_FALSE; 361 362 if (vs->vs_mtx && !pthread_mutex_isowned_np(vs->vs_mtx)) { 363 unlock = B_TRUE; 364 pthread_mutex_lock(vs->vs_mtx); 365 } 366 #else 367 VS_LOCK(vs); 368 #endif 369 vs->vs_isr |= isr; 370 pci_generate_msi(vs->vs_pi, 0); 371 pci_lintr_assert(vs->vs_pi); 372 #ifndef __FreeBSD__ 373 if (unlock) 374 pthread_mutex_unlock(vs->vs_mtx); 375 #else 376 VS_UNLOCK(vs); 377 #endif 378 } 379 } 380 381 /* 382 * Deliver an interrupt to the guest on the given virtual queue (if 383 * possible, or a generic MSI interrupt if not using MSI-X). 384 */ 385 static inline void 386 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 387 { 388 389 vi_interrupt(vs, VIRTIO_PCI_ISR_INTR, vq->vq_msix_idx); 390 } 391 392 static inline void 393 vq_kick_enable(struct vqueue_info *vq) 394 { 395 396 vq->vq_used->flags &= ~VRING_USED_F_NO_NOTIFY; 397 /* 398 * Full memory barrier to make sure the store to vq_used->flags 399 * happens before the load from vq_avail->idx, which results from a 400 * subsequent call to vq_has_descs(). 401 */ 402 atomic_thread_fence_seq_cst(); 403 } 404 405 static inline void 406 vq_kick_disable(struct vqueue_info *vq) 407 { 408 409 vq->vq_used->flags |= VRING_USED_F_NO_NOTIFY; 410 } 411 412 struct iovec; 413 414 /* 415 * Request description returned by vq_getchain. 416 * 417 * Writable iovecs start at iov[req.readable]. 418 */ 419 struct vi_req { 420 int readable; /* num of readable iovecs */ 421 int writable; /* num of writable iovecs */ 422 unsigned int idx; /* ring index */ 423 }; 424 425 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 426 void *dev_softc, struct pci_devinst *pi, 427 struct vqueue_info *queues); 428 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 429 void vi_reset_dev(struct virtio_softc *); 430 void vi_set_io_bar(struct virtio_softc *, int); 431 432 int vq_getchain(struct vqueue_info *vq, struct iovec *iov, int niov, 433 struct vi_req *reqp); 434 void vq_retchains(struct vqueue_info *vq, uint16_t n_chains); 435 void vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx, 436 uint32_t iolen); 437 void vq_relchain_publish(struct vqueue_info *vq); 438 void vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen); 439 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 440 441 uint64_t vi_pci_read(struct vmctx *ctx, struct pci_devinst *pi, 442 int baridx, uint64_t offset, int size); 443 void vi_pci_write(struct vmctx *ctx, struct pci_devinst *pi, 444 int baridx, uint64_t offset, int size, uint64_t value); 445 446 #ifndef __FreeBSD__ 447 void vi_vq_init(struct virtio_softc *, uint32_t); 448 #endif 449 450 #endif /* _BHYVE_VIRTIO_H_ */ 451