1 /*- 2 * Copyright (c) 2013 Chris Torek <torek @ torek net> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #ifndef _VIRTIO_H_ 30 #define _VIRTIO_H_ 31 32 /* 33 * These are derived from several virtio specifications. 34 * 35 * Some useful links: 36 * https://github.com/rustyrussell/virtio-spec 37 * http://people.redhat.com/pbonzini/virtio-spec.pdf 38 */ 39 40 /* 41 * A virtual device has zero or more "virtual queues" (virtqueue). 42 * Each virtqueue uses at least two 4096-byte pages, laid out thus: 43 * 44 * +-----------------------------------------------+ 45 * | "desc": <N> descriptors, 16 bytes each | 46 * | ----------------------------------------- | 47 * | "avail": 2 uint16; <N> uint16; 1 uint16 | 48 * | ----------------------------------------- | 49 * | pad to 4k boundary | 50 * +-----------------------------------------------+ 51 * | "used": 2 x uint16; <N> elems; 1 uint16 | 52 * | ----------------------------------------- | 53 * | pad to 4k boundary | 54 * +-----------------------------------------------+ 55 * 56 * The number <N> that appears here is always a power of two and is 57 * limited to no more than 32768 (as it must fit in a 16-bit field). 58 * If <N> is sufficiently large, the above will occupy more than 59 * two pages. In any case, all pages must be physically contiguous 60 * within the guest's physical address space. 61 * 62 * The <N> 16-byte "desc" descriptors consist of a 64-bit guest 63 * physical address <addr>, a 32-bit length <len>, a 16-bit 64 * <flags>, and a 16-bit <next> field (all in guest byte order). 65 * 66 * There are three flags that may be set : 67 * NEXT descriptor is chained, so use its "next" field 68 * WRITE descriptor is for host to write into guest RAM 69 * (else host is to read from guest RAM) 70 * INDIRECT descriptor address field is (guest physical) 71 * address of a linear array of descriptors 72 * 73 * Unless INDIRECT is set, <len> is the number of bytes that may 74 * be read/written from guest physical address <addr>. If 75 * INDIRECT is set, WRITE is ignored and <len> provides the length 76 * of the indirect descriptors (and <len> must be a multiple of 77 * 16). Note that NEXT may still be set in the main descriptor 78 * pointing to the indirect, and should be set in each indirect 79 * descriptor that uses the next descriptor (these should generally 80 * be numbered sequentially). However, INDIRECT must not be set 81 * in the indirect descriptors. Upon reaching an indirect descriptor 82 * without a NEXT bit, control returns to the direct descriptors. 83 * 84 * Except inside an indirect, each <next> value must be in the 85 * range [0 .. N) (i.e., the half-open interval). (Inside an 86 * indirect, each <next> must be in the range [0 .. <len>/16).) 87 * 88 * The "avail" data structures reside in the same pages as the 89 * "desc" structures since both together are used by the device to 90 * pass information to the hypervisor's virtual driver. These 91 * begin with a 16-bit <flags> field and 16-bit index <idx>, then 92 * have <N> 16-bit <ring> values, followed by one final 16-bit 93 * field <used_event>. The <N> <ring> entries are simply indices 94 * indices into the descriptor ring (and thus must meet the same 95 * constraints as each <next> value). However, <idx> is counted 96 * up from 0 (initially) and simply wraps around after 65535; it 97 * is taken mod <N> to find the next available entry. 98 * 99 * The "used" ring occupies a separate page or pages, and contains 100 * values written from the virtual driver back to the guest OS. 101 * This begins with a 16-bit <flags> and 16-bit <idx>, then there 102 * are <N> "vring_used" elements, followed by a 16-bit <avail_event>. 103 * The <N> "vring_used" elements consist of a 32-bit <id> and a 104 * 32-bit <len> (vu_tlen below). The <id> is simply the index of 105 * the head of a descriptor chain the guest made available 106 * earlier, and the <len> is the number of bytes actually written, 107 * e.g., in the case of a network driver that provided a large 108 * receive buffer but received only a small amount of data. 109 * 110 * The two event fields, <used_event> and <avail_event>, in the 111 * avail and used rings (respectively -- note the reversal!), are 112 * always provided, but are used only if the virtual device 113 * negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature 114 * negotiation. Similarly, both rings provide a flag -- 115 * VRING_AVAIL_F_NO_INTERRUPT and VRING_USED_F_NO_NOTIFY -- in 116 * their <flags> field, indicating that the guest does not need an 117 * interrupt, or that the hypervisor driver does not need a 118 * notify, when descriptors are added to the corresponding ring. 119 * (These are provided only for interrupt optimization and need 120 * not be implemented.) 121 */ 122 #define VRING_ALIGN 4096 123 124 #define VRING_DESC_F_NEXT (1 << 0) 125 #define VRING_DESC_F_WRITE (1 << 1) 126 #define VRING_DESC_F_INDIRECT (1 << 2) 127 128 struct virtio_desc { /* AKA vring_desc */ 129 uint64_t vd_addr; /* guest physical address */ 130 uint32_t vd_len; /* length of scatter/gather seg */ 131 uint16_t vd_flags; /* VRING_F_DESC_* */ 132 uint16_t vd_next; /* next desc if F_NEXT */ 133 } __packed; 134 135 struct virtio_used { /* AKA vring_used_elem */ 136 uint32_t vu_idx; /* head of used descriptor chain */ 137 uint32_t vu_tlen; /* length written-to */ 138 } __packed; 139 140 #define VRING_AVAIL_F_NO_INTERRUPT 1 141 142 struct vring_avail { 143 uint16_t va_flags; /* VRING_AVAIL_F_* */ 144 uint16_t va_idx; /* counts to 65535, then cycles */ 145 uint16_t va_ring[]; /* size N, reported in QNUM value */ 146 /* uint16_t va_used_event; -- after N ring entries */ 147 } __packed; 148 149 #define VRING_USED_F_NO_NOTIFY 1 150 struct vring_used { 151 uint16_t vu_flags; /* VRING_USED_F_* */ 152 uint16_t vu_idx; /* counts to 65535, then cycles */ 153 struct virtio_used vu_ring[]; /* size N */ 154 /* uint16_t vu_avail_event; -- after N ring entries */ 155 } __packed; 156 157 /* 158 * The address of any given virtual queue is determined by a single 159 * Page Frame Number register. The guest writes the PFN into the 160 * PCI config space. However, a device that has two or more 161 * virtqueues can have a different PFN, and size, for each queue. 162 * The number of queues is determinable via the PCI config space 163 * VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means 164 * queue #0, 1 means queue#1, etc. Once a queue is selected, the 165 * remaining PFN and QNUM registers refer to that queue. 166 * 167 * QNUM is a read-only register containing a nonzero power of two 168 * that indicates the (hypervisor's) queue size. Or, if reading it 169 * produces zero, the hypervisor does not have a corresponding 170 * queue. (The number of possible queues depends on the virtual 171 * device. The block device has just one; the network device 172 * provides either two -- 0 = receive, 1 = transmit -- or three, 173 * with 2 = control.) 174 * 175 * PFN is a read/write register giving the physical page address of 176 * the virtqueue in guest memory (the guest must allocate enough space 177 * based on the hypervisor's provided QNUM). 178 * 179 * QNOTIFY is effectively write-only: when the guest writes a queue 180 * number to the register, the hypervisor should scan the specified 181 * virtqueue. (Reading QNOTIFY currently always gets 0). 182 */ 183 184 /* 185 * PFN register shift amount 186 */ 187 #define VRING_PFN 12 188 189 /* 190 * Virtio device types 191 * 192 * XXX Should really be merged with <dev/virtio/virtio.h> defines 193 */ 194 #define VIRTIO_TYPE_NET 1 195 #define VIRTIO_TYPE_BLOCK 2 196 #define VIRTIO_TYPE_CONSOLE 3 197 #define VIRTIO_TYPE_ENTROPY 4 198 #define VIRTIO_TYPE_BALLOON 5 199 #define VIRTIO_TYPE_IOMEMORY 6 200 #define VIRTIO_TYPE_RPMSG 7 201 #define VIRTIO_TYPE_SCSI 8 202 #define VIRTIO_TYPE_9P 9 203 204 /* experimental IDs start at 65535 and work down */ 205 206 /* 207 * PCI vendor/device IDs 208 */ 209 #define VIRTIO_VENDOR 0x1AF4 210 #define VIRTIO_DEV_NET 0x1000 211 #define VIRTIO_DEV_BLOCK 0x1001 212 213 /* 214 * PCI config space constants. 215 * 216 * If MSI-X is enabled, the ISR register is generally not used, 217 * and the configuration vector and queue vector appear at offsets 218 * 20 and 22 with the remaining configuration registers at 24. 219 * If MSI-X is not enabled, those two registers disappear and 220 * the remaining configuration registers start at offset 20. 221 */ 222 #define VTCFG_R_HOSTCAP 0 223 #define VTCFG_R_GUESTCAP 4 224 #define VTCFG_R_PFN 8 225 #define VTCFG_R_QNUM 12 226 #define VTCFG_R_QSEL 14 227 #define VTCFG_R_QNOTIFY 16 228 #define VTCFG_R_STATUS 18 229 #define VTCFG_R_ISR 19 230 #define VTCFG_R_CFGVEC 20 231 #define VTCFG_R_QVEC 22 232 #define VTCFG_R_CFG0 20 /* No MSI-X */ 233 #define VTCFG_R_CFG1 24 /* With MSI-X */ 234 #define VTCFG_R_MSIX 20 235 236 /* 237 * Bits in VTCFG_R_STATUS. Guests need not actually set any of these, 238 * but a guest writing 0 to this register means "please reset". 239 */ 240 #define VTCFG_STATUS_ACK 0x01 /* guest OS has acknowledged dev */ 241 #define VTCFG_STATUS_DRIVER 0x02 /* guest OS driver is loaded */ 242 #define VTCFG_STATUS_DRIVER_OK 0x04 /* guest OS driver ready */ 243 #define VTCFG_STATUS_FAILED 0x80 /* guest has given up on this dev */ 244 245 /* 246 * Bits in VTCFG_R_ISR. These apply only if not using MSI-X. 247 * 248 * (We don't [yet?] ever use CONF_CHANGED.) 249 */ 250 #define VTCFG_ISR_QUEUES 0x01 /* re-scan queues */ 251 #define VTCFG_ISR_CONF_CHANGED 0x80 /* configuration changed */ 252 253 #define VIRTIO_MSI_NO_VECTOR 0xFFFF 254 255 /* 256 * Feature flags. 257 * Note: bits 0 through 23 are reserved to each device type. 258 */ 259 #define VIRTIO_F_NOTIFY_ON_EMPTY (1 << 24) 260 #define VIRTIO_RING_F_INDIRECT_DESC (1 << 28) 261 #define VIRTIO_RING_F_EVENT_IDX (1 << 29) 262 263 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 264 static inline size_t 265 vring_size(u_int qsz) 266 { 267 size_t size; 268 269 /* constant 3 below = va_flags, va_idx, va_used_event */ 270 size = sizeof(struct virtio_desc) * qsz + sizeof(uint16_t) * (3 + qsz); 271 size = roundup2(size, VRING_ALIGN); 272 273 /* constant 3 below = vu_flags, vu_idx, vu_avail_event */ 274 size += sizeof(uint16_t) * 3 + sizeof(struct virtio_used) * qsz; 275 size = roundup2(size, VRING_ALIGN); 276 277 return (size); 278 } 279 280 struct vmctx; 281 struct pci_devinst; 282 struct vqueue_info; 283 284 /* 285 * A virtual device, with some number (possibly 0) of virtual 286 * queues and some size (possibly 0) of configuration-space 287 * registers private to the device. The virtio_softc should come 288 * at the front of each "derived class", so that a pointer to the 289 * virtio_softc is also a pointer to the more specific, derived- 290 * from-virtio driver's softc. 291 * 292 * Note: inside each hypervisor virtio driver, changes to these 293 * data structures must be locked against other threads, if any. 294 * Except for PCI config space register read/write, we assume each 295 * driver does the required locking, but we need a pointer to the 296 * lock (if there is one) for PCI config space read/write ops. 297 * 298 * When the guest reads or writes the device's config space, the 299 * generic layer checks for operations on the special registers 300 * described above. If the offset of the register(s) being read 301 * or written is past the CFG area (CFG0 or CFG1), the request is 302 * passed on to the virtual device, after subtracting off the 303 * generic-layer size. (So, drivers can just use the offset as 304 * an offset into "struct config", for instance.) 305 * 306 * (The virtio layer also makes sure that the read or write is to/ 307 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 308 * However, the driver must verify the read or write size and offset 309 * and that no one is writing a readonly register.) 310 * 311 * The BROKED flag ("this thing done gone and broked") is for future 312 * use. 313 */ 314 #define VIRTIO_USE_MSIX 0x01 315 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 316 #define VIRTIO_BROKED 0x08 /* ??? */ 317 318 struct virtio_softc { 319 struct virtio_consts *vs_vc; /* constants (see below) */ 320 int vs_flags; /* VIRTIO_* flags from above */ 321 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 322 struct pci_devinst *vs_pi; /* PCI device instance */ 323 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 324 struct vqueue_info *vs_queues; /* one per vc_nvq */ 325 int vs_curq; /* current queue */ 326 uint8_t vs_status; /* value from last status write */ 327 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 328 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 329 }; 330 331 #define VS_LOCK(vs) \ 332 do { \ 333 if (vs->vs_mtx) \ 334 pthread_mutex_lock(vs->vs_mtx); \ 335 } while (0) 336 337 #define VS_UNLOCK(vs) \ 338 do { \ 339 if (vs->vs_mtx) \ 340 pthread_mutex_unlock(vs->vs_mtx); \ 341 } while (0) 342 343 struct virtio_consts { 344 const char *vc_name; /* name of driver (for diagnostics) */ 345 int vc_nvq; /* number of virtual queues */ 346 size_t vc_cfgsize; /* size of dev-specific config regs */ 347 void (*vc_reset)(void *); /* called on virtual device reset */ 348 void (*vc_qnotify)(void *, struct vqueue_info *); 349 /* called on QNOTIFY if no VQ notify */ 350 int (*vc_cfgread)(void *, int, int, uint32_t *); 351 /* called to read config regs */ 352 int (*vc_cfgwrite)(void *, int, int, uint32_t); 353 /* called to write config regs */ 354 uint32_t vc_hv_caps; /* hypervisor-provided capabilities */ 355 }; 356 357 /* 358 * Data structure allocated (statically) per virtual queue. 359 * 360 * Drivers may change vq_qsize after a reset. When the guest OS 361 * requests a device reset, the hypervisor first calls 362 * vs->vs_vc->vc_reset(); then the data structure below is 363 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 364 * 365 * The remaining fields should only be fussed-with by the generic 366 * code. 367 * 368 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 369 * computable from each other, but it's a lot simpler if we just 370 * keep a pointer to each one. The event indices are similarly 371 * (but more easily) computable, and this time we'll compute them: 372 * they're just XX_ring[N]. 373 */ 374 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 375 #define VQ_BROKED 0x02 /* ??? */ 376 struct vqueue_info { 377 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 378 void (*vq_notify)(void *, struct vqueue_info *); 379 /* called instead of vc_notify, if not NULL */ 380 381 struct virtio_softc *vq_vs; /* backpointer to softc */ 382 uint16_t vq_num; /* we're the num'th queue in the softc */ 383 384 uint16_t vq_flags; /* flags (see above) */ 385 uint16_t vq_last_avail; /* a recent value of vq_avail->va_idx */ 386 uint16_t vq_save_used; /* saved vq_used->vu_idx; see vq_endchains */ 387 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 388 389 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 390 391 volatile struct virtio_desc *vq_desc; /* descriptor array */ 392 volatile struct vring_avail *vq_avail; /* the "avail" ring */ 393 volatile struct vring_used *vq_used; /* the "used" ring */ 394 395 }; 396 /* as noted above, these are sort of backwards, name-wise */ 397 #define VQ_AVAIL_EVENT_IDX(vq) \ 398 (*(volatile uint16_t *)&(vq)->vq_used->vu_ring[(vq)->vq_qsize]) 399 #define VQ_USED_EVENT_IDX(vq) \ 400 ((vq)->vq_avail->va_ring[(vq)->vq_qsize]) 401 402 /* 403 * Is this ring ready for I/O? 404 */ 405 static inline int 406 vq_ring_ready(struct vqueue_info *vq) 407 { 408 409 return (vq->vq_flags & VQ_ALLOC); 410 } 411 412 /* 413 * Are there "available" descriptors? (This does not count 414 * how many, just returns True if there are some.) 415 */ 416 static inline int 417 vq_has_descs(struct vqueue_info *vq) 418 { 419 420 return (vq_ring_ready(vq) && vq->vq_last_avail != 421 vq->vq_avail->va_idx); 422 } 423 424 /* 425 * Called by virtio driver as it starts processing chains. Each 426 * completed chain (obtained from vq_getchain()) is released by 427 * calling vq_relchain(), then when all are done, vq_endchains() 428 * can tell if / how-many chains were processed and know whether 429 * and how to generate an interrupt. 430 */ 431 static inline void 432 vq_startchains(struct vqueue_info *vq) 433 { 434 435 vq->vq_save_used = vq->vq_used->vu_idx; 436 } 437 438 /* 439 * Deliver an interrupt to guest on the given virtual queue 440 * (if possible, or a generic MSI interrupt if not using MSI-X). 441 */ 442 static inline void 443 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 444 { 445 446 if (pci_msix_enabled(vs->vs_pi)) 447 pci_generate_msix(vs->vs_pi, vq->vq_msix_idx); 448 else { 449 VS_LOCK(vs); 450 vs->vs_isr |= VTCFG_ISR_QUEUES; 451 pci_generate_msi(vs->vs_pi, 0); 452 pci_lintr_assert(vs->vs_pi); 453 VS_UNLOCK(vs); 454 } 455 } 456 457 struct iovec; 458 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 459 void *dev_softc, struct pci_devinst *pi, 460 struct vqueue_info *queues); 461 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 462 void vi_reset_dev(struct virtio_softc *); 463 void vi_set_io_bar(struct virtio_softc *, int); 464 465 int vq_getchain(struct vqueue_info *vq, 466 struct iovec *iov, int n_iov, uint16_t *flags); 467 void vq_relchain(struct vqueue_info *vq, uint32_t iolen); 468 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 469 470 uint64_t vi_pci_read(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 471 int baridx, uint64_t offset, int size); 472 void vi_pci_write(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 473 int baridx, uint64_t offset, int size, uint64_t value); 474 #endif /* _VIRTIO_H_ */ 475