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 _VIRTIO_H_ 32 #define _VIRTIO_H_ 33 34 /* 35 * These are derived from several virtio specifications. 36 * 37 * Some useful links: 38 * https://github.com/rustyrussell/virtio-spec 39 * http://people.redhat.com/pbonzini/virtio-spec.pdf 40 */ 41 42 /* 43 * A virtual device has zero or more "virtual queues" (virtqueue). 44 * Each virtqueue uses at least two 4096-byte pages, laid out thus: 45 * 46 * +-----------------------------------------------+ 47 * | "desc": <N> descriptors, 16 bytes each | 48 * | ----------------------------------------- | 49 * | "avail": 2 uint16; <N> uint16; 1 uint16 | 50 * | ----------------------------------------- | 51 * | pad to 4k boundary | 52 * +-----------------------------------------------+ 53 * | "used": 2 x uint16; <N> elems; 1 uint16 | 54 * | ----------------------------------------- | 55 * | pad to 4k boundary | 56 * +-----------------------------------------------+ 57 * 58 * The number <N> that appears here is always a power of two and is 59 * limited to no more than 32768 (as it must fit in a 16-bit field). 60 * If <N> is sufficiently large, the above will occupy more than 61 * two pages. In any case, all pages must be physically contiguous 62 * within the guest's physical address space. 63 * 64 * The <N> 16-byte "desc" descriptors consist of a 64-bit guest 65 * physical address <addr>, a 32-bit length <len>, a 16-bit 66 * <flags>, and a 16-bit <next> field (all in guest byte order). 67 * 68 * There are three flags that may be set : 69 * NEXT descriptor is chained, so use its "next" field 70 * WRITE descriptor is for host to write into guest RAM 71 * (else host is to read from guest RAM) 72 * INDIRECT descriptor address field is (guest physical) 73 * address of a linear array of descriptors 74 * 75 * Unless INDIRECT is set, <len> is the number of bytes that may 76 * be read/written from guest physical address <addr>. If 77 * INDIRECT is set, WRITE is ignored and <len> provides the length 78 * of the indirect descriptors (and <len> must be a multiple of 79 * 16). Note that NEXT may still be set in the main descriptor 80 * pointing to the indirect, and should be set in each indirect 81 * descriptor that uses the next descriptor (these should generally 82 * be numbered sequentially). However, INDIRECT must not be set 83 * in the indirect descriptors. Upon reaching an indirect descriptor 84 * without a NEXT bit, control returns to the direct descriptors. 85 * 86 * Except inside an indirect, each <next> value must be in the 87 * range [0 .. N) (i.e., the half-open interval). (Inside an 88 * indirect, each <next> must be in the range [0 .. <len>/16).) 89 * 90 * The "avail" data structures reside in the same pages as the 91 * "desc" structures since both together are used by the device to 92 * pass information to the hypervisor's virtual driver. These 93 * begin with a 16-bit <flags> field and 16-bit index <idx>, then 94 * have <N> 16-bit <ring> values, followed by one final 16-bit 95 * field <used_event>. The <N> <ring> entries are simply indices 96 * indices into the descriptor ring (and thus must meet the same 97 * constraints as each <next> value). However, <idx> is counted 98 * up from 0 (initially) and simply wraps around after 65535; it 99 * is taken mod <N> to find the next available entry. 100 * 101 * The "used" ring occupies a separate page or pages, and contains 102 * values written from the virtual driver back to the guest OS. 103 * This begins with a 16-bit <flags> and 16-bit <idx>, then there 104 * are <N> "vring_used" elements, followed by a 16-bit <avail_event>. 105 * The <N> "vring_used" elements consist of a 32-bit <id> and a 106 * 32-bit <len> (vu_tlen below). The <id> is simply the index of 107 * the head of a descriptor chain the guest made available 108 * earlier, and the <len> is the number of bytes actually written, 109 * e.g., in the case of a network driver that provided a large 110 * receive buffer but received only a small amount of data. 111 * 112 * The two event fields, <used_event> and <avail_event>, in the 113 * avail and used rings (respectively -- note the reversal!), are 114 * always provided, but are used only if the virtual device 115 * negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature 116 * negotiation. Similarly, both rings provide a flag -- 117 * VRING_AVAIL_F_NO_INTERRUPT and VRING_USED_F_NO_NOTIFY -- in 118 * their <flags> field, indicating that the guest does not need an 119 * interrupt, or that the hypervisor driver does not need a 120 * notify, when descriptors are added to the corresponding ring. 121 * (These are provided only for interrupt optimization and need 122 * not be implemented.) 123 */ 124 #define VRING_ALIGN 4096 125 126 #define VRING_DESC_F_NEXT (1 << 0) 127 #define VRING_DESC_F_WRITE (1 << 1) 128 #define VRING_DESC_F_INDIRECT (1 << 2) 129 130 struct virtio_desc { /* AKA vring_desc */ 131 uint64_t vd_addr; /* guest physical address */ 132 uint32_t vd_len; /* length of scatter/gather seg */ 133 uint16_t vd_flags; /* VRING_F_DESC_* */ 134 uint16_t vd_next; /* next desc if F_NEXT */ 135 } __packed; 136 137 struct virtio_used { /* AKA vring_used_elem */ 138 uint32_t vu_idx; /* head of used descriptor chain */ 139 uint32_t vu_tlen; /* length written-to */ 140 } __packed; 141 142 #define VRING_AVAIL_F_NO_INTERRUPT 1 143 144 struct vring_avail { 145 uint16_t va_flags; /* VRING_AVAIL_F_* */ 146 uint16_t va_idx; /* counts to 65535, then cycles */ 147 uint16_t va_ring[]; /* size N, reported in QNUM value */ 148 /* uint16_t va_used_event; -- after N ring entries */ 149 } __packed; 150 151 #define VRING_USED_F_NO_NOTIFY 1 152 struct vring_used { 153 uint16_t vu_flags; /* VRING_USED_F_* */ 154 uint16_t vu_idx; /* counts to 65535, then cycles */ 155 struct virtio_used vu_ring[]; /* size N */ 156 /* uint16_t vu_avail_event; -- after N ring entries */ 157 } __packed; 158 159 /* 160 * The address of any given virtual queue is determined by a single 161 * Page Frame Number register. The guest writes the PFN into the 162 * PCI config space. However, a device that has two or more 163 * virtqueues can have a different PFN, and size, for each queue. 164 * The number of queues is determinable via the PCI config space 165 * VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means 166 * queue #0, 1 means queue#1, etc. Once a queue is selected, the 167 * remaining PFN and QNUM registers refer to that queue. 168 * 169 * QNUM is a read-only register containing a nonzero power of two 170 * that indicates the (hypervisor's) queue size. Or, if reading it 171 * produces zero, the hypervisor does not have a corresponding 172 * queue. (The number of possible queues depends on the virtual 173 * device. The block device has just one; the network device 174 * provides either two -- 0 = receive, 1 = transmit -- or three, 175 * with 2 = control.) 176 * 177 * PFN is a read/write register giving the physical page address of 178 * the virtqueue in guest memory (the guest must allocate enough space 179 * based on the hypervisor's provided QNUM). 180 * 181 * QNOTIFY is effectively write-only: when the guest writes a queue 182 * number to the register, the hypervisor should scan the specified 183 * virtqueue. (Reading QNOTIFY currently always gets 0). 184 */ 185 186 /* 187 * PFN register shift amount 188 */ 189 #define VRING_PFN 12 190 191 /* 192 * Virtio device types 193 * 194 * XXX Should really be merged with <dev/virtio/virtio.h> defines 195 */ 196 #define VIRTIO_TYPE_NET 1 197 #define VIRTIO_TYPE_BLOCK 2 198 #define VIRTIO_TYPE_CONSOLE 3 199 #define VIRTIO_TYPE_ENTROPY 4 200 #define VIRTIO_TYPE_BALLOON 5 201 #define VIRTIO_TYPE_IOMEMORY 6 202 #define VIRTIO_TYPE_RPMSG 7 203 #define VIRTIO_TYPE_SCSI 8 204 #define VIRTIO_TYPE_9P 9 205 206 /* experimental IDs start at 65535 and work down */ 207 208 /* 209 * PCI vendor/device IDs 210 */ 211 #define VIRTIO_VENDOR 0x1AF4 212 #define VIRTIO_DEV_NET 0x1000 213 #define VIRTIO_DEV_BLOCK 0x1001 214 #define VIRTIO_DEV_CONSOLE 0x1003 215 #define VIRTIO_DEV_RANDOM 0x1005 216 #define VIRTIO_DEV_SCSI 0x1008 217 218 /* 219 * PCI config space constants. 220 * 221 * If MSI-X is enabled, the ISR register is generally not used, 222 * and the configuration vector and queue vector appear at offsets 223 * 20 and 22 with the remaining configuration registers at 24. 224 * If MSI-X is not enabled, those two registers disappear and 225 * the remaining configuration registers start at offset 20. 226 */ 227 #define VTCFG_R_HOSTCAP 0 228 #define VTCFG_R_GUESTCAP 4 229 #define VTCFG_R_PFN 8 230 #define VTCFG_R_QNUM 12 231 #define VTCFG_R_QSEL 14 232 #define VTCFG_R_QNOTIFY 16 233 #define VTCFG_R_STATUS 18 234 #define VTCFG_R_ISR 19 235 #define VTCFG_R_CFGVEC 20 236 #define VTCFG_R_QVEC 22 237 #define VTCFG_R_CFG0 20 /* No MSI-X */ 238 #define VTCFG_R_CFG1 24 /* With MSI-X */ 239 #define VTCFG_R_MSIX 20 240 241 /* 242 * Bits in VTCFG_R_STATUS. Guests need not actually set any of these, 243 * but a guest writing 0 to this register means "please reset". 244 */ 245 #define VTCFG_STATUS_ACK 0x01 /* guest OS has acknowledged dev */ 246 #define VTCFG_STATUS_DRIVER 0x02 /* guest OS driver is loaded */ 247 #define VTCFG_STATUS_DRIVER_OK 0x04 /* guest OS driver ready */ 248 #define VTCFG_STATUS_FAILED 0x80 /* guest has given up on this dev */ 249 250 /* 251 * Bits in VTCFG_R_ISR. These apply only if not using MSI-X. 252 * 253 * (We don't [yet?] ever use CONF_CHANGED.) 254 */ 255 #define VTCFG_ISR_QUEUES 0x01 /* re-scan queues */ 256 #define VTCFG_ISR_CONF_CHANGED 0x80 /* configuration changed */ 257 258 #define VIRTIO_MSI_NO_VECTOR 0xFFFF 259 260 /* 261 * Feature flags. 262 * Note: bits 0 through 23 are reserved to each device type. 263 */ 264 #define VIRTIO_F_NOTIFY_ON_EMPTY (1 << 24) 265 #define VIRTIO_RING_F_INDIRECT_DESC (1 << 28) 266 #define VIRTIO_RING_F_EVENT_IDX (1 << 29) 267 268 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 269 static inline size_t 270 vring_size(u_int qsz) 271 { 272 size_t size; 273 274 /* constant 3 below = va_flags, va_idx, va_used_event */ 275 size = sizeof(struct virtio_desc) * qsz + sizeof(uint16_t) * (3 + qsz); 276 size = roundup2(size, VRING_ALIGN); 277 278 /* constant 3 below = vu_flags, vu_idx, vu_avail_event */ 279 size += sizeof(uint16_t) * 3 + sizeof(struct virtio_used) * qsz; 280 size = roundup2(size, VRING_ALIGN); 281 282 return (size); 283 } 284 285 struct vmctx; 286 struct pci_devinst; 287 struct vqueue_info; 288 289 /* 290 * A virtual device, with some number (possibly 0) of virtual 291 * queues and some size (possibly 0) of configuration-space 292 * registers private to the device. The virtio_softc should come 293 * at the front of each "derived class", so that a pointer to the 294 * virtio_softc is also a pointer to the more specific, derived- 295 * from-virtio driver's softc. 296 * 297 * Note: inside each hypervisor virtio driver, changes to these 298 * data structures must be locked against other threads, if any. 299 * Except for PCI config space register read/write, we assume each 300 * driver does the required locking, but we need a pointer to the 301 * lock (if there is one) for PCI config space read/write ops. 302 * 303 * When the guest reads or writes the device's config space, the 304 * generic layer checks for operations on the special registers 305 * described above. If the offset of the register(s) being read 306 * or written is past the CFG area (CFG0 or CFG1), the request is 307 * passed on to the virtual device, after subtracting off the 308 * generic-layer size. (So, drivers can just use the offset as 309 * an offset into "struct config", for instance.) 310 * 311 * (The virtio layer also makes sure that the read or write is to/ 312 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 313 * However, the driver must verify the read or write size and offset 314 * and that no one is writing a readonly register.) 315 * 316 * The BROKED flag ("this thing done gone and broked") is for future 317 * use. 318 */ 319 #define VIRTIO_USE_MSIX 0x01 320 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 321 #define VIRTIO_BROKED 0x08 /* ??? */ 322 323 struct virtio_softc { 324 struct virtio_consts *vs_vc; /* constants (see below) */ 325 int vs_flags; /* VIRTIO_* flags from above */ 326 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 327 struct pci_devinst *vs_pi; /* PCI device instance */ 328 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 329 struct vqueue_info *vs_queues; /* one per vc_nvq */ 330 int vs_curq; /* current queue */ 331 uint8_t vs_status; /* value from last status write */ 332 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 333 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 334 }; 335 336 #define VS_LOCK(vs) \ 337 do { \ 338 if (vs->vs_mtx) \ 339 pthread_mutex_lock(vs->vs_mtx); \ 340 } while (0) 341 342 #define VS_UNLOCK(vs) \ 343 do { \ 344 if (vs->vs_mtx) \ 345 pthread_mutex_unlock(vs->vs_mtx); \ 346 } while (0) 347 348 struct virtio_consts { 349 const char *vc_name; /* name of driver (for diagnostics) */ 350 int vc_nvq; /* number of virtual queues */ 351 size_t vc_cfgsize; /* size of dev-specific config regs */ 352 void (*vc_reset)(void *); /* called on virtual device reset */ 353 void (*vc_qnotify)(void *, struct vqueue_info *); 354 /* called on QNOTIFY if no VQ notify */ 355 int (*vc_cfgread)(void *, int, int, uint32_t *); 356 /* called to read config regs */ 357 int (*vc_cfgwrite)(void *, int, int, uint32_t); 358 /* called to write config regs */ 359 void (*vc_apply_features)(void *, uint64_t); 360 /* called to apply negotiated features */ 361 uint64_t vc_hv_caps; /* hypervisor-provided capabilities */ 362 }; 363 364 /* 365 * Data structure allocated (statically) per virtual queue. 366 * 367 * Drivers may change vq_qsize after a reset. When the guest OS 368 * requests a device reset, the hypervisor first calls 369 * vs->vs_vc->vc_reset(); then the data structure below is 370 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 371 * 372 * The remaining fields should only be fussed-with by the generic 373 * code. 374 * 375 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 376 * computable from each other, but it's a lot simpler if we just 377 * keep a pointer to each one. The event indices are similarly 378 * (but more easily) computable, and this time we'll compute them: 379 * they're just XX_ring[N]. 380 */ 381 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 382 #define VQ_BROKED 0x02 /* ??? */ 383 struct vqueue_info { 384 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 385 void (*vq_notify)(void *, struct vqueue_info *); 386 /* called instead of vc_notify, if not NULL */ 387 388 struct virtio_softc *vq_vs; /* backpointer to softc */ 389 uint16_t vq_num; /* we're the num'th queue in the softc */ 390 391 uint16_t vq_flags; /* flags (see above) */ 392 uint16_t vq_last_avail; /* a recent value of vq_avail->va_idx */ 393 uint16_t vq_save_used; /* saved vq_used->vu_idx; see vq_endchains */ 394 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 395 396 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 397 398 volatile struct virtio_desc *vq_desc; /* descriptor array */ 399 volatile struct vring_avail *vq_avail; /* the "avail" ring */ 400 volatile struct vring_used *vq_used; /* the "used" ring */ 401 402 }; 403 /* as noted above, these are sort of backwards, name-wise */ 404 #define VQ_AVAIL_EVENT_IDX(vq) \ 405 (*(volatile uint16_t *)&(vq)->vq_used->vu_ring[(vq)->vq_qsize]) 406 #define VQ_USED_EVENT_IDX(vq) \ 407 ((vq)->vq_avail->va_ring[(vq)->vq_qsize]) 408 409 /* 410 * Is this ring ready for I/O? 411 */ 412 static inline int 413 vq_ring_ready(struct vqueue_info *vq) 414 { 415 416 return (vq->vq_flags & VQ_ALLOC); 417 } 418 419 /* 420 * Are there "available" descriptors? (This does not count 421 * how many, just returns True if there are some.) 422 */ 423 static inline int 424 vq_has_descs(struct vqueue_info *vq) 425 { 426 427 return (vq_ring_ready(vq) && vq->vq_last_avail != 428 vq->vq_avail->va_idx); 429 } 430 431 /* 432 * Deliver an interrupt to guest on the given virtual queue 433 * (if possible, or a generic MSI interrupt if not using MSI-X). 434 */ 435 static inline void 436 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 437 { 438 439 if (pci_msix_enabled(vs->vs_pi)) 440 pci_generate_msix(vs->vs_pi, vq->vq_msix_idx); 441 else { 442 VS_LOCK(vs); 443 vs->vs_isr |= VTCFG_ISR_QUEUES; 444 pci_generate_msi(vs->vs_pi, 0); 445 pci_lintr_assert(vs->vs_pi); 446 VS_UNLOCK(vs); 447 } 448 } 449 450 struct iovec; 451 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 452 void *dev_softc, struct pci_devinst *pi, 453 struct vqueue_info *queues); 454 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 455 void vi_reset_dev(struct virtio_softc *); 456 void vi_set_io_bar(struct virtio_softc *, int); 457 458 int vq_getchain(struct vqueue_info *vq, uint16_t *pidx, 459 struct iovec *iov, int n_iov, uint16_t *flags); 460 void vq_retchain(struct vqueue_info *vq); 461 void vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen); 462 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 463 464 uint64_t vi_pci_read(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 465 int baridx, uint64_t offset, int size); 466 void vi_pci_write(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 467 int baridx, uint64_t offset, int size, uint64_t value); 468 #endif /* _VIRTIO_H_ */ 469