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_RANDOM 0x1005 175 #define VIRTIO_DEV_SCSI 0x1008 176 #define VIRTIO_DEV_9P 0x1009 177 178 /* From section 2.3, "Virtqueue Configuration", of the virtio specification */ 179 static inline int 180 vring_size_aligned(u_int qsz) 181 { 182 return (roundup2(vring_size(qsz, VRING_ALIGN), VRING_ALIGN)); 183 } 184 185 struct vmctx; 186 struct pci_devinst; 187 struct vqueue_info; 188 189 /* 190 * A virtual device, with some number (possibly 0) of virtual 191 * queues and some size (possibly 0) of configuration-space 192 * registers private to the device. The virtio_softc should come 193 * at the front of each "derived class", so that a pointer to the 194 * virtio_softc is also a pointer to the more specific, derived- 195 * from-virtio driver's softc. 196 * 197 * Note: inside each hypervisor virtio driver, changes to these 198 * data structures must be locked against other threads, if any. 199 * Except for PCI config space register read/write, we assume each 200 * driver does the required locking, but we need a pointer to the 201 * lock (if there is one) for PCI config space read/write ops. 202 * 203 * When the guest reads or writes the device's config space, the 204 * generic layer checks for operations on the special registers 205 * described above. If the offset of the register(s) being read 206 * or written is past the CFG area (CFG0 or CFG1), the request is 207 * passed on to the virtual device, after subtracting off the 208 * generic-layer size. (So, drivers can just use the offset as 209 * an offset into "struct config", for instance.) 210 * 211 * (The virtio layer also makes sure that the read or write is to/ 212 * from a "good" config offset, hence vc_cfgsize, and on BAR #0. 213 * However, the driver must verify the read or write size and offset 214 * and that no one is writing a readonly register.) 215 * 216 * The BROKED flag ("this thing done gone and broked") is for future 217 * use. 218 */ 219 #define VIRTIO_USE_MSIX 0x01 220 #define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */ 221 #define VIRTIO_BROKED 0x08 /* ??? */ 222 223 struct virtio_softc { 224 struct virtio_consts *vs_vc; /* constants (see below) */ 225 int vs_flags; /* VIRTIO_* flags from above */ 226 pthread_mutex_t *vs_mtx; /* POSIX mutex, if any */ 227 struct pci_devinst *vs_pi; /* PCI device instance */ 228 uint32_t vs_negotiated_caps; /* negotiated capabilities */ 229 struct vqueue_info *vs_queues; /* one per vc_nvq */ 230 int vs_curq; /* current queue */ 231 uint8_t vs_status; /* value from last status write */ 232 uint8_t vs_isr; /* ISR flags, if not MSI-X */ 233 uint16_t vs_msix_cfg_idx; /* MSI-X vector for config event */ 234 }; 235 236 #define VS_LOCK(vs) \ 237 do { \ 238 if (vs->vs_mtx) \ 239 pthread_mutex_lock(vs->vs_mtx); \ 240 } while (0) 241 242 #define VS_UNLOCK(vs) \ 243 do { \ 244 if (vs->vs_mtx) \ 245 pthread_mutex_unlock(vs->vs_mtx); \ 246 } while (0) 247 248 struct virtio_consts { 249 const char *vc_name; /* name of driver (for diagnostics) */ 250 int vc_nvq; /* number of virtual queues */ 251 size_t vc_cfgsize; /* size of dev-specific config regs */ 252 void (*vc_reset)(void *); /* called on virtual device reset */ 253 void (*vc_qnotify)(void *, struct vqueue_info *); 254 /* called on QNOTIFY if no VQ notify */ 255 int (*vc_cfgread)(void *, int, int, uint32_t *); 256 /* called to read config regs */ 257 int (*vc_cfgwrite)(void *, int, int, uint32_t); 258 /* called to write config regs */ 259 void (*vc_apply_features)(void *, uint64_t); 260 /* called to apply negotiated features */ 261 uint64_t vc_hv_caps; /* hypervisor-provided capabilities */ 262 }; 263 264 /* 265 * Data structure allocated (statically) per virtual queue. 266 * 267 * Drivers may change vq_qsize after a reset. When the guest OS 268 * requests a device reset, the hypervisor first calls 269 * vs->vs_vc->vc_reset(); then the data structure below is 270 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq). 271 * 272 * The remaining fields should only be fussed-with by the generic 273 * code. 274 * 275 * Note: the addresses of vq_desc, vq_avail, and vq_used are all 276 * computable from each other, but it's a lot simpler if we just 277 * keep a pointer to each one. The event indices are similarly 278 * (but more easily) computable, and this time we'll compute them: 279 * they're just XX_ring[N]. 280 */ 281 #define VQ_ALLOC 0x01 /* set once we have a pfn */ 282 #define VQ_BROKED 0x02 /* ??? */ 283 struct vqueue_info { 284 uint16_t vq_qsize; /* size of this queue (a power of 2) */ 285 void (*vq_notify)(void *, struct vqueue_info *); 286 /* called instead of vc_notify, if not NULL */ 287 288 struct virtio_softc *vq_vs; /* backpointer to softc */ 289 uint16_t vq_num; /* we're the num'th queue in the softc */ 290 291 uint16_t vq_flags; /* flags (see above) */ 292 uint16_t vq_last_avail; /* a recent value of vq_avail->idx */ 293 uint16_t vq_next_used; /* index of the next used slot to be filled */ 294 uint16_t vq_save_used; /* saved vq_used->idx; see vq_endchains */ 295 uint16_t vq_msix_idx; /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */ 296 297 uint32_t vq_pfn; /* PFN of virt queue (not shifted!) */ 298 299 volatile struct vring_desc *vq_desc; /* descriptor array */ 300 volatile struct vring_avail *vq_avail; /* the "avail" ring */ 301 volatile struct vring_used *vq_used; /* the "used" ring */ 302 303 }; 304 /* as noted above, these are sort of backwards, name-wise */ 305 #define VQ_AVAIL_EVENT_IDX(vq) \ 306 (*(volatile uint16_t *)&(vq)->vq_used->ring[(vq)->vq_qsize]) 307 #define VQ_USED_EVENT_IDX(vq) \ 308 ((vq)->vq_avail->ring[(vq)->vq_qsize]) 309 310 /* 311 * Is this ring ready for I/O? 312 */ 313 static inline int 314 vq_ring_ready(struct vqueue_info *vq) 315 { 316 317 return (vq->vq_flags & VQ_ALLOC); 318 } 319 320 /* 321 * Are there "available" descriptors? (This does not count 322 * how many, just returns True if there are some.) 323 */ 324 static inline int 325 vq_has_descs(struct vqueue_info *vq) 326 { 327 328 return (vq_ring_ready(vq) && vq->vq_last_avail != 329 vq->vq_avail->idx); 330 } 331 332 /* 333 * Deliver an interrupt to guest on the given virtual queue 334 * (if possible, or a generic MSI interrupt if not using MSI-X). 335 */ 336 static inline void 337 vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq) 338 { 339 340 if (pci_msix_enabled(vs->vs_pi)) 341 pci_generate_msix(vs->vs_pi, vq->vq_msix_idx); 342 else { 343 #ifndef __FreeBSD__ 344 boolean_t unlock = B_FALSE; 345 346 if (vs->vs_mtx && !pthread_mutex_isowned_np(vs->vs_mtx)) { 347 unlock = B_TRUE; 348 pthread_mutex_lock(vs->vs_mtx); 349 } 350 #else 351 VS_LOCK(vs); 352 #endif 353 vs->vs_isr |= VTCFG_ISR_QUEUES; 354 pci_generate_msi(vs->vs_pi, 0); 355 pci_lintr_assert(vs->vs_pi); 356 #ifndef __FreeBSD__ 357 if (unlock) 358 pthread_mutex_unlock(vs->vs_mtx); 359 #else 360 VS_UNLOCK(vs); 361 #endif 362 } 363 } 364 365 static inline void 366 vq_kick_enable(struct vqueue_info *vq) 367 { 368 369 vq->vq_used->flags &= ~VRING_USED_F_NO_NOTIFY; 370 /* 371 * Full memory barrier to make sure the store to vq_used->flags 372 * happens before the load from vq_avail->idx, which results from a 373 * subsequent call to vq_has_descs(). 374 */ 375 atomic_thread_fence_seq_cst(); 376 } 377 378 static inline void 379 vq_kick_disable(struct vqueue_info *vq) 380 { 381 382 vq->vq_used->flags |= VRING_USED_F_NO_NOTIFY; 383 } 384 385 struct iovec; 386 void vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc, 387 void *dev_softc, struct pci_devinst *pi, 388 struct vqueue_info *queues); 389 int vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix); 390 void vi_reset_dev(struct virtio_softc *); 391 void vi_set_io_bar(struct virtio_softc *, int); 392 393 int vq_getchain(struct vqueue_info *vq, uint16_t *pidx, 394 struct iovec *iov, int n_iov, uint16_t *flags); 395 void vq_retchains(struct vqueue_info *vq, uint16_t n_chains); 396 void vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx, 397 uint32_t iolen); 398 void vq_relchain_publish(struct vqueue_info *vq); 399 void vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen); 400 void vq_endchains(struct vqueue_info *vq, int used_all_avail); 401 402 uint64_t vi_pci_read(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 403 int baridx, uint64_t offset, int size); 404 void vi_pci_write(struct vmctx *ctx, int vcpu, struct pci_devinst *pi, 405 int baridx, uint64_t offset, int size, uint64_t value); 406 #endif /* _BHYVE_VIRTIO_H_ */ 407