sys/amd64/vmm/vmm_dev.c

   1 /*-
   2  * Copyright (c) 2011 NetApp, Inc.
   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 NETAPP, INC ``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 NETAPP, INC 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 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/kernel.h>
  34 #include <sys/queue.h>
  35 #include <sys/lock.h>
  36 #include <sys/mutex.h>
  37 #include <sys/malloc.h>
  38 #include <sys/conf.h>
  39 #include <sys/sysctl.h>
  40 #include <sys/libkern.h>
  41 #include <sys/ioccom.h>
  42 #include <sys/mman.h>
  43 #include <sys/uio.h>
  44
  45 #include <vm/vm.h>
  46 #include <vm/pmap.h>
  47 #include <vm/vm_map.h>
  48
  49 #include <machine/vmparam.h>
  50 #include <machine/vmm.h>
  51 #include <machine/vmm_dev.h>
  52
  53 #include "vmm_lapic.h"
  54 #include "vmm_stat.h"
  55 #include "vmm_mem.h"
  56 #include "io/ppt.h"
  57 #include "io/vatpic.h"
  58 #include "io/vioapic.h"
  59 #include "io/vhpet.h"
  60
  61 struct vmmdev_softc {
  62         struct vm       *vm;            /* vm instance cookie */
  63         struct cdev     *cdev;
  64         SLIST_ENTRY(vmmdev_softc) link;
  65         int             flags;
  66 };
  67 #define VSC_LINKED              0x01
  68
  69 static SLIST_HEAD(, vmmdev_softc) head;
  70
  71 static struct mtx vmmdev_mtx;
  72
  73 static MALLOC_DEFINE(M_VMMDEV, "vmmdev", "vmmdev");
  74
  75 SYSCTL_DECL(_hw_vmm);
  76
  77 static struct vmmdev_softc *
  78 vmmdev_lookup(const char *name)
  79 {
  80         struct vmmdev_softc *sc;
  81
  82 #ifdef notyet   /* XXX kernel is not compiled with invariants */
  83         mtx_assert(&vmmdev_mtx, MA_OWNED);
  84 #endif
  85
  86         SLIST_FOREACH(sc, &head, link) {
  87                 if (strcmp(name, vm_name(sc->vm)) == 0)
  88                         break;
  89         }
  90
  91         return (sc);
  92 }
  93
  94 static struct vmmdev_softc *
  95 vmmdev_lookup2(struct cdev *cdev)
  96 {
  97
  98         return (cdev->si_drv1);
  99 }
 100
 101 static int
 102 vmmdev_rw(struct cdev *cdev, struct uio *uio, int flags)
 103 {
 104         int error, off, c, prot;
 105         vm_paddr_t gpa;
 106         void *hpa, *cookie;
 107         struct vmmdev_softc *sc;
 108
 109         static char zerobuf[PAGE_SIZE];
 110
 111         error = 0;
 112         sc = vmmdev_lookup2(cdev);
 113         if (sc == NULL)
 114                 error = ENXIO;
 115
 116         prot = (uio->uio_rw == UIO_WRITE ? VM_PROT_WRITE : VM_PROT_READ);
 117         while (uio->uio_resid > 0 && error == 0) {
 118                 gpa = uio->uio_offset;
 119                 off = gpa & PAGE_MASK;
 120                 c = min(uio->uio_resid, PAGE_SIZE - off);
 121
 122                 /*
 123                  * The VM has a hole in its physical memory map. If we want to
 124                  * use 'dd' to inspect memory beyond the hole we need to
 125                  * provide bogus data for memory that lies in the hole.
 126                  *
 127                  * Since this device does not support lseek(2), dd(1) will
 128                  * read(2) blocks of data to simulate the lseek(2).
 129                  */
 130                 hpa = vm_gpa_hold(sc->vm, gpa, c, prot, &cookie);
 131                 if (hpa == NULL) {
 132                         if (uio->uio_rw == UIO_READ)
 133                                 error = uiomove(zerobuf, c, uio);
 134                         else
 135                                 error = EFAULT;
 136                 } else {
 137                         error = uiomove(hpa, c, uio);
 138                         vm_gpa_release(cookie);
 139                 }
 140         }
 141         return (error);
 142 }
 143
 144 static int
 145 vmmdev_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
 146              struct thread *td)
 147 {
 148         int error, vcpu, state_changed;
 149         struct vmmdev_softc *sc;
 150         struct vm_memory_segment *seg;
 151         struct vm_register *vmreg;
 152         struct vm_seg_desc *vmsegdesc;
 153         struct vm_run *vmrun;
 154         struct vm_exception *vmexc;
 155         struct vm_lapic_irq *vmirq;
 156         struct vm_lapic_msi *vmmsi;
 157         struct vm_ioapic_irq *ioapic_irq;
 158         struct vm_isa_irq *isa_irq;
 159         struct vm_capability *vmcap;
 160         struct vm_pptdev *pptdev;
 161         struct vm_pptdev_mmio *pptmmio;
 162         struct vm_pptdev_msi *pptmsi;
 163         struct vm_pptdev_msix *pptmsix;
 164         struct vm_nmi *vmnmi;
 165         struct vm_stats *vmstats;
 166         struct vm_stat_desc *statdesc;
 167         struct vm_x2apic *x2apic;
 168         struct vm_gpa_pte *gpapte;
 169
 170         sc = vmmdev_lookup2(cdev);
 171         if (sc == NULL)
 172                 return (ENXIO);
 173
 174         error = 0;
 175         vcpu = -1;
 176         state_changed = 0;
 177
 178         /*
 179          * Some VMM ioctls can operate only on vcpus that are not running.
 180          */
 181         switch (cmd) {
 182         case VM_RUN:
 183         case VM_GET_REGISTER:
 184         case VM_SET_REGISTER:
 185         case VM_GET_SEGMENT_DESCRIPTOR:
 186         case VM_SET_SEGMENT_DESCRIPTOR:
 187         case VM_INJECT_EXCEPTION:
 188         case VM_GET_CAPABILITY:
 189         case VM_SET_CAPABILITY:
 190         case VM_PPTDEV_MSI:
 191         case VM_PPTDEV_MSIX:
 192         case VM_SET_X2APIC_STATE:
 193                 /*
 194                  * XXX fragile, handle with care
 195                  * Assumes that the first field of the ioctl data is the vcpu.
 196                  */
 197                 vcpu = *(int *)data;
 198                 if (vcpu < 0 || vcpu >= VM_MAXCPU) {
 199                         error = EINVAL;
 200                         goto done;
 201                 }
 202
 203                 error = vcpu_set_state(sc->vm, vcpu, VCPU_FROZEN, true);
 204                 if (error)
 205                         goto done;
 206
 207                 state_changed = 1;
 208                 break;
 209
 210         case VM_MAP_PPTDEV_MMIO:
 211         case VM_BIND_PPTDEV:
 212         case VM_UNBIND_PPTDEV:
 213         case VM_MAP_MEMORY:
 214                 /*
 215                  * ioctls that operate on the entire virtual machine must
 216                  * prevent all vcpus from running.
 217                  */
 218                 error = 0;
 219                 for (vcpu = 0; vcpu < VM_MAXCPU; vcpu++) {
 220                         error = vcpu_set_state(sc->vm, vcpu, VCPU_FROZEN, true);
 221                         if (error)
 222                                 break;
 223                 }
 224
 225                 if (error) {
 226                         while (--vcpu >= 0)
 227                                 vcpu_set_state(sc->vm, vcpu, VCPU_IDLE, false);
 228                         goto done;
 229                 }
 230
 231                 state_changed = 2;
 232                 break;
 233
 234         default:
 235                 break;
 236         }
 237
 238         switch(cmd) {
 239         case VM_RUN:
 240                 vmrun = (struct vm_run *)data;
 241                 error = vm_run(sc->vm, vmrun);
 242                 break;
 243         case VM_STAT_DESC: {
 244                 statdesc = (struct vm_stat_desc *)data;
 245                 error = vmm_stat_desc_copy(statdesc->index,
 246                                         statdesc->desc, sizeof(statdesc->desc));
 247                 break;
 248         }
 249         case VM_STATS: {
 250                 CTASSERT(MAX_VM_STATS >= MAX_VMM_STAT_ELEMS);
 251                 vmstats = (struct vm_stats *)data;
 252                 getmicrotime(&vmstats->tv);
 253                 error = vmm_stat_copy(sc->vm, vmstats->cpuid,
 254                                       &vmstats->num_entries, vmstats->statbuf);
 255                 break;
 256         }
 257         case VM_PPTDEV_MSI:
 258                 pptmsi = (struct vm_pptdev_msi *)data;
 259                 error = ppt_setup_msi(sc->vm, pptmsi->vcpu,
 260                                       pptmsi->bus, pptmsi->slot, pptmsi->func,
 261                                       pptmsi->addr, pptmsi->msg,
 262                                       pptmsi->numvec);
 263                 break;
 264         case VM_PPTDEV_MSIX:
 265                 pptmsix = (struct vm_pptdev_msix *)data;
 266                 error = ppt_setup_msix(sc->vm, pptmsix->vcpu,
 267                                        pptmsix->bus, pptmsix->slot,
 268                                        pptmsix->func, pptmsix->idx,
 269                                        pptmsix->addr, pptmsix->msg,
 270                                        pptmsix->vector_control);
 271                 break;
 272         case VM_MAP_PPTDEV_MMIO:
 273                 pptmmio = (struct vm_pptdev_mmio *)data;
 274                 error = ppt_map_mmio(sc->vm, pptmmio->bus, pptmmio->slot,
 275                                      pptmmio->func, pptmmio->gpa, pptmmio->len,
 276                                      pptmmio->hpa);
 277                 break;
 278         case VM_BIND_PPTDEV:
 279                 pptdev = (struct vm_pptdev *)data;
 280                 error = vm_assign_pptdev(sc->vm, pptdev->bus, pptdev->slot,
 281                                          pptdev->func);
 282                 break;
 283         case VM_UNBIND_PPTDEV:
 284                 pptdev = (struct vm_pptdev *)data;
 285                 error = vm_unassign_pptdev(sc->vm, pptdev->bus, pptdev->slot,
 286                                            pptdev->func);
 287                 break;
 288         case VM_INJECT_EXCEPTION:
 289                 vmexc = (struct vm_exception *)data;
 290                 error = vm_inject_exception(sc->vm, vmexc->cpuid, vmexc);
 291                 break;
 292         case VM_INJECT_NMI:
 293                 vmnmi = (struct vm_nmi *)data;
 294                 error = vm_inject_nmi(sc->vm, vmnmi->cpuid);
 295                 break;
 296         case VM_LAPIC_IRQ:
 297                 vmirq = (struct vm_lapic_irq *)data;
 298                 error = lapic_intr_edge(sc->vm, vmirq->cpuid, vmirq->vector);
 299                 break;
 300         case VM_LAPIC_LOCAL_IRQ:
 301                 vmirq = (struct vm_lapic_irq *)data;
 302                 error = lapic_set_local_intr(sc->vm, vmirq->cpuid,
 303                     vmirq->vector);
 304                 break;
 305         case VM_LAPIC_MSI:
 306                 vmmsi = (struct vm_lapic_msi *)data;
 307                 error = lapic_intr_msi(sc->vm, vmmsi->addr, vmmsi->msg);
 308                 break;
 309         case VM_IOAPIC_ASSERT_IRQ:
 310                 ioapic_irq = (struct vm_ioapic_irq *)data;
 311                 error = vioapic_assert_irq(sc->vm, ioapic_irq->irq);
 312                 break;
 313         case VM_IOAPIC_DEASSERT_IRQ:
 314                 ioapic_irq = (struct vm_ioapic_irq *)data;
 315                 error = vioapic_deassert_irq(sc->vm, ioapic_irq->irq);
 316                 break;
 317         case VM_IOAPIC_PULSE_IRQ:
 318                 ioapic_irq = (struct vm_ioapic_irq *)data;
 319                 error = vioapic_pulse_irq(sc->vm, ioapic_irq->irq);
 320                 break;
 321         case VM_IOAPIC_PINCOUNT:
 322                 *(int *)data = vioapic_pincount(sc->vm);
 323                 break;
 324         case VM_ISA_ASSERT_IRQ:
 325                 isa_irq = (struct vm_isa_irq *)data;
 326                 error = vatpic_assert_irq(sc->vm, isa_irq->atpic_irq);
 327                 if (error == 0 && isa_irq->ioapic_irq != -1)
 328                         error = vioapic_assert_irq(sc->vm,
 329                             isa_irq->ioapic_irq);
 330                 break;
 331         case VM_ISA_DEASSERT_IRQ:
 332                 isa_irq = (struct vm_isa_irq *)data;
 333                 error = vatpic_deassert_irq(sc->vm, isa_irq->atpic_irq);
 334                 if (error == 0 && isa_irq->ioapic_irq != -1)
 335                         error = vioapic_deassert_irq(sc->vm,
 336                             isa_irq->ioapic_irq);
 337                 break;
 338         case VM_ISA_PULSE_IRQ:
 339                 isa_irq = (struct vm_isa_irq *)data;
 340                 error = vatpic_pulse_irq(sc->vm, isa_irq->atpic_irq);
 341                 if (error == 0 && isa_irq->ioapic_irq != -1)
 342                         error = vioapic_pulse_irq(sc->vm, isa_irq->ioapic_irq);
 343                 break;
 344         case VM_MAP_MEMORY:
 345                 seg = (struct vm_memory_segment *)data;
 346                 error = vm_malloc(sc->vm, seg->gpa, seg->len);
 347                 break;
 348         case VM_GET_MEMORY_SEG:
 349                 seg = (struct vm_memory_segment *)data;
 350                 seg->len = 0;
 351                 (void)vm_gpabase2memseg(sc->vm, seg->gpa, seg);
 352                 error = 0;
 353                 break;
 354         case VM_GET_REGISTER:
 355                 vmreg = (struct vm_register *)data;
 356                 error = vm_get_register(sc->vm, vmreg->cpuid, vmreg->regnum,
 357                                         &vmreg->regval);
 358                 break;
 359         case VM_SET_REGISTER:
 360                 vmreg = (struct vm_register *)data;
 361                 error = vm_set_register(sc->vm, vmreg->cpuid, vmreg->regnum,
 362                                         vmreg->regval);
 363                 break;
 364         case VM_SET_SEGMENT_DESCRIPTOR:
 365                 vmsegdesc = (struct vm_seg_desc *)data;
 366                 error = vm_set_seg_desc(sc->vm, vmsegdesc->cpuid,
 367                                         vmsegdesc->regnum,
 368                                         &vmsegdesc->desc);
 369                 break;
 370         case VM_GET_SEGMENT_DESCRIPTOR:
 371                 vmsegdesc = (struct vm_seg_desc *)data;
 372                 error = vm_get_seg_desc(sc->vm, vmsegdesc->cpuid,
 373                                         vmsegdesc->regnum,
 374                                         &vmsegdesc->desc);
 375                 break;
 376         case VM_GET_CAPABILITY:
 377                 vmcap = (struct vm_capability *)data;
 378                 error = vm_get_capability(sc->vm, vmcap->cpuid,
 379                                           vmcap->captype,
 380                                           &vmcap->capval);
 381                 break;
 382         case VM_SET_CAPABILITY:
 383                 vmcap = (struct vm_capability *)data;
 384                 error = vm_set_capability(sc->vm, vmcap->cpuid,
 385                                           vmcap->captype,
 386                                           vmcap->capval);
 387                 break;
 388         case VM_SET_X2APIC_STATE:
 389                 x2apic = (struct vm_x2apic *)data;
 390                 error = vm_set_x2apic_state(sc->vm,
 391                                             x2apic->cpuid, x2apic->state);
 392                 break;
 393         case VM_GET_X2APIC_STATE:
 394                 x2apic = (struct vm_x2apic *)data;
 395                 error = vm_get_x2apic_state(sc->vm,
 396                                             x2apic->cpuid, &x2apic->state);
 397                 break;
 398         case VM_GET_GPA_PMAP:
 399                 gpapte = (struct vm_gpa_pte *)data;
 400                 pmap_get_mapping(vmspace_pmap(vm_get_vmspace(sc->vm)),
 401                                  gpapte->gpa, gpapte->pte, &gpapte->ptenum);
 402                 error = 0;
 403                 break;
 404         case VM_GET_HPET_CAPABILITIES:
 405                 error = vhpet_getcap((struct vm_hpet_cap *)data);
 406                 break;
 407         default:
 408                 error = ENOTTY;
 409                 break;
 410         }
 411
 412         if (state_changed == 1) {
 413                 vcpu_set_state(sc->vm, vcpu, VCPU_IDLE, false);
 414         } else if (state_changed == 2) {
 415                 for (vcpu = 0; vcpu < VM_MAXCPU; vcpu++)
 416                         vcpu_set_state(sc->vm, vcpu, VCPU_IDLE, false);
 417         }
 418
 419 done:
 420         /* Make sure that no handler returns a bogus value like ERESTART */
 421         KASSERT(error >= 0, ("vmmdev_ioctl: invalid error return %d", error));
 422         return (error);
 423 }
 424
 425 static int
 426 vmmdev_mmap_single(struct cdev *cdev, vm_ooffset_t *offset,
 427                    vm_size_t size, struct vm_object **object, int nprot)
 428 {
 429         int error;
 430         struct vmmdev_softc *sc;
 431
 432         sc = vmmdev_lookup2(cdev);
 433         if (sc != NULL && (nprot & PROT_EXEC) == 0)
 434                 error = vm_get_memobj(sc->vm, *offset, size, offset, object);
 435         else
 436                 error = EINVAL;
 437
 438         return (error);
 439 }
 440
 441 static void
 442 vmmdev_destroy(void *arg)
 443 {
 444
 445         struct vmmdev_softc *sc = arg;
 446
 447         if (sc->cdev != NULL)
 448                 destroy_dev(sc->cdev);
 449
 450         if (sc->vm != NULL)
 451                 vm_destroy(sc->vm);
 452
 453         if ((sc->flags & VSC_LINKED) != 0) {
 454                 mtx_lock(&vmmdev_mtx);
 455                 SLIST_REMOVE(&head, sc, vmmdev_softc, link);
 456                 mtx_unlock(&vmmdev_mtx);
 457         }
 458
 459         free(sc, M_VMMDEV);
 460 }
 461
 462 static int
 463 sysctl_vmm_destroy(SYSCTL_HANDLER_ARGS)
 464 {
 465         int error;
 466         char buf[VM_MAX_NAMELEN];
 467         struct vmmdev_softc *sc;
 468         struct cdev *cdev;
 469
 470         strlcpy(buf, "beavis", sizeof(buf));
 471         error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
 472         if (error != 0 || req->newptr == NULL)
 473                 return (error);
 474
 475         mtx_lock(&vmmdev_mtx);
 476         sc = vmmdev_lookup(buf);
 477         if (sc == NULL || sc->cdev == NULL) {
 478                 mtx_unlock(&vmmdev_mtx);
 479                 return (EINVAL);
 480         }
 481
 482         /*
 483          * The 'cdev' will be destroyed asynchronously when 'si_threadcount'
 484          * goes down to 0 so we should not do it again in the callback.
 485          */
 486         cdev = sc->cdev;
 487         sc->cdev = NULL;
 488         mtx_unlock(&vmmdev_mtx);
 489
 490         /*
 491          * Schedule the 'cdev' to be destroyed:
 492          *
 493          * - any new operations on this 'cdev' will return an error (ENXIO).
 494          *
 495          * - when the 'si_threadcount' dwindles down to zero the 'cdev' will
 496          *   be destroyed and the callback will be invoked in a taskqueue
 497          *   context.
 498          */
 499         destroy_dev_sched_cb(cdev, vmmdev_destroy, sc);
 500
 501         return (0);
 502 }
 503 SYSCTL_PROC(_hw_vmm, OID_AUTO, destroy, CTLTYPE_STRING | CTLFLAG_RW,
 504             NULL, 0, sysctl_vmm_destroy, "A", NULL);
 505
 506 static struct cdevsw vmmdevsw = {
 507         .d_name         = "vmmdev",
 508         .d_version      = D_VERSION,
 509         .d_ioctl        = vmmdev_ioctl,
 510         .d_mmap_single  = vmmdev_mmap_single,
 511         .d_read         = vmmdev_rw,
 512         .d_write        = vmmdev_rw,
 513 };
 514
 515 static int
 516 sysctl_vmm_create(SYSCTL_HANDLER_ARGS)
 517 {
 518         int error;
 519         struct vm *vm;
 520         struct cdev *cdev;
 521         struct vmmdev_softc *sc, *sc2;
 522         char buf[VM_MAX_NAMELEN];
 523
 524         strlcpy(buf, "beavis", sizeof(buf));
 525         error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
 526         if (error != 0 || req->newptr == NULL)
 527                 return (error);
 528
 529         mtx_lock(&vmmdev_mtx);
 530         sc = vmmdev_lookup(buf);
 531         mtx_unlock(&vmmdev_mtx);
 532         if (sc != NULL)
 533                 return (EEXIST);
 534
 535         error = vm_create(buf, &vm);
 536         if (error != 0)
 537                 return (error);
 538
 539         sc = malloc(sizeof(struct vmmdev_softc), M_VMMDEV, M_WAITOK | M_ZERO);
 540         sc->vm = vm;
 541
 542         /*
 543          * Lookup the name again just in case somebody sneaked in when we
 544          * dropped the lock.
 545          */
 546         mtx_lock(&vmmdev_mtx);
 547         sc2 = vmmdev_lookup(buf);
 548         if (sc2 == NULL) {
 549                 SLIST_INSERT_HEAD(&head, sc, link);
 550                 sc->flags |= VSC_LINKED;
 551         }
 552         mtx_unlock(&vmmdev_mtx);
 553
 554         if (sc2 != NULL) {
 555                 vmmdev_destroy(sc);
 556                 return (EEXIST);
 557         }
 558
 559         error = make_dev_p(MAKEDEV_CHECKNAME, &cdev, &vmmdevsw, NULL,
 560                            UID_ROOT, GID_WHEEL, 0600, "vmm/%s", buf);
 561         if (error != 0) {
 562                 vmmdev_destroy(sc);
 563                 return (error);
 564         }
 565
 566         mtx_lock(&vmmdev_mtx);
 567         sc->cdev = cdev;
 568         sc->cdev->si_drv1 = sc;
 569         mtx_unlock(&vmmdev_mtx);
 570
 571         return (0);
 572 }
 573 SYSCTL_PROC(_hw_vmm, OID_AUTO, create, CTLTYPE_STRING | CTLFLAG_RW,
 574             NULL, 0, sysctl_vmm_create, "A", NULL);
 575
 576 void
 577 vmmdev_init(void)
 578 {
 579         mtx_init(&vmmdev_mtx, "vmm device mutex", NULL, MTX_DEF);
 580 }
 581
 582 int
 583 vmmdev_cleanup(void)
 584 {
 585         int error;
 586
 587         if (SLIST_EMPTY(&head))
 588                 error = 0;
 589         else
 590                 error = EBUSY;
 591
 592         return (error);
 593 }