sys/dev/vmgenc/vmgenc_acpi.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 /*
  29  * VM Generation Counter driver
  30  *
  31  * See, e.g., the "Virtual Machine Generation ID" white paper:
  32  * https://go.microsoft.com/fwlink/p/?LinkID=260709 , and perhaps also:
  33  * https://docs.microsoft.com/en-us/windows/win32/hyperv_v2/virtual-machine-generation-identifier ,
  34  * https://azure.microsoft.com/en-us/blog/accessing-and-using-azure-vm-unique-id/
  35  *
  36  * Microsoft introduced the concept in 2013 or so and seems to have
  37  * successfully driven it to a consensus standard among hypervisors, not just
  38  * HyperV/Azure:
  39  * - QEMU: https://bugzilla.redhat.com/show_bug.cgi?id=1118834
  40  * - VMware/ESXi: https://kb.vmware.com/s/article/2032586
  41  * - Xen: https://github.com/xenserver/xen-4.5/blob/master/tools/firmware/hvmloader/acpi/dsdt.asl#L456
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/bus.h>
  46 #include <sys/eventhandler.h>
  47 #include <sys/kernel.h>
  48 #include <sys/lock.h>
  49 #include <sys/malloc.h>
  50 #include <sys/module.h>
  51 #include <sys/mutex.h>
  52 #include <sys/random.h>
  53 #include <sys/sysctl.h>
  54 #include <sys/systm.h>
  55
  56 #include <contrib/dev/acpica/include/acpi.h>
  57
  58 #include <dev/acpica/acpivar.h>
  59 #include <dev/random/random_harvestq.h>
  60 #include <dev/vmgenc/vmgenc_acpi.h>
  61
  62 #ifndef ACPI_NOTIFY_STATUS_CHANGED
  63 #define ACPI_NOTIFY_STATUS_CHANGED      0x80
  64 #endif
  65
  66 #define GUID_BYTES      16
  67
  68 static const char *vmgenc_ids[] = {
  69         "VM_GEN_COUNTER",
  70         NULL
  71 };
  72 #if 0
  73 MODULE_PNP_INFO("Z:_CID", acpi, vmgenc, vmgenc_ids, nitems(vmgenc_ids) - 1);
  74 #endif
  75
  76 struct vmgenc_softc {
  77         volatile void   *vmg_pguid;
  78         uint8_t         vmg_cache_guid[GUID_BYTES];
  79 };
  80
  81 static void
  82 vmgenc_harvest_all(const void *p, size_t sz)
  83 {
  84         size_t nbytes;
  85
  86         while (sz > 0) {
  87                 nbytes = MIN(sz,
  88                     sizeof(((struct harvest_event *)0)->he_entropy));
  89                 random_harvest_direct(p, nbytes, RANDOM_PURE_VMGENID);
  90                 p = (const char *)p + nbytes;
  91                 sz -= nbytes;
  92         }
  93 }
  94
  95 static void
  96 vmgenc_status_changed(void *context)
  97 {
  98         uint8_t guid[GUID_BYTES];
  99         struct vmgenc_softc *sc;
 100         device_t dev;
 101
 102         dev = context;
 103         sc = device_get_softc(dev);
 104
 105         /* Check for spurious notify events. */
 106         memcpy(guid, __DEVOLATILE(void *, sc->vmg_pguid), sizeof(guid));
 107         if (memcmp(guid, sc->vmg_cache_guid, GUID_BYTES) == 0)
 108                 return; /* No change. */
 109
 110         /* Update cache. */
 111         memcpy(sc->vmg_cache_guid, guid, GUID_BYTES);
 112
 113         vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
 114
 115         EVENTHANDLER_INVOKE(acpi_vmgenc_event);
 116         acpi_UserNotify("VMGenerationCounter", acpi_get_handle(dev), 0);
 117 }
 118
 119 static void
 120 vmgenc_notify(ACPI_HANDLE h, UINT32 notify, void *context)
 121 {
 122         device_t dev;
 123
 124         dev = context;
 125         switch (notify) {
 126         case ACPI_NOTIFY_STATUS_CHANGED:
 127                 /*
 128                  * We're possibly in GPE / interrupt context, kick the event up
 129                  * to a taskqueue.
 130                  */
 131                 AcpiOsExecute(OSL_NOTIFY_HANDLER, vmgenc_status_changed, dev);
 132                 break;
 133         default:
 134                 device_printf(dev, "unknown notify %#x\n", notify);
 135                 break;
 136         }
 137 }
 138
 139 static int
 140 vmgenc_probe(device_t dev)
 141 {
 142         int rv;
 143
 144         if (acpi_disabled("vmgenc"))
 145                 return (ENXIO);
 146         rv = ACPI_ID_PROBE(device_get_parent(dev), dev,
 147             __DECONST(char **, vmgenc_ids), NULL);
 148         if (rv <= 0)
 149                 device_set_desc(dev, "VM Generation Counter");
 150         return (rv);
 151 }
 152
 153 static const char *
 154 vmgenc_acpi_getname(ACPI_HANDLE handle, char data[static 256])
 155 {
 156     ACPI_BUFFER buf;
 157
 158     buf.Length = 256;
 159     buf.Pointer = data;
 160
 161     if (ACPI_SUCCESS(AcpiGetName(handle, ACPI_FULL_PATHNAME, &buf)))
 162         return (data);
 163     return ("(unknown)");
 164 }
 165
 166 static int
 167 acpi_GetPackedUINT64(device_t dev, ACPI_HANDLE handle, char *path,
 168     uint64_t *out)
 169 {
 170         char hpath[256];
 171         ACPI_STATUS status;
 172         ACPI_BUFFER buf;
 173         ACPI_OBJECT param[3];
 174
 175         buf.Pointer = param;
 176         buf.Length = sizeof(param);
 177         status = AcpiEvaluateObject(handle, path, NULL, &buf);
 178         if (!ACPI_SUCCESS(status)) {
 179                 device_printf(dev, "%s(%s::%s()): %s\n", __func__,
 180                     vmgenc_acpi_getname(handle, hpath), path,
 181                     AcpiFormatException(status));
 182                 return (ENXIO);
 183         }
 184         if (param[0].Type != ACPI_TYPE_PACKAGE) {
 185                 device_printf(dev, "%s(%s::%s()): Wrong type %#x\n", __func__,
 186                     vmgenc_acpi_getname(handle, hpath), path,
 187                     param[0].Type);
 188                 return (ENXIO);
 189         }
 190         if (param[0].Package.Count != 2) {
 191                 device_printf(dev, "%s(%s::%s()): Wrong number of results %u\n",
 192                     __func__, vmgenc_acpi_getname(handle, hpath), path,
 193                     param[0].Package.Count);
 194                 return (ENXIO);
 195         }
 196         if (param[0].Package.Elements[0].Type != ACPI_TYPE_INTEGER ||
 197             param[0].Package.Elements[1].Type != ACPI_TYPE_INTEGER) {
 198                 device_printf(dev, "%s(%s::%s()): Wrong type results %#x, %#x\n",
 199                     __func__, vmgenc_acpi_getname(handle, hpath), path,
 200                     param[0].Package.Elements[0].Type,
 201                     param[0].Package.Elements[1].Type);
 202                 return (ENXIO);
 203         }
 204
 205         *out = (param[0].Package.Elements[0].Integer.Value & UINT32_MAX) |
 206             ((uint64_t)param[0].Package.Elements[1].Integer.Value << 32);
 207         if (*out == 0)
 208                 return (ENXIO);
 209         return (0);
 210
 211 }
 212
 213 static int
 214 vmgenc_attach(device_t dev)
 215 {
 216         struct vmgenc_softc *sc;
 217         uint64_t guid_physaddr;
 218         ACPI_HANDLE h;
 219         int error;
 220
 221         h = acpi_get_handle(dev);
 222         sc = device_get_softc(dev);
 223
 224         error = acpi_GetPackedUINT64(dev, h, "ADDR", &guid_physaddr);
 225         if (error != 0)
 226                 return (error);
 227
 228         SYSCTL_ADD_OPAQUE(device_get_sysctl_ctx(dev),
 229             SYSCTL_CHILDREN(device_get_sysctl_tree(dev)), OID_AUTO, "guid",
 230             CTLFLAG_RD, sc->vmg_cache_guid, GUID_BYTES, "",
 231             "latest cached VM generation counter (128-bit UUID)");
 232
 233         sc->vmg_pguid = AcpiOsMapMemory(guid_physaddr, GUID_BYTES);
 234         memcpy(sc->vmg_cache_guid, __DEVOLATILE(void *, sc->vmg_pguid),
 235             sizeof(sc->vmg_cache_guid));
 236
 237         random_harvest_register_source(RANDOM_PURE_VMGENID);
 238         vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
 239
 240         AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev);
 241         return (0);
 242 }
 243
 244 static device_method_t vmgenc_methods[] = {
 245         DEVMETHOD(device_probe,         vmgenc_probe),
 246         DEVMETHOD(device_attach,        vmgenc_attach),
 247         DEVMETHOD_END
 248 };
 249
 250 static driver_t vmgenc_driver = {
 251         "vmgenc",
 252         vmgenc_methods,
 253         sizeof(struct vmgenc_softc),
 254 };
 255
 256 DRIVER_MODULE(vmgenc, acpi, vmgenc_driver, NULL, NULL);
 257 MODULE_DEPEND(vmgenc, acpi, 1, 1, 1);
 258 MODULE_DEPEND(vemgenc, random_harvestq, 1, 1, 1);