2 * SPDX-License-Identifier: BSD-2-Clause
4 * Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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
29 * VM Generation Counter driver
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/
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
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
44 #include <sys/cdefs.h>
45 #include <sys/param.h>
47 #include <sys/eventhandler.h>
48 #include <sys/kernel.h>
50 #include <sys/malloc.h>
51 #include <sys/module.h>
52 #include <sys/mutex.h>
53 #include <sys/random.h>
54 #include <sys/sysctl.h>
55 #include <sys/systm.h>
57 #include <contrib/dev/acpica/include/acpi.h>
59 #include <dev/acpica/acpivar.h>
60 #include <dev/random/random_harvestq.h>
61 #include <dev/vmgenc/vmgenc_acpi.h>
63 #ifndef ACPI_NOTIFY_STATUS_CHANGED
64 #define ACPI_NOTIFY_STATUS_CHANGED 0x80
69 static const char *vmgenc_ids[] = {
74 MODULE_PNP_INFO("Z:_CID", acpi, vmgenc, vmgenc_ids, nitems(vmgenc_ids) - 1);
78 volatile void *vmg_pguid;
79 uint8_t vmg_cache_guid[GUID_BYTES];
83 vmgenc_harvest_all(const void *p, size_t sz)
89 sizeof(((struct harvest_event *)0)->he_entropy));
90 random_harvest_direct(p, nbytes, RANDOM_PURE_VMGENID);
91 p = (const char *)p + nbytes;
97 vmgenc_status_changed(void *context)
99 uint8_t guid[GUID_BYTES];
100 struct vmgenc_softc *sc;
104 sc = device_get_softc(dev);
106 /* Check for spurious notify events. */
107 memcpy(guid, __DEVOLATILE(void *, sc->vmg_pguid), sizeof(guid));
108 if (memcmp(guid, sc->vmg_cache_guid, GUID_BYTES) == 0)
109 return; /* No change. */
112 memcpy(sc->vmg_cache_guid, guid, GUID_BYTES);
114 vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
116 EVENTHANDLER_INVOKE(acpi_vmgenc_event);
117 acpi_UserNotify("VMGenerationCounter", acpi_get_handle(dev), 0);
121 vmgenc_notify(ACPI_HANDLE h, UINT32 notify, void *context)
127 case ACPI_NOTIFY_STATUS_CHANGED:
129 * We're possibly in GPE / interrupt context, kick the event up
132 AcpiOsExecute(OSL_NOTIFY_HANDLER, vmgenc_status_changed, dev);
135 device_printf(dev, "unknown notify %#x\n", notify);
141 vmgenc_probe(device_t dev)
145 if (acpi_disabled("vmgenc"))
147 rv = ACPI_ID_PROBE(device_get_parent(dev), dev,
148 __DECONST(char **, vmgenc_ids), NULL);
150 device_set_desc(dev, "VM Generation Counter");
155 vmgenc_acpi_getname(ACPI_HANDLE handle, char data[static 256])
162 if (ACPI_SUCCESS(AcpiGetName(handle, ACPI_FULL_PATHNAME, &buf)))
164 return ("(unknown)");
168 acpi_GetPackedUINT64(device_t dev, ACPI_HANDLE handle, char *path,
174 ACPI_OBJECT param[3];
177 buf.Length = sizeof(param);
178 status = AcpiEvaluateObject(handle, path, NULL, &buf);
179 if (!ACPI_SUCCESS(status)) {
180 device_printf(dev, "%s(%s::%s()): %s\n", __func__,
181 vmgenc_acpi_getname(handle, hpath), path,
182 AcpiFormatException(status));
185 if (param[0].Type != ACPI_TYPE_PACKAGE) {
186 device_printf(dev, "%s(%s::%s()): Wrong type %#x\n", __func__,
187 vmgenc_acpi_getname(handle, hpath), path,
191 if (param[0].Package.Count != 2) {
192 device_printf(dev, "%s(%s::%s()): Wrong number of results %u\n",
193 __func__, vmgenc_acpi_getname(handle, hpath), path,
194 param[0].Package.Count);
197 if (param[0].Package.Elements[0].Type != ACPI_TYPE_INTEGER ||
198 param[0].Package.Elements[1].Type != ACPI_TYPE_INTEGER) {
199 device_printf(dev, "%s(%s::%s()): Wrong type results %#x, %#x\n",
200 __func__, vmgenc_acpi_getname(handle, hpath), path,
201 param[0].Package.Elements[0].Type,
202 param[0].Package.Elements[1].Type);
206 *out = (param[0].Package.Elements[0].Integer.Value & UINT32_MAX) |
207 ((uint64_t)param[0].Package.Elements[1].Integer.Value << 32);
215 vmgenc_attach(device_t dev)
217 struct vmgenc_softc *sc;
218 uint64_t guid_physaddr;
222 h = acpi_get_handle(dev);
223 sc = device_get_softc(dev);
225 error = acpi_GetPackedUINT64(dev, h, "ADDR", &guid_physaddr);
229 SYSCTL_ADD_OPAQUE(device_get_sysctl_ctx(dev),
230 SYSCTL_CHILDREN(device_get_sysctl_tree(dev)), OID_AUTO, "guid",
231 CTLFLAG_RD, sc->vmg_cache_guid, GUID_BYTES, "",
232 "latest cached VM generation counter (128-bit UUID)");
234 sc->vmg_pguid = AcpiOsMapMemory(guid_physaddr, GUID_BYTES);
235 memcpy(sc->vmg_cache_guid, __DEVOLATILE(void *, sc->vmg_pguid),
236 sizeof(sc->vmg_cache_guid));
238 random_harvest_register_source(RANDOM_PURE_VMGENID);
239 vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
241 AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev);
245 static device_method_t vmgenc_methods[] = {
246 DEVMETHOD(device_probe, vmgenc_probe),
247 DEVMETHOD(device_attach, vmgenc_attach),
251 static driver_t vmgenc_driver = {
254 sizeof(struct vmgenc_softc),
257 DRIVER_MODULE(vmgenc, acpi, vmgenc_driver, NULL, NULL);
258 MODULE_DEPEND(vmgenc, acpi, 1, 1, 1);
259 MODULE_DEPEND(vemgenc, random_harvestq, 1, 1, 1);