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); 259