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/cdefs.h> 45 #include <sys/param.h> 46 #include <sys/bus.h> 47 #include <sys/eventhandler.h> 48 #include <sys/kernel.h> 49 #include <sys/lock.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> 56 57 #include <contrib/dev/acpica/include/acpi.h> 58 59 #include <dev/acpica/acpivar.h> 60 #include <dev/random/random_harvestq.h> 61 #include <dev/vmgenc/vmgenc_acpi.h> 62 63 #ifndef ACPI_NOTIFY_STATUS_CHANGED 64 #define ACPI_NOTIFY_STATUS_CHANGED 0x80 65 #endif 66 67 #define GUID_BYTES 16 68 69 static const char *vmgenc_ids[] = { 70 "VM_GEN_COUNTER", 71 NULL 72 }; 73 #if 0 74 MODULE_PNP_INFO("Z:_CID", acpi, vmgenc, vmgenc_ids, nitems(vmgenc_ids) - 1); 75 #endif 76 77 struct vmgenc_softc { 78 volatile void *vmg_pguid; 79 uint8_t vmg_cache_guid[GUID_BYTES]; 80 }; 81 82 static void 83 vmgenc_harvest_all(const void *p, size_t sz) 84 { 85 size_t nbytes; 86 87 while (sz > 0) { 88 nbytes = MIN(sz, 89 sizeof(((struct harvest_event *)0)->he_entropy)); 90 random_harvest_direct(p, nbytes, RANDOM_PURE_VMGENID); 91 p = (const char *)p + nbytes; 92 sz -= nbytes; 93 } 94 } 95 96 static void 97 vmgenc_status_changed(void *context) 98 { 99 uint8_t guid[GUID_BYTES]; 100 struct vmgenc_softc *sc; 101 device_t dev; 102 103 dev = context; 104 sc = device_get_softc(dev); 105 106 /* 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. */ 110 111 /* Update cache. */ 112 memcpy(sc->vmg_cache_guid, guid, GUID_BYTES); 113 114 vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid)); 115 116 EVENTHANDLER_INVOKE(acpi_vmgenc_event); 117 acpi_UserNotify("VMGenerationCounter", acpi_get_handle(dev), 0); 118 } 119 120 static void 121 vmgenc_notify(ACPI_HANDLE h, UINT32 notify, void *context) 122 { 123 device_t dev; 124 125 dev = context; 126 switch (notify) { 127 case ACPI_NOTIFY_STATUS_CHANGED: 128 /* 129 * We're possibly in GPE / interrupt context, kick the event up 130 * to a taskqueue. 131 */ 132 AcpiOsExecute(OSL_NOTIFY_HANDLER, vmgenc_status_changed, dev); 133 break; 134 default: 135 device_printf(dev, "unknown notify %#x\n", notify); 136 break; 137 } 138 } 139 140 static int 141 vmgenc_probe(device_t dev) 142 { 143 int rv; 144 145 if (acpi_disabled("vmgenc")) 146 return (ENXIO); 147 rv = ACPI_ID_PROBE(device_get_parent(dev), dev, 148 __DECONST(char **, vmgenc_ids), NULL); 149 if (rv <= 0) 150 device_set_desc(dev, "VM Generation Counter"); 151 return (rv); 152 } 153 154 static const char * 155 vmgenc_acpi_getname(ACPI_HANDLE handle, char data[static 256]) 156 { 157 ACPI_BUFFER buf; 158 159 buf.Length = 256; 160 buf.Pointer = data; 161 162 if (ACPI_SUCCESS(AcpiGetName(handle, ACPI_FULL_PATHNAME, &buf))) 163 return (data); 164 return ("(unknown)"); 165 } 166 167 static int 168 acpi_GetPackedUINT64(device_t dev, ACPI_HANDLE handle, char *path, 169 uint64_t *out) 170 { 171 char hpath[256]; 172 ACPI_STATUS status; 173 ACPI_BUFFER buf; 174 ACPI_OBJECT param[3]; 175 176 buf.Pointer = param; 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)); 183 return (ENXIO); 184 } 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, 188 param[0].Type); 189 return (ENXIO); 190 } 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); 195 return (ENXIO); 196 } 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); 203 return (ENXIO); 204 } 205 206 *out = (param[0].Package.Elements[0].Integer.Value & UINT32_MAX) | 207 ((uint64_t)param[0].Package.Elements[1].Integer.Value << 32); 208 if (*out == 0) 209 return (ENXIO); 210 return (0); 211 212 } 213 214 static int 215 vmgenc_attach(device_t dev) 216 { 217 struct vmgenc_softc *sc; 218 uint64_t guid_physaddr; 219 ACPI_HANDLE h; 220 int error; 221 222 h = acpi_get_handle(dev); 223 sc = device_get_softc(dev); 224 225 error = acpi_GetPackedUINT64(dev, h, "ADDR", &guid_physaddr); 226 if (error != 0) 227 return (error); 228 229 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)"); 233 234 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)); 237 238 random_harvest_register_source(RANDOM_PURE_VMGENID); 239 vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid)); 240 241 AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev); 242 return (0); 243 } 244 245 static device_method_t vmgenc_methods[] = { 246 DEVMETHOD(device_probe, vmgenc_probe), 247 DEVMETHOD(device_attach, vmgenc_attach), 248 DEVMETHOD_END 249 }; 250 251 static driver_t vmgenc_driver = { 252 "vmgenc", 253 vmgenc_methods, 254 sizeof(struct vmgenc_softc), 255 }; 256 257 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); 260