Add vmgenc(4) driver for ACPI VM generation counter
The VM generation counter is a 128-bit value exposed by the BIOS via ACPI. The value changes to another unique identifier whenever a VM is duplicated. Additionally, ACPI provides notification events when such events occur. The driver decodes the pointer to the UUID, exports the value to userspace via OPAQUE sysctl blob, and forwards the ACPI notifications in the form of an EVENTHANDLER invocation as well as userspace devctl events. See design paper: https://go.microsoft.com/fwlink/p/?LinkID=260709
This commit is contained in:
Conrad Meyer
parent
e87e283ce3
commit
ffac39deae
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=356001
@ -3398,6 +3398,7 @@ dev/virtio/scsi/virtio_scsi.c optional virtio_scsi
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dev/virtio/random/virtio_random.c optional virtio_random
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dev/virtio/console/virtio_console.c optional virtio_console
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dev/vkbd/vkbd.c optional vkbd
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dev/vmgenc/vmgenc_acpi.c optional acpi
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dev/vr/if_vr.c optional vr pci
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dev/vt/colors/vt_termcolors.c optional vt
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dev/vt/font/vt_font_default.c optional vt
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240
sys/dev/vmgenc/vmgenc_acpi.c
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240
sys/dev/vmgenc/vmgenc_acpi.c
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@ -0,0 +1,240 @@
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/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* VM Generation Counter driver
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*
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* See, e.g., the "Virtual Machine Generation ID" white paper:
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* https://go.microsoft.com/fwlink/p/?LinkID=260709 , and perhaps also:
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* https://docs.microsoft.com/en-us/windows/win32/hyperv_v2/virtual-machine-generation-identifier ,
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* https://azure.microsoft.com/en-us/blog/accessing-and-using-azure-vm-unique-id/
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*
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* Microsoft introduced the concept in 2013 or so and seems to have
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* successfully driven it to a consensus standard among hypervisors, not just
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* HyperV/Azure:
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* - QEMU: https://bugzilla.redhat.com/show_bug.cgi?id=1118834
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* - VMware/ESXi: https://kb.vmware.com/s/article/2032586
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* - Xen: https://github.com/xenserver/xen-4.5/blob/master/tools/firmware/hvmloader/acpi/dsdt.asl#L456
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <sys/eventhandler.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/mutex.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <contrib/dev/acpica/include/acpi.h>
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#include <dev/acpica/acpivar.h>
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#include <dev/vmgenc/vmgenc_acpi.h>
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#ifndef ACPI_NOTIFY_STATUS_CHANGED
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#define ACPI_NOTIFY_STATUS_CHANGED 0x80
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#endif
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#define GUID_BYTES 16
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static const char *vmgenc_ids[] = {
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"VM_GEN_COUNTER",
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NULL
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};
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#if 0
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MODULE_PNP_INFO("Z:_CID", acpi, vmgenc, vmgenc_ids, nitems(vmgenc_ids) - 1);
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#endif
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struct vmgenc_softc {
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volatile void *vmg_pguid;
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uint8_t vmg_cache_guid[GUID_BYTES];
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};
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static void
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vmgenc_status_changed(void *context)
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{
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uint8_t guid[GUID_BYTES];
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struct vmgenc_softc *sc;
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device_t dev;
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dev = context;
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sc = device_get_softc(dev);
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/* Check for spurious notify events. */
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memcpy(guid, __DEVOLATILE(void *, sc->vmg_pguid), sizeof(guid));
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if (memcmp(guid, sc->vmg_cache_guid, GUID_BYTES) == 0)
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return; /* No change. */
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/* Update cache. */
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memcpy(sc->vmg_cache_guid, guid, GUID_BYTES);
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EVENTHANDLER_INVOKE(acpi_vmgenc_event);
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acpi_UserNotify("VMGenerationCounter", acpi_get_handle(dev), 0);
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}
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static void
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vmgenc_notify(ACPI_HANDLE h, UINT32 notify, void *context)
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{
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device_t dev;
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dev = context;
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switch (notify) {
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case ACPI_NOTIFY_STATUS_CHANGED:
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/*
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* We're possibly in GPE / interrupt context, kick the event up
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* to a taskqueue.
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*/
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AcpiOsExecute(OSL_NOTIFY_HANDLER, vmgenc_status_changed, dev);
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break;
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default:
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device_printf(dev, "unknown notify %#x\n", notify);
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break;
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}
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}
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static int
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vmgenc_probe(device_t dev)
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{
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int rv;
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if (acpi_disabled("vmgenc"))
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return (ENXIO);
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rv = ACPI_ID_PROBE(device_get_parent(dev), dev,
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__DECONST(char **, vmgenc_ids), NULL);
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if (rv <= 0)
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device_set_desc(dev, "VM Generation Counter");
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return (rv);
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}
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static const char *
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vmgenc_acpi_getname(ACPI_HANDLE handle, char data[static 256])
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{
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ACPI_BUFFER buf;
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buf.Length = 256;
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buf.Pointer = data;
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if (ACPI_SUCCESS(AcpiGetName(handle, ACPI_FULL_PATHNAME, &buf)))
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return (data);
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return ("(unknown)");
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}
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static int
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acpi_GetPackedUINT64(device_t dev, ACPI_HANDLE handle, char *path,
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uint64_t *out)
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{
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char hpath[256];
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ACPI_STATUS status;
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ACPI_BUFFER buf;
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ACPI_OBJECT param[3];
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buf.Pointer = param;
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buf.Length = sizeof(param);
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status = AcpiEvaluateObject(handle, path, NULL, &buf);
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if (!ACPI_SUCCESS(status)) {
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device_printf(dev, "%s(%s::%s()): %s\n", __func__,
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vmgenc_acpi_getname(handle, hpath), path,
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AcpiFormatException(status));
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return (ENXIO);
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}
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if (param[0].Type != ACPI_TYPE_PACKAGE) {
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device_printf(dev, "%s(%s::%s()): Wrong type %#x\n", __func__,
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vmgenc_acpi_getname(handle, hpath), path,
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param[0].Type);
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return (ENXIO);
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}
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if (param[0].Package.Count != 2) {
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device_printf(dev, "%s(%s::%s()): Wrong number of results %u\n",
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__func__, vmgenc_acpi_getname(handle, hpath), path,
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param[0].Package.Count);
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return (ENXIO);
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}
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if (param[0].Package.Elements[0].Type != ACPI_TYPE_INTEGER ||
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param[0].Package.Elements[1].Type != ACPI_TYPE_INTEGER) {
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device_printf(dev, "%s(%s::%s()): Wrong type results %#x, %#x\n",
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__func__, vmgenc_acpi_getname(handle, hpath), path,
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param[0].Package.Elements[0].Type,
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param[0].Package.Elements[1].Type);
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return (ENXIO);
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}
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*out = (param[0].Package.Elements[0].Integer.Value & UINT32_MAX) |
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((uint64_t)param[0].Package.Elements[1].Integer.Value << 32);
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if (*out == 0)
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return (ENXIO);
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return (0);
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}
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static int
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vmgenc_attach(device_t dev)
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{
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struct vmgenc_softc *sc;
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uint64_t guid_physaddr;
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ACPI_HANDLE h;
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int error;
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h = acpi_get_handle(dev);
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sc = device_get_softc(dev);
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error = acpi_GetPackedUINT64(dev, h, "ADDR", &guid_physaddr);
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if (error != 0)
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return (error);
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SYSCTL_ADD_OPAQUE(device_get_sysctl_ctx(dev),
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SYSCTL_CHILDREN(device_get_sysctl_tree(dev)), OID_AUTO, "guid",
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CTLFLAG_RD, sc->vmg_cache_guid, GUID_BYTES, "",
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"latest cached VM generation counter (128-bit UUID)");
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sc->vmg_pguid = AcpiOsMapMemory(guid_physaddr, GUID_BYTES);
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memcpy(sc->vmg_cache_guid, __DEVOLATILE(void *, sc->vmg_pguid),
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sizeof(sc->vmg_cache_guid));
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AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev);
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return (0);
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}
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static device_method_t vmgenc_methods[] = {
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DEVMETHOD(device_probe, vmgenc_probe),
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DEVMETHOD(device_attach, vmgenc_attach),
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DEVMETHOD_END
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};
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static driver_t vmgenc_driver = {
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"vmgenc",
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vmgenc_methods,
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sizeof(struct vmgenc_softc),
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};
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static devclass_t vmgenc_devclass;
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DRIVER_MODULE(vmgenc, acpi, vmgenc_driver, vmgenc_devclass, NULL, NULL);
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MODULE_DEPEND(vmgenc, acpi, 1, 1, 1);
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47
sys/dev/vmgenc/vmgenc_acpi.h
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47
sys/dev/vmgenc/vmgenc_acpi.h
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@ -0,0 +1,47 @@
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/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/_eventhandler.h>
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/*
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* VM Generation Counter driver
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*
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* This driver has two functions: first, it provides a system event (both in
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* the kernel EVENTHANDLER framework as well as a userspace devctl event)
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* whenever a VM has been (HyperV doc, for example):
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* - Snapped and the snapshot is executing
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* - Recovered from backup
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* - Failed over in a HA setup
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* - Imported, copied, or cloned
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* - And unspecified if VM configuration changes might cause a changed
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* generation counter
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*
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* Second, it can read the current VM generation counter, a 128-bit GUID.
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*/
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typedef void (*vmgenc_handler)(void *);
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EVENTHANDLER_DECLARE(acpi_vmgenc_event, vmgenc_handler);
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