[PATCH v5] drivers/misc: vm_gen_counter: initial driver implementation

Or Idgar
2018-03-01T14:22:15Z

From: Or Idgar <oridgar@gmail.com>

This patch is a driver which expose the Virtual Machine Generation ID
via sysfs. The ID is a UUID value used to differentiate between virtual
machines.

The VM-Generation ID is a feature defined by Microsoft (paper:
http://go.microsoft.com/fwlink/?LinkId=260709) and supported by multiple
hypervisor vendors.

Signed-off-by: Or Idgar <oridgar@gmail.com>
---

Changes in v5:
- added to VMGENID module dependency on ACPI module.

Documentation/ABI/testing/sysfs-hypervisor | 13 +++
drivers/misc/Kconfig | 7 ++
drivers/misc/Makefile | 1 +
drivers/misc/vmgenid.c | 142 +++++++++++++++++++++++++++++
4 files changed, 163 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-hypervisor
create mode 100644 drivers/misc/vmgenid.c

diff --git a/Documentation/ABI/testing/sysfs-hypervisor b/Documentation/ABI/testing/sysfs-hypervisor
new file mode 100644
index 000000000000..2f9a7b8eab70
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-hypervisor
@@ -0,0 +1,13 @@
+What: /sys/hypervisor/vm_gen_counter
+Date: February 2018
+Contact: Or Idgar <idgar@virtualoco.com>
+ Gal Hammer <ghammer@redhat.com>
+Description: Expose the virtual machine generation ID. The directory
+ contains two files: "generation_id" and "raw". Both files
+ represent the same information.
+
+ "generation_id" file is a UUID string
+ representation.
+
+ "raw" file is a 128-bit integer
+ representation (binary).
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 03605f8fc0dc..a39feff6a867 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -500,6 +500,13 @@ config MISC_RTSX
tristate
default MISC_RTSX_PCI || MISC_RTSX_USB

+config VMGENID
+ depends on ACPI
+ tristate "Virtual Machine Generation ID driver"
+ help
+ This is a Virtual Machine Generation ID driver which provides
+ a virtual machine unique identifier.
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index c3c8624f4d95..067aa666bb6a 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_ASPEED_LPC_SNOOP) += aspeed-lpc-snoop.o
obj-$(CONFIG_PCI_ENDPOINT_TEST) += pci_endpoint_test.o
obj-$(CONFIG_OCXL) += ocxl/
obj-$(CONFIG_MISC_RTSX) += cardreader/
+obj-$(CONFIG_VMGENID) += vmgenid.o

lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_bugs.o
diff --git a/drivers/misc/vmgenid.c b/drivers/misc/vmgenid.c
new file mode 100644
index 000000000000..6c8d8fe75335
--- /dev/null
+++ b/drivers/misc/vmgenid.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Virtual Machine Generation ID driver
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All rights reserved.
+ * Authors:
+ * Or Idgar <oridgar@gmail.com>
+ * Gal Hammer <ghammer@redhat.com>
+ *
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/acpi.h>
+#include <linux/uuid.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Or Idgar <oridgar@gmail.com>");
+MODULE_AUTHOR("Gal Hammer <ghammer@redhat.com>");
+MODULE_DESCRIPTION("Virtual Machine Generation ID");
+MODULE_VERSION("0.1");
+
+ACPI_MODULE_NAME("vmgenid");
+
+static u64 phys_addr;
+
+static ssize_t generation_id_show(struct device *_d,
+ struct device_attribute *attr, char *buf)
+{
+ void __iomem *uuid_map;
+ uuid_t uuid;
+ ssize_t result;
+
+ uuid_map = acpi_os_map_iomem(phys_addr, sizeof(uuid_t));
+ if (!uuid_map)
+ return -EFAULT;
+
+ memcpy_fromio(&uuid, uuid_map, sizeof(uuid_t));
+ result = sprintf(buf, "%pUl\n", &uuid);
+ acpi_os_unmap_iomem(uuid_map, sizeof(uuid_t));
+ return result;
+}
+static DEVICE_ATTR_RO(generation_id);
+
+static ssize_t raw_show(struct device *_d,
+ struct device_attribute *attr,
+ char *buf)
+{
+ void __iomem *uuid_map;
+
+ uuid_map = acpi_os_map_iomem(phys_addr, sizeof(uuid_t));
+ if (!uuid_map)
+ return -EFAULT;
+ memcpy_fromio(buf, uuid_map, sizeof(uuid_t));
+ acpi_os_unmap_iomem(uuid_map, sizeof(uuid_t));
+ return sizeof(uuid_t);
+}
+static DEVICE_ATTR_RO(raw);
+
+static struct attribute *vmgenid_attrs[] = {
+ &dev_attr_generation_id.attr,
+ &dev_attr_raw.attr,
+ NULL,
+};
+static const struct attribute_group vmgenid_group = {
+ .name = "vm_gen_counter",
+ .attrs = vmgenid_attrs,
+};
+
+static int get_vmgenid(acpi_handle handle)
+{
+ int i;
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ acpi_status status;
+ union acpi_object *pss;
+ union acpi_object *element;
+
+ status = acpi_evaluate_object(handle, "ADDR", NULL, &buffer);
+ if (ACPI_FAILURE(status)) {
+ ACPI_EXCEPTION((AE_INFO, status, "Evaluating _ADDR"));
+ return -ENODEV;
+ }
+ pss = buffer.pointer;
+ if (!pss || pss->type != ACPI_TYPE_PACKAGE || pss->package.count != 2)
+ return -EFAULT;
+
+ phys_addr = 0;
+ for (i = 0; i < pss->package.count; i++) {
+ element = &(pss->package.elements[i]);
+ if (element->type != ACPI_TYPE_INTEGER)
+ return -EFAULT;
+ phys_addr |= element->integer.value << i*32;
+ }
+ return 0;
+}
+
+static int acpi_vmgenid_add(struct acpi_device *device)
+{
+ int retval;
+
+ if (!device)
+ return -EINVAL;
+ retval = get_vmgenid(device->handle);
+ if (retval < 0)
+ return retval;
+ return sysfs_create_group(hypervisor_kobj, &vmgenid_group);
+}
+
+static int acpi_vmgenid_remove(struct acpi_device *device)
+{
+ sysfs_remove_group(hypervisor_kobj, &vmgenid_group);
+ return 0;
+}
+
+static const struct acpi_device_id vmgenid_ids[] = {
+ {"QEMUVGID", 0},
+ {"", 0},
+};
+
+static struct acpi_driver acpi_vmgenid_driver = {
+ .name = "vm_gen_counter",
+ .ids = vmgenid_ids,
+ .owner = THIS_MODULE,
+ .ops = {
+ .add = acpi_vmgenid_add,
+ .remove = acpi_vmgenid_remove,
+ }
+};
+
+static int __init vmgenid_init(void)
+{
+ return acpi_bus_register_driver(&acpi_vmgenid_driver);
+}
+
+static void __exit vmgenid_exit(void)
+{
+ acpi_bus_unregister_driver(&acpi_vmgenid_driver);
+}
+
+module_init(vmgenid_init);
+module_exit(vmgenid_exit);
--
2.14.3