hw/acpi/vmgenid.c - qemu - Git at Google

 /*
  *  Virtual Machine Generation ID Device
  *
  *  Copyright (C) 2017 Skyport Systems.
  *
  *  Author: Ben Warren <ben@skyportsystems.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  *
  */

 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/module.h"
 #include "hw/acpi/acpi.h"
 #include "hw/acpi/aml-build.h"
 #include "hw/acpi/vmgenid.h"
 #include "hw/nvram/fw_cfg.h"
 #include "hw/qdev-properties.h"
 #include "hw/qdev-properties-system.h"
 #include "migration/vmstate.h"
 #include "sysemu/reset.h"

 void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
                         BIOSLinker *linker, const char *oem_id)
 {
     Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
     uint32_t vgia_offset;
     QemuUUID guid_le;
     AcpiTable table = { .sig = "SSDT", .rev = 1,
                         .oem_id = oem_id, .oem_table_id = "VMGENID" };

     /* Fill in the GUID values.  These need to be converted to little-endian
      * first, since that's what the guest expects
      */
     g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data));
     guid_le = qemu_uuid_bswap(vms->guid);
     /* The GUID is written at a fixed offset into the fw_cfg file
      * in order to implement the "OVMF SDT Header probe suppressor"
      * see docs/specs/vmgenid.txt for more details
      */
     g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
                         ARRAY_SIZE(guid_le.data));

     /* Put VMGNEID into a separate SSDT table */
     acpi_table_begin(&table, table_data);
     ssdt = init_aml_allocator();

     /* Storage for the GUID address */
     vgia_offset = table_data->len +
         build_append_named_dword(ssdt->buf, "VGIA");
     scope = aml_scope("\\_SB");
     dev = aml_device("VGEN");
     aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
     aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter")));
     aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter")));

     /* Simple status method to check that address is linked and non-zero */
     method = aml_method("_STA", 0, AML_NOTSERIALIZED);
     addr = aml_local(0);
     aml_append(method, aml_store(aml_int(0xf), addr));
     if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
     aml_append(if_ctx, aml_store(aml_int(0), addr));
     aml_append(method, if_ctx);
     aml_append(method, aml_return(addr));
     aml_append(dev, method);

     /* the ADDR method returns two 32-bit words representing the lower and
      * upper halves * of the physical address of the fw_cfg blob
      * (holding the GUID)
      */
     method = aml_method("ADDR", 0, AML_NOTSERIALIZED);

     addr = aml_local(0);
     aml_append(method, aml_store(aml_package(2), addr));

     aml_append(method, aml_store(aml_add(aml_name("VGIA"),
                                          aml_int(VMGENID_GUID_OFFSET), NULL),
                                  aml_index(addr, aml_int(0))));
     aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
     aml_append(method, aml_return(addr));

     aml_append(dev, method);
     aml_append(scope, dev);
     aml_append(ssdt, scope);

     /* attach an ACPI notify */
     method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED);
     aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
     aml_append(ssdt, method);

     g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);

     /* Allocate guest memory for the Data fw_cfg blob */
     bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096,
                              false /* page boundary, high memory */);

     /* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob
      * so QEMU can write the GUID there.  The address is expected to be
      * < 4GB, but write 64 bits anyway.
      * The address that is patched in is offset in order to implement
      * the "OVMF SDT Header probe suppressor"
      * see docs/specs/vmgenid.txt for more details.
      */
     bios_linker_loader_write_pointer(linker,
         VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
         VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET);

     /* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve
      * and read it.  Note that while we provide storage for 64 bits, only
      * the least-signficant 32 get patched into AML.
      */
     bios_linker_loader_add_pointer(linker,
         ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
         VMGENID_GUID_FW_CFG_FILE, 0);

     /* must be called after above command to ensure correct table checksum */
     acpi_table_end(linker, &table);
     free_aml_allocator();
 }

 void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
 {
     /* Create a read-only fw_cfg file for GUID */
     fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
                     VMGENID_FW_CFG_SIZE);
     /* Create a read-write fw_cfg file for Address */
     fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
                              vms->vmgenid_addr_le,
                              ARRAY_SIZE(vms->vmgenid_addr_le), false);
 }

 static void vmgenid_update_guest(VmGenIdState *vms)
 {
     Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
     uint32_t vmgenid_addr;
     QemuUUID guid_le;

     if (obj) {
         /* Write the GUID to guest memory */
         memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
         vmgenid_addr = le32_to_cpu(vmgenid_addr);
         /* A zero value in vmgenid_addr means that BIOS has not yet written
          * the address
          */
         if (vmgenid_addr) {
             /* QemuUUID has the first three words as big-endian, and expect
              * that any GUIDs passed in will always be BE.  The guest,
              * however, will expect the fields to be little-endian.
              * Perform a byte swap immediately before writing.
              */
             guid_le = qemu_uuid_bswap(vms->guid);
             /* The GUID is written at a fixed offset into the fw_cfg file
              * in order to implement the "OVMF SDT Header probe suppressor"
              * see docs/specs/vmgenid.txt for more details.
              */
             cpu_physical_memory_write(vmgenid_addr, guid_le.data,
                                       sizeof(guid_le.data));
             /* Send _GPE.E05 event */
             acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
         }
     }
 }

 /* After restoring an image, we need to update the guest memory and notify
  * it of a potential change to VM Generation ID
  */
 static int vmgenid_post_load(void *opaque, int version_id)
 {
     VmGenIdState *vms = opaque;
     vmgenid_update_guest(vms);
     return 0;
 }

 static const VMStateDescription vmstate_vmgenid = {
     .name = "vmgenid",
     .version_id = 1,
     .minimum_version_id = 1,
     .post_load = vmgenid_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
         VMSTATE_END_OF_LIST()
     },
 };

 static void vmgenid_handle_reset(void *opaque)
 {
     VmGenIdState *vms = VMGENID(opaque);
     /* Clear the guest-allocated GUID address when the VM resets */
     memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
 }

 static void vmgenid_realize(DeviceState *dev, Error **errp)
 {
     VmGenIdState *vms = VMGENID(dev);

     if (!bios_linker_loader_can_write_pointer()) {
         error_setg(errp, "%s requires DMA write support in fw_cfg, "
                    "which this machine type does not provide", TYPE_VMGENID);
         return;
     }

     /* Given that this function is executing, there is at least one VMGENID
      * device. Check if there are several.
      */
     if (!find_vmgenid_dev()) {
         error_setg(errp, "at most one %s device is permitted", TYPE_VMGENID);
         return;
     }

     qemu_register_reset(vmgenid_handle_reset, vms);

     vmgenid_update_guest(vms);
 }

 static Property vmgenid_device_properties[] = {
     DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid),
     DEFINE_PROP_END_OF_LIST(),
 };

 static void vmgenid_device_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);

     dc->vmsd = &vmstate_vmgenid;
     dc->realize = vmgenid_realize;
     device_class_set_props(dc, vmgenid_device_properties);
     dc->hotpluggable = false;
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 }

 static const TypeInfo vmgenid_device_info = {
     .name          = TYPE_VMGENID,
     .parent        = TYPE_DEVICE,
     .instance_size = sizeof(VmGenIdState),
     .class_init    = vmgenid_device_class_init,
 };

 static void vmgenid_register_types(void)
 {
     type_register_static(&vmgenid_device_info);
 }

 type_init(vmgenid_register_types)
	/*
	* Virtual Machine Generation ID Device
	*
	* Copyright (C) 2017 Skyport Systems.
	*
	* Author: Ben Warren <ben@skyportsystems.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*
	*/

	#include "qemu/osdep.h"
	#include "qapi/error.h"
	#include "qemu/module.h"
	#include "hw/acpi/acpi.h"
	#include "hw/acpi/aml-build.h"
	#include "hw/acpi/vmgenid.h"
	#include "hw/nvram/fw_cfg.h"
	#include "hw/qdev-properties.h"
	#include "hw/qdev-properties-system.h"
	#include "migration/vmstate.h"
	#include "sysemu/reset.h"

	void vmgenid_build_acpi(VmGenIdState vms, GArray table_data, GArray *guid,
	BIOSLinker linker, const char oem_id)
	{
	Aml ssdt, dev, scope, method, addr, if_ctx;
	uint32_t vgia_offset;
	QemuUUID guid_le;
	AcpiTable table = { .sig = "SSDT", .rev = 1,
	.oem_id = oem_id, .oem_table_id = "VMGENID" };

	/* Fill in the GUID values. These need to be converted to little-endian
	* first, since that's what the guest expects
	*/
	g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data));
	guid_le = qemu_uuid_bswap(vms->guid);
	/* The GUID is written at a fixed offset into the fw_cfg file
	* in order to implement the "OVMF SDT Header probe suppressor"
	* see docs/specs/vmgenid.txt for more details
	*/
	g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
	ARRAY_SIZE(guid_le.data));

	/* Put VMGNEID into a separate SSDT table */
	acpi_table_begin(&table, table_data);
	ssdt = init_aml_allocator();

	/* Storage for the GUID address */
	vgia_offset = table_data->len +
	build_append_named_dword(ssdt->buf, "VGIA");
	scope = aml_scope("\\_SB");
	dev = aml_device("VGEN");
	aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
	aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter")));
	aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter")));

	/* Simple status method to check that address is linked and non-zero */
	method = aml_method("_STA", 0, AML_NOTSERIALIZED);
	addr = aml_local(0);
	aml_append(method, aml_store(aml_int(0xf), addr));
	if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
	aml_append(if_ctx, aml_store(aml_int(0), addr));
	aml_append(method, if_ctx);
	aml_append(method, aml_return(addr));
	aml_append(dev, method);

	/* the ADDR method returns two 32-bit words representing the lower and
	* upper halves * of the physical address of the fw_cfg blob
	* (holding the GUID)
	*/
	method = aml_method("ADDR", 0, AML_NOTSERIALIZED);

	addr = aml_local(0);
	aml_append(method, aml_store(aml_package(2), addr));

	aml_append(method, aml_store(aml_add(aml_name("VGIA"),
	aml_int(VMGENID_GUID_OFFSET), NULL),
	aml_index(addr, aml_int(0))));
	aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
	aml_append(method, aml_return(addr));

	aml_append(dev, method);
	aml_append(scope, dev);
	aml_append(ssdt, scope);

	/* attach an ACPI notify */
	method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED);
	aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
	aml_append(ssdt, method);

	g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);

	/* Allocate guest memory for the Data fw_cfg blob */
	bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096,
	false /* page boundary, high memory */);

	/* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob
	* so QEMU can write the GUID there. The address is expected to be
	* < 4GB, but write 64 bits anyway.
	* The address that is patched in is offset in order to implement
	* the "OVMF SDT Header probe suppressor"
	* see docs/specs/vmgenid.txt for more details.
	*/
	bios_linker_loader_write_pointer(linker,
	VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
	VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET);

	/* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve
	* and read it. Note that while we provide storage for 64 bits, only
	* the least-signficant 32 get patched into AML.
	*/
	bios_linker_loader_add_pointer(linker,
	ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
	VMGENID_GUID_FW_CFG_FILE, 0);

	/* must be called after above command to ensure correct table checksum */
	acpi_table_end(linker, &table);
	free_aml_allocator();
	}

	void vmgenid_add_fw_cfg(VmGenIdState vms, FWCfgState s, GArray *guid)
	{
	/* Create a read-only fw_cfg file for GUID */
	fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
	VMGENID_FW_CFG_SIZE);
	/* Create a read-write fw_cfg file for Address */
	fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
	vms->vmgenid_addr_le,
	ARRAY_SIZE(vms->vmgenid_addr_le), false);
	}

	static void vmgenid_update_guest(VmGenIdState *vms)
	{
	Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
	uint32_t vmgenid_addr;
	QemuUUID guid_le;

	if (obj) {
	/* Write the GUID to guest memory */
	memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
	vmgenid_addr = le32_to_cpu(vmgenid_addr);
	/* A zero value in vmgenid_addr means that BIOS has not yet written
	* the address
	*/
	if (vmgenid_addr) {
	/* QemuUUID has the first three words as big-endian, and expect
	* that any GUIDs passed in will always be BE. The guest,
	* however, will expect the fields to be little-endian.
	* Perform a byte swap immediately before writing.
	*/
	guid_le = qemu_uuid_bswap(vms->guid);
	/* The GUID is written at a fixed offset into the fw_cfg file
	* in order to implement the "OVMF SDT Header probe suppressor"
	* see docs/specs/vmgenid.txt for more details.
	*/
	cpu_physical_memory_write(vmgenid_addr, guid_le.data,
	sizeof(guid_le.data));
	/* Send _GPE.E05 event */
	acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
	}
	}
	}

	/* After restoring an image, we need to update the guest memory and notify
	* it of a potential change to VM Generation ID
	*/
	static int vmgenid_post_load(void *opaque, int version_id)
	{
	VmGenIdState *vms = opaque;
	vmgenid_update_guest(vms);
	return 0;
	}

	static const VMStateDescription vmstate_vmgenid = {
	.name = "vmgenid",
	.version_id = 1,
	.minimum_version_id = 1,
	.post_load = vmgenid_post_load,
	.fields = (VMStateField[]) {
	VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
	VMSTATE_END_OF_LIST()
	},
	};

	static void vmgenid_handle_reset(void *opaque)
	{
	VmGenIdState *vms = VMGENID(opaque);
	/* Clear the guest-allocated GUID address when the VM resets */
	memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
	}

	static void vmgenid_realize(DeviceState dev, Error *errp)
	{
	VmGenIdState *vms = VMGENID(dev);

	if (!bios_linker_loader_can_write_pointer()) {
	error_setg(errp, "%s requires DMA write support in fw_cfg, "
	"which this machine type does not provide", TYPE_VMGENID);
	return;
	}

	/* Given that this function is executing, there is at least one VMGENID
	* device. Check if there are several.
	*/
	if (!find_vmgenid_dev()) {
	error_setg(errp, "at most one %s device is permitted", TYPE_VMGENID);
	return;
	}

	qemu_register_reset(vmgenid_handle_reset, vms);

	vmgenid_update_guest(vms);
	}

	static Property vmgenid_device_properties[] = {
	DEFINE_PROP_UUID(VMGENID_GUID, VmGenIdState, guid),
	DEFINE_PROP_END_OF_LIST(),
	};

	static void vmgenid_device_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);

	dc->vmsd = &vmstate_vmgenid;
	dc->realize = vmgenid_realize;
	device_class_set_props(dc, vmgenid_device_properties);
	dc->hotpluggable = false;
	set_bit(DEVICE_CATEGORY_MISC, dc->categories);
	}

	static const TypeInfo vmgenid_device_info = {
	.name = TYPE_VMGENID,
	.parent = TYPE_DEVICE,
	.instance_size = sizeof(VmGenIdState),
	.class_init = vmgenid_device_class_init,
	};

	static void vmgenid_register_types(void)
	{
	type_register_static(&vmgenid_device_info);
	}

	type_init(vmgenid_register_types)