efi_loader: Implement EFI variable handling via OP-TEE
In OP-TEE we can run EDK2's StandAloneMM on a secure partition.
StandAloneMM is responsible for the UEFI variable support. In
combination with OP-TEE and it's U-Boot supplicant, variables are
authenticated/validated in secure world and stored on an RPMB partition.
So let's add a new config option in U-Boot implementing the necessary
calls to OP-TEE for the variable management.
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Pipat Methavanitpong <pipat1010@gmail.com>
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 1cfa24f..aad37b7 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -164,4 +164,13 @@
it is signed with a trusted key. To do that, you need to install,
at least, PK, KEK and db.
+config EFI_MM_COMM_TEE
+ bool "UEFI variables storage service via OP-TEE"
+ depends on OPTEE
+ default n
+ help
+ If OP-TEE is present and running StandAloneMM, dispatch all UEFI variable
+ related operations to that. The application will verify, authenticate and
+ store the variables on an RPMB.
+
endif
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 84d61df..57c7e66 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -35,7 +35,11 @@
obj-y += efi_runtime.o
obj-y += efi_setup.o
obj-$(CONFIG_EFI_UNICODE_COLLATION_PROTOCOL2) += efi_unicode_collation.o
+ifeq ($(CONFIG_EFI_MM_COMM_TEE),y)
+obj-y += efi_variable_tee.o
+else
obj-y += efi_variable.o
+endif
obj-y += efi_watchdog.o
obj-$(CONFIG_LCD) += efi_gop.o
obj-$(CONFIG_DM_VIDEO) += efi_gop.o
diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
new file mode 100644
index 0000000..cacc76e
--- /dev/null
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -0,0 +1,662 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * EFI variable service via OP-TEE
+ *
+ * Copyright (C) 2019 Linaro Ltd. <sughosh.ganu@linaro.org>
+ * Copyright (C) 2019 Linaro Ltd. <ilias.apalodimas@linaro.org>
+ */
+
+#include <common.h>
+#include <efi.h>
+#include <efi_api.h>
+#include <efi_loader.h>
+#include <tee.h>
+#include <malloc.h>
+#include <mm_communication.h>
+
+static efi_uintn_t max_buffer_size; /* comm + var + func + data */
+static efi_uintn_t max_payload_size; /* func + data */
+
+struct mm_connection {
+ struct udevice *tee;
+ u32 session;
+};
+
+/**
+ * get_connection() - Retrieve OP-TEE session for a specific UUID.
+ *
+ * @conn: session buffer to fill
+ * Return: status code
+ */
+static int get_connection(struct mm_connection *conn)
+{
+ static const struct tee_optee_ta_uuid uuid = PTA_STMM_UUID;
+ struct udevice *tee = NULL;
+ struct tee_open_session_arg arg;
+ int rc;
+
+ tee = tee_find_device(tee, NULL, NULL, NULL);
+ if (!tee)
+ return -ENODEV;
+
+ memset(&arg, 0, sizeof(arg));
+ tee_optee_ta_uuid_to_octets(arg.uuid, &uuid);
+ rc = tee_open_session(tee, &arg, 0, NULL);
+ if (!rc) {
+ conn->tee = tee;
+ conn->session = arg.session;
+ }
+
+ return rc;
+}
+
+/**
+ * optee_mm_communicate() - Pass a buffer to StandaloneMM running in OP-TEE
+ *
+ * @comm_buf: locally allocted communcation buffer
+ * @dsize: buffer size
+ * Return: status code
+ */
+static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)
+{
+ ulong buf_size;
+ efi_status_t ret;
+ struct efi_mm_communicate_header *mm_hdr;
+ struct mm_connection conn = { NULL, 0 };
+ struct tee_invoke_arg arg;
+ struct tee_param param[2];
+ struct tee_shm *shm = NULL;
+ int rc;
+
+ if (!comm_buf)
+ return EFI_INVALID_PARAMETER;
+
+ mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+ buf_size = mm_hdr->message_len + sizeof(efi_guid_t) + sizeof(size_t);
+
+ if (dsize != buf_size)
+ return EFI_INVALID_PARAMETER;
+
+ rc = get_connection(&conn);
+ if (rc) {
+ log_err("Unable to open OP-TEE session (err=%d)\n", rc);
+ return EFI_UNSUPPORTED;
+ }
+
+ if (tee_shm_register(conn.tee, comm_buf, buf_size, 0, &shm)) {
+ log_err("Unable to register shared memory\n");
+ return EFI_UNSUPPORTED;
+ }
+
+ memset(&arg, 0, sizeof(arg));
+ arg.func = PTA_STMM_CMDID_COMMUNICATE;
+ arg.session = conn.session;
+
+ memset(param, 0, sizeof(param));
+ param[0].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
+ param[0].u.memref.size = buf_size;
+ param[0].u.memref.shm = shm;
+ param[1].attr = TEE_PARAM_ATTR_TYPE_VALUE_OUTPUT;
+
+ rc = tee_invoke_func(conn.tee, &arg, 2, param);
+ if (rc)
+ return EFI_INVALID_PARAMETER;
+ tee_shm_free(shm);
+ tee_close_session(conn.tee, conn.session);
+
+ switch (param[1].u.value.a) {
+ case ARM_SMC_MM_RET_SUCCESS:
+ ret = EFI_SUCCESS;
+ break;
+
+ case ARM_SMC_MM_RET_INVALID_PARAMS:
+ ret = EFI_INVALID_PARAMETER;
+ break;
+
+ case ARM_SMC_MM_RET_DENIED:
+ ret = EFI_ACCESS_DENIED;
+ break;
+
+ case ARM_SMC_MM_RET_NO_MEMORY:
+ ret = EFI_OUT_OF_RESOURCES;
+ break;
+
+ default:
+ ret = EFI_ACCESS_DENIED;
+ }
+
+ return ret;
+}
+
+/**
+ * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
+ * it to OP-TEE
+ *
+ * @comm_buf: locally allocted communcation buffer
+ * @dsize: buffer size
+ * Return: status code
+ */
+static efi_status_t mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
+{
+ efi_status_t ret;
+ struct efi_mm_communicate_header *mm_hdr;
+ struct smm_variable_communicate_header *var_hdr;
+
+ dsize += MM_COMMUNICATE_HEADER_SIZE + MM_VARIABLE_COMMUNICATE_SIZE;
+ mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+ var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
+
+ ret = optee_mm_communicate(comm_buf, dsize);
+ if (ret != EFI_SUCCESS) {
+ log_err("%s failed!\n", __func__);
+ return ret;
+ }
+
+ return var_hdr->ret_status;
+}
+
+/**
+ * setup_mm_hdr() - Allocate a buffer for StandAloneMM and initialize the
+ * header data.
+ *
+ * @dptr: pointer address of the corresponding StandAloneMM
+ * function
+ * @payload_size: buffer size
+ * @func: standAloneMM function number
+ * @ret: EFI return code
+ * Return: buffer or NULL
+ */
+static u8 *setup_mm_hdr(void **dptr, efi_uintn_t payload_size,
+ efi_uintn_t func, efi_status_t *ret)
+{
+ const efi_guid_t mm_var_guid = EFI_MM_VARIABLE_GUID;
+ struct efi_mm_communicate_header *mm_hdr;
+ struct smm_variable_communicate_header *var_hdr;
+ u8 *comm_buf;
+
+ /* In the init function we initialize max_buffer_size with
+ * get_max_payload(). So skip the test if max_buffer_size is initialized
+ * StandAloneMM will perform similar checks and drop the buffer if it's
+ * too long
+ */
+ if (max_buffer_size && max_buffer_size <
+ (MM_COMMUNICATE_HEADER_SIZE +
+ MM_VARIABLE_COMMUNICATE_SIZE +
+ payload_size)) {
+ *ret = EFI_INVALID_PARAMETER;
+ return NULL;
+ }
+
+ comm_buf = calloc(1, MM_COMMUNICATE_HEADER_SIZE +
+ MM_VARIABLE_COMMUNICATE_SIZE +
+ payload_size);
+ if (!comm_buf) {
+ *ret = EFI_OUT_OF_RESOURCES;
+ return NULL;
+ }
+
+ mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+ guidcpy(&mm_hdr->header_guid, &mm_var_guid);
+ mm_hdr->message_len = MM_VARIABLE_COMMUNICATE_SIZE + payload_size;
+
+ var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
+ var_hdr->function = func;
+ if (dptr)
+ *dptr = var_hdr->data;
+ *ret = EFI_SUCCESS;
+
+ return comm_buf;
+}
+
+/**
+ * get_max_payload() - Get variable payload size from StandAloneMM.
+ *
+ * @size: size of the variable in storage
+ * Return: status code
+ */
+efi_status_t EFIAPI get_max_payload(efi_uintn_t *size)
+{
+ struct smm_variable_payload_size *var_payload = NULL;
+ efi_uintn_t payload_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ if (!size) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ payload_size = sizeof(*var_payload);
+ comm_buf = setup_mm_hdr((void **)&var_payload, payload_size,
+ SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE, &ret);
+ if (!comm_buf)
+ goto out;
+
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret != EFI_SUCCESS)
+ goto out;
+
+ *size = var_payload->size;
+
+out:
+ free(comm_buf);
+ return ret;
+}
+
+/**
+ * efi_get_variable() - retrieve value of a UEFI variable
+ *
+ * This function implements the GetVariable runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @name: name of the variable
+ * @guid: vendor GUID
+ * @attr: attributes of the variable
+ * @data_size: size of the buffer to which the variable value is copied
+ * @data: buffer to which the variable value is copied
+ * Return: status code
+ */
+efi_status_t EFIAPI efi_get_variable(u16 *name, const efi_guid_t *guid,
+ u32 *attr, efi_uintn_t *data_size,
+ void *data)
+{
+ struct smm_variable_access *var_acc;
+ efi_uintn_t payload_size;
+ efi_uintn_t name_size;
+ efi_uintn_t tmp_dsize;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ EFI_ENTRY("\"%ls\" %pUl %p %p %p", name, guid, attr, data_size, data);
+
+ if (!name || !guid || !data_size) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Check payload size */
+ name_size = u16_strsize(name);
+ if (name_size > max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Trim output buffer size */
+ tmp_dsize = *data_size;
+ if (name_size + tmp_dsize >
+ max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
+ tmp_dsize = max_payload_size -
+ MM_VARIABLE_ACCESS_HEADER_SIZE -
+ name_size;
+ }
+
+ /* Get communication buffer and initialize header */
+ payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + tmp_dsize;
+ comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
+ SMM_VARIABLE_FUNCTION_GET_VARIABLE, &ret);
+ if (!comm_buf)
+ goto out;
+
+ /* Fill in contents */
+ guidcpy(&var_acc->guid, guid);
+ var_acc->data_size = tmp_dsize;
+ var_acc->name_size = name_size;
+ var_acc->attr = attr ? *attr : 0;
+ memcpy(var_acc->name, name, name_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
+ /* Update with reported data size for trimmed case */
+ *data_size = var_acc->data_size;
+ }
+ if (ret != EFI_SUCCESS)
+ goto out;
+
+ if (attr)
+ *attr = var_acc->attr;
+ if (data)
+ memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
+ var_acc->data_size);
+ else
+ ret = EFI_INVALID_PARAMETER;
+
+out:
+ free(comm_buf);
+ return EFI_EXIT(ret);
+}
+
+/**
+ * efi_get_next_variable_name() - enumerate the current variable names
+ *
+ * @variable_name_size: size of variable_name buffer in bytes
+ * @variable_name: name of uefi variable's name in u16
+ * @guid: vendor's guid
+ *
+ * This function implements the GetNextVariableName service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * Return: status code
+ */
+efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
+ u16 *variable_name,
+ efi_guid_t *guid)
+{
+ struct smm_variable_getnext *var_getnext;
+ efi_uintn_t payload_size;
+ efi_uintn_t out_name_size;
+ efi_uintn_t in_name_size;
+ efi_uintn_t tmp_dsize;
+ efi_uintn_t name_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, guid);
+
+ if (!variable_name_size || !variable_name || !guid) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ out_name_size = *variable_name_size;
+ in_name_size = u16_strsize(variable_name);
+
+ if (out_name_size < in_name_size) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ name_size = u16_strsize(variable_name);
+ if (name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Trim output buffer size */
+ tmp_dsize = *variable_name_size;
+ if (name_size + tmp_dsize >
+ max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE) {
+ tmp_dsize = max_payload_size -
+ MM_VARIABLE_GET_NEXT_HEADER_SIZE -
+ name_size;
+ }
+
+ payload_size = MM_VARIABLE_GET_NEXT_HEADER_SIZE + out_name_size;
+ comm_buf = setup_mm_hdr((void **)&var_getnext, payload_size,
+ SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME,
+ &ret);
+ if (!comm_buf)
+ goto out;
+
+ /* Fill in contents */
+ guidcpy(&var_getnext->guid, guid);
+ var_getnext->name_size = out_name_size;
+ memcpy(var_getnext->name, variable_name, in_name_size);
+ memset((u8 *)var_getnext->name + in_name_size, 0x0,
+ out_name_size - in_name_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
+ /* Update with reported data size for trimmed case */
+ *variable_name_size = var_getnext->name_size;
+ }
+ if (ret != EFI_SUCCESS)
+ goto out;
+
+ guidcpy(guid, &var_getnext->guid);
+ memcpy(variable_name, (u8 *)var_getnext->name,
+ var_getnext->name_size);
+
+out:
+ free(comm_buf);
+ return EFI_EXIT(ret);
+}
+
+/**
+ * efi_set_variable() - set value of a UEFI variable
+ *
+ * This function implements the SetVariable runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @name: name of the variable
+ * @guid: vendor GUID
+ * @attr: attributes of the variable
+ * @data_size: size of the buffer with the variable value
+ * @data: buffer with the variable value
+ * Return: status code
+ */
+efi_status_t EFIAPI efi_set_variable(u16 *name, const efi_guid_t *guid,
+ u32 attr, efi_uintn_t data_size,
+ const void *data)
+{
+ struct smm_variable_access *var_acc;
+ efi_uintn_t payload_size;
+ efi_uintn_t name_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ EFI_ENTRY("\"%ls\" %pUl %x %zu %p", name, guid, attr, data_size, data);
+
+ if (!name || name[0] == 0 || !guid) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+ if (data_size > 0 && !data) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Check payload size */
+ name_size = u16_strsize(name);
+ payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
+ if (payload_size > max_payload_size) {
+ ret = EFI_INVALID_PARAMETER;
+ goto out;
+ }
+
+ /* Get communication buffer and initialize header */
+ comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
+ SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
+ if (!comm_buf)
+ goto out;
+
+ /* Fill in contents */
+ guidcpy(&var_acc->guid, guid);
+ var_acc->data_size = data_size;
+ var_acc->name_size = name_size;
+ var_acc->attr = attr;
+ memcpy(var_acc->name, name, name_size);
+ memcpy((u8 *)var_acc->name + name_size, data, data_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+
+out:
+ free(comm_buf);
+ return EFI_EXIT(ret);
+}
+
+/**
+ * efi_query_variable_info() - get information about EFI variables
+ *
+ * This function implements the QueryVariableInfo() runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @attributes: bitmask to select variables to be
+ * queried
+ * @maximum_variable_storage_size: maximum size of storage area for the
+ * selected variable types
+ * @remaining_variable_storage_size: remaining size of storage are for the
+ * selected variable types
+ * @maximum_variable_size: maximum size of a variable of the
+ * selected type
+ * Returns: status code
+ */
+efi_status_t EFIAPI __efi_runtime
+efi_query_variable_info(u32 attributes, u64 *max_variable_storage_size,
+ u64 *remain_variable_storage_size,
+ u64 *max_variable_size)
+{
+ struct smm_variable_query_info *mm_query_info;
+ efi_uintn_t payload_size;
+ efi_status_t ret;
+ u8 *comm_buf;
+
+ EFI_ENTRY("%x %p %p %p", attributes, max_variable_storage_size,
+ remain_variable_storage_size, max_variable_size);
+
+ payload_size = sizeof(*mm_query_info);
+ comm_buf = setup_mm_hdr((void **)&mm_query_info, payload_size,
+ SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO,
+ &ret);
+ if (!comm_buf)
+ goto out;
+
+ mm_query_info->attr = attributes;
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret != EFI_SUCCESS)
+ goto out;
+ *max_variable_storage_size = mm_query_info->max_variable_storage;
+ *remain_variable_storage_size =
+ mm_query_info->remaining_variable_storage;
+ *max_variable_size = mm_query_info->max_variable_size;
+
+out:
+ free(comm_buf);
+ return EFI_EXIT(ret);
+}
+
+/**
+ * efi_get_variable_runtime() - runtime implementation of GetVariable()
+ *
+ * @variable_name: name of the variable
+ * @guid: vendor GUID
+ * @attributes: attributes of the variable
+ * @data_size: size of the buffer to which the variable value is copied
+ * @data: buffer to which the variable value is copied
+ * Return: status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
+ u32 *attributes, efi_uintn_t *data_size, void *data)
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_get_next_variable_name_runtime() - runtime implementation of
+ * GetNextVariable()
+ *
+ * @variable_name_size: size of variable_name buffer in byte
+ * @variable_name: name of uefi variable's name in u16
+ * @guid: vendor's guid
+ * Return: status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
+ u16 *variable_name, efi_guid_t *guid)
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_query_variable_info() - get information about EFI variables
+ *
+ * This function implements the QueryVariableInfo() runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @attributes: bitmask to select variables to be
+ * queried
+ * @maximum_variable_storage_size: maximum size of storage area for the
+ * selected variable types
+ * @remaining_variable_storage_size: remaining size of storage are for the
+ * selected variable types
+ * @maximum_variable_size: maximum size of a variable of the
+ * selected type
+ * Return: status code
+ */
+efi_status_t EFIAPI __efi_runtime
+efi_query_variable_info_runtime(u32 attributes, u64 *max_variable_storage_size,
+ u64 *remain_variable_storage_size,
+ u64 *max_variable_size)
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_set_variable_runtime() - runtime implementation of SetVariable()
+ *
+ * @variable_name: name of the variable
+ * @guid: vendor GUID
+ * @attributes: attributes of the variable
+ * @data_size: size of the buffer with the variable value
+ * @data: buffer with the variable value
+ * Return: status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
+ u32 attributes, efi_uintn_t data_size,
+ const void *data)
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
+ */
+void efi_variables_boot_exit_notify(void)
+{
+ u8 *comm_buf;
+ efi_status_t ret;
+
+ comm_buf = setup_mm_hdr(NULL, 0,
+ SMM_VARIABLE_FUNCTION_EXIT_BOOT_SERVICE, &ret);
+ if (comm_buf)
+ ret = mm_communicate(comm_buf, 0);
+ else
+ ret = EFI_NOT_FOUND;
+
+ if (ret != EFI_SUCCESS)
+ log_err("Unable to notify StMM for ExitBootServices\n");
+ free(comm_buf);
+
+ /* Update runtime service table */
+ efi_runtime_services.query_variable_info =
+ efi_query_variable_info_runtime;
+ efi_runtime_services.get_variable = efi_get_variable_runtime;
+ efi_runtime_services.get_next_variable_name =
+ efi_get_next_variable_name_runtime;
+ efi_runtime_services.set_variable = efi_set_variable_runtime;
+ efi_update_table_header_crc32(&efi_runtime_services.hdr);
+}
+
+/**
+ * efi_init_variables() - initialize variable services
+ *
+ * Return: status code
+ */
+efi_status_t efi_init_variables(void)
+{
+ efi_status_t ret;
+
+ ret = get_max_payload(&max_payload_size);
+ if (ret != EFI_SUCCESS)
+ return ret;
+
+ max_buffer_size = MM_COMMUNICATE_HEADER_SIZE +
+ MM_VARIABLE_COMMUNICATE_SIZE +
+ max_payload_size;
+
+ return EFI_SUCCESS;
+}