u-boot/lib/efi_loader/efi_variable_tee.c

// 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>
 *  Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
 *
 *  Authors:
 *    Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
 */

#include <common.h>
#if CONFIG_IS_ENABLED(ARM_FFA_TRANSPORT)
#include <arm_ffa.h>
#endif
#include <cpu_func.h>
#include <dm.h>
#include <efi.h>
#include <efi_api.h>
#include <efi_loader.h>
#include <efi_variable.h>
#include <malloc.h>
#include <mapmem.h>
#include <mm_communication.h>
#include <tee.h>

#if CONFIG_IS_ENABLED(ARM_FFA_TRANSPORT)
/* MM return codes */
#define MM_SUCCESS (0)
#define MM_NOT_SUPPORTED (-1)
#define MM_INVALID_PARAMETER (-2)
#define MM_DENIED (-3)
#define MM_NO_MEMORY (-5)

static const char *mm_sp_svc_uuid = MM_SP_UUID;
static u16 mm_sp_id;
#endif

extern struct efi_var_file __efi_runtime_data *efi_var_buf;
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 = -ENODEV;

	tee = tee_find_device(tee, NULL, NULL, NULL);
	if (!tee)
		goto out;

	memset(&arg, 0, sizeof(arg));
	tee_optee_ta_uuid_to_octets(arg.uuid, &uuid);
	rc = tee_open_session(tee, &arg, 0, NULL);
	if (rc)
		goto out;

	/* Check the internal OP-TEE result */
	if (arg.ret != TEE_SUCCESS) {
		rc = -EIO;
		goto out;
	}

	conn->tee = tee;
	conn->session = arg.session;

	return 0;
out:
	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");
		tee_close_session(conn.tee, conn.session);
		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);
	tee_shm_free(shm);
	tee_close_session(conn.tee, conn.session);
	if (rc)
		return EFI_DEVICE_ERROR;
	if (arg.ret == TEE_ERROR_EXCESS_DATA)
		log_err("Variable payload too large\n");
	if (arg.ret != TEE_SUCCESS)
		return EFI_DEVICE_ERROR;

	switch (param[1].u.value.a) {
	case ARM_SVC_SPM_RET_SUCCESS:
		ret = EFI_SUCCESS;
		break;

	case ARM_SVC_SPM_RET_INVALID_PARAMS:
		ret = EFI_INVALID_PARAMETER;
		break;

	case ARM_SVC_SPM_RET_DENIED:
		ret = EFI_ACCESS_DENIED;
		break;

	case ARM_SVC_SPM_RET_NO_MEMORY:
		ret = EFI_OUT_OF_RESOURCES;
		break;

	default:
		ret = EFI_ACCESS_DENIED;
	}

	return ret;
}

#if CONFIG_IS_ENABLED(ARM_FFA_TRANSPORT)
/**
 * ffa_notify_mm_sp() - Announce there is data in the shared buffer
 *
 * Notify the MM partition in the trusted world that
 * data is available in the shared buffer.
 * This is a blocking call during which trusted world has exclusive access
 * to the MM shared buffer.
 *
 * Return:
 *
 * 0 on success
 */
static int ffa_notify_mm_sp(void)
{
	struct ffa_send_direct_data msg = {0};
	int ret;
	int sp_event_ret;
	struct udevice *dev;

	ret = uclass_first_device_err(UCLASS_FFA, &dev);
	if (ret) {
		log_err("EFI: Cannot find FF-A bus device, notify MM SP failure\n");
		return ret;
	}

	msg.data0 = CONFIG_FFA_SHARED_MM_BUF_OFFSET; /* x3 */

	ret = ffa_sync_send_receive(dev, mm_sp_id, &msg, 1);
	if (ret)
		return ret;

	sp_event_ret = msg.data0; /* x3 */

	switch (sp_event_ret) {
	case MM_SUCCESS:
		ret = 0;
		break;
	case MM_NOT_SUPPORTED:
		ret = -EINVAL;
		break;
	case MM_INVALID_PARAMETER:
		ret = -EPERM;
		break;
	case MM_DENIED:
		ret = -EACCES;
		break;
	case MM_NO_MEMORY:
		ret = -EBUSY;
		break;
	default:
		ret = -EACCES;
	}

	return ret;
}

/**
 * ffa_discover_mm_sp_id() - Query the MM partition ID
 *
 * Use the FF-A driver to get the MM partition ID.
 * If multiple partitions are found, use the first one.
 * This is a boot time function.
 *
 * Return:
 *
 * 0 on success
 */
static int ffa_discover_mm_sp_id(void)
{
	u32 count = 0;
	int ret;
	struct ffa_partition_desc *descs;
	struct udevice *dev;

	ret = uclass_first_device_err(UCLASS_FFA, &dev);
	if (ret) {
		log_err("EFI: Cannot find FF-A bus device, MM SP discovery failure\n");
		return ret;
	}

	/* Ask the driver to fill the buffer with the SPs info */
	ret = ffa_partition_info_get(dev, mm_sp_svc_uuid, &count, &descs);
	if (ret) {
		log_err("EFI: Failure in querying SPs info (%d), MM SP discovery failure\n", ret);
		return ret;
	}

	/* MM SPs found , use the first one */

	mm_sp_id = descs[0].info.id;

	log_info("EFI: MM partition ID 0x%x\n", mm_sp_id);

	return 0;
}

/**
 * ffa_mm_communicate() - Exchange EFI services data with  the MM partition using FF-A
 * @comm_buf:		locally allocated communication buffer used for rx/tx
 * @dsize:				communication buffer size
 *
 * Issue a door bell event to notify the MM partition (SP) running in OP-TEE
 * that there is data to read from the shared buffer.
 * Communication with the MM SP is performed using FF-A transport.
 * On the event, MM SP can read the data from the buffer and
 * update the MM shared buffer with response data.
 * The response data is copied back to the communication buffer.
 *
 * Return:
 *
 * EFI status code
 */
static efi_status_t ffa_mm_communicate(void *comm_buf, ulong comm_buf_size)
{
	ulong tx_data_size;
	int ffa_ret;
	efi_status_t efi_ret;
	struct efi_mm_communicate_header *mm_hdr;
	void *virt_shared_buf;

	if (!comm_buf)
		return EFI_INVALID_PARAMETER;

	/* Discover MM partition ID at boot time */
	if (!mm_sp_id && ffa_discover_mm_sp_id()) {
		log_err("EFI: Failure to discover MM SP ID at boot time, FF-A MM comms failure\n");
		return EFI_UNSUPPORTED;
	}

	mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
	tx_data_size = mm_hdr->message_len + sizeof(efi_guid_t) + sizeof(size_t);

	if (comm_buf_size != tx_data_size || tx_data_size > CONFIG_FFA_SHARED_MM_BUF_SIZE)
		return EFI_INVALID_PARAMETER;

	/* Copy the data to the shared buffer */

	virt_shared_buf = map_sysmem((phys_addr_t)CONFIG_FFA_SHARED_MM_BUF_ADDR, 0);
	memcpy(virt_shared_buf, comm_buf, tx_data_size);

	/*
	 * The secure world might have cache disabled for
	 * the device region used for shared buffer (which is the case for Optee).
	 * In this case, the secure world reads the data from DRAM.
	 * Let's flush the cache so the DRAM is updated with the latest data.
	 */
#ifdef CONFIG_ARM64
	invalidate_dcache_all();
#endif

	/* Announce there is data in the shared buffer */

	ffa_ret = ffa_notify_mm_sp();

	switch (ffa_ret) {
	case 0: {
		ulong rx_data_size;
		/* Copy the MM SP response from the shared buffer to the communication buffer */
		rx_data_size = ((struct efi_mm_communicate_header *)virt_shared_buf)->message_len +
			sizeof(efi_guid_t) +
			sizeof(size_t);

		if (rx_data_size > comm_buf_size) {
			efi_ret = EFI_OUT_OF_RESOURCES;
			break;
		}

		memcpy(comm_buf, virt_shared_buf, rx_data_size);
		efi_ret = EFI_SUCCESS;
		break;
	}
	case -EINVAL:
		efi_ret = EFI_DEVICE_ERROR;
		break;
	case -EPERM:
		efi_ret = EFI_INVALID_PARAMETER;
		break;
	case -EACCES:
		efi_ret = EFI_ACCESS_DENIED;
		break;
	case -EBUSY:
		efi_ret = EFI_OUT_OF_RESOURCES;
		break;
	default:
		efi_ret = EFI_ACCESS_DENIED;
	}

	unmap_sysmem(virt_shared_buf);
	return efi_ret;
}

/**
 * get_mm_comms() - detect the available MM transport
 *
 * Make sure the FF-A bus is probed successfully
 * which means FF-A communication with secure world works and ready
 * for use.
 *
 * If FF-A bus is not ready, use OPTEE comms.
 *
 * Return:
 *
 * MM_COMMS_FFA or MM_COMMS_OPTEE
 */
static enum mm_comms_select get_mm_comms(void)
{
	struct udevice *dev;
	int ret;

	ret = uclass_first_device_err(UCLASS_FFA, &dev);
	if (ret) {
		log_debug("EFI: Cannot find FF-A bus device, trying Optee comms\n");
		return MM_COMMS_OPTEE;
	}

	return MM_COMMS_FFA;
}
#endif

/**
 * mm_communicate() - Adjust the communication buffer to the MM SP and send
 * it to OP-TEE
 *
 * @comm_buf:		locally allocated communication buffer
 * @dsize:		buffer size
 *
 * The SP (also called partition) can be any MM SP such as  StandAlonneMM or smm-gateway.
 * The comm_buf format is the same for both partitions.
 * When using the u-boot OP-TEE driver, StandAlonneMM is supported.
 * When using the u-boot FF-A  driver, any MM SP is supported.
 *
 * 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;
#if CONFIG_IS_ENABLED(ARM_FFA_TRANSPORT)
	enum mm_comms_select mm_comms;
#endif

	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;

#if CONFIG_IS_ENABLED(ARM_FFA_TRANSPORT)
	mm_comms = get_mm_comms();
	if (mm_comms == MM_COMMS_FFA)
		ret = ffa_mm_communicate(comm_buf, dsize);
	else
		ret = optee_mm_communicate(comm_buf, dsize);
#else
		ret = optee_mm_communicate(comm_buf, dsize);
#endif

	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;

	/* Make sure the buffer is big enough for storing variables */
	if (var_payload->size < MM_VARIABLE_ACCESS_HEADER_SIZE + 0x20) {
		ret = EFI_DEVICE_ERROR;
		goto out;
	}
	*size = var_payload->size;
	/*
	 * There seems to be a bug in EDK2 miscalculating the boundaries and
	 * size checks, so deduct 2 more bytes to fulfill this requirement. Fix
	 * it up here to ensure backwards compatibility with older versions
	 * (cf. StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c.
	 * sizeof (EFI_MM_COMMUNICATE_HEADER) instead the size minus the
	 * flexible array member).
	 *
	 * size is guaranteed to be > 2 due to checks on the beginning.
	 */
	*size -= 2;
out:
	free(comm_buf);
	return ret;
}

/*
 * StMM can store internal attributes and properties for variables, i.e enabling
 * R/O variables
 */
static efi_status_t set_property_int(const u16 *variable_name,
				     efi_uintn_t name_size,
				     const efi_guid_t *vendor,
				     struct var_check_property *var_property)
{
	struct smm_variable_var_check_property *smm_property;
	efi_uintn_t payload_size;
	u8 *comm_buf = NULL;
	efi_status_t ret;

	payload_size = sizeof(*smm_property) + name_size;
	if (payload_size > max_payload_size) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}
	comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
				SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET,
				&ret);
	if (!comm_buf)
		goto out;

	guidcpy(&smm_property->guid, vendor);
	smm_property->name_size = name_size;
	memcpy(&smm_property->property, var_property,
	       sizeof(smm_property->property));
	memcpy(smm_property->name, variable_name, name_size);

	ret = mm_communicate(comm_buf, payload_size);

out:
	free(comm_buf);
	return ret;
}

static efi_status_t get_property_int(const u16 *variable_name,
				     efi_uintn_t name_size,
				     const efi_guid_t *vendor,
				     struct var_check_property *var_property)
{
	struct smm_variable_var_check_property *smm_property;
	efi_uintn_t payload_size;
	u8 *comm_buf = NULL;
	efi_status_t ret;

	memset(var_property, 0, sizeof(*var_property));
	payload_size = sizeof(*smm_property) + name_size;
	if (payload_size > max_payload_size) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}
	comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
				SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET,
				&ret);
	if (!comm_buf)
		goto out;

	guidcpy(&smm_property->guid, vendor);
	smm_property->name_size = name_size;
	memcpy(smm_property->name, variable_name, name_size);

	ret = mm_communicate(comm_buf, payload_size);
	/*
	 * Currently only R/O property is supported in StMM.
	 * Variables that are not set to R/O will not set the property in StMM
	 * and the call will return EFI_NOT_FOUND. We are setting the
	 * properties to 0x0 so checking against that is enough for the
	 * EFI_NOT_FOUND case.
	 */
	if (ret == EFI_NOT_FOUND)
		ret = EFI_SUCCESS;
	if (ret != EFI_SUCCESS)
		goto out;
	memcpy(var_property, &smm_property->property, sizeof(*var_property));

out:
	free(comm_buf);
	return ret;
}

efi_status_t efi_get_variable_int(const u16 *variable_name,
				  const efi_guid_t *vendor,
				  u32 *attributes, efi_uintn_t *data_size,
				  void *data, u64 *timep)
{
	struct var_check_property var_property;
	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, tmp;

	if (!variable_name || !vendor || !data_size) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	/* Check payload size */
	name_size = u16_strsize(variable_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, vendor);
	var_acc->data_size = tmp_dsize;
	var_acc->name_size = name_size;
	var_acc->attr = attributes ? *attributes : 0;
	memcpy(var_acc->name, variable_name, name_size);

	/* Communicate */
	ret = mm_communicate(comm_buf, payload_size);
	if (ret != EFI_SUCCESS && ret != EFI_BUFFER_TOO_SMALL)
		goto out;

	/* Update with reported data size for trimmed case */
	*data_size = var_acc->data_size;
	/*
	 * UEFI > 2.7 needs the attributes set even if the buffer is
	 * smaller
	 */
	if (attributes) {
		tmp = get_property_int(variable_name, name_size, vendor,
				       &var_property);
		if (tmp != EFI_SUCCESS) {
			ret = tmp;
			goto out;
		}
		*attributes = var_acc->attr;
		if (var_property.property &
		    VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)
			*attributes |= EFI_VARIABLE_READ_ONLY;
	}

	/* return if ret is EFI_BUFFER_TOO_SMALL */
	if (ret != EFI_SUCCESS)
		goto out;

	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 ret;
}

efi_status_t efi_get_next_variable_name_int(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;
	u8 *comm_buf = NULL;
	efi_status_t ret;

	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;
	}

	if (in_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	/* Trim output buffer size */
	if (out_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
		out_name_size = max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_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, var_getnext->name, var_getnext->name_size);

out:
	free(comm_buf);
	return ret;
}

efi_status_t efi_set_variable_int(const u16 *variable_name,
				  const efi_guid_t *vendor, u32 attributes,
				  efi_uintn_t data_size, const void *data,
				  bool ro_check)
{
	efi_status_t ret, alt_ret = EFI_SUCCESS;
	struct var_check_property var_property;
	struct smm_variable_access *var_acc;
	efi_uintn_t payload_size;
	efi_uintn_t name_size;
	u8 *comm_buf = NULL;
	bool ro;

	if (!variable_name || variable_name[0] == 0 || !vendor) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}
	if (data_size > 0 && !data) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}
	/* Check payload size */
	name_size = u16_strsize(variable_name);
	payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
	if (payload_size > max_payload_size) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	/*
	 * Allocate the buffer early, before switching to RW (if needed)
	 * so we won't need to account for any failures in reading/setting
	 * the properties, if the allocation fails
	 */
	comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
				SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
	if (!comm_buf)
		goto out;

	ro = !!(attributes & EFI_VARIABLE_READ_ONLY);
	attributes &= EFI_VARIABLE_MASK;

	/*
	 * The API has the ability to override RO flags. If no RO check was
	 * requested switch the variable to RW for the duration of this call
	 */
	ret = get_property_int(variable_name, name_size, vendor,
			       &var_property);
	if (ret != EFI_SUCCESS)
		goto out;

	if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY) {
		/* Bypass r/o check */
		if (!ro_check) {
			var_property.property &= ~VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
			ret = set_property_int(variable_name, name_size, vendor, &var_property);
			if (ret != EFI_SUCCESS)
				goto out;
		} else {
			ret = EFI_WRITE_PROTECTED;
			goto out;
		}
	}

	/* Fill in contents */
	guidcpy(&var_acc->guid, vendor);
	var_acc->data_size = data_size;
	var_acc->name_size = name_size;
	var_acc->attr = attributes;
	memcpy(var_acc->name, variable_name, name_size);
	memcpy((u8 *)var_acc->name + name_size, data, data_size);

	/* Communicate */
	ret = mm_communicate(comm_buf, payload_size);
	if (ret != EFI_SUCCESS)
		alt_ret = ret;

	if (ro && !(var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)) {
		var_property.revision = VAR_CHECK_VARIABLE_PROPERTY_REVISION;
		var_property.property |= VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
		var_property.attributes = attributes;
		var_property.minsize = 1;
		var_property.maxsize = var_acc->data_size;
		ret = set_property_int(variable_name, name_size, vendor, &var_property);
	}

	if (alt_ret != EFI_SUCCESS)
		goto out;

	if (!u16_strcmp(variable_name, u"PK"))
		alt_ret = efi_init_secure_state();
out:
	free(comm_buf);
	return alt_ret == EFI_SUCCESS ? ret : alt_ret;
}

efi_status_t efi_query_variable_info_int(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;

	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 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
 * 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)
{
	efi_status_t ret;
	u8 *comm_buf;
	loff_t len;
	struct efi_var_file *var_buf;

	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 the MM partition for ExitBootServices\n");
	free(comm_buf);

	/*
	 * Populate the list for runtime variables.
	 * asking EFI_VARIABLE_RUNTIME_ACCESS is redundant, since
	 * efi_var_mem_notify_exit_boot_services will clean those, but that's fine
	 */
	ret = efi_var_collect(&var_buf, &len, EFI_VARIABLE_RUNTIME_ACCESS);
	if (ret != EFI_SUCCESS)
		log_err("Can't populate EFI variables. No runtime variables will be available\n");
	else
		efi_var_buf_update(var_buf);
	free(var_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;

	/* Create a cached copy of the variables that will be enabled on ExitBootServices() */
	ret = efi_var_mem_init();
	if (ret != EFI_SUCCESS)
		return 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;

	ret = efi_init_secure_state();
	if (ret != EFI_SUCCESS)
		return ret;

	return EFI_SUCCESS;
}