[PATCH v14 10/11] arm_ffa: efi: introduce FF-A MM communication

[Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>]

Add MM communication support using FF-A transport

This feature allows accessing MM partitions services through
EFI MM communication protocol. MM partitions such as StandAlonneMM
or smm-gateway secure partitions which reside in secure world.

An MM shared buffer and a door bell event are used to exchange
the data.

The data is used by EFI services such as GetVariable()/SetVariable()
and copied from the communication buffer to the MM shared buffer.

The secure partition is notified about availability of data in the
MM shared buffer by an FF-A message (door bell).

On such event, MM SP can read the data and updates the MM shared
buffer with the response data.

The response data is copied back to the communication buffer and
consumed by the EFI subsystem.

MM communication protocol supports FF-A 64-bit direct messaging.

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Tested-by: Gowtham Suresh Kumar <gowtham.sureshkumar@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jens Wiklander <jens.wiklander@linaro.org>

---

Changelog:
===============

v14:

Ilias:

* drop truncating var_payload->size when using FF-A
* map the MM SP return codes to errnos

v13:

* remove FF-A and Optee ifdefs

v12:

* drop use of calloc when querying SPs
* address nits

v11:

* rename select_ffa_mm_comms() to select_mm_comms()
* improve the logic of MM transport selection in mm_communicate()
* addressing nits

v10:

* use the FF-A driver Uclass operations
* use uclass_first_device()
* addressing nits

v9: align how FF-A is used with FF-A discovery through DM

v8:

* isolate the compilation choices between FF-A and OP-TEE
* update partition_info_get() second argument to be an SP count
* pass NULL device pointer to the FF-A bus discovery and operations

v7:

* set the MM door bell event to use 64-bit direct messaging
* issue a compile time error when one of these macros are not found :
  FFA_SHARED_MM_BUFFER_SIZE, FFA_SHARED_MM_BUFFER_OFFSET, FFA_SHARED_MM_BUFFER_ADDR
* make mm_sp_svc_uuid static
* replace EINVAL with ENOMEM in ffa_discover_mm_sp_id() when calloc() fails
* improve use of unmap_sysmem() in ffa_mm_communicate()

v6:

* add FF-A runtime discovery at MM communication level
* drop EFI runtime support for FF-A MM communication
* revert the changes in include/mm_communication.h for
  efi_mm_communicate_header and smm_variable_access structures

v4:

* use the new FF-A driver interfaces
* discover MM partitions at runtime
* copy FF-A driver private data to EFI runtime section at
  ExitBootServices()
* drop use of FFA_ERR_STAT_SUCCESS error code
* replace EFI_BUFFER_TOO_SMALL with EFI_OUT_OF_RESOURCES
  in ffa_mm_communicate(). No need for efi_memcpy_runtime() anymore
* revert the error log in mm_communicate() in case of failure
* remove packed attribute from efi_mm_communicate_header and
  smm_variable_communicate_header

v2:

* set default values to 0 for FFA_SHARED_MM_BUFFER_SIZE, FFA_SHARED_MM_BUFFER_ADDR and MM_SP_UUID_DATA and add warnings

v1:

* introduce FF-A MM communication

 include/mm_communication.h        |  13 ++
 lib/efi_loader/Kconfig            |  16 +-
 lib/efi_loader/efi_variable_tee.c | 272 +++++++++++++++++++++++++++++-
 3 files changed, 294 insertions(+), 7 deletions(-)

diff --git a/include/mm_communication.h b/include/mm_communication.h
index e65fbde60d..f17847583b 100644
--- a/include/mm_communication.h
+++ b/include/mm_communication.h
@@ -6,6 +6,9 @@
  *  Copyright (c) 2017, Intel Corporation. All rights reserved.
  *  Copyright (C) 2020 Linaro Ltd. <sughosh.ganu@linaro.org>
  *  Copyright (C) 2020 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>
  */
 
 #ifndef _MM_COMMUNICATION_H_
@@ -13,6 +16,9 @@
 
 #include <part_efi.h>
 
+/* MM service UUID string (big-endian format). This UUID is  common across all MM SPs */
+#define MM_SP_UUID	"33d532ed-e699-0942-c09c-a798d9cd722d"
+
 /*
  * Interface to the pseudo Trusted Application (TA), which provides a
  * communication channel with the Standalone MM (Management Mode)
@@ -248,4 +254,11 @@ struct smm_variable_var_check_property {
 	u16                       name[];
 };
 
+/* supported MM transports */
+enum mm_comms_select {
+	MM_COMMS_UNDEFINED,
+	MM_COMMS_FFA,
+	MM_COMMS_OPTEE
+};
+
 #endif /* _MM_COMMUNICATION_H_ */
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index c5835e6ef6..cb26e110fd 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -55,13 +55,25 @@ config EFI_VARIABLE_FILE_STORE
 	  stored as file /ubootefi.var on the EFI system partition.
 
 config EFI_MM_COMM_TEE
-	bool "UEFI variables storage service via OP-TEE"
-	depends on OPTEE
+	bool "UEFI variables storage service via the trusted world"
+	select ARM_FFA_TRANSPORT
+	select TEE
+	select OPTEE
 	help
+	  Allowing access to the MM SP services (SPs such as  StandAlonneMM, smm-gateway).
+	  When using the u-boot OP-TEE driver, StandAlonneMM is supported.
+	  When using the u-boot FF-A  driver any MM SP is supported.
+
 	  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.
 
+	  When ARM_FFA_TRANSPORT is used, dispatch all UEFI variable related
+	  operations to the MM SP running in the secure world.
+	  A door bell mechanism is used to notify the SP when there is data in the shared
+	  MM buffer. The data is copied by u-boot to the shared buffer before issuing
+	  the door bell event.
+
 config EFI_VARIABLE_NO_STORE
 	bool "Don't persist non-volatile UEFI variables"
 	help
diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index dfef18435d..aef75cb42b 100644
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -4,17 +4,49 @@
  *
  *  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>
+#include <arm_ffa.h>
+#include <cpu_func.h>
+#include <dm.h>
 #include <efi.h>
 #include <efi_api.h>
 #include <efi_loader.h>
 #include <efi_variable.h>
-#include <tee.h>
 #include <malloc.h>
+#include <mapmem.h>
 #include <mm_communication.h>
+#include <tee.h>
 
+#ifndef FFA_SHARED_MM_BUFFER_SIZE
+#error "FFA_SHARED_MM_BUFFER_SIZE must be defined in include/configs/<board>.h"
+#define FFA_SHARED_MM_BUFFER_SIZE 0
+#endif
+
+#ifndef FFA_SHARED_MM_BUFFER_OFFSET
+#error "FFA_SHARED_MM_BUFFER_OFFSET must be defined in include/configs/<board>.h"
+#define FFA_SHARED_MM_BUFFER_OFFSET 0
+#endif
+
+#ifndef FFA_SHARED_MM_BUFFER_ADDR
+#error "FFA_SHARED_MM_BUFFER_ADDR must be defined in include/configs/<board>.h"
+#define FFA_SHARED_MM_BUFFER_ADDR 0
+#endif
+
+/* 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;
 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 */
@@ -145,16 +177,241 @@ static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)
 }
 
 /**
- * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
+ * 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 = FFA_SHARED_MM_BUFFER_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 > FFA_SHARED_MM_BUFFER_SIZE)
+		return EFI_INVALID_PARAMETER;
+
+	/* Copy the data to the shared buffer */
+
+	virt_shared_buf = map_sysmem((phys_addr_t)FFA_SHARED_MM_BUFFER_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_err("EFI: Cannot find FF-A bus device, trying Optee comms\n");
+		return MM_COMMS_OPTEE;
+	}
+
+	return MM_COMMS_FFA;
+}
+
+/**
+ * mm_communicate() - Adjust the communication buffer to the MM SP and send
  * it to OP-TEE
  *
- * @comm_buf:		locally allocted communcation buffer
+ * @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;
+	enum mm_comms_select mm_comms;
 	struct efi_mm_communicate_header *mm_hdr;
 	struct smm_variable_communicate_header *var_hdr;
 
@@ -162,7 +419,12 @@ static efi_status_t mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
 	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);
+	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);
+
 	if (ret != EFI_SUCCESS) {
 		log_err("%s failed!\n", __func__);
 		return ret;
@@ -697,7 +959,7 @@ void efi_variables_boot_exit_notify(void)
 		ret = EFI_NOT_FOUND;
 
 	if (ret != EFI_SUCCESS)
-		log_err("Unable to notify StMM for ExitBootServices\n");
+		log_err("Unable to notify the MM partition for ExitBootServices\n");
 	free(comm_buf);
 
 	/*
-- 
2.25.1